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By C. W. Phillips, D. N. Frey

A commercial Ti-Fe-Cr alloy, Ti-150, exhibits a martensitic transformation on cooling and two nucleation and growth reactions, one above and one below the Mg-Mf region, on isothermal holding below the single-phase ß temperature range. The reactions were followed by metallographic, X-ray diffraction, and microhardness methods. THE rapidly expanding engineering application of titanium and its alloys makes increasingly urgent an adequate knowledge of the effect of heat treatment on this material. The work herein reported is an attempt to determine certain aspects of the behavior of a commercially available alloy, Ti-150, during heat treatment. The alloy, with a nominal composition of 2.7 pct Cr, 1.3 pct Fe, 0.25 pct 0, 0.02 pct N, and 0.02 pct C, was received in the as-rolled condition as a 3/4 in. round. Slugs 0.11 to 0.12 in. thick were cut under a coolant using a silicon carbide wheel. Preliminary work established that the alloy consists of two phases, a (hexagonal close-packed) and /3 (body-centered cubic), at temperatures below 1750" to 1775"F, and of only /3 phase at higher temperatures. The slugs were heated for 1 hr in air at 1800°F to form a single-phase /3 matrix, then transferred to molten tin (1250° to 1650°F) or lead (1150°F and below) for isothermal holding. Holding temperatures ranged from 700° to 1650°F, times from 0.001 to 23 hr. The treated slugs were then sectioned, one part for metallographic examination and diamond pyramid hardness, the other, after deep etching to remove the high oxygen surface,' for comparative lattice parameter determination and X-ray phase identification. Hardness measurements were taken on the lightly etched surfaces of the metallographic specimens; a 1000 g load on a 136° diamond pyramid was used. Five impressions on each sample were made and the average of the hardness calculated. The use of microhardness measurements to follow the course of an isothermal transformation reaction is undesirable because of the possibility of wide differences in microconstituent hardness.' They were used in this case, however, because of the small amount of material available. At the higher transformation temperatures, where the above-mentioned objection was apparent, the readings were proportioned to correspond to the estimated ratio of transformed and untransformed constituents present. At lower temperatures, resulting in much finer microconstituents, the microhardness measurements were more uniform. The standard deviation of the mean of five impressions calculated from these latter values was 4.2 DPH. Employing 2a limits (probability 0.95) the experimental error of the hardness measurements averages was 8.4 DPH. The etchant used was composed of one part glyc-erol and one part 48 pct hydrofluoric acid." Of a number of etches tried, this one appeared most satisfactory. All micrographs were taken at 500X magnification and with oblique lighting to permit easier identification of the acicular structure resulting from rapid cooling. No advantage was gained by using polarized light for metallographic examination. Phase identification and lattice parameter measurements were made with a North American Philips high angle spectrometer in conjunction with a recording potentiometer. Considerable difficulty was encountered with some of the lattice parameter measurements because of the extreme broadness of the few diffraction lines obtained from samples consisting mainly of strained, untempered, quenched structures.

Jan 1, 1953

By J. A. Hren, G. Thomas

A high-temperature stage has been used to study precipitation and dissolution in thin foils of Al-20pct Ag alloy directly in the electron microscope. The results show that the aging characteristics are similar to those observed for bulk materials, and in addition, direct evidence is presented for clustering at the solid solution temperature. The limit of solubility of G. P. zones is-350°C. The heterogeneous precipitation, the growth and dissolution of ?&apos;have been studied in detail. Growth of ?&apos; parallel to the basal planes, occurs by continuous motion of inter -facial partial dislocations. Growth stops at intersecting particles due to formation of sessile a/6 <110> interfacial dislocations. Growth normal to the habit plane occurs by the spontaneous nucleation of partial dislocations on alternate (111) planes and the thickening rate is --10-3= times the lengthening rate. The precipitates dissolve in layers and the final product is a whole a/2 <110> dislocation . The nucleation -growth -dissolution processes are thus completely reversible. Kinetic data obtained from the dissolution rates of ?&apos;particles enable the diffusion coefficient to be determined and the activation energy is found to be 37.5(±4) kcal mol-1, which is that expected for dzffusion of silver in aluminum. The velocity of the interfacial dislocations is thus dependent solely on the rate of diffusion of silver atoms. RECENTLY it was demonstrated that a high-temperature stage could be effectively used in the electron microscope to follow directly the processes of precipitation and dissolution in thin foils of A1-4 pct Cu alloy.&apos; These experiments also provided kinetic data which enabled the diffusion coefficient to be estimated. This new development of electron metallography opens up many fruitful areas of research and it was decided to investigate the aging behavior in thin foils of A1-20 pct Ag alloy, particularly the mechanism of heterogeneous precipitation (i.e., precipitation on lattice defects). This system was chosen because the aging characteristics of bulk specimens are now well known,2"7 and because we wished to obtain more details of the role played by partial dislocations and stacking faults in the nucleation growth and dissolution of the hcp ?&apos; phase. This is of interest for the general case of fcc-- hcp transformations. Part of the A1-Ag phase diagram is shown in Fig. 1. The use of a high-temperature stage also enables a study to be made of the clustering process (formation of G. P. zones) and to determine the structure of the solid solution prior to the usual quenching and aging procedures. It is also possible to obtain kinetic data from measurements of the rates of dissolution of precipitate particles. Unlike the results of previous experiments on A1-4 pct CU 1 where much of the initial precipitation occurred on the foil surfaces, the results on the A1-20 pct A1 alloy were identical to those reported for bulk specimens6,7 and no surface precipitation was ever observed. Thus, it was possible to follow the aging sequence: G.P. zones — ?&apos; — ? directly in the thin foils. This paper is concerned with the formation and dissolution of zones and the ?&apos; phase, and no attempt has been made so far to follow the mode of discontinuous precipitation of ?. I) EXPERIMENTAL DETAILS The high-purity A1-20 pct Ag alloy was prepared by the Aluminum Co. of America in the form of 0.001-in.-thick sheets. These were cold rolled with intermediate anneals to a thickness of 0.0004 in.,

Jan 1, 1963

By James T. Waber, Allen C. Larson, Karl Gschneidner, Margaret Y. Prince

The original graphical method proposed by Darken and Gurry for predicting which elements are soluble in a given element was slightly modified and was used to predict terminal solubilities in 1455 known binary combinations. it was found that the modified Darken and Gurry method had a reliability of 61.7 pct in predicting extensive solid solubility (greater than 5 at. pct) and of 84.8pct in predicting limited solid solubility (less than 5 at. pct), an over-all reliability percentage of 76.6. Using the same experimental data, it was found that using only the simple Hume-Rothery size-effect criterion was 50.1 pct reliable in predicting extensive solid solubility, only slightly better than a purely random choice. and 90.3 pct reliable for predicting limited solid solubility, an over-all reliability percentage of 67.6. THE first rational rules for determining a priori whether two metals are not freely soluble in the solid state were announced by Hume-Rothery and coworkers.1,2 These well-known rules have been accorded a special place in metallurgical literature. Since the "electronegative" and "relative valence effect" rules of Hume-Rothery were only qualitative in nature it was difficult to use them in a quantitative analysis. The next major step was made by Darken and gurry3 and apparently went unexplored for a number of years. They prepared graphs illustrating the influence of both electronegativity and size difference on the solubility of elements in silver, magnesium, and aluminum, and they drew elliptical figures, whose maximum width was ±15 pct of the solvent radius and the maximum height was ±0.4 electronegativity units. The purpose of the present paper is to assess and compare the effectiveness of using the simple size-factor and the Darken-Gurry criteria to predict which elements will be soluble and insoluble in a given solute. In 1957, waber4 prepared Darken-Gurry plots for determining the solutes that were likely to be soluble in 6 and plutonium and introduced an inner ellipse as an aid to determining which elements should be soluble to a considerable extent. As illustrated in Fig. 1, the major axis of the outer ellipse corresponded to ±0.4 electronegativity units (OD) while the minor axis corresponded to ±15 pct of the radius of the solvent phase (OB). This simultaneous "action" of the two Hume-Rothery criteria was used to indicate which elements would have little or no solubility in the host lattice, namely those elements whose points lay outside this ellipse. An inner ellipse, "centered" over the same point of the solvent was drawn with ±0.2 electronegativity units (OC) and ±8 pct (OA) as the major and minor axes. Solutes with points lying within the inner ellipse were expected to be capable of forming extensive solid solutions with the host element. Use of this method of applying the earlier Hume-Rothery criteria was moderately successful for plutonium. For 6-phase plutonium, only one element out of the eight predicted to be extensively soluble was known to be almost insoluble, and of the sixteen elements predicted to have more restricted solubility, five were known to be essentially insoluble. The success of discerning solubility in the E phase by this method was comparable. One prediction made on the basis of this analysis was that the heavier rare earth metals, such as holmium, erbium, and thulium, should be soluble in the 6 phase, whereas the lighter rare earth elements, such as lanthanum or

Jan 1, 1963

By Donald A. Brobst

The minerals barite (BaSO4) and witherite (BaCO3) are the chief sources of the element barium and its compounds needed for many industrial processes and products. Barite, the principal ore mineral, is found the world over and is abundant and widely distributed throughout the United States.3 Witherite is much less common than barite, though more desirable in many ways as a raw material for the production of barium chemicals. England is the chief producer of witherite. Witherite is not mined in the United States at the present time, but it has been mined with barite from a deposit at El Portal, California. Barite is also called barytes, tiff, cawk, or heavy spar. Ordinarily it is a heavy mineral that crystallizes in the orthorhombic system. It is colorless, white, or gray, and transparent to opaque. In some deposits barite is black, yellow, brown, red, green, or blue because of included impurities. The streak is white and the luster vitreous to resinous or pearly. The specific gravity of pure barite (65.7 pct BaO and 34.3 pct SO3) is calculated to be 4.5, but inclusions and impurities in natural barite may reduce this value considerably. Well-formed crystals are generally tabular and have three cleavages. The barite of many deposits, however, has an uneven fracture and an apparent cleavage caused by separation along planes between successively deposited layers. The hardness is 2.5 to 3.5 on Mohs&apos; scale. Commercially the terms "hard" and "soft" are used to refer to ease of grinding. Barite is relatively insoluble in water and acid, and thus can be used as a chemically inert material. Witherite, the natural carbonate of barium (77.7 pct BaO and 22.3 pct CO2), crystallizes in the orthorhombic system. The fracture is uneven and the luster is vitreous to resinous. The hardness is 3 to 3.5. The specific gravity of the pure mineral is calculated to be 4.29. It is transparent to opaque. The color is ordinarily white, gray, yellow, brown, or green. Geology and Distribution of Deposits Workable deposits of barite are widely distributed throughout the world in many geologic environments in sedimentary, igneous, and metamorphic rocks. Most deposits can be classified into three main types: (1) vein and cavityfilling deposits; (2) bedded deposits; and (3) residual deposits. 1. Vein and cavity-filling deposits are those in which barite and associated minerals occur along faults, gashes, joints, and bedding planes, and in breccia zones and solution channels. They also occur in various collapse and sink structures in limestone. Sharp contacts of the veins and cavity fillings with wall rocks are common. Barite cements fault and collapse breccia by replacement of the matrix or by filling voids. Large-scale replacement of the wall rocks beyond ore-controlling structures is rare. Barite in vein and cavity filling deposits is generally dense, "hard," and white to gray. Associated minerals are fluorite, calcite, ankerite, dolomite, quartz, and many sulfide minerals, especially pyrite, chalcopyrite, galena, and sphalerite. Gold, silver, and rare earth minerals occur with barite in some deposits in the western United States. Barite is also a gangue mineral in metallic ore deposits but production as a byproduct from such deposits will be affected by many economic factors. The host rocks are igneous, sedimentary, and metamorphic rocks of pre-Cambrian to

Jan 1, 1960

By C. H. Samans, G. F. Tisinai

HARDENING and embrittlement of the ferritic chromium stainless steels at temperatures near 885 °F have been known for a long time.&apos; However, no satisfactory explanation has been given. Both ordering and precipitation hardening have been suggested. Fisher, Dulis, and Carroll2 discovered a chromium-rich body-centered-cubic precipitate in embrittled alloys. Subsequently, Williams&apos; and Wright4 also have found evidence of this body-centered-cubic constituent. William&apos;s hardness, electrical resistance, and magnetic studies led to his proposal of a new constitutional diagram for the Fe-Cr alloys. The new feature of this diagram is the eutec-toidal decomposition, below about 970°F, of the s phase into two stable body-centered-cubic solid solutions, one rich in iron and the other rich in chromium. An observation of Heger5 that the amount of s phase has increased and the amount of chromium-rich body-centered-cubic phase decreased in the interval 5000 to 32,600 hr at 900°F, even though the alloy increased in hardness, casts some doubt on this diagram. If precipitation hardening causes the embrittlement, the precipitate probably is always coherent with the matrix, since no evidence of overaging has been reported. It cannot be stated positively, however, that Fisher&apos;s body-centered-cubic constituent is the embrittling phase. According to Preston&apos;s data,6 such a chromium-rich phase should have a parameter less than about 0.5 pct larger than that of the iron-rich matrix lattice. Moreover, the constitutional relationships whereby Fisher&apos;s constituent forms, and whether it is stable, metastable, or a transition phase, are not yet completely clear. The recent studies of Wright4 and of Lommel,7 as well as the earlier studies of Becket8 and of Hochmann,9 have shown that 885°F hardening occurs in relatively pure Fe-Cr alloys. No evidence of its occurrence or absence in chromium itself has been reported. The rate of hardening in high purity alloys seems appreciably slower than that in alloys containing larger amounts of impurities (chiefly carbon and nitrogen). This may be due merely to the absence of hardening and straining effects from precipitated carbides and/or nitrides. These observations on high purity alloys make it seem unlikely that 885 °F hardening is caused by a constituent containing other than iron and chromium atoms, e.g., carbides and/or nitrides. Wright,4 Lommel,7 and Lena and Hawkes10 emonstrated the accelerating effects of a finely dispersed precipitate of (probably) chromium nitride on the hardening reaction. This appears to be evidence that lattice straining increases the rate of nucleation of the hardening constituent. Some new observations on 885°F hardening are reported here. They show an effect of preheat treatment that should contribute to a better understanding of the 885°F hardening phenomenon. They also clarify a discrepancy which exists in the literature. Some investigators have reported most rapid hardening at 885", whereas others have reported it at 930°F. The present work also shows that 885°F hardening does not occur in electrolytic chromium, and that any long range ordering type of reaction affecting any sizeable part of the volume is unlikely. Materials Studied Table I shows the currlposition of the alloys used in this investigation. In these alloys carbon and nitrogen are present in roughly similar amounts. Presumably both elements precipitate, as carbides and/or nitrides, during the heat treatments given.

Jan 1, 1958

By H. S. Wang, Y. P. Gupta

Diffusion of zinc and germanium in liquid silver is measured in the temperature range 975" to 1400°C by use of the capillary-reservoir technique. The ex-perinzental results are discussed in terms of the fluctuation and the "hole" theories of liquid diffusion, assunzing the solute as a point charge equal to the difference in the valences of the solute and solvent atoms. The additional coulombic interaction term due to the excess solute charge is evaluated in terms of the Thomas-Fenni approximation. The theoretical and experimental results agree with both the fluctuation and "hole" theories of liquid diffusion. No perceptible effect on solute diffusion in liquid silver of the size difference between the solute and solvent atoms/ions is apparent. DIFFUSION in liquid silver of electropositive solutes indium, tin, antimony, and homovalent gold has been previously reported by Leak and Swalin1 and Gupta,&apos; respectively. These solutes have nearly the same atomic size but differ principally from one another in excess valence (+2, +3, +4, respectively). The observed differences in the temperature dependence and the rate of solute diffusion were explained in terms of an added coulombic interaction between the solute and the solvent atoms. In the case of diffusion of gold in liquid silver, the data were found to be consistent with an effective valence for gold of -0.85, as proposed by Le Claire.3 Recently, Wang and Gupta4 have reported a study of diffusion of ruthenium, iron, and cobalt in liquid silver. The results of diffusion of these solutes and their temperature dependence were found consistent with the hole theories and the fluctuation theories of liquid diffusion, if ruthenium, iron, and cobalt were diffusing in liquid silver with relative valences -2, -1.3, and -0.5, respectively, instead of -3, -3, and -2 as suggested by the relative position of these elements in the Periodic Table of Elements. Furthermore, the predicted valences for these solutes were observed to be consistent with the sparsely available information on the magnetic properties of some of the dilute alloys of copper and silver with these solutes. In theoretical calculations of solute diffusivity, the solute was assumed as a point excess charge equal to the difference in the valences of the solute and solvent atoms. Both the assumption of a point excess solute charge and the use of the Thomas-Fermi approximation to calculate the potential of a solute charge are less precise for the case of electronegative solutes. Therefore, it was not possible to infer from the data on ruthenium, iron, and cobalt an effect, if any, on solute diffusion of the relative differences in either the Period or the size of the solute and solvent atoms or the solute atoms themselves. A study of the diffusion of Period 4 elements, specifically zinc and germanium was, therefore, undertaken since zinc and germanium, respectively, have relative valences of +1 and +3 in liquid silver and the data obtained on diffusion of these solutes could be compared with the available data on diffusion of Period 5 electropositive solutes, indium, tin, and antimony in liquid silver. From such a comparison, it was hoped to learn something about the effect, if any, of the ion size or the structure of the ion core on impurity diffusion in liquid silver. EXPERIMENT The diffusion of tracer zinc and germanium in liquid silver was studied by the capillary reservoir technique, modified adequately for use at high temperatures. In principle, capillaries containing liquid silver

Jan 1, 1970

By Charles C. Templeton

Any explanation of the nature of multiphase fluid flow through porous media must ultimately involve a knowledge of the mechanism of such flow through the individual pores of the medium. To provide quantitative information of the latter type, a study was made of gas-liquid and liquid-liquid displacements in single uniform Pyrex capillaries with diameters as small as 4 microns. Quantitative observation of air-liquid displacements with zero contact. angle indicates the adequacy of a model based on Poiseuille&apos;s Law and the independence of capillary pressure and interfacial velocity. Consequently, this work discounts previous claims that flow is abnormally retarded in very small capillaries. For the displacement of a very viscous oil by water in a capillary initially filled with water, flow is faster than predicted by the above model. This behavior is probably due to the existence of a thin annular film of water between the oil column and the capi1lary wall as postulated by Yuster. INTRODUCTION The need for experimental observation of the microscopic nature of multiphase fluid flow, to further the understanding of the results of macroscopic flow investigations, has been previously recognized. Chatenever and Calhoun1 in connection with the API Project 47B have extensively studied the flow of fluids through layers of glass or lucite spheres between glass or lucite plates. Lowman2 prepared an interesting film concerning flow in a single capillary, using an apparatus which made a moving interface appear stationary in the field of a microscope. The purpose of the present investigation was to deter- mine what contribution might be made to this field by comprehensive quantitative observation of gas-liquid and liquid-liquid displacements in single capillaries of uniform, very small diameter. The techniques used are similar to those of Lowman but incorporate improvements necessary for quantitative work. Quantitative observations must begin with fluids of simple chemical composition to provide a basis for analyzing the more complex behavior that may be expected with natural reservoir fluids. However, some qualitative observations on systems involving crude oils are presented. Experiments of this sort involve the observation of the velocity of the interface separating two fluids, and have been performed in horizontal or vertical capillaries by several investigators.3,4,5,6,7,8 The most general treatment of their mechanics, by Brittin,9 involves forces due to capillarity, viscous resistance, gravity, an "end-drag" effect, and the rate of change of momentum of the capillary contents. Since the range of pore diameters of interest in petroleum reservoirs is about 0.1 to 100 microns, it was desired to perform these experiments in the smallest capillaries possible, to ascertain whether capillary diameter had any effect on the existing theory based on data from larger capillaries.* It was also important to be able more systematically to vary the direction and rate of displacement than was done by previous investigators. Finally, to concentrate attention on viscous and capillary forces by eliminating gravity as a parameter, this study involves only horizontal capillaries. The work of Eley and Pepper&apos; with a "large" (0.766-mm diameter) horizontal capillary is the previous investigation which is most similar to the present method of quantitative observation. Here capillaries with diameters as small as 4 microns will be studied.

Jan 1, 1955

By F. A. Veer, W. G. Burgers, B. H. Kolster

Starting-- from Cu-Si diffusion couples a study of diffusion in the intermetallic compound Cu3Si of the Cu-Si system has been made. Mmker experiments showed copper to be the diffusing element. From the rate of growth of the Cu3Si phase diffusion coefficients were derived. The activation energy for diffusion is 18.6 kcal per mole. The couples show some interesting microscopic features, for which a tentative explanation is given. THE synthesis of dimethyldichlorosilane, (CH3)2SiC12, an important compound in the manufacture of methyl-silicones, takes place at the surface of a thin Cu3Si layer deposited on a mass of silicon particles."&apos; By passing CH3C1 vapor at about 350°C, silicon atoms are consumed from Cu3Si in forming the volatile silane molecules, thus leaving copper atoms at the surface. It is well-known that copper acts as a poison for the above-mentioned reaction by catalyzing the dissociation of methylchloride.&apos; However, no poisonous effect is observed, at least not before most of the silicon from the particles is converted into silane.3 This would be understandable, if either the copper atoms diffuse through the Cu3Si deposit to the underlying silicon or silicon atoms diffuse in the reverse direction to the copper, both processes resulting in the formation of new Cu3Si and so ensuring the proceeding of the reaction. In this paper experiments are described, demonstrating copper to be the diffusing element. Also a very low activation energy for the diffusion is observed. EXPERIMENTAL The silicon used contained 1 ppm Mg and 1 ppm Cu; the copper was spectroscopically pure (Fe: 2 ppm; Ag, Mg, Si: 1 ppm). The copper and silicon samples were prepared in the form of blocks of approximately 10 by 10 by 5 mm with two parallel sides by spark-machining. The blocks were ground on emery paper (grit 600), etched (copper with nitric acid, silicon with a 4:l nitric acid:hydrofluoric acid mixture), and cleaned with alcohol. As the brittleness of the silicon did not allow a welding procedure to prepare the diffusion couples, the copper and silicon blocks were pressed together in a steel clamp. The pressure exerted by the clamp brought about contact between the parts of the couple and so ensured proceeding of the diffusion. The couples were heated in a vacuum furnace (about 10"5 Torr). The temperature was stabilized within 1 pct. After a heat treatment a section parallel to the direction of diffusion was examined in the microscope and in the X-ray scanning microanalyzer. To determine whether copper or silicon is the diffusing element marker experiments were carried out using tungsten wires with a 20-p diam. EXPERIMENTAL RESULTS Figs. 1, 2, 3, and 4 give micrographs of diffusion zones of Cu/Si couples. Analysis by the electron mi-croprobe of the Cu/Si samples after a definite heat treatment revealed the existence of only one intermetallic phase as can be seen from the line scan shown in Fig. 5. From the X-ray diffraction pattern it could be deduced that this phase was CU 3 Si.4 Even when diffusion zones of considerable width (up to 600 p) were obtained, no other phases occurring in the Cu-Si system could be detected, neither by the electron microprobe nor by X-ray diffraction analysis. The optical anisotropy of the Cu3Si phase made it possible to observe the columnar shape of the crystal-

Jan 1, 1969

By J. F. Havard

Gypsum is a useful industrial mineral found abundantly on the earth&apos;s crust. It is inexpensive to mine and process, and its calcined products have a wide range of readily controllable properties such as strength, density and setting time. It has proven to be such a useful material indeed, that ten American companies, operating some 57 calcining plants in 25 states in 1958, produced or imported in that year a total of 13,649,000 tons of the crude mineral valued at $39,361,000, which they then converted into manufactured products with a value of $329,070,000. Gypsum (CaSO4.2H2O) is calcium sulfate with two molecules of combined water, which are responsible for most of its useful properties. It is closely associated in most deposits with anhydrite (CaSO4), which contains no combined water and has limited commercial value in the United States. Man has long recognized the useful qualities of gypsum. It was utilized by the Egyptians in the construction of the pyramids and, later, by the Romans for important structures. Many of the ancient peoples prized gypsum for artistic and ornamental purposes, carving statuary from alabaster and making casts with plaster. The tabular variety, selenite, was used for windows, and the light transmitted through these windows reminded people of light from the moon (selene), hence the name selenite. The use of gypsum continued through the Middle Ages and into modem times. Benjamin Franklin was a famed exponent of gypsum because he applied ground gypsum to clover fields in the form of large letters which later read, in the more luxuriant growth, "land plaster used here." Gypsum is still used as an effective conditioner for some soils, but in recent decades, particularly in North America and Europe, it has become much more important as a major material for the building industry. Description Gypsum and anhydrite are closely associated minerals. Gypsum is found in a number of forms: massive rock gypsum, alabaster, selenite, satin spar, and gypsite. Anhydrite is found as massive rock or as smaller bodies or isolated crystals included in gypsum. Massive Rock Gypsum comprises most of the commercial gypsum and occurs as a sedimentary rock, interbedded in most places with shale, limestone or dolomite. This rock is soft and crystalline. Its color is white or shades of gray, pink, yellow, brown or other colors. Alabaster is a pure, compact and fine-grained variety suitable for use in sculpture or turning into artistic forms; it may be white or selected for attractive coloration. Selenite is gypsum crystallized in flat, transparent, flexible foliated plates, found in clays or in surface vugs in gypsum. Satin Spar is a fine silky fibrous variety with the axes of the crystalline fibers perpendicular to the vein or joint in which it has formed. Gypsite is an earthy mixture of gypsum with clay and sand in secondary formations; it is sometimes useful as a soil conditioner and has been used in making base-coat plasters. Pure gypsum contains 20.9 pct combined water, 46.6 pct sulfur trioxide (SO3) and 32.5 pct lime (CaO). Standard specifications (American Society for Testing Materials Designation C 22-50) read that minimum purity for material to be called gypsum is 70 pct CaSO4.2H20. Most of the commercial gypsum is 85 to 95 pct pure as produced. Impurities in

Jan 1, 1960

By S. F. Frederick, G. F. Pittinato

The deformation mechanisms operating in Ti-5Al-2.5Sn at 20°K under uniaxial and biaxial stress fields were determined by using both optical and electron microscopy. In the uniaxially stressed specimens, de-fu~rnation twins were found only in the immediate vicinity of the fracture. Twinning was, however, established as a deformation mechanism under biaxial stress conditions. The same slip systems were opera-tiz,e under both uniaxial and biaxial stress. Prismatic slip was identified as the major slip syslem; however, basal and first-order pyramidal slip also occurred, but to a lesser degree. The interaction of moving dis-locations on intersecting slip planes resulted in the formation of jogs and dipoles. Hexagonal dislocation networks were formed only under biaxial stress conditions. A discussion is given on the formation of hexagonal dislocation networks. IT has been shown that titanium alloys can exhibit unusually high strengths when tested in a biaxial stress field.&apos;-" The high biaxial strengths are a consequence of a strong basal plane sheet texture which results in distinctly anisotropic flow properties. This texture strengthening appears to decrease with decreasing temperature2 and would seem to indicate a change in deformation modes. For example, in a uniaxial tensile test, Ti-5A1-2.5Sn yields isotropically at 20°K but is strongly anisotropic at room temperature. The increase in biaxial ultimate over uniaxial strength at 20°K is also much less than at room temperature. It is known that titanium car] form deformation twins more readily at cryogenic temperatures than at room temperature.4 Since the formation of deformation twins will reduce the degree of basal texture in sheet material,&apos; an accompanying decrease in texture strengthening would be expected. To investigate more fully the nature of texture strengthening at cryogenic temperatures, the deformation modes of Ti-5A1-2.5Sn tested in uniaxial and 1:1 biaxial tension at 20°K were studied by optical and electron transmission microscopy. EXPERIMENTAL PROCEDURE The uniaxial and biaxial stress test specimens were prepared from 0.020-in. thick sheets of Ti-5A1-2.5Sn ELI having the composition shown in Table I. Uniaxial stress conditions were obtained by using flat tensile specimens machined from the sheet material. The longitudinal axis of the tensile specimens was aligned perpendicular to the rolling direction of the sheet. Tile biaxial test specimens were prepared by rolling precut, 19-in.-lengths of sheet into 4-in.-diam cyl- inders. Following longitudinal butt welding, the cylinders were stress relieved at 1000°F for 4 hr. A 9-in. sq "window" was then chemically milled into each cylinder&apos;s surface reducing the wall thickness in the milled area to approximately 0.006 in. The testing procedure consisted of pressurizing the cylinders while simultaneously applying a tensile load. Using this technique, a 1:l axial to hoop stress was obtained. Complete details of the specimen and testing procedures are given in Refs. 1 and 2. The biaxial and uniaxial stress specimens were all tested in liquid hydrogen. Specimens for electron transmission microscopy were prepared by first chemically milling to a thickness of about 0.001 in. followed by electrolytic polishing to electron transmission thickness. The chemical milling solution, consisting of 800 ml of water,

Jan 1, 1970

By L. A. Roe, John Jan

Iodine is a soft, lustrous, grayish-black nonmetallic element with a density of 4.9. It is the least active of the four members of the halogen family. The other members are, in order of increasing activity, bromine, chlorine, and fluorine. Iodine is a solid at ordinary temperatures, while bromine is a liquid and chlorine and fluorine are gases. Iodine melts at 113°C and volatilizes at 184.4°C to a blue-violet gas with an irritating odor. It occurs in nature only as iodates and iodides or other combined forms. It was discovered by Bernard Courtois in France in 1811, who noticed its presence as an unknown substance in crude soda ash obtained from burning seaweed. Gay-Lussac recognized it as a new element and named it iode, from the Greek word "ioeides or iodes" for violet color (MacMillan, 1970). The world production is not known with any great certainty, but it is probably between 25 and 35 million lb per year, of which about 30% is consumed in the United States. Geology and Mineralogy Iodine compounds occur as a minor constituent as a mineral in the Chilean nitrate deposits and in solution in brines and seawater. According to the US Geological Survey, it is the 47th most abundant element in the earth&apos;s crust. The minerals lautarite, Ca (I03)3 (calcium iodate), and dietzeite, Cat (103)2 (CrO4), (calcium iodate-chromate) are found in Chilean nitrate deposits which are located in Antofagasta and Tarapaca provinces on the eastern slope of the coast range in a desert area. Various brines contain iodine compounds. Seawater contains about 0.05 ppm of iodine and some seaweeds will extract and accumulate it up to 0.45% on a dry basis. Some coals in West Germany also contain iodine compounds. The known and potential sources of iodine reported in 1968 are given in Table 1. Table 2 lists estimated world iodine reserves. Iodine has been recovered from brines in Java, Indonesia, France, England, and the USSR. Iodine has also been recovered from seaweed in Ireland, Scotland, France, Japan, Norway, and the USSR. The indicated reserves and future resources of iodine are large but have never been adequately measured. Analysis Iodine as the free element can be detected by the characteristic blue color it gives to a starch solution. Quantitatively it is determined as the free element by titration with standard thiosulfate solutions using starch as an indicator. Colorimetric methods are also applicable. Markets and Prices Iodine and its compounds are generally marketed in the form of: iodine, crude; iodine, resublimed; calcium iodates; calcium iodide; potassium iodide, sodium iodide, and numerous organic compounds. Product Specifications Crude iodine, World market: 99-99.5% 12. Crude iodine, US produced, average: 99.8% 12. Crude iodine, USP XVII Specs: not less than 99.8% percent I2. Resublimed iodine is usually 99.9% and ACS specifications call for not over 0.005% total bromine and 0.020% nonvolatile materials (Anon., 1971). Prices, c.i.f. United States, for iodine have been steadily increasing from $1.18 per lb of crude in 1967 to $6.37-7.27 in January 1981 (Anon., 1981). In 1980 the price of iodine increased by 50%.

Jan 1, 1983

By R. B. Porter, R. P. Porter, R. A. Lothrop

Changes became necessary in dredging methods employed in Idaho through passage of the Dredge Mining Protective Act (1954). Among other provisions, the law requires dredge operators to construct settling ponds of sufficient capacity and character to reasonably clarify the water used in the mining process before such water is discharged into the stream. Porter Bros. Corp., a placer mining company with many years operating experience in Oregon and Montana, became interested in strategic mineral placers in Idaho in 1950 when it was learned that prospectors had discovered a radioactive mineral deposit in Bear Valley Creek, 95 miles northeast of Boise. The company acquired mining leases and proceeded with exploration and development work on the property. After extensive research had resulted in the determination of successful separation processes, contracts were negotiated with the federal government and deliveries of columbium-tantalum and uranium concentrates commenced in 1956. The mining operations are located in a primitive area of Idaho among salmon spawning grounds and crystal-clear mountain trout streams. To avoid involvement in a very controversial issue, it appeared advisable for the company to develop water treatment procedures exceeding those requirements stated in the Idaho Dredge Mining Protective Act. Operation: The company operates one 6 cu ft continuous bucketline dredge and one 4 1/4 cu ft continuous bucketline dredge on the property. The dredges are jig-equipped, with feed being screened to 3 in. by trommels. The screening and gravity concentration methods satisfactorily separate the heavy minerals from companion clays, sand, and gravel. However, this separation of the heavy minerals requires water from the dredge pond with a minimum content of silt and colloids; therefore, water for dilution is added continuously to the dredge pond to suppress solids buildup. Discharge of this highly turbid water to maintain the proper pond level would ultimately result in an excessive silt load in Bear Valley Creek. To prohibit the turbid pond water from flowing directly into Bear Valley Creek, it was necessary to isolate the dredging area. Main by-pass canals were constructed along each side of the dredge pond and numerous secondary canals were dug for diverting seepage and snow runoff. One by-pass canal, extending more than two miles along the west side of the valley, diverts the main stream as well as tributaries entering from the west; a canal east of the dredge area diverts streams entering from that direction. At the beginning of operations in 1956, the dredge pond effluent was filtered through tailings and settled by use of coagulents in a series of lagoons. The filtrate was then discharged directly into the stream. Although this procedure gave satisfactory results in conformance with the state law, ice buildup and lagoon freezing hindered the efficiency of the process during periods of low temperature. For this reason, testing began in 1956 on a water treatment process that would operate efficiently under the extreme weather conditions encountered in Bear Valley. Development of Water Treatment System: Porter Bros. Corp. established the following requirements for effective continuous treatment of dredge pond effluent to the stream which, at low flow conditions, effluent to the stream which, at low flow conditions, would not result in a turbidity exceeding 25 ppm in the stream, 2) produce a sludge sufficiently dense to minimize disposal area requirements, 3) be semi-portable to follow dredge movements, 4) be capable of operating at low temperatures, and 5) be capable of handling a variety of capacities and turbidities.

Jan 1, 1961

By W. L. Phillips

Nickel alloys containing approximately 0.5, 2.0, and 6.0 at. pct of Os, Pd, Ru, and Rh were Prepared by vacuum melting. Tension tests were carried out at 25°, 500°, 800°, and 1000°C; stress-rupture tests were carried out at 650° and 800°C. The room- and elevated-temperature tensile strength, as well as the stress-rupture life, increased for the same atomic percent in the order palladium, rhodium, ruthenium, osmium. The ductility decreased with increasing concentration or temperature for a given concentration. The results are discussed in terms of solid-solution theory. BOTH solid-solution strengthening and weakening have been observed in alloys. The simple rules which have been suggested to explain alloy strengthening are subject to several exceptions and deviations based on atom size and valency effects. The purpose of the present investigation was to extend the knowledge of the effect of solid-solution alloying on the mechanical properties of several Ni-Pt group metal alloys at room and elevated temperatures. The platinum group metals, osmium, ruthenium, rhodium, and palladium were chosen as the solute elements because of their different valencies and atom sizes. Nickel was chosen as the base material because of the large amount of previous literature available on nickel alloys. EXPERIMENTAL PROCEDURE Grade A Carbonyl nickel powder having the following composition: C, 0.07 pct; Fe, 0.013 pct; Mn, 0.0005 pct; Si, 0.016 pct; Mg, 0.0003 pct; S, 0.003 pct, was purchased from the International Nickel Co. The platinum-group metal powders were purchased from A. D. Mackay Co. The powders were weighed, cone-blended for 4 hr, and vacuum-melted into 1-in.-diam billets, approximately 2 in. long. The ingots were homogenized for 5 hr at 1800°F before being extruded into 1/4-in. rods at 2100°F. The alloy compositions are shown in Table I. Typical impurity values were not significantly different than that of the as-received nickel. All alloys were single phase. The lattice parameter of each alloy after the heat treatment described below is also included in Table I. Each alloy was annealed at 2200°F for 1 hr and air-quenched to comparable grain sizes (ASTM G.S. No. 4-5). The rods were then machined into test samples 0.160-in. diam and 0.750-in. gage length. Tension testing was carried out in an In-stron tension-testing machine at a strain rate of 0.02 in. per in. per min. An extensometer was used to determine the room-temperature yield stress. Stress-rupture testing was carried out in an Arc Weld stress-rupture unit. All testing was performed in air. EXPERIMENTAL RESULTS A) Room-Temperature Mechanical Properties. The 0.2 pct yield stress, ultimate tensile strength, and elongation for all alloys tested at room temperature are plotted as a function of atomic percent solute element in Fig. 1. The ultimate tensile strength for the same atomic percent increases in the order palladium, rhodium, ruthenium, osmium. The yield strength at low concentrations, -0.5 at. pct, increases in the order osmium, palladium, ruthenium, rhodium. At higher concentrations, 3.0 and 10.0 pct, the yield strength increases in the same order as the tensile strength. Both yield strength and tensile strength increase rapidly ini-

Jan 1, 1964

By S. S. Shen, M. J. Pool, P. J. Spencer, J. R. Guadagno

VERY few thermodynamic data are available for rare-earth alloys, partly because of the difficulties of obtaining the metals in sufficiently pure form and also because of their comparative scarcity up to the present time. The rare earths form a very interesting series in the periodic table in view of the progressive filling of their 4f subvalence electron shell and would be expected to provide useful information with regard to alloying characteristics of transition elements. It has been found in recent calorimetric investigations that the heats of solution of a number of the rare-earth metals in liquid tin are highly exothermic.1-4 Exceptionally strong bonding between rare-earth and tin atoms is clearly indicated in the liquid solutions. Continued thermodynamic studies of the behavior of rare earths in solution could thus contribute a great deal to present theoretical knowledge of alloying behavior and would yield an insight into bonding of a strength hitherto unencountered in liquid alloys. The determination of the heats of solution of the pure components in liquid tin is an essential preliminary to calorimetric work of this nature. Heats of solution of praseodymium, neodymium, and samarium in liquid tin at 750" &apos; and the heats of mixing of Pr-Nd solid solutions&apos; have already been determined in this laboratory. The present investigations with lanthanum continue the study of rare-earth elements. Details of the construction and operation of the liquid metal solution calorimeter used in this work have been published previously by Pool and Peluso and no further description will be given here. The lanthanum used in heat of solution determinations was supplied by Lunex who quoted the purity as 99.9 pct. Their detailed analysis of the material is given in Table I. Samples of 0.0003 to 0.0005 g-atom were used for each run and great care was taken to remove all surface oxide prior to weighing. The samples were stored at all other times in a beaker of oil to prevent their otherwise rapid oxidation. The compounds LaSn (Cudu, L1P type structure) and La&, (structure not classified) were prepared from the appropriate quantities of the two pure components by arc melting under a purified argon atmosphere and once again great precautions were taken to avoid any subsequent oxidation of the specimens. Although no structural examination of the compounds was made, the consistency of thermodynarnic measurements carried out on twenty or so individual samples of each indicates that the compounds were in fact homogeneous, single phase alloys. Samples of the compounds consisting of 0.0003 to 0.002 moles were used in the calorimetric measurements. A solvent bath consisting of approximately 80 g of 99.9 pct pure Sn was used for each series of runs and its heat capacity was determined at regular intervals throughout the experiments using pure tin or tungsten calibration samples. Measurements were made of the heat of solution of lanthanum in liquid tin at 725", 750C, and 775°K and at compositions up to 2.21, 4.76, and 5.25 at. pct La at the three temperatures respectively. In every case, the heat of solution of lanthanum remained constant at its limiting value, within experimental limits, up to the highest lanthanum concentration investigated. Since no change in was observed, it was concluded that the liquid/liquid + LaSn, phase boundary had not been

Jan 1, 1969

By O. N. Carlson, D. G. Alexander

THE hardness anisotropy of metals and alloys has been of increasing interest in recent years but silicon ferrite,1 niobium,2 and tungsten3,4 are the only bcc metals about which this type of information has been reported. This investigation was carried out on vanadium and chromium single crystals in an effort to determine to what degree the hardness variations observed in these metals are due to orientation effects and to compare their behavior with other bcc metals. In earlier work the authors had observed a small angular dependence in the Diamond Pyramid Hardness of single crystalline vanadium on the (100) plane but no anisotropic effects were noted on either the (110) or (111) planes. At the suggestion of R. G. wheeler5 it was decided to investigate this effect in greater detail using the more asymmetric Knoop indentor. The vanadium metal used in the study was prepared by the aluminothermic reduction of V2O5 followed by electron beam melting.6 The principal analyzed impurities were 230 ppm C, 230 ppm O, 65 ppm N, 90 pprn Al, Cr not detected, 50 ppm Fe, 60 ppm Ni, and 200 ppm Si. The chromium was an iodide-refined product obtained from the Chromalloy Corporation. Analysis of this material showed the following amounts of impurities present: 10 ppm C, 9 ppm O, 2 ppm N, 0.4 ppm H, 3 ppm Al, 2 ppm Ca, 2 ppm Cu, 20 ppm Fe, 1 ppm Mg, 0.3 ppm Mn, 1 ppm Mo, 3 ppm Ni, 10 ppm Si, and 1 ppm V. Single crystals of both metals about 1 cm in diam and 10 cm in length were grown by an arc-zone melt- ing technique.7 The chromium crystal was annealed at 1600°C for 6 hr in a purified argon atmosphere to remove any strains or inhomogeneities, but the vanadium was tested in the as-grown condition. The crystals were oriented by the Laue back-reflection method and then sectioned with a spark cutter into individual specimens with a (loo), (110), or (111) plane parallel to the crystal surface. They were mounted in Lucite and carefully ground to a flat surface. The vanadium specimens were then electropolished in a 6 pct perchloric acid-methanol mixture while the chromium specimens were mechanically polished on a Syntron vibratory polisher using an alumina abrasive. The orientation of each crystal was then rechecked by the back-reflection X-ray method. All of them were found to lie within 2 deg of the desired orientation with the exception of the (110)-Oriented chromium crystal which was within 4 deg. Microhardness impressions were taken at 10 deg intervals from the common (110) direction by rotating the crystal in the plane of the crystal surface. A Knoop indentor was used with a 400-g load on the vanadium crystals and an 800-g load on the chromium. The hardness values are averages of 6 impressions and standard deviations were calculated for each set of data. The values reported for the (111) plane of vanadium are based on from 10 to 15 measurements for each point. The microhardness results for vanadium and chromium are plotted as a function of the angular rotation of the long axis of a Knoop indentor from the (110)

Jan 1, 1970

By B. C. Craft, Murray F. Hawkins, John R. Rayne

A reservoir mechanism of sulfur recovery by the Frasch process is presented. Improving the economic, of recovery appears to be largely a well, rather than a reservoir problem. A most important factor is the limitation of the lateral extraction of .sulfur about the wells due to the almost vertical .flow of the injected hot water. Model studies are described which confirin the mechanism of sulfur recovery by presently used methods. Studies on a five-spot system indicate improved econo171ics regarding recovery, recovery rate, therinal efficiency, and well spacing. INTRODUCTION Sulfur mining by the Frasch process is one of the most important methods of sulfur production. Developed by Herman Frasch in 1894, it enjoyed a rapid growth and presently supplies 40 per cent of the world&apos;s sulfur and about 80 per cent of the U. S. sulfur." The Frasch process of mining the underground native sulfur deposits involves melting the sulfur in place by introducing super-heated water into the sulfur bearing formations, and producing the sulfur as a liquid. Many problems are encountered in mining these native sulfur deposits, and sulfur production depends chiefly upon the nature of the sulfur deposit and the underground thermal efficiency of the heat transfer system. THE RECOVERY MECHANISM Sulfur is typically found in salt dome cap rock as crystal aggregates occurring within the cavities, seams, and pores of limestone and gypsum formations.&apos; Sulfur-bearing limestone is typically cavernous, vugular, and fractured. Porosity averages about 20 per cent and sulfur saturation averages approximately 25 per cent by weight.1,15 Vhe sulfur bearing formations are very heterogeneous in nature and physical characteristics vary widely within small distances. Total cap rock thickness may vary from 50 to more than 1,000 ft, and net productive thicknesses from a few feet to a few hundred feet. In most cases the upper portion of the limestone formation is barren of sulfur, varying from 5 to 200 ft in thickness.1,15,33 The immediately overlying sediments and the underlying dense anhydrite formation provide permeability barriers to the flow of water from the cap rock section.&apos;" Sulfur wells are drilled with conventional oilfield drilling rigs. Fig. 1 illustrates the casing program of a completed sulfur well. The cap rock sections are drilled with core bits and continuous core logs are recorded. After coring, the cap rock section is underreamed to a diameter of 9 7/8 in. The bottom of the 8-in. casing is welded closed and rests on the bottom of the drill hole, which extends through the cap rock to a few feet above the bottom of the sulfur-bearing formation. The 8-in. pipe contains 5 ft of 3/4-in. perforations on 6-in. centers and 15 ft of 1-in. perforations on 1-ft centers. The 20-ft perforated section is set opposite the lower 20 ft of the sulfur-bearing formation. The 4-in. sulfur pipe is set inside the 8-in. water line on a seat ring at the top of the 5-ft section of 3/4-in. perforations. The mining water, heated to about 330°F under a pressure of 250 psi, is forced down the annulus between the 8-in. and 441-1. pipes and through the 1-in. perforations to the sulfur-bearing formation. Compressed air, at 400 psi pressure, is supplied through a 1-in. air line near the bottom of the well to provide air-lift of the liquid

Jan 1, 1957

By H. R. Ogden, E. S. Bartlett, A. G. Imgram

Notched and unnotched tensile specimens of wrought and recrystallized, oxygmted and hydro-genated tantalum and columbium were tested over a range of temperatures selected to encompass the ductile-to-brittle transition. Increasing the oxygen content of tantalum and columbium increased their strength, and raised their ductility transition temperature, but did not cause a marked deterioration of notch properties below that of commercially pure material. The adverse effects of oxygen were more pronounced for recrystallized structures than for wrought material. The effects of hydrogen are complicated by strain aging or slow strain rate hydrogen embrittlement at -105°F. However, in general, hydrogen had only a minor effect an strength, but markedly increased the effective transition tem-terature and caused a deterioration of notch properties . BCC metals including the refractory metals in Groups Va and VIa (V, Cb, Ta and Cr, Mo, W) can be expected to undergo a ductile-to-brittle transition and exhibit brittle fractures at low temperatures.&apos; Notch embrittlement is associated with this phenomenon, and can be a serious design problem. Table I compares the tensile transition behavior and notch sensitivity of commercially pure Group Va and VIa refractory metals. The Group VIa refractory metals have considerably higher transition temperatures, and become notch sensitive at higher temperatures, than do the Group Va refractory metals. In addition, the Group VIa refractory metals are sensitive to metallurgical structure. Recrystallized structures generally have higher transition temperatures than wrought material of the same composition. The relatively poor transition behavior of the recrystallized structures of these metals is generally attributed to the segregation of interstitial impurity atoms at grain boundaries. Pronounced sensitivity to structure is not evident with commercially pure Group Va refractory metals, however. Since these metals have higher solubilities for interstitial elements than do the Group VIa metals ,4 it can be expected that higher total interstitial concentrations are necessary to develop a comparable degree of grain boundary segregation and to produce a similar sensitivity of transition temperature to structure. Increasing only the concentration of interstitial atoms in solution would tend to increase the flow stress of a metal in relation to its cleavage fracture stress and thereby raise its transition temperature, but would not be expected to cause a marked sensitivity of transition temperature to structure. A research program has been conducted at the Battelle Memorial Institute to evaluate the effects of interstitial oxygen and hydrogen on the transition behavior and notch sensitivity of tantalum and columbium, and to evaluate the effects of structure on "contaminated" material. EXPERIMENTAL PROCEDURES Notched and unnotched tensile specimens of oxygenated and hydrogenated tantalum and columbium with both wrought and recrystallized structures were tested over a range of temperatures selected to encompass the ductile-to-brittle transition Oxygen levels selected for study in both tantalum and columbium were nominally 500 and 1000 ppm, whereas nominal hydrogen contents were 150 and 500 ppm in tantalum and 150 and 300 ppm in columbium. Oxygen and hydrogen additions were made directly to 6-in. lengths of 1/2-in.-diam electron beam melted wrought bar stock, in a Sieverts Apparatus. Subsequent high-temperature annealing was required for homogenization of the oxygenated material, but was not necessary in the case of hydrogenated stock. The oxygenated and hydrogenated bars were then swaged to 1/4-in.-diam rods. Tensile specimen blanks were cut from the 1/4-in.-diam rods and annealed to achieve stress-re-

Jan 1, 1963

By Guy Borden, Michael J. Rzasa

Laboratory data on bubble point pressures and reservoir volume factors have been correlated as functions of solution gas-oil ratio, calculated gas gravity of the pentanes-and-lighter fraction of the entire fluid, differential residual oil gravity, and reservoir temperatures. INTRODUCTION Several correlations of crude oil properties have appeared in the literature. D. L. Katz4 in 1942 presented five methods of predicting oil shrinkage. these being of decreasing accuracy for decreasing amounts of information available. M. B. Standing- in 1947 published three correlations of laboratory flash vaporization data of California crudes. From values of GOR (gas-oil ratio), gas gravity, liquid gravity, and temperature, his correlations will predict bubble point pressure, formation volumes of bubble point liquids, and two-phase formation volumes. Curtis and Brinkley2 in 1949 presented several correlations. From the gas-oil ratio, an approximation of reservoir volume factor and barrels of condensate recoverable per barrel of reservoir space may be obtained; along with liquid gravity and reservoir temperature, the GOR will allow prediction of bubble point pressure. These last cor- relations seem to be more qualitative than quantitative. Generally, laboratory bottom hole sample tests furnish information on solution gas-oil ratios, residual oil gravities. bubble point pressures, viscosities of oils, liquid shrinkages, and occasionally gas gravities. Each of these data has its own applications and use in reservoir engineering calculations. The particular uses of correlated bottom hole sample data are found in (1 Providing a basis for obtaining estimates of formation crude properties in fields where bottom hole sampling is impractical or impossible. (2) Greatly reducing the time in obtaining the desired information. (3) Determining the applicability of the results from various bottom hole samples to particular field problems. (4) Avoiding, in many cases, the uncertainties of sampling by replacing it with an element over which greater control can be exercised. (5) Permitting use of preliminary field data in application of production procedures before a bottom hole sample can be obtained and analyzed in the laboratory. (6) Serving as a check on data which may appear out of line. (7) Estimating for a particular type crude the appropriate equilibrium constants by working backward from the bubble point pressure. (8) Estimating original or other past history properties of reservoirs that were not sampled in the past. PROCEDURE Application of the published correlations4,6 to Stanolind laboratory data indicated that the general scheme presented by Standing" could give dedrable results if changes were made in parameter positions and scales. The correlation curves were drawn with all the variables having consistent gradations except the temperature increments which were drawn in to best fit the data. The variables from available Stanolind laboratory data are defined below: (1) Gas-oil Ratio: Gas is liberated at reservoir temperature by differential vaporization (or rather by a series of flashes, approaching differential vaporization) and measured at atmospheric pressure and temperature, at which the compressibility factor is assumed to be unity. The oil is the residual liquid remaining after the pressure has been reduced to atmospheric. For the gas-oil ratio both volumes are corrected to standard conditions of 14.7 psia and 60°F. (2) Gas Gravity: It was decided to arbitrarily divide the hydrocarbons of the entire bottom hole sample into pentanes-and-lighter and hex-anes-and-heavier, and use a calculated gas gravity of the pentanes-and-lighter for a correlating variable. (Sample calculation is shown in Table 111.) (3) Liquid Gravity: This is the API gravity of the residual liquid from the differential vaporization. The gravity is measured at room temperature and corrected to 60°F.

Jan 1, 1950

By Charles H. Thurman

The data given herein were first included in a paper read before San Francisco Section, A.I.M.E., in October 1940, and are applicable to conditions existing until the gold-dredging industry was temporarily suspended by Order L-208 of the War Production Board in the fall of 1942. There is no doubt that gold dredging will be resumed at some future time, and on a scale equivalent to that of the recent past, but the cost data given herein will be affected to some extent by conditions existing at that time, and by labor rates and prices for materials then prevailing. Dragline vs. Bucket-line Dragline dredges should not be considered for mining large areas of low-grade placer gravel. In such deposits a dragline operator with a 5-cu. yd. dragline would be doing well to maintain an operating cost of 6¢ per cu. yd., while a bucket-line dredge with buckets no smaller than 7 cu. ft. each could be operated for less than 4¢ per cu. yd. By operating costs, I mean only field charges such as direct operating and overhead, which includes pay roll, power or fuel, repairs and maintenance, insurance, land clearing and general expenses, but not including such items as prospecting, depletion, depreciation of equipment, State Franchise Tax, or Federal Income Tax. It is not to be inferred that a dragline dredge cannot make a profit in small low-grade deposits, where the extent of a given property is too small to justify the use of the more costly bucket-line dredge. Consider small deposits of 106 gravel. It is obvious that a deposit of 5,000,000 cu. yd. of such gravel could not be mined profitably with a new 7-cu. ft, bucket-line dredge, costing upward of $250,000, and in operation costs at 4¢ per cu. yd., paying for land or royalties out of earnings; nor could a new combination 5-cu. yd. dragline and washing plant, worth upward of $125,000 and working at 6¢ Per cu. yd., make a profit. These comparisons are made because the hourly capacity of both types of dredges is nearly the same. The bucket-line dredge averages 93 per cent operating time in 24 hr., as against about 80 per cent or less for the dragline dredge. These Percentages of operating time are important factors in making a comparison of this kind- The bucket-line dredge has greater efficiency in cleaning soft bedrock, usually characteristic of dredging deposits, and a 7-cu. ft. bucket-line dredge can be efficient to a total digging depth of 80 ft- (65 ft. below water, 15 ft. above). A 5-cu. Yd. dragline dredge is limited to about 30 ft. of efficient digging depth, 5 ft. of which could be above water. In small areas of gravel not over 30 ft. deep, a 5-cu. yd. dragline dredge could make a profit where a bucket-line dredge could not do so. As an example: compare the dredging of 3,000,000 cu. yd. of 10 gravel 28 ft. deep with bucket line, costin 4¢ Per cu. yd., and with a 5-cu. yd. dragline dredge operating at 6¢ Per cu. yd. Because of small yardage, new equipment is not warranted, therefore we can assume that the dredges of both types are used equip-ment, fully depreciated. Dismantling, mov-

Jan 1, 1946

By R. E. Carter, C. Wagner, F. D. Richardson

By means of inert markers of radio-platinum, it has been shown that cobalt metal oxidizes by out-ward diffusion of cobalt atoms through the oxide. Oxidation rates have been measured at various temperatures and oxygen pressures and have been found to agree with the rates calculated from the Wagner equation and the authors&apos; values for the diffusion coefficient of cobalt in the oxide. The distribution of radio-cobalt in growing oxide loyers has been accurately measured and found to be different from that predicted from the Wagner oxidation theory. Attempts have been made to measure the change of lattice parameter of the oxide with composition. SEVERAL investigators have shown that cobalt metal oxidizes according to the parabolic law,1-3 but no detailed study has been made of the oxidation mechanism. Cobaltous oxide has a metal-deficient lattice, but the defect concentration which is dependent on the oxygen pressure is only approximately known.&apos; From the similarities in the structures of "CoO" and "FeO" and the rate laws governing the oxidation of cobalt and iron, Gulbransen- as suggested that cobalt, like iron," oxidizes by diffusion of cobaltous ions through the oxide layer. To substantiate this hypothesis, he has attempted to measure the oxidation rate of cobalt as a function of the oxygen pressure but has been able to report only that the rate depends on a "small" power of the pressure. On the other hand, Preece," Valensi,&apos; and Arkharov&apos; all have suggested from indirect evidence that oxygen diffuses through the COO to the metal-oxide interface. The present authors, in a previous paper,&apos; have shown that the rate of diffusion of cobalt in cobaltous oxide is dependent on the oxygen pressure. In that investigation, they also found that cobaltous oxide disks made by complete oxidation of cobalt metal were porous at their centers (Fig. 5L, ref. 4). Both these facts strongly suggest that oxidation of the metal proceeds via outward diffusion of cations. In order to establish the mechanism unequivocally, oxidation experiments were made with inert radioactive platinum markers, and the dependence of oxidation rate on oxygen pressure was measured. In addition, an attempt was made to determine the form of the cation vacancy gradient, which the marker experiment showed must exist across a growing oxide layer. This was done by depositing radioactive Co on the surface of a cobalt disk and then measuring the tracer distribution across the oxide layer produced by partial oxidation of the metal. Finally, an X-ray examination was made in an attempt to find the expected change of lattice parameter of COO with oxygen pressure. Experimental The apparatus and materials used were substantially the same as those previously described by the authors.4 Marker Studies: The use of inert markers to follow oxidation reactions was first attempted by Pfeil" in 1929, and radioactive markers have recently been used by Davies et al.&apos; In the investigation reported here, the markers were applied as an (NH4)2PtCI6 slurry in several thin streaks across both faces of four disks of cobalt metal 1 mm thick and 14 mm in diameter. The disks were then oxidized almost to completion at 1200°C in pure oxygen. After oxidation, they were mounted and sectioned and auto-radiographs were taken to locate the markers. Oxidation Rate: The oxidation rate of cobalt was measured at 1148°C at oxygen pressures ranging from 0.0055 to 1.0 atm and at 1000°, 1148", and 1350°C under 1 atm of oxygen. The rate was deter-

Jan 1, 1956