Search Documents

By J. Pohlig

It is with more than ordinary pleasure that I have complied with the request of the President of the Verein Deutscher Eisenh?tten leute, to read before this meeting and in this country a paper on a system of transport by wire ropeways which, during the past twenty years, has advanced with rapid strides in Europe, and more partic ularly in Germany. America, with its immense network of railways and water communications, should offer peculiarly favorable oppor tunities for the introduction of these ropeways as feeders, more par ticularly in the mining districts, where, as in Europe, a hilly or mountainous region frequently opposes serious obstacles to the em ployment of surface railroads. The importance of the aerial ropeway as a factor in the develop ment of mineral resources deserves the consideration of every mining engineer. As a case in point, the rich iron-ore of the sierra de Bedar in southern Spain, would probably remain untouched to this day but for an aerial ropeway, 15.6 km. (9 3/4 miles) long, which con nects the mines with the shore of the Mediterranean near the town of Garrucha, affording cheap carriage to the nearest shipping point. A railway would have cost about $480,000 (£100,000), but such a heavy outlay would have more than absorbed all prospective profits on the sale of ore. As the aërial ropeway could be built for a little more than one-fourth of that amount, or $124,800 (£26,000), its erection furnished the successful solution of a profitable mining enterprise. This line has been in satisfactory operation for over two yearn; its details will be referred to later. But beside their importance as feeders, ropeways are valuable as a means of conveyance between works and distant warehouses, and between separate buildings in the same works. Their rapidly spreading introduction for such purposes indicates how keenly the necessity of effecting economies is felt under the stress of an everaccentuating competitiop.

Jan 1, 1891

By F. G. Smith

A FEW years ago, the writer encountered a, problem that, at first, seemed to be due to peculiar conditions affecting grain growth. Large cups made from heavy metal failed in the first drawing operation in the process of making seamless tubes. The metal, as cast, appeared to be sound and strong; it rolled successfully and withstood the first cupping operation, but on the first draw it failed, with a crystalline fracture. The failure appeared in the slightly worked part of the bottom of the cup, and microscopic examination revealed exceptionally large grains. Knowing the general conditions governing recrystallization of brass, which were later published by Matthewson and Phillips, an investigation was outlined with the idea of including various conditions under which new grains might form, and which would include the effect that a previous anneal might have upon the anneal following. These conditions were produced by annealing specimens of brass at five different temperatures, indenting them with a 10-inn. ball under four different pressures, and then reannealing at each of the five temperatures five specimens each of which had been annealed at one of the five temperatures.

Jan 8, 1919

By Earl Oliver

IN times like these, the A. I. M. E. and similar societies have their greatest usefulness. . . . Individuals and companies acting alone in the development of public opinion are merely voices crying in the wilderness. United and organized they make a great force that can and does influence public action. . . . What part, if any, then, shall the A. I. M. E. take in these great stabilization processes of civilization? Shall it help to give direction and force to scientific knowledge which comes within its field of activity or shall it merely develop more of it? . . . Is it the A. I. M. E.'s function to help bring system, order and direction out of this situation so that the world can again have forward economic movement, or should it rest on its oars until other agenciess develop that public understanding and direction so necessary for economic progress? As we understand the functions of the A. I. M. E. Petro¬leum Division, they are to discover and promote knowl¬edge for the benefit of society on the mining of oil and gas. To the individual member of the Petroleum Division, there are certain advantages of social and professional contacts, but the collective purpose is that described. And the individual is benefited by membership only as the Division measures up to the purposes of its existence. Consequently, the welfare of this Division and that of its members depends on the extent to which it keeps pace with the needs of society on matters relating to the mining of oil and gas.

Jan 1, 1932

By R. E. Zimmerman

Wide attention is being placed upon various methods for cleaning the fine sizes of bituminous coals. The author describes and analyzes the results achieved on wet concentrating .tables of modern design on unclassified feeds of - 1/2 in. particle sizes, including tests on high-sulphur coals.

Jan 1, 1950

By Stanley Rajnak, John E. Dorn

The saddle-point activation energy for the nu-cleation of a pair of kinks is estimated as a function of the applied stress, the lattice constants, and the height and shape of the Peierls' hill by employing the line-energy model of a dislocation. The kinetics of disloration motion by the Peierls' mechanism are discussed and the microscopic dislocation velocities and macroscopic strain rates are formulated by the Arrkenius type of approach in terms of the activation energy for the formation of pairs of PEIERLS was the first to illustrate that a straight-dislocation line has its lowest energy when it lies in a potential valley parallel to lines of closest packing kinks. The log of the dislocation velocity is found to be approximately proportional to the log of the local applied stress. It is also shown that the low-temperature mechmical properties of several bcc metals might be explained in terms of the Peierls mechanism, good agreement being obtained between theory and experiment for the flow stress us ternperature, activation energy vs stress, and activation volume us stress curves for these metals. of atoms on the slip plane. When such a straight dislocation is moved rigidly from one valley toward the next, the atoms in the vicinity of the core of the dislocation change their positions and bond angles, causing the energy of the dislocation to increase. Midway between two adjacent valleys, the disloca-tion energy reaches a maximum value and any additional small displacement will cause the dislocation to fall down the hill into the next valley. The maximum shear stress necessary to promote such

Jan 1, 1964

By Henry M. Howe

COLUMBIA UNIVERSITY The Equilibrium Position of A 1.—Some of the most important data on this subject are collected in Table I. Definition of Ae 1.—-Just as we call A 1 of rising temperature Ac 1, and that of falling temperature Ar 1, so we may give the symbol Ae 1 to the equilibrium position of A 1. Preliminary Assumptions.—In deciding what weight to assign the various data, and indeed what data are to count, three assumptions should be made. These are : 1. The corollary from the phase rule, that the temperature of Ae 1 is constant and independent of the carbon content, though, of course, it may be changed by the presence of other elements. 2. That because neither in heating nor in cooling can the transformatioil begin before the temperature reaches Ae 1, though it may be delayed by lag till after the temperature has passed beyond Ae 1, therefore Ae 1 should be at or below the observed beginning of Ac 1 and at or above the observed beginning of Ar 1, and, a fortiori, it should be at or below the observed maximum of Ac 1, and at or above the observed maximum of Ar 1. It may be necessary to take these maxima into consideration in view of the experimental difficulty of detecting these beginnings. 3. Because of the extraordinary degree of lag in the immediate neighborhood of Ae 1, as proved by Brayshaw, little weight should be attached even to the most conclusive evidence that the transformation has not occurred on reaching, or even staying at, a given temperature, because that failure to occur may always be due to lag. Evidence that the transformation has occurred, or has even begun, at a given temperature deserves incomparably greater weight. In other words, the temperature may pass beyond Ae 1 without inducing the ' transformation, but the transformation cannot be induced except by

Jan 1, 1914

By Charles R. Keyes

Discussion of the paper of Charles R. Keyes, Bi-Monthly Bulletin, No. 19, January, 1908, pp. 1 to 31. BERNARD MACDONALD, Guanajuato, Mexico (communication to the Secretary*) :-Mr. Keyes's paper is very interesting to me because of my personal experience with the development of the ore-deposits of Lake Valley. Seeing that many of the important facts connected with the early history of the development of these mines are either now unknown, or have become more or less distorted, and thinking that it would be interesting as well as valuable to have these recorded as a historical supplement to Mr. Keyes's elaborate paper, I present the following narrative: In February, 1881, soon after the Atchison, Topeka & Santa Fé railroad made connection with the Southern Pacific at Denting, N. M., the Lake Valley properties were brought to the attention of New York and Philadelphia capitalists by John A. Miller, of Silver City, N. M. At that time silver was $1.10 all ounce and silver-mining was very attractive. Vast fortunes were being made in Leadville and other Colorado camps, and Tombstone was pouring out its millions. Lake Valley, like all' other mining-camps in their early history, had its drawbacks, but the railroad, then passing within 14 miles of it, mitigated many of these. The camp lay in the foot-hills of the Black range, in which the Apaches had their stronghold, and raided, when it suited their convenience, the surrounding country, killing the prospectors and pioneer settlers and stealing their cattle. This band of Indians was joined by the outlaws and desperadoes from the frontiers of Texas, Arizona, and Mexico, who collectively defied the United States soldiers, restrained, as the latter were, by the mollycoddles from the East. The brutality of the Indian raids through Arizona and New Mexico in those days would scarcely be believed now, but they stain in deep

Feb 1, 1909

PRELIMINARY REPORT PUBLISHED FOR THE PURPOSE. OF INVITING SUGGESTIONS FOR, THE BENEFIT OF THE COMMITTEE 1 As a result of invitations extended by The American Society of Mechanical Engineers, a, number of associations of national scope have appointed representatives on a Joint. Committee on Standards for Graphic Presentation:- Below are the names of the members of the committee and of the associations which have co-operated in its formation. WILLARD C. BRINTON, Chairman,. American Society of Mechanical Engineers. [7 East 42nd Street, New York City.] LEONARD P. AYRES,Secretary, American Statistical Association. [130 East 22nd Street, New York City.] N. A. CARLE, American Institute of Electrical Engineers. ROBERT E. CHADDOCK, American Association for the Advancement of Science. FREDERICK A. CLEVELAND, American Academy of Political and Social Science. H. E. CRAMPTON, American, Genetic Association. WALTER S. GIFFORD, American Economic Association. J. ARTHUR HARRIS, American Society of Naturalists. H. E. HAWKES, American Mathematical Society. JOSEPH, A. HILL, United States Census Bureau. HENRY D. HUBBARD, United States Bureau of Standards. ROBERT H: MONTGOMERY, American Association of Public Accountants. HENRY H. NORRIS, Society for the Promotion of Engineering Education. ALEXANDER. SMITH,. American Chemical Society. JUDD STEWART, American Institute of Mining Engineers. WENDALL M. STRONG, Actuarial Society of America. EDWARD L. THORNDIKE, American Psychological Association.

Jan 10, 1915

By L. A. Cowan

IF the elements of personality be those characteristics in which humans differ, and if this definition be applied to the purchasing department for the Climax operations in Colorado, it must he concluded that this department has no distinguishing traits that would give it a departmental personality different from that possessed by the similar department of any progressive mining enterprise. Or, one may go further by stating that the rudimentary functions of any purchasing practice employed principally in the acquisition of maintenance, repair, and operating supplies are much alike, whether or not the industry involved be mining or milling. However, in the fact that the principal purchases of a mining company are materials for maintenance and repair and consumable operating supplies lies that essential characteristic which differentiates mining and milling purchasing functions from those of the manufacturer, the fabricator, or the ordinary processor.

Jan 1, 1946

By H. L. Marcus, P. W. Palmberg

As can be seen from the phase diagram A1-W1 the equilibrium solubility of tungsten in aluminum is practically nil at room temperature. By quenching from the liquid state (50,000°C per sec), Varic, Burov, and Kolesnicenko2 obtained A1-W solid solutions up to 0.15 at. pct W. The quenched alloys were in the form of foils, 0.2 to 0.3 mm thick. Considering the results of Duwez and Willens,3 it is obvious that this thickness, which makes impossible a sufficiently rapid quenching, was the main reason for the relatively low content of tungsten dissolved in aluminum found by Varic.2 he present note shows that the metastable solubility of tungsten in aluminum can be appreciably extended in aluminum-rich A1-W alloys. The quenching technique and the procedure employed for the preparation of the alloys have been described previously.475 The resulting quenched flakes varied in thickness from 1 to 20 µm from experiment to experiment. However, the measurements of the lattice parameters were carried out only with flakes thinner than 5 µm. The areas of quenched flakes were between 0.1 and 15 mm2. The quenched flakes were placed into a 0.3-mm glass capillary tube which was then mounted in a 114.6-mm-diam Debye-Scherrer camera. Straumanis asymmetric film position and nickel-filtered CuKa radiation were used. The lattice spacings were computed taking X(CuKa1) = 1.54050A for resolved and ?(CuKa) = 1.54178A for unresolved doublets. All specimens were rotated at room temperature, 26" +2°C. The lattice parameters were estimated from extrapolation against the Nelson-Riley function. It was estimated that the error in the lattice parameter of the measurements on a single film lies within +0.0004A for lower and about +0.001A for higher concentrations of tungsten. The lattice parameters of the metastable solid solutions A1-W are plotted vs the concentration of tungsten in Fig. 1 together with the parameters measured by previous investigators.' Each point of the present measurements represents a determination of the lattice spacing on different quenched flakes, for a given concentration of tungsten. With experimental accuracy, the lattice parameters of the metastable solid solutions fall on the straight line passing through the already known data.' As estimated from the uncertainties in the lattice spacings of the solid solutions, the alloys were homogeneous within 0.1 at. pct W. The solubility of tungsten in aluminum-rich A1-W solid solutions obtained by a very rapid quenching technique is increased to about 0.95 at. pct W. This value is 6 times greater than the amount known up to now. -he lattice parameters of the resultant aluminum solid solutions with higher concentrations of tungsten than 0.95 at. pct W did not remain constant AUGER electron spectroscopy has been used to clarify the role of impurities in the embrittlement of AISI 3340 steel. Analysis of fracture surfaces has shown that the embrittled condition is correlated with appreciable antimony segregation at grain boundaries. The low temperature (400" to 600°C) temper embrittlement of low alloy steels containing various combinations of Cr, Ni, Sb, Mn, P, Sn, and As has been examined extensively for many years. General reviews of the area have been made by McMahon1 in 1968, LOW' in 1959, woodfine3 in 1953, and Holloman4 in 1946. Recent work by Low, Stein, Turkalo, and LaForce5 has done much in separating the alloy and

Jan 1, 1970

By Niels Hansen

The substructure formed by drawing at room temperature in aluminum (99.5 and 99.998 pct purity) and in recrystallized aluminum aluminum-oxide products containing from 0.2 to 4.7 wt pct of aluminum -oxide was examined by transmission electron microscopy, and the flow stress of the drawn materials was measured by tensile testing at room temperature. A sub-grain structure was present after a reduction in area by drawing of 10 to 20 pct, and the subgrain size was observed to decrease with increasing deformation. The tensile data show that the increase in flow stress (0.2 pct offset) by drawing from 10 to 95 pct depends on the reduction in area, not on the composition of the materials. Dispersion strengthening and subgrain bowzdary strengtlzening contribute to the flow stress, and these strengthening processes have been found to be linearly additive. The flow stress (0) can be related to the subgrain size &) by the Petclz relation = uo + k . t, where go is dependent on the composition of the products and k is approximately the same far all materials. THE microstructure of dispersion-strengthened aluminum aluminum-oxide products consists of small oxide plates distributed in an aluminum matrix. The matrix structure depends on the manufacturing history, and in hot-worked as well as cold-worked products the matrix is divided by subgrain (or dislocation) boundaries. For hot-extruded products it has been shown1 that dispersion strengthening and subgrain boundary strengthening are linearly additive, and the flow stress (0.2 pct offset.) at room temperature has been related to the subgrain size (ts) by a Petch equation,2,3 s = so + k . ts-1/2, where s0, increases with increasing oxide content. For cold-worked products containing subgrains no systematic work has been reported, and it was the aim of the present study to examine the microstructure and the relationship between the flow stress and the subgrain size for such products. The behavior of' aluminum aluminum-oxide products depends on the purity of the aluminum matrix, and aluminum of the matrix purity (99.5 pct) was included in the investigation. The literature contains few data about the behavior of this impure aluminum, and aluminum of a higher purity (99.998 pct) was therefore also examined. As regards the relationship between the flow stress and the subgrain size in cold-worked dispersion-strengthened products, no systematic work has been reported. For aged cold-worked structures containing fine precipitates (Fe-Mo carbide) a Petch relation has been found,4 and it has been shown that the k value NlELS HANSEN is Head, Metallurgy Department, Danish Atomic Energy Commission, Research Establishment Riso, Denmark. Manuscriot submitted January 9, 1969. IMD is approximately the same as in iron, whereas the s0 value is higher owing to the presence of the precipi-tates. Investigations of metals such as tungsten,' ferrous metals,4,6 and molybdenum7 cold drawn or swaged at room temperature have shown that the flow stress can be related to the subgrain size by a Petch relation when ts is taken as the subgrain size perpendicular to the direction of deformation. For aluminum no work has been reported on the relationship between the flow stress and the subgrain size after deformation at room temperature, whereas for aluminum tensile strained at different temperatures in the range -183" to 375°C a Petch relation has been found by taking ts equal to the subgrain size.' In the present study two aluminum materials (99.998 and 99.5 pct) and three aluminum aluminum-oxide products (containing 0.2, 1.0, and 4.7 wt pct oxide) were drawn at room temperature to reductions in area from about 10 to about 95 pct. The structures were studied by transmission electron microscopy, and the flow stress (0.2 pct offset) was measured at room temperature. EXPERIMENTAL Materials. The materials are given in Table I together with the chemical analysis. The three aluminum aluminum-oxide products were manufactured from aluminum powder that had been compacted and Table I. Chemical Analysis of Materials Al203 Fe SI Material wt pct wt pct wt pct 99.998 pct* - 0.0004 0.0012 Aluminum 99.5 pctt - 0.36 0.16 Aluminum AlMD13† 0.2 0.16 0.12 Aluminum- -Oxide AlMD105† 1.0 0.26 0.18 Products SAPISML960s† 4.7 0.22 0.19 *Other impurities: O.0004 pct max each of Cu and Zn (supplier's analysis). †Other impurities: 0.03 pct max Cu. 0.02 pct max each of Mn, Mg, Zn, Ti. Table 11. Mean Diameter of Aluminum-Oxide Particles in Extruded and in Cold--Drawn Aluminum Aluminum-Oxide Products Mean Diam. of A1203-Plates* Material State A AlMD105 Extruded 540 Cold Drawn 97 pct 510 SAP ISML 960 Extruded 770 Cold Drawn 95 pct 820 *The standard deviation of the mean is approx. 5 ±pct.

Jan 1, 1970

By A. Tonejc, A. Bonefacic

As can be seen from the phase diagram A1-W1 the equilibrium solubility of tungsten in aluminum is practically nil at room temperature. By quenching from the liquid state (50,000°C per sec), Varic, Burov, and Kolesnicenko2 obtained A1-W solid solutions up to 0.15 at. pct W. The quenched alloys were in the form of foils, 0.2 to 0.3 mm thick. Considering the results of Duwez and Willens,3 it is obvious that this thickness, which makes impossible a sufficiently rapid quenching, was the main reason for the relatively low content of tungsten dissolved in aluminum found by varic.2 he present note shows that the metastable solubility of tungsten in aluminum can be appreciably extended in aluminum-rich A1-W alloys. The quenching technique and the procedure employed for the preparation of the alloys have been described previously.475 The resulting quenched flakes varied in thickness from 1 to 20 µm from experiment to experiment. However, the measurements of the lattice parameters were carried out only with flakes thinner than 5 µm. The areas of quenched flakes were between 0.1 and 15 mm2. The quenched flakes were placed into a 0.3-mm glass capillary tube which was then mounted in a 114.6-mm-diam Debye-Scherrer camera. Straumanis asymmetric film position and nickel-filtered CuKa radiation were used. The lattice spacings were computed taking X(CuKa1) = 1.54050A for resolved and ?(CuKa) = 1.54178A for unresolved doublets. All specimens were rotated at room temperature, 26o +2°C. The lattice parameters were estimated from extrapolation against the Nelson-Riley function. It was estimated that the error in the lattice parameter of the measurements on a single film lies within +0.0004A for lower and about +0.001A for higher concentrations of tungsten. The lattice parameters of the metastable solid solutions A1-W are plotted vs the concentration of tungsten in Fig. 1 together with the parameters measured by previous investigators.' Each point of the present measurements represents a determination of the lattice spacing on different quenched flakes, for a given concentration of tungsten. With experimental accuracy, the lattice parameters of the metastable solid solutions fall on the straight line passing through the already known data.' As estimated from the uncertainties in the lattice spacings of the solid solutions, the alloys were homogeneous within 0.1 at. pct W. The solubility of tungsten in aluminum-rich A1-W solid solutions obtained by a very rapid quenching technique is increased to about 0.95 at. pct W. This value is 6 times greater than the amount known up to now. -he lattice parameters of the resultant aluminum solid solutions with higher concentrations of tungsten than 0.95 at. pct W did not remain constant AUGER electron spectroscopy has been used to clarify the role of impurities in the embrittlement of AISI 3340 steel. Analysis of fracture surfaces has shown that the embrittled condition is correlated with appreciable antimony segregation at grain boundaries. The low temperature (400" to 600°C) temper embrittlement of low alloy steels containing various combinations of Cr , Ni , Sb , Mn , P , Sn , and As has been examined extensively for many years. General reviews of the area have been made by McMahon1 in 1968, LOW' in 1959, woodfine3 in 1953, and Holloman4 in 1946. Recent work by Low, Stein, Turkalo, and LaForce5 has done much in separating the alloy and

Jan 1, 1970

THREE regional meetings are planned for this summer and fall following the spring meeting held under the auspices of the Iron and Steel Committee and the Ohio Section at Cleveland in April and in lieu of a general fall meeting of the Institute. Plans for all of them are maturing rapidly. Excellent programs and. interesting visits to points of local tech¬nical interest are already assured. THE SALT LAKE CITY MEETING This meeting will be under the auspices of the Milling Committee and the Utah Section. It will be one of the features of the joint convention held the week of August 22 to 26 with the Western Division of the American Mining Congress. The Congress will be responsible for the general arrangements and for the program on the first day. The following general committees have been appointed:

Jan 7, 1927

By Robert M. Grogan

Fluorspar is the commercial name for fluorite, which is the mineral having the composition CaF2, calcium fluoride. Its valuable properties are due to its content of fluorine, and it is the only important commercial source of that element. The name is derived from the Latin fluere, to flow, because the mineral melts easily and is a good flux. History The mineral has been known since Greek and Roman times, when it was used for drinking cups and ornamental slabs. Various peoples including the Chinese and the American Indians have carved ornaments from large crystals. Its usefulness as a flux was known to Agricola, who wrote about it in 1546.1 Mining began in England about 1775 15 and at various places in the United States during the period 1820 to 1840.28 Substantial production was achieved first in the period 1888 to 1900 in consequence of the development and widespread adoption of the basic open hearth method of making steel, in which fluorspar is used as a flux. After that, production and usage was stimulated by growth in the steel, aluminum, chemical, and ceramic industries and accelerated by World Wars I and II. The organic fluorides called "Freons" entered the picture in 1931, and the use of anhydrous HF as a catalyst in the manufacture of alkylate for high octane fuel blends began in 1942. The development of the froth flotation process in the late 1920's, a differential flotation scheme for separating fluorspar from galena, sphalerite, and other minerals in the 1930's, and the application of heavy-media concentrating methods to the treatment of low-grade ores in the 1940's were outstanding technological contributions that enabled increased production of fluorspar concentrates. Composition and Properties Fluorite in its purest form contains 51.1 pct calcium and 48.9 pct fluorine. Substitution of small percentages of cerium and yttrium for calcium have been noted.4 Mechanical inclusions of gases and fluids such as petroleum and water, and of other solid minerals such as pyrite, marcasite, and chalcopyrite are common. The fluorspar of commerce contains attached and admixed mineral impurities, chiefly calcite, quartz, barite, celestite, and various sulfides. It is interesting that the purest commercial form in which the mineral is sold, acid grade concentrate, contains a minimum of 97 pct CaF2, and as such is of comparable purity to many reagents used in chemical laboratories. Fluorite has a marked tendency to occur in large, well-formed crystals sometimes six to ten inches on a side. It crystallizes in the isometric system, frequently forming cubic and octahedral crystals or combinations thereof. The mineral also occurs in massive and in earthy forms, and in crusts or globular aggregates with radial fibrous texture. Crystalline fluorspar exhibits a great array of colors, from colorless and water clear to yellow, blue, purple, green, rose, red, bluish and purplish black, and brown. The colors are often arranged in alternating bands parallel to cube faces. They may be altered by exposure to X-rays, heat, ultraviolet light, and pressure, and are caused by a variety of factors including the presence of trace impurities and displaced ions in the lattice. Sometimes the changes induced by X-rays can be reversed by ultraviolet radiation. The mineral has a hardness of 4, and is the model of that hardness on the Mobs scale.

Jan 1, 1960

By Danforth R. Hale

Minerals for electronic and optical uses divide easily into two sections: (1) quartz and (2) minerals other than quartz. Quartz Quartz, having a great usefulness discovered by the radio communication enthusiasts about 1918, has become a subject of amazingly expanded interest in the U.S. over the past decade as a man-made mineral and a $3 million crystal-growing business. An economic summary of the commercial growing of quartz crystals has a place in a handbook directed to the mineral engineering industry when it is remembered that quartz crystals have long been an important commercial mineral, and that the raw material for “cultured quartz”- that is to say, quartz crystals grown through the ingenuity of man-is still natural quartz. Nearly all the natural crystals come from Brazil. The larger pieces which meet rigorous standards of quality are used for electronic and, to a lesser extent, optical components. Smaller pieces and fragments are used for vitreous silica. The need for high quality material in quantity led to U.S. government-sponsored research programs in the 1940s that have resulted in the factory growing of beautiful crystals of prescribed shape, size, and quality. The development of the cultured quartz crystal is typical of man's success in adapting the product of the mine to increasingly sophisticated uses. A remarkable achievement perhaps, but foreshadowed by experiments in 1908 by Giorgio Spezia (1908), an Italian geologist studying the relative effects of temperature and alkaline environment on the solubility of quartz. Modern radio equipment is most often controlled as to frequency by the presence in the circuit of a separately added "crystal"-the 1918 discovery responsible for the existence and growth of the quartz industry. The "crystal" is quartz, but this component is a carefully oriented and prepared slice from a crystal, but not a crystal as recognized by a rock hound or seen in a museum. How quartz operates to control frequencies is not a proper subject for a handbook on industrial minerals, and references should be consulted (Cady, 1964; Mason, 1964). Quartz belongs to that class of materials called dielectrics: those that do not conduct an electric current but permit electric fields to exist and act across them. Quartz shows the "piezo-electric effect," which means that when a quartz plate is mechanically deformed against its natural stiffness, one of its surfaces becomes negatively charged, the other, positively charged. When the plate is released from the stress quickly, the charges disappear as the plate regains its original shape, but because of mechanical momentum the plate deforms in the opposite direction (to a lesser amount) and the surfaces correspondingly become charged in the opposite direction. By coating the two surfaces thinly with metal and attaching flexible wires, these charges may be brought into an electronic circuit. If the surfaces are suddenly electrically charged by movement of current through the wires, the "converse piezoelectric effect" occurs -the plate deforms. Carry the thought further and it is realized that an alternating current flowing through the wires responds to the mechanical oscillation of the plate and is keyed to this oscillation. By controlling the thickness of the plate its mechanical vibration frequency can bevaried through a wide range. One type of quartz plate, called the AT-cut, having a precisely defined orientation with respect to the crystallographic axes of the crystal, vibrates on a microscopic scale much as a book would deform when placed flat on a table and the top cover moved parallel back and forth with the hand. There are at least 17 other orientations which have been studied, some of

Jan 1, 1975

By Ray W. Carpenter, Ralph Hultgren, Raymond L. Orr

Heats of formation of Au-Zn alloys of compositions Au3Zn and AuZn were rneasured at several temperatures by liquid tin solution calorimetry. The data for Au3Zn show that much smaller heat and entropy effects are associated with the a2- a1 transformation than for the a1 - a transformation. This result is consistent with reported X-ray diffraction studies which indicate that the a1 and (a2 phases have ordered structures which only slightly differ, whereas the a phase is disordered. The heat of formation of AuZn(ß') does not change significantly between 322o and 8000 K, confirming that the ß' alloy remains highly ordered to high temperatures. Not many measurements have been made of the energies of order-disorder transformations in alloy phases. In many cases these energies may be conveniently determined by measuring heats of formation as a function of temperature. Many alloy phases approximately obey Kopp's law of additivity of heat capacities; as a consequence their heats of formation do not change with temperature. In ordered alloys, however, a decrease in degree of order with increasing temperature will contribute an endothermic component to the heat of formation. Thus, for ordered phases where other anomalous contributions to heat capacity in the alloy or its pure components are absent, a measured change in the heat of formation may be attributed to the energy of disordering. A portion of the Au-Zn phase diagram1" is shown in Fig. 1. The composition AuZn(ß') has a well-ordered superlattice structure of the CsCl type at room temperature. The alloy is considered to remain ordered to its melting point,1 although, from X-ray diffraction data and electromotive force measurements of zinc activities, Terpilowski3 concluded that considerable disordering began at -673°K. The Au3Zn composition is a disordered fee solid solution (a) at high temperatures. Between 693o and 543oK, the ailoy orders to form the a1 phase, having a structure based on the L12(AuCu3) type, but with a regular distribution of ordering faults in the c direction, making it tetragonal. Below 543oK, the alloy orders further by means of slight atomic shifts, without diffusion, yielding a complex long-period orthorhom-bic superlattice structure, a2.4-7 Heats of formation of Au3Zn(a2) and AuZn(ß') were measured at 363°K by Biltz et al.8 by aqueous solution calorimetry. Heat capacities of several alloys between 14.9 and 38.4 at. pet Zn in the range from 373" to 723°K were measured by Iwasaki ef al.6 Stoichiometric Au3Zn, however, was not included in the alloys measured, the nearest composition being 26.1 at, pet Zn. Also, the heating rate used for the measurements, 2 deg per min, may not have permitted equilibrium to be reached in the neighborhood of the transformations. Heat contents of solid and liquid AuZn were measured between 488o and 1138°K by Kubaschewski.9 It was decided to determine the ordering energies of Au3Zn and to check on the possible disordering of AuZn by measuring the heats of formation of these alloys at several temperatures. The present paper reports measurements by liquid tin solution calorimetry of the heats of formation of the three phases of Au3Zn at temperatures within their regions of stability, and of AuZn at a low (322°K) and a high (800°K) temperature. EXPERIMENTAL Alloy Preparation and X-Ray Examination. Ten-gram ingots of Au3Zn and AuZn were prepared by melting weighed amounts of gold (99.95 pct Au) and zinc (99.99 pet Zn) together in sealed evacuated Vycor tubes at 1060°K, followed by rapid quenching. The resulting ingots were homogenized at 900°K for 10 days. The Au3Zn alloy lost no weight in preparation, the loss from the AuZn alloy was enough to introduce an uncertainty of only 0.1 at. pet in its composition. Filings for X-ray examination were taken from various parts of each ingot and strain-annealed at 723°K for 20 min in vacuo. The Au3Zn filings were quenched rapidly to retain the disordered phase. Diffraction patterns were determined with an X-ray dif-fractometer using copper Ka radiation.

Jan 1, 1968

By AIME AIME

LOCAL COMMITTEES. GENERAL RECEPTION COMMITTEE.-Mr. and Mrs. H. S. Chamberlain, Mr. and Mrs. J. T. Lupton, Mr. and Mrs. T. H Lasley, Mr. and Mrs. R. S. Faxon, Mr. and Mrs. H. Clay Evans, Mr. and Mrs. C. E. James, Mr. and Mrs. B. F. Thomas, Air. and Mrs. H. S. Probasco, Mr. and Mrs. W. M. Lasley, Mr. and Mrs. L. W. Llewellyn, Mr. and Airs. T. G. Montague, Mr. and Mrs. E. B. Thomasson, Mr. and Mrs. C. F. Milburn, Mr. and Mrs. C. A. Raht, Mr. and Mrs. C. C. Notting¬ham, Mr. and Airs. Z. C. Patten, Mr. and Mrs. Willard Warner, Mr. and Mrs. S. R. Read, Mr. and Mrs. Carl White, Mr. and Mrs. M. M. Allison, Air. and Mrs. C. E. Buck, Mr. and Airs. H. F. Temple, Air. and Mrs. M. M. Hedges, Mr. and Airs. X. Wheeler, Mr. and Airs. John A. Patten, Air. and Airs. N. T. Montague, Mr. and Mrs. R. H. Williams, Mr. and Mrs. T. R. Preston, Mr. and Airs. Morrow Chamberlain, Mr. and Airs. T. C. Thompson, Mr. and Airs. T. L. Montague, Mr. and Mrs. O. L. Hurlbut, Air. and Mrs. C. A. Lyerly, Mr. and Mrs. Garnett Andrews, Air. and Mrs. M. B. Ochs, Mr. and Airs. Webster James, Mr. and Mrs. D. P. Montague, Mr. and Mrs. Z. C. Patten, Jr., Mr. and Mrs. W. A. Sadd, Mr. and Mrs. J. B. Pound, Air. and Mrs. George D. Lancaster, Air. and Airs. J. F. Johnston, Mr. and Mrs. R. W. Barr, Air. acrd Mrs. W. B. Davis, Mr. and Airs. Douglas Baxter, Air. and Mrs. W. R. Crabtree, Mr. and Mrs. Lewis M. Coleman, Mr. and Mrs. Newell Sanders, Mr. and Mrs. E. Y. Chapin, Mr. and Mrs. W: B. Riddell,. Mr. and Mrs. J. B. Frazier, Mr. and Mrs. John A. Moon, Mr. and Mrs. C. D. Mitchell, Dr. and Airs. J. H. Race, Mr. and Airs. A. W. Chambliss, Mr. and Mrs. J. P. Smartt, Mr. and Mrs. J. F. Tarwater, Mr. and Mrs. L. D. Drewry, Capt. and Mrs. A. B. Putnam, Mrs. Minnie C. Ewing, Mr. G. F. Meehan, Mr. Sam S. Gerstle, Mr. P. A. Brawner, Mr. C. M. Preston, Air. George M. Guild, Mr. L. M. Mansfield, Dr. J. W. Johnson, Dr. J. AI. Hogshead. EXECUTIVE COMMITTEE.-H. S. Chamberlain, Chairman; H. S. Probasco, C. M. Preston, H. Clay Evans, J. T. Lupton, M. B. Ochs, C. C. Nottingham, Al. Al. Alli¬son, R. S. Faxon, C. E. James, C. A. Raht. EXCURSION TO CHICKAMAUGA PARK.-T. C. Thompson, Chairman; B. F. Thomas, G. F. Meehan, Morrow Chamberlain, W. J. Bass, J. K. McGoodwin. EXCURSION TO HALES BAR LOCK AND DAM.-R. H. Williams, Chairman; John A. Patten, Newell Sanders, George M. Guild, Capt. A. B. Putnam. EXCURSION TO ROCK-WOOD.-F. H. Clymer, Chairman; T. L. Brown, T. A. Wright, J. P. Tarwater, T. L. Peterman. INSTITUTE HEADQUARTERS.-The Hotel Patten. THE first session, held Thursday evening, Oct. 1, in the Banquet Hall of the Hotel Patten, was called to order by Capt. H. S. Chamberlain, Chairman of the Local Committee, who, in behalf of the city of Chattanooga, extended a hearty welcome to the members and guests of the Institute.

Nov 1, 1908

By R. Ehrlich, F. E. Crane

A consolidated porous medium is mathematically modeled by networks of irregularly shaped, interconnected pore channels. Mechanisms are described that form residual saturations during immiscible displacement both by entire pore channels being bypassed and by fluids being isolated by the movement of an interface within individual pore channels. This latter mechanism is shown to depend strongly on pore channel irregularity. Together, these mechanisms provide an explanation for the drainage-imbibition-hysteresis effect. The calculation of steady-state relative permeabilities, based on a pore-size distribution obtained from a Berea sandstone, is described. These relative permeability curves agree qualitatively with curves that are generally accepted to be typical for highly consolidated materials. In situations where interfacial effects predominate over viscous and gravitational effects, the following conclusions are reached. 1. Relative permeability at a given saturation is everywhere independent of flow rate. 2. Relative permeability is independent of viscosity ratio everywhere except at very low values of wetting-phase relative permeability. 3. Irreducible wetting-phase saturation following steady-state drainage decreases with increasing ratio of nonwetting- to wetting-phase viscosity. 4. lrreducible wetting-phase saturation following unsteady-state drainage is lower than fir steady-state drainage. 5. Irreducible nonwetting-phase saturation 101lowing imbibition is independent of viscosity ratio, whether or not the imbibition is carried out under steady- or unsteady-state conditions. Experiments qualithtiveIy verify the conclusions regarding unsteady-state residual wetting-phase saturation. Implications of these conclusions are discussed. INTRODUCTION Natural and artificial porous materials are generally composed of matrix substance brought together in a more or less random manner. This leads to the creation of a network of interconnected pore spaces of highly irregular shape. Since the geometry of such a network is impossible to describe, we can never obtain a complete description of its flow behavior. We can, however, abstract those properties of the porous medium pertinent to the type of flow under consideration, and thus obtain an adequate description of that flow. Thus, the Kozeny-Carmen equation, by considering a porous medium as a bundle of noninterconnecting capillary tubes, provides an adequate description of single-phase flow. With the addition of a saturation-dependent tortuosity parameter in two-phase flow to account for flow path elongation, the Kozeny-Carmen equation has been used to predict relative permeabilities for the displacement of a wetting liquid by a gas. 1-5 It has long been recognized that relative permeability depends not only on saturation but also on saturation history as we11.6,7 Naar and Henderson8 described a mathematical model in which differences between drainage and imbibition behavior are explained in terms of a bypassing mechanism by which oil is trapped during imbibition. Fatt9 proposed a model for a porous medium that consisted of regular networks of cylindrical tubes of randomly distributed radii. From this he calculated the drainage relative permeability curves. Moore and slobod,10 Rose and Witherspoon,11 and Rose and Cleary12 each considered flow in a pore doublet (a parallel arrangement of a small and large diameter cylindrical capillary tube). They concluded that, because of the different rates of flow in each tube, trapping would occur in one of the tubes; the extent of which would depend upon viscosity ratio and capillary pressure. They limited

Jan 1, 1970

By AIME AIME

I am happy to welcome you to the twenty-third conference of the National Open-Hearth Committee, and our joint conference with the Blast Furnace Committee, of the American Institute of Mining and Metallurgical Engineers. It is appropriate that, for our fifteenth year anniversary, we should meet in the hotel and the city where this Open-Hearth Committee was inaugurated in 1925. At that first meeting, only a handful of men from a number of steel companies met to discuss ways and means to start a movement to improve the practical and metallurgical technique of open-hearth operations among independent manufacturers, as the United States Steel Corporation had carried on for many years.

Jan 1, 1940

By Kenneth R. Hancock

Iron oxides are unique in that they are the only significant colored mineral found in a natural state suitable for use as a pigment after being pulverized to pigmentary size. The current world production of iron oxide pigments is estimated by the author to be between 499 and 590 kt (550,000 and 650,000 st) based on 1979 data. The fact that highly colored natural deposits of iron ore are found throughout the world accounts for its use in prehistoric man's artistic cave paintings. These early artists did not realize that they had established man's first paint test fence which now has some 20,000 years of exposure. In addition to abundance, constituting about 7 % of the earth's crust, iron oxides have the advantages of low cost, permanency, and are not toxic. Through the centuries, succeeding civilizations have utilized iron oxides as a major source for decoration and protection when coloring was desired. In the last century the chemical industry has improved on nature by developing a complete range of synthetic iron oxide pigments which surpass the pigments produced from natural iron ores in uniformity, color quality, and chemical purity. In the United States alone, the combined production of natural and synthetic iron oxides produced sales of over $28,000,000 in 1970 (Stipp, 1970) and increasing to $97 million by 1980 (Spinrad, 1980). Nomenclature With the increasing importance of the synthetic iron oxides it is necessary to make a distinction between the natural or mineral pigments and the synthetic pigments. Natural pigments are those products which are derived from selected ores and should not be confused with iron ores mined for steel production. Iron ores that are mined for steel must be capable of being mined and reduced to iron on a commercial basis. These ores are selected on the basis of iron content and processing economics. It is therefore unusual when iron ores for steel production are suitable for use as mineral pigments. Natural pigment ore sources are selected for their special physical-chemical properties and can command a premium price. Synthetic pigments, and in this instance iron oxides, are those pigments produced from basic chemicals. Through chemical synthesis pigmentary sized particles are produced as opposed to comminution, the major procedure common to all natural iron oxide pigments. Classification An important characteristic of a pigment is its color and, therefore, a logical separation can be made on this basis. A. Yellow Iron Oxide Pigments 1. Natural mineral origin a) Goethite b) Lepidocrocite c) Ochres d) Siennas e) Limonite 2. Synthetic pigments a) Goethite B. Red Iron Oxide Pigments 1. Natural mineral origin a) Hematite b) Siderite (calcined) c) Pyrites (calcined) 2. Synthetic pigments a) Hematite C. Brown Iron Oxide Pigments 1. Natural mineral origin a) Umbers b) Limonite (calcined) c) Siderite (calcined) d) Goethite (bog ore or sulfur mud) 2. Synthetic pigments a) Blends of hematite, goethite, and magnetite

Jan 1, 1983