Search Documents

By R. A. Meussner, C. T. Fujii

Chromium solution in wustite depresses the oxygen activity in a nonideal manner and expands the lattice slightly. Gravimetric measurements of the equilibrium compositions of wustite containing 0.00 to 1.38 wt pct Cr define the oxygen potential (CO2-CO atm) and the limits of the phase field at 1000°C. These data extrapolate to a maximum solubility of 2 wt pct Cr. The lattice parameter data, room-temperature measurements of quenched samples, differ significantly from those in the literature. Both pure and chromium wus-tites contract at uniform and equal rates as the oxygen content (metal deficit) increases. The a. US metal deficit relationships are straight lines showing none of the curvature previously reported. At constant metal deficit, the a. expands by 0.002? on alloying with 0.4 to 0.5 wt pct Cr but is insensitive to further chromium additions: a small expansion rather than a marked contraction. These results require a modification of the accepted alloying mechanism. IN the high-temperature oxidation of Fe-Cr alloys in Ha-H,and CO2-CO atmospheres the vapor transfer of oxygen from the continuous wustite outer scale to the porous inner scale/alloy interface sustains the high oxidation rates.1"3 The driving force for this transport is the difference in the oxygen activity of the outer wustite and that at the inner scale/alloy interface. In pure CO2, as well as in CO2-CO atmospheres, carburization of the alloy accompanies this oxidation. Current efforts to evaluate the parameters controlling this carburization have shown that the process is not simple; i.e., the carbon concentration in the alloy initially increases rapidly, reaches a maximum, and then decreases slowly as the oxidation time is extended. This is the same pattern reported by McCoy for the more complex oxidation-carburization of stainless steels and an Fe-Cr alloy in CO2 at lower temperatures.4 These changes in the carburization process occur while the overall oxidation rate and the lattice parameters of the scale layers remain constant. If this invariance of the lattice parameter is assumed to indicate a constant scale composition and thus a constant oxygen potential, the carburization results are not easily explained. Electron microprobe traces across the thickness of these outer scales, however, have revealed distinct chromium gradients penetrating 10 to 50 µ from the inner surface where the chromium concentrations were estimated at a few tenths percent. The variation of the chromium cmcentration on the inner surface of the scale, and the resulting change of the oxygen activity, during the oxidation process is considered to be important in defining the carburization process. Thus, to gain an understanding of the complex oxidation-carburization proc- ess, it was necessary to measure the properties of wustite containing known amounts of chromium (chromium wustite). Although the general features of the Fe-Cr-0 equilibrium diagram between 900° and 1300°C have been fairly well established by Richards and white: Wood-house and White,6 Seybolt,7 and Katsura and Muan,8 there have been no detailed studies of the limits of the chromium wustite phase field or the properties of these alloyed wustites. The recent results of a limited study of chromium wustite by Levin and wagner9 indicate that more than 0.67 wt pct Cr is soluble in wustite above 850°C and that this alloying is accompanied by a substantial lattice contraction. This change in the lattice parameter was not evident in the X-ray diffraction patterns of wustite layers from the oxidation experiments;1,3 the lines were sharp even though a chromium gradient existed in the scale. The present paper describes gravimetric equilibrium experiments which delineate the boundaries of the chromium wustite single-phase field at 1000°C and define the changes in the oxygen activity and the lattice parameter of wustite as functions of chromium and oxygen contents. The lattice parameter data of chromium wustite obtained from these equilibrium and special quenching experiments differ considerably from those reported.9 Those for pure wustite show significant differences from the widely accepted data of Jette and Foote.10 Since the causes of these differences are not easily assignable, and since the literature contains many sets of data on wustite which if not in conflict are at best not in harmony, the experimental procedures are discussed in the present paper. EXPERIMENTAL Oxide Preparation. The specimens used in these studies were porous pellets compacted from high-purity (Fe,Cr)2O3 or Fe2O3 powders. These powders were prepared from electrolytic chromium (99.8 pct purity) and electrolytic iron purified by consumable-electrode, vacuum arc-melting processing (299.9 pct purity).11 The oxides were produced by standard analytical procedures: solution of the metals in acids (HC1, then HNO3 added), coprecipitation of the hydroxides (NHaOH), and filtering and washing these precipitates. Initial dehydration of the coprecipitated hydroxides was done in a porcelain evaporating dish heated by a Meker-type burner, final dehydration by firing in a recrystallized alumina crucible at 1000" to 1050°C for 20 hr in an electrically heated furnace. Spectrographic analysis detected the following impurities: silicon, 0.01 pct or less; aluminum, 0.001 pct to trace; manganese and copper, 0.0001 pct to none. Each of these levels is at least one order of magnitude lower than in commercially available CP grade ferric and chromic oxides. Fluorescence analy-

Jan 1, 1969

By L. S. Castleman, R. K. Hotzler

We are currently studying the effects on recrys-tallization of impurities diffused into dispersion-hardened alloys. Our interest in this phenomenon was originally aroused by the observation that the recrystallization temperature range of tungsten "doped" with alumina and silica, or with thoria, is lowered drastically if nickel is plated onto the tungsten prior to heat treatment.' In this note, we report a similar effect that sulfur has on the recrystallization behavior of thoriated nickel. The experimental procedure for this exploratory phase of the investigation has consisted simply in heating commercially obtained stress-relieved samples of thoriated nickel for varying temperatures and times in sealed capsules containing air and small quantities of sulfur. The samples contain 2.4 vol pct thoria and initially less than 18 ppm S by weight; they are prepared either from 0.5-in.-ciiam rod stock or from 0.092-in. sheet and are in the "as-received" (stress-relieved) condition prior to exposure. In an atmosphere free of sulfur, such samples do not show evidence of recrystallization after being annealed for 1 hr at a temperature of 2500°F (1372C).2 The photomicrograph in Fig. 1 shows the microstructure of one of our samples annealed for 75 hr at 1000° C (1832°F) in a sulfur-free capsule. The grain structure is hardly evident (if at all) at 465 times magnification. In contrast, the photomicrograph of Fig. 2 shows the recrystallization that has taken place in a sample exposed to sulfur for 5 hr at 1000°C (1832°F). A nickel sulfide phase is visible at the grain boundaries of the light-appearing grains. We have also observed recrystallization to occur in a sample annealed at 600°C (1112°F) for 25 hr. This temperature is below the 637°C (1178°F) eutectic in the Ni-S system. In the latter case, no nickel sulfide phase is evident in the microstructure. Moreover, we have noticed the occur-

Jan 1, 1969

By W. J. Carlson, I. Iwasaki

A previous article reported a combination process for recovering both metallic iron and metallic manganese from the manganiferous iron ores of the Cuyuna Range in Minnesota.' In this process, the iron was recovered by direct reduction and magnetic separation and the manganese was recovered from the nonmagnetic tailing by leaching and electrolysis. The current efficiency during the electrolysis of manganese is quite low, in the range of 60 to 70%, due to the simultaneous plating of hydrogen.2,3 The parameters that affect the current efficiency are (1) the concentrations of the manganese ion and the ammonium sulfate buffer, (2) the effect of autoxidant, (3) temperature, (4) pH, and (5) current density. To study the plating characteristics of manganese metal.

Jan 1, 1969

By D. A. Elgillani, M. C. Fuerstenau, M. C. Kuhn

The species responsible for flotation when xanthate is added as collector for pyrite is dixanthogen. Measured oxidation potentials of these systems show that xanthate should be oxidized to dixanthogen, and the presence of dixanthogen on the pyrite surface is confirmed by infrared absorption. Zeta potential measurements are presented and related to collector adsorption. In spite of the normal presence of pyrite in most sulfide ore deposits, only a modest amount of study has been devoted to the xanthate-pyrite flotation system in the absence of activators and depressant~.'-~ As a result, little is known about the mechanism of xanthate adsorption on pyrite. From the few studies that have been made, however, a number of significant observations have been forthcoming. For example, the dependence of flotation response on the state of oxidation of the surface was noted in two studies — one conducted by Plante and Sutherland4 and a later one by plaksin.~ In another study, Gaudin and wilkinson3 found that ferric xanthate was not present on a pyrite surface. In a later investigation, however, Gaudin' and his colleagues did extract a small amount of ferric xanthate into benzene when pyrite was ground in an evacuated mill with water, benzene, and xanthate. This quantity was apparently

Jan 1, 1969

By James A. Robertson

"This paper is the result of a continuing investigation begun in 1953 by government geologists and mining companies. Previous work is reviewed and the development of several stratigraphic nomenclatures and correlation schemes is traced, culminating with the interim report of the Federal-Provincial Committee on Huronian Stratigraphy formed in 1966.The stratigraphy, structure and correlation of the Huronian rocks of the Blind River area and the region between Sault Ste. Marie and Sudbury are reviewed. The area is underlain by three Precambrian units: (1) the Archean greenstones and granites, (2) the Huronian sedimentary and volcanic rocks and (3) the post-Huronian intrusive rocks. The Huronian rocks, largely quartzite and conglomerate with greywackes, argillites and carbonates, were laid down in shallow water transgressing over the eroded Archean basement. Thickness and facies changes indicate a northwesterly source, northerly overlap and deposition controlled by basement topography. Polymictic conglomerates, occurring at least at three horizons, represent tillites and are associated with varvites with dropped clasts. These are best developed in the Gowganda formation, which varies from a continental glacial environment in the north to a marine glacial environment in the southeast.There were at least three phases of post-Huronian igneous activity, probably related to several periods or phases of late Precambrian deformation and metamorphism: (1) sills of Nipissing diabase and rather younger diabase dikes; (2) the Cutler Granite and Croker Island Complex; and (3) dikes of Keweenawan olivine diabase.Copper mineralization is associated with the Nipissing diabase. The uranium ores are found in pyritic quartz-pebble conglomerate near the Huronian Archean unconformity, particularly in ancient valleys; they are considered to be placer deposits modified by later events. Uranium production from the Blind River camp to the end of 1966 was 128,160,096 pounds U308 valued at $1,203,840,848 derived from 56,077,179 tons of ore grading 0.11 per cent U308.Within the Blind River and adjacent areas, future discoveries will probably be the result of costly systematic deep-drilling programs accompanied by detailed geologic studies of the type carried out by oil companies and probably computer-oriented."

Jan 1, 1969

By J. Spreadborough, D. LaW. King, E. Anderson

Tmzsile tests were performed on Armco iron samples, at various ternpe.ralures and strain rates, ocer a wide range of grain sizes. Analysis of the data suggests that the plot of the lower yield stress, against d-1/2,where 2d is the acerage grain diameter, is not linear (as is often assumed) but is concave toward the d. axis over the range of d-from 7 to 53 . The different values of the parameters obtained by other workers can be explained, in part at least, by the observed curvature. This curvalure is shown to be consistent with a model of yielding based on dislocation pile-ups; however, the values of obtained by fitting our data to this model differ appreciably from the values generally reported. The equation proposed by Cottrell, viz.: is a plausible empirical fit to the experimental results. The purpose of this paper is to comment on the validity of the widely used linear relationship first proposed by all' and Petch and coworkers2"4 between ay, the lower yield stress, and 2d, the average grain diameter, for bcc metals, viz.: Many workers, see Refs. 2 to 7 and Table 11, have fitted this equation to their experimental results and have obtained acceptable fits over the relatively narrow range of grain sizes used by most of them. Indeed, in some cases, so few data points were available that any more sophisticated fit would have been irrational. In most of the interpretations,'-' oi is thought to be a measure of the friction stress accompanying dislocation movement, and ky was originally inter- preted as a measure of the dislocation locking but is now believed by Cottrell" to be a function of the dislocation creation rate. In the "unpinning" theories, k, is equated to where od is the unpinning stress and 1 is the average distance from the boundary of the grain where yielding is taking place to the nearest dislocation source in an unyielded grain. Other considerations (see, for example, Refs. 11 and 12) lead to equations with a similar form to [I] where different meanings may be attributed to the parameters. While there are doubts as to the physical significance of the parameters i and k, they continue to be used by many workers; interpretations of the variations in the behavior of ferrite materials following certain treatments, e.g., aging,'3 neutron irradiation,14 have been given frequently in terms of these parameters. Some theories of the mechanical behavior of bcc metals are based on this relationship. We have investigated experimentally the oy - d-'lZ relationship for Armco iron over a wider range of grain sizes and with more data points than those given in published results. The analysis of our data suggests that the oy—d-'" relationship is not linear but is in fact concave towards the d-'I2 axis. RESULTS AND DISCUSSION The experimental work was carried out on 3-mm-diam Armco iron rods which were prepared by wire drawing from 5-mm-diam rods. By annealing in vacuum at temperatures between 7000 and 1200°C for various times, grain sizes from 7 to 20,000 grains per sq mm were obtained, the grains in all cases being regularly shaped. Grain sizes were measured by lineal interceptand by area methods; only specimens with Amax/A values of 3 to 6 were used in the Petch-Hall plots (where A is the average area of a grain and Amax is the area of the largest grain observed). For all the specimens used, the number of grains in a cross section exceeded 50, which should be adequate to avoid grain size effects.'= Tensile tests were performed at 296", 219, and 17l°K, using

Jan 1, 1969

By M. Ahlers, Horace Pops

Slip features and formation of stress-induced mm-tensite have been studied in single crystals of fl phase Cu-Zn alloys in the composition range between 43 and 48 at. pct Zn. A phenomenological analysis is presented in which the glide planes and directions that me associated with the inhomogeneous shear in the martensite phase are predicted from the experimentally determined habit planes and macroscopic shear directions. It is shozun that the resolved shew component of the applied stress on the secondary shew system is a very important factor governing the formation of stress-induced martensite. A comparison is made between martensitic phases that form spontaneously upon cooling and those phases that arise from deformation. THE ß phase in Cu-Zn alloys is unstable and may transform spontaneously by a martensitic transformation1-3 during cooling. Thermoelastic and burst-type spontaneous martensitic phases have been observed3 in the composition range between 38 and 42 at. pct Zn. Martensite forms in alloys containing more than 42 at. pct Zn only by cold work below a temperature denoted as Md.4 Thus, alloys near the equiatomic composition can undergo a stress-induced transformation upon cold work at room temperature. Although data have been obtained concerning the effect of temperature5 and composition4 on the deformation of polycrystalline Cu-Zn alloys, it is rather surprising that few detailed studies6-8 on 6 brass have been conducted for single crystals where the stresses acting on crystallographic planes can be determined. A thorough understanding of transformation mechanisms requires knowledge of the role of stress and plastic strain. With this objective in mind we have made an investigation of the stress-induced rnartensite transformation in single crystals of 0 brass in the composition range between 43 and 48 at. pct Zn. Particular emphasis is given to the morphology and crystallographic features and a comparison is made between stress-induced and spontaneous martensite. I) EXPERIMENTAL PROCEDURE Master alloys having nominal zinc contents of 43, 45, and 48 at. pct were prepared from spectroscop-ically pure metals (>99.999 pct) in sealed quartz tubes under a partial pressure of helium. These alloys were cut into several pieces and converted into small rods by melting in quartz tubes. Subsequently, single crystals were grown from the rods by the Bridgman technique and homogenized for 3 hr at 820°C. Lattice parameter measurements were made from stress- relieved filings. Compositions, as determined from the reported variation of lattice parameter with atomic percent zinc,' indicated a zinc loss of less than approximately 0.25 at. pct. The single crystals were electroturned using a phosphoric acid electrolyte into tensile specimens each with a center section of 1 mm diam and 1 cm gage length. Cylindrical specimens approximately 3 mm in diam and 10 mm long and spark-machined rectangular blocks approximately 3 by 3 by 10 mm were prepared for compression studies. These blocks were stress-relieved and electropolished to eliminate any stresses introduced by spark machining. Crystal orientations were determined to an accuracy of ±2 deg primarily from back-reflection Laue photographs, and sometimes by the rotating single-crystal method. Figs. 1 to 3 show the location of the tension and compression axes within unit stereographic triangles. All specimens were deformed plastically at room temperature using an Instron machine, the crosshead speed being 0.02 or 0.05 cm per min. A hard steel hemisphere was placed at the upper end of the compression samples to achieve uniaxial loading. Trace normals of slip markings and habit planes of strain-induced martensite were determined to an accuracy of ±4 deg from the rectangular blocks by a two-surface analysis and from cylindrical specimens by measuring the angle between the tensile (or compression) axis and the tangent to the surface trace for different rotations about the deformation axis. Slip

Jan 1, 1969

By G. H. Bishop

The kinetics of the inter granular penetration and embrittlement of [100] tilt boundaries in 99.998 pct pure nickel upon exposure to bismuth-rich Ni-Bi liquids have been determined in the temperature range from 700° to 900°C. The kinetics of penetration are parabolic in time at constant temperature over most of the temperature range. In a series of 43-deg bicrystals the rate of penetration is anisotropic with respect to the direction of penetration into the grain boundaries. In lower-angle bicrystals the penetration rate is isotropic. The rate of penetration decreases with tilt angle at 700°C. The activation energy for penetration in the 43-deg bicrystals is 42 kcal per g-atom independent of direction. It is concluded that the intergranular penetration and embrittlement in the presence of the liquid proceeds by a grain boundary diffusion process and not by the intrusion of a liquid film. This was confirmed by a determination that the kinetics of penetration and embrittlement were the same in the 43-deg bicrystals upon exposure to bismuth vapor under conditions such that no bulk liquid phase would be thermodynamically stable. WhEN solid metals are exposed to a corrosive liquid-metal environment, the grain boundaries are sites of preferential attack. Depending on the temperature, the composition of the liquid, and the composition, structure, and state of stress of the solid, a number of modes of attack are possible. This paper reports a study of the kinetics of intergranular penetration and embrittlement of high-purity nickel bicrystals upon exposure to bismuth which, together with an earlier study by Cheney, Hochgraf, and Spencer,&apos; demonstrates that there are at least two modes of intergranular attack possible in the Ni-Bi system. In the study by Cheney et al., columnar-grain specimens of 99.5 pct pure nickel were exposed to liquid bismuth presaturated with nickel in the temperature range 670" to 1050°C. They found that the majority of the boundaries, which were predominantely high-angle boundaries, were penetrated by capillary liquid films, the attack proceeding by a process which will be termed grain boundary wetting. This process occurs in a stress-free solid when twice the liquid-solid surface tension is less than the surface tension of the grain boundary,* i.e., when 2yLs < YGB In this case the penetration of the grain boundary by the liquid occurs at a relatively rapid rate, resulting in the severe embrittlement of a polycrystalline solid. Grain boundary wetting is a common mode of intergranular attack in systems in which the lower melting component is relatively insoluble in the solid, but the solid has an appreciable solubility in the liquid, for example, the Ni-Bi system, Fig. 1. In systems of this type at temperatures above the range of stability of any intermetallic phases, once the liquid is saturated with respect to the solid so that no gross solution occurs, chemical gradients are small, and surface tensions become major driving forces for attack, provided the solid is stress-free. The results of Cheney et al. appear to be typical of those encountered when grain boundary wetting occurs.&apos; Capillary films were observed in the boundaries after quenching from the exposure temperature. The mean depth of penetration increased linearly with time, and the activation energy for the process was found to be 22 kcal per g-atom. In a study of the Cu-Bi system Yukawa and sinott4 found that the depth of penetration of bismuth into high-purity copper bicrystals of orientations from 22 to 63 deg of tilt about (100) at 649°C ranged from 0.05 to 0.25 in. after a 12-hr anneal. This corresponds to a linear rate of 6 to 15 X 10~6 cm per sec. At the same reduced temperature of 0.68 the rate for the Ni-Bi system&apos; was 7 x lo-&apos; cm per sec. In another study of the Cu-Bi system, Scheil and schess15 determined the kinetics of grain boundary wetting in hot-worked commercial rod. While there were several complicating factors present in this study, there is general agreement with the above results. The kinetics of penetration were linear, the activation energy was 20 kcal per g-atom, and at 650°C the rate of wetting was 2 to 5 x 10-6 cm per sec. The rate of wetting in the A1-Ga system6 is somewhat

Jan 1, 1969

By P. B. Mee

The secondary re crystallization behavior of two vacuum-melted, nominally 3 pct Si-Fe alloys has been studied, one alloy being produced from pure electrolytic iron and semiconductor-grade silicon and the other from commercial-purity hot band. The vacuum-melted and vacuum-remelted alloys were found to develop {110}(hhl) and {lll)(hkl), respectively, on annealing in high vacuum and {100}(0kl) and {11l}(hkl), respectively on annealing in pure hydrogen of dew point, < — 60°C. H2S doping of the hydrogen or annealing in commercial argon was found to effect a reversal for the vacuum-remelted alloy from (111) to (100) secondary recrys-tallization, while prolonged vacuum annealing at 2 x 10-6 Tow resulted in a tertiary re crystallization from (111} to (110). The growth selection of the {lll}(hkl) component was found to be governed predominantly by the {111}/planar misorientation, the maximum deviation of the resulting secondaries being 5 deg. It is considered that the driving force for {111}(hkl) secondary recrystallization arises from the preferential lowering of ?111, possibly by phosphorus or nitrogen diffusion, just as oxygen and sulfur under certain conditions have been found to preferentially lower ?100. When heavily cold-rolled metals are annealed at high temperatures, primary recrystallization usually occurs rapidly and may be followed by considerable grain growth. However, in the presence of a fine dispersion of inclusions1"3 or with a strong matrix preferred orientation4&apos;&apos; the matrix may be stabilized and a secondary recrystallization may then be effected. Also, in vacuum-melted Si-Fe it has been shown possible to develop {100}(001) and {110}(001)6 surface energy driven secondary recrystallization textures. Further, it has been found that, on annealing very pure metals, grain growth normally ceases when a grain size approximately twice the strip thickness is acquired, due to the formation of V-shaped thermal grooves which result in an equilibrium being set up between surface and grain boundary stresses. If, however, a surface energy difference ??s, exists between adjacent grains (of the order of a few percent of the grain boundary energy ?b), then according to Mullins8 a secondary recrystallization may be effected, since the grains having lowest ?s would grow at the expense of their higher-energy neighbors. For clean bee metal surfaces ?110 should be lowest; however, for 3 pct Fe-Si (100) secondary structures have frequently been developed and have been attributed by Walter and Dunn9 to an alteration of the relative surface energies due to the preferential chemisorption of oxygen on (100) planes. Kohler,10 however, indicated that this reversal may be achieved by employing minute quantities of highly polar compounds in the annealing atmosphere, i.e., sulfur compounds, in par- ticular H2S being beneficial in (100) growth. This work has been verified by Kramer" using {100)/{110} bicrystals, while Mager12 demonstrated the importance of sulfur diffusion within the strip. Detert13 has intimated that carbon may be responsible for the preferential lowering of ?110 although no direct evidence has appeared yet to support this supposition. It must , be appreciated that the above-mentioned examples of surface energy driven secondary recrystallization were obtained with very pure vacuum-melted materials with oxygen contents (which is now known to be a critical factor") less than 35 ppm. During the course of a textural study on Si-Fe it has been found that under certain conditions (111) secondary recrystallization can be obtained by what is believed to be a surface energy growth selection mechanism. The purpose of the present paper is to briefly describe this result and to try and postulate the possible causes. EXPERIMENTAL Two vacuum-induction-melted, nominally 3 pct Si-Fe alloys were produced, one from pure electrolytic iron and semiconductor-grade silicon designated A and the other from commercial-purity hot band, designated B.

Jan 1, 1969

By Wilson R. G

The Bulli and Wongawilli Seams, the two principal sources of coking coal for the Port KKembla steelworks of Australian Iron and Steel Pty. Ltd., vary in rank and in type over the Southern and -South Western Coalfields. The Bulli Seam, ranging widely in type, produces coke varying from weak to strong. The Wongawilli Seam, more consistent in type, produces coke of more consistent strength, but considerably less strong than that from the best Bulli Seam coal. Plans of seam variation show the regional trends in rank and type for each sear. The strongest coke is derived from coal containing between 45 and 55 per cent vitrinite, m.m.f. This is obtainable from the Bulli Sean in a zone embracing Bulli and Appin Colleries.

Jan 1, 1969

By G. J. Wilson

Difficulties experienced in correlating vertical and lateral locations of subsurface features that are encountered in directional wells prompted critical review of the tangential method of computing directional surveys. Inherent discrepancies were indicated to cause small incremental but significantly large cumulative errors in computed vertical depth and horizontal departure. A radius of curvature method, developed for planning and analyzing directional wells, was studied as a means of more accurately calculating survey data. Errors incurred in the tangential method were not present in the radius of curvature method. Conflicting assumptions in calculating dog-leg severity by the tangential method were resolved by a new procedure that was derived from the radius of curvature method. Results of the investigation showed the radius of curvature method to be an improved method for computing directional surveys. Introduction Many improvements in directional drilling tools and techniques have been made in the past 10 years,&apos; but the method of computing survey data has remained virtually unchanged. While use of computers greatly aids the process of calculation&apos; and eliminates many human errors, manual and computer calculations are still made with the assumption that the wellbore consists of straight-line segments. This paper points out discrepancies in the method and presents an improved method in which the wellbore is assumed to be curved. Tangential Method The method presently used to calculate vertical depth, horizontal departure and direction coordinates with measured values of well depth, inclination angle and direction angle is termed the tangential method. This term stems from performing calculations with a series of straight-line segments, with each segment assumed to be tangent to the wellbore at a corresponding survey point. A segment is defined by inclination and direction angles measured at only the lower or deeper end. Consequently, a discrepancy or error is introduced for each segment. Errors are not of extreme magnitude, but cumulatively are significant due to the need to define as accurately as possible the vertical and lateral location of subsurface features such as pay tops, fluid contacts and fault cuts encountered in expensive directional well bores. In Fig. 1, the curved-line segment ab represents a portion of the actual borehole as viewed in the vertical plane. Points a and b are survey stations and +, is the inclination angle at point b. The curved-line segment ab is assumed to be the straight-line segment arb of a length equal to ab and tangent at point b to the curved-line segment. Lengths a&apos;c&apos; and c&apos;b are equal to a&apos;b cos +, and a&apos;b sin +,, respectively. Point a already has been fixed by calcillations performed with survey data obtained at point a, and calculated lengths m&apos;c&apos; and c&apos;b are projected as lengths from point a, rather than from point a&apos;. Point b1 is thus fixed and assumed to represent the actual point b. Calculated length ac" is shorter than actual length ac, and calculated length c"bl is longer than actual length cb. Since b1 is the point from which the next deeper segment will be projected, errors are cumulative. Cumulative error continues to increase as long as the inclination angle continues to increase. When the inclination angle decreases (Fig. 2), calculated length ac" is longer than actual length ac, and calculated length c"bl is shorter than actual length cb. These errors also are cumulative, but differences between calculated and actual lengths are opposite in mathematical sign to differences demonstrated in

Jan 1, 1969

By William E. Bonini

Gravitational field anomalies have been observed over many igneous intrusives of medium (4000 km2) to small (100 km2) size in outcrop area. These studies give good results because the residual anomalies can be separated from larger scale crustal anomalies and density contrasts usually are present. Although unique solutions are not possible, the analysis of the gravity anomalies can put limits upon the geologic interpretation of such bodies. Three examples in Montana, U. S. A. are discussed: (1) the Boulder Batholith, a late Cretaceous quartz monzonite series of intrusives of 4000 km2 outcrop area; (2) the Little Rocky Mountains, an up-domed area, in which an Eocene porphyry (130 km2) has intruded the Precambrian crystallines and lower Cambrian sediments; and (3) the Crazy Mountains, an Eocene diorite (100 km2), which has intruded the Paleozoic and Mesozoic sediments. In both the Boulder Batholith and the Little Rocky Mountains, intrusive rocks are less dense than the surrounding rocks and negative anomalies are found (40 and 28 mgal, resp.). In the Crazy Mountains, the intrusive is more dense than the surrounding sediments and a sharp positive residual anomaly of 42 mgal is observed. The analyses of the gravity anomalies predict that: (1) the thickness of the Boulder Batholith is on the order of 10 to 15 kms and is concave upward; (2) the Little Rocky Mountain syenite is not a simple laccolith, but is T-shaped and extends in depth to about 16 kms; (3) the Crazy Mountain diorite is not a simple small scale series of stocks, but a large connected body extending in depth 5 kms to the basement (although nothing can be said of it within the basement because there is little density contrast). The analyses of the anomalies place important limits on both the areal and depth extent of the intrusive bodies. Of all possible geophysical techniques, gravity studies offer the most promise in the determination of the shape in depth of intrusive bodies.

Jan 1, 1969

Laboratory induced polarization measurements were made on representative samples of concentrated sulphide ores from three environments in New South Wales Comparisons were made with the membrane polarization exhibited by an argillaceous sandstone. The sulphide samples showed a strong polarization effect, the magmtude of whIch depended directly on the conductivity of tlIe pore electrolyte.

Jan 1, 1969

By L. W. Holm

This study shows that in the presence of foam, gas and liquid flow separately through porous media representative of reservoir rock. These results were obtained by using tracer techniques to measure the flow of the gas and liquid comprising the foam. Foam does not flow through the porous medium as a body even when the liquid and gas are combined outside the system and injected as foam. Instead, the liquid and gas forming the foam separate as the foam films break and then re-form in the porous system. Liquid moves through the porous medium via the film network of the bubbles and gas moves progressively through the system by breaking and re-forming bubbles throughout the length of the flow path. The flow rates of the gas and liquid are a function of the number and strength of the films in the porous medium. There is no free flow of gas; i.e., no continuous gas phase. On the basis of these results, foam can be expected to improve a water flood or gas drive by decreasing the permeability of the reseruoir rock to a displacing liquid or gas. This improves the mobility ratio and thus the conformance of the flood. INTRODUCTION Foam is formed when gas and a solution of a surface active agent are injected into a porous medium either simultaneously or intermittently. During the past few years, several papers have been published on the subject of foam flow in Dorous media. Foam has been used successfully in the removal of capillary water blocks from producing formations.&apos;&apos;2 The use of foam in gas storage reservoirs to reduce gas leaks and to increase storage capacity has been considered in recent years. Foam has also been investigated as an oil displacing agent,3-5 and as an agent to improve the mobility ratio in a waterflood.6-10 However, the mechanism by which the gas and liquid phases comprising the foam flow through a porous medium has nor been described adequately. Normally, when two immiscible phases (gas and liquid) flow concurrently through a porous medium, each phase follows separate paths or channels. At given saturations of the two phases, a certain number of channels are available to each phase, and as saturations change, the number and configuration of the channels available for each phase also change. The effective permeability of each phase is a function of the saturation of that phase only, and the flow of each phase can be described by Darcy&apos;s law. When foam is present, the effective permeability of the porous medium to each phase is greatly reduced compaced with permeabilities measured in the absence of foam.6,11-13 Based upon the observed flow of surfactant solutions and gas in capillaries, it has been concluded that the gas and liquid may flow separately or they may flow combined as foam. At least four mechanisms have been postulated to explain how fluids flow with foam present: 1. A large portion of the gas is trapped in the porous medium and a small fraction flows as free gas, following Darcy&apos;s law.9 2. The foam structure moves as a body; the rate of gas flow is the same as the rate of liquid flow. 6,13 3. Gas flows as a discontinuous phase by breaking and re-forming films. Liquid flows as a free phase.12 4. A portion of the liquid and gas move as a foam body while excess surfactant solution moves as a free phase.14 It also has been suggested that different flow mechanisms exist for high quality (dry) foams made from dilute surfactant solutions and for foams made from more concentrated solutions. Studies conducted on the flow of foam through capillaries have shown that a plug-type flow occurs and that foam flows as a body.6,15 Fried also has described the flow of foam through porous media as

Jan 1, 1969

By Phillip J. Maddex

Transportation is a major part of yours in the industrial minerals industry. Whereas federal income taxes merely take 50 per cent of your firms profits, transportation cost may take 50 per cent of the gross realization - selling price plus transportation - on your product, f. o. b. customers plant.

Jan 1, 1969

By T. K. Perkins, W. W. Krech

Jan 1, 1969

By Raul A. Deju

This paper shows how one can relate the chemical reactions between water and a silicate bed to the equations of flow. First the reaction mechanism is studied both theoretically and experimentally. Once the reaction mechanism is established, the equations of flow are solved and a solution (under physically reasonable side conditions) is obtained. Experiments to substantiate the solution are also presented.

Jan 1, 1969

By P. R. Sahm, T. V. Pruss, D. A. Gandolfo

Cb 3 Sn powders were hot-pressed to estahlish densi-fication conditions and assess the possible use of such compacts in multiphase structures with ceramic or magnetic inclusions. Superconducting transition temperatures, Tc, were measured as a function of powder particle size, pressing temperature, and second-phase admixtures. The highest transition temperatures were found in coarse powder (5 to 500 u) compacts and were only weakly depended on pressing temperatures up to 1200°C. Fine powders (below 5 p), however, both single-phase CbsSn and Cb3 Sn-composites, showed a stronger dependence on hot-pressing temperatures. While Al2 O3 phase admixtures did not affect T, much more, a Pronounced T, degradation was observed upon the addition of ferrimagnetic Fe2 Mno. 5 Zno.5 O4 powders. Likewise, critical current densities, Jc, at 4.2° K were lowered appreciably in the ferrite doped samples, whereas the neutral A1203 inclusiow gave slightly improved Jc values. MULTIPHASE structures in electronically active materials have recently gained in interest as pointed out by Galasso in a review article.&apos; In superconductors the most widely reported group are eutectic alloys which have been mostly investigated with respect to the proximity effect.2"4 In addition, "artificial eu-tectics", for example in the form of mercury-vycor glass sponge5 or fine niobium wires imbedded in a copper matrix,= have been prepared to attain higher critical fields and critical current densities. The idea was to enhance flux pinning phenomena by second-phase inclusions or ho1es. 7 Flux pinning should also be possible by the introduction of insulator inclusions into a superconducting matrix. Ceramic-metal combinations are most easily produced by hot pressing (= pressure sintering), as it permits an almost unlimited selection of material combinations. Cb 3 Sn has been prepared by vapor phase growths or in the form of thin films. Large compacts must be sintered,1° however, and normally present difficulties. At temperatures below 1350°C insufficient densities are obtained and at higher temperatures the loss of tin due to dissociation upsets the stoichiometry. Hot pressing is a natural approach to circumvent the problems, since one can obtain satisfactory densities despite low sintering temperatures. This work was mostly concerned with establishing conditions to hot press Cb3 Sn and Cb3 Sn multiphase structures (= composites), because no data are presently available, and to evaluate these with respect to their transition temperatures. However, a few measurements on critical current densities were also carried out, in particular to assess the value of ferrimagnetic inclusions. I) EXPERIMENTAL PROCEDURE The experimental procedure involved the preparation of feed material and powders, hot pressing, and evaluation of the resulting ingots. As no attempts were made to synthesize Cb3Sn from the elements during hot pressing, feed material had to be produced. For this purpose, a stoichiometric Cb-Sn powder mixture was compacted into a 3-cm-diam ingot (80,000 psi) and then inserted into a quartz tube and evacuated. Rf heating was employed. Above the tin melting point (230°C) liquid tin was forced out of the ingot, but was pulled back by capillary action after approximately 0.5 hr of continuous pumping at 700°C. Thus, it appears that evacuation at this temperature caused desorption of impurity gas creating wetting surfaces which, later on, favored alloying at relatively low temperatures. After a presintering period of 17 hr at 800°C, the quartz tube was tipped off and sealed into another such larger-diameter tube which, in turn, was connected to a pump system. This configuration permitted a temperature treatment at 1400°C, carried out for 65 hr, without collapsing of the glass walls or unfavorable chemical interaction of Cb3Sn with the quartz. The resulting material was

Jan 1, 1969

By James Paone

The Bureau of Mines conducted laboratory drillability studies on nine rock types using two mining-type percussive drills. Percussive-bit action was simulated by dropping a known weight on a rock sample to obtain a coefficient of rock strength for each rock drilled. While no single physical property of a rock is completely satisfactory as a predictor of penetration rate, coefficient of rock strength showed a better correlation with penetration rate than did other physical properties. Results also indicate that over the range of energies investigated, energy per unit volume in a given rock is independent of blow energy. A drillability index for the percussive system is proposed that utilizes the coefficient of rock strength test to determine energy per unit volume for a given rock which, along with the work rate of a given drill and the bit diameter, is used to predict the penetration rate as shown in the following equation: [R = 4P pD2 E, where R = penetration rate, in/min, P = work rate, in lb/min, D = bit diameter, in, and Ev = energy required to produce a given volume of rock, in lb/in3.] Laboratory tests indicate this method&apos;s potential as a simple and reasonably accurate method of predicting penetration rates with any percussive drill and bit combination.

Jan 1, 1969

By A. R. Krause, C. Laird

In order to establish whether or not there is a real temperature effect in fatigue (independent of environment) , poly crystalline copper and Cu- 7.9 A1 alloy have been cycled at 298° and 7° K in vacuo and the fatigue lives compared with those in air and in liquid nitrogen. The lives of both copper and the alloy were found to be highly temperature-dependent in the absence of environment. This result casts serious doubt on the validity of the cell structure hypothesis for stage I crack propagation as presently formulated, because it predicts that there should be no such tempevnture dependence. On the other hand, the plastic blunling process is consistent with the result. Effects of environment aside, the homogenization of slip which accompanies testing at low temperature, and at low strains, seems to be the main cause for increased fatigue life. At high strain amplitudes, the fatigue lives of wavy slip materials, typically copper, are independent of temperature.&apos; It is well-known, however, that low-strain lives greatly as as the temperature of testing is decreased. By contrast, the lives of planar slip materials, such as Cu-7.9 pct A1 alloy, increase to an even greater extent with decreasing temperature throughout both the high and low strain ranges.1&apos;2&apos;5 The mechanism of this temperature effect is associated with the earliest stages of fatigue failure,&apos;" crack nucleation, and stage I growth,"&apos; which is slow propagation along slip bands to the depth of a few grain diameters. Such life behavior has been interpreted on at least two different bases. On the one hand, those interested in the temperature effect at high strain amplitudes1 believe that stage I growth occurs by the plastic blunting process of crack propagation.7&apos;9 They explain the effect in planar slip materials by the homogenization of slip* which accompanies fatigue testing at low temper- atures and serves both to delay crack nucleation and to decrease the rate of stage I propagation. On the other hand, Holt and Backofen,2 who have studied the effect in low strain fatigue, believe that stage I growth can be interpreted by a cell structure hypothesis.10-12 They have challenged2 the conclusion that there is a real temperature effect in this regime of fatigue testing and have interpreted the increased fatigue lives almost entirely in terms of the "environmental-protective&apos;&apos; effect of the liquid nitrogen and helium baths used to obtain low temperatures. This interpretation by Holt and Backofen2 may offer a means of discriminating between these two mechanisms as currently formulated and used to explain stage I growth. On the basis of the plastic blunting process applied to stage I crack propagation,7* the low strain fatigue lives of both wavy and planar slip materials should be increased with decreasing temperature. This follows because both materials show increased slip homogenization in this strain regime."13 Consequently, crack nucleation in intensified bands will be delayed and the linking of such small cracks into larger stage I cracks will be difficult. In addition, the blunting process required to lengthen a stage I crack from the order of 2 to 10 (where the strain concentration of the crack begins to overcome the slip homogenization property of the material) will also be retarded. These delays will give rise to longer lives in both kinds of material. In contrast to the blunting hypothesis, no temperature dependence has been predicted on the basis of the cell structure hypothesis, because it is well-known that materials cycled at low temperature show no differences in type of dislocation structure for a given strain amplitude.18"20 If the lives of wavy and planar slip materials do show a temperature dependence when the environment is eliminated as a variable, then it is questionable whether cell structures per se have a fundamental role in fatigue fracture. Accordingly, specimens of copper and Cu-7.9 wt pct A1 have been cycled at 298° and 77°K in vacuo and the fatigue lives compared with those in air and in liquid nitrogen, in order to establish whether or not there is a real temperature effect in low strain fatigue. Since it is difficult to measure the strains in specimens when cycled in vacuo, S-N curves have been used as the basis of comparison. In studying the influence of temperature on fatigue life in ordinary environment, Holt and Backofen2 used the superior basis of E-N curves. However, they also published S-N curves and thus established the relationship between E-N and S-N curves. This relationship is used to support the S-N comparison reported in the present investigation. EXPERIMENTAL Materials. The copper employed in this investigation was of 99.99 pct purity and the cu-7.9 pct A1 was prepared from metals of the same purity. The stock, of 3 in. initial diam, was reduced in size by rolling

Jan 1, 1969