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By Claus G. Goetzel

SOME of the reactions and procedures upon which modern techniques in the production of metal powders are based were used for 2000 years by the ancients to reduce iron and other metals from their ores. Despite this, however, the art of powder metallurgy is relatively new and probably stems from the introduction of incandescent electric lamp filaments. Attempts to improve upon Edison's carbon filaments led to the production, in order. of metallic filaments of osmium. tantalum.. and finally of tungsten, which ha, replaced the others and is the commercial product of today. These metallic filaments were originally manufactured by the extrusion and sintering of a mixture of the metal or its oxide with a reducing agent which also served as a binder. Further progress in this direction was in the pressing of a small percentage of nickel with the tungsten. The sintering operation was carried out in an atmosphere of hydrogen, at a tem-

Jan 1, 1944

By John D. Morgan

Uncertain world conditions of the present time require that this country be prepared to meet: 1) all out nuclear war with attack on the U. S.; 2) limited wars; 3) political, economic, and/or pyschological warfare. Our present position as a major world power derives in large measure from our free institutions and great industrial productivity, and this productivity in turn depends on a continuing flow of raw materials-metals, minerals, fuels, and agricultural products. The U. S., with only about 6 pct of the world's population, uses from one to two thirds of the world's annual supplies of most metals and minerals. The U. S. strategic materials stockpiling program is designed to enhance our national security position: as stated in the preamble of the Stock Piling Act, to decrease and prevent wherever possible a dangerous and costly dependence upon foreign nations for supplies of strategic and critical materials in times of national emergency.

Jan 8, 1960

By Marling J. Ankeny

MINING research in the U. S. today is indeed complex, whether it involves the Government, a small private concern, or a large one. And it promises to become more so, despite great advances already made in developing equipment and technology. The U. S. Bureau of Mines is committed to place greater emphasis on mining research as expressed in a recent policy statement to Congress on the "Long Range Minerals Program," by Secretary Fred A. Seaton, quoted above.

Jan 1, 1958

By F. M. d’Heurle

Films of molybdenum have been prepared by sputtering onto oxidized silicon substrates. The resistivity. lattice parameter, orientation, and grain size were studied as a function of substrate temperature and substrate bias. Under normal sputtering conditions, the resistivity of the films was found to be quite high (600 x 10 ohm-crn). However, with the use of the negative substrate bias of 100 v and a substrate temperature of 350°C, films weve produced with a resistivity of ahout twice that of bulk molybdenum. The lattice parameters measured in a direction nornzal to the surface of the films weve found to be gveatev than the bulk value. This was interpreted as being at least partly due to the presence of compressive stresses. The effects of annealing in an Ar-H atmosphere were studied in terms of diffraction line width, lattice parameter, and resistivity. BECAUSE of its relatively low bulk resistivity (5.6 x 106 ohm-cm)' molybdenum is potentially interesting as a thin-film conductor in integrated circuits. An additional feature which makes it attractive for this purpose is its low coefficient of expansion (5.6 x KT6 per "c),' which is fairly well matched to that of silicon (3.2 x 10 per c). It is possible to deposit molybdenum films by evaporation but generally films produced in this manner have a high resistivity. In order to achieve resistivities close to bulk value, Holmwood and Glang found it necessary to operate in a vacuum of about 107 Torr and to maintain the substrates at 600 C during film deposition. Sputtered molybdenum films have been examined by Belser et a1.7 and, recently, by Glang et al.' This paper describes the results of an attempt to extend some of that work and examine the effects of annealing and getter sputtering on the physical and structural properties of the films produced. SPUTTERING APPARATUS AND PROCEDURE The apparatus used for most of the film sputtering work described here consisted of two "fingers" serving as anode and cathode, respectively, which were mounted within an 18-in.-diam glass chamber. A liquid nitrogen-trapped 6-in. diffusion-pump system was used to achieve a vacuum of about 1 x 107 Torr within the chamber prior to sputtering. The essential features of the equipment are shown in Fig. 1. Cathode and anode fingers are stainless-steel tubes isolated from the top and bottom plates by Teflon collars. In order to limit the discharge to the space between anode and cathode, each finger is surrounded by an aluminum hield, at ground potential, having an internal diameter 18 in. larger than the outside diameter of the finger. The cathode and anode fingers are 6 and 4 in. in diam, respectively. A 116-in.-thick sheet of molybdenum is brazed with a 10 pct Pd, 58 pct Ag, 32 pct Cu alloy to a copper disc which is mounted by means of screws and a large 0 ring onto the lower end of the cathode finger. The disc is cooled during sputtering by water circulation inside the finger. The use of several feet of plastic tubing for the water input and outputg reduces leakage to ground to less than 1 ma when the cathode potential is raised to 5 kv. The upper end of the anode finger is terminated by a brazed-on copper block. A variety of specimen holders can be easily mounted on the upper face of this block. Substrate heating or cooling is achieved by use of an appropriate unit attached to the lower face of the same block. Heating is achieved by means of cartridge-type heaters and cooling by copper coils fed with forming gas under pressure. The inner chamber of the specimen finger constitutes a small vacuum chamber of its own which is evacuated by an auxiliary mechanical pump in order to limit heating element oxidation and heat transfer by convection currents. An advantage of the finger arrangement is the absence of cooling and heating coils and wires within the main chamber. The stain less-steel shutter is useful to establish a discharge for cleaning the cathode at the beginning of each sputtering run. Water cooling of the shutter reduces heating and the out-gassing of impurities which might condense on the nearby substrates. Unless otherwise specified, the substrates used in these experiments were 1-in.-diam oxidized silicon wafe:s, 0.007 in. thick, having an oxide thickness of 6000A. The substrate holders were large copper discs onto the surface of which a number of molybdenum discs, 116 in. thick and 78 in. in diam, were brazed. The wafers were clamped to the molybdenum discs

Jan 1, 1967

By Arnulf Muan, Carlos Landolt

Equilibria involving Cu-Pt alloys, copper oxides, and atmospheres of known ox2gen pressures have been determined at 1000' and 1200 C. The data obtained have been used to calculate activity-composition relations in the alloys. A moderate negative deviation from ideality is found. At high copper concentrations, the results of the present study are in good agreement with those of previous investigators, whereas at low copper concentrations the activities obtained in this investigation are slightly higher than those reported previously. The present study is part of a research program dealing with the determination of phase relations and thermodynamic properties of copper-containing systems at high temperatures. The information available for such systems is very scanty, particularly for copper oxides and their combinations with other oxide components. Platinum is commonly used as a container in studies of oxide equilibria. To evaluate quantitatively the extent of reaction between the oxide and the container, a knowledge of activity-composition relations in Cu-Pt alloys is necessary. Such data are not available for Cu-Pt alloys in the temperature range of particular interest in the present research program, and particularly for alloys low in copper. Studies of various aspects of the systems Cu-Pt and Cu-0 have been reported in previous literature. The system Cu-Pt is known1 to form a continuous solid-solution series above 812.C, whereas ordered phases are present in certain composition ranges at lower temperatures. Thermodynamic data for the system have been reviewed by Hultgren et al.,' who presented free energies of mixing at 65Oo C, mainly derived from electromotive force cell measurements by Weibke and Matthes.3 Enthalpies of mixing at 640°C have been obtained by Oriani and Murphy4 with liquid tin calorime-try. Their results differ considerably from those derived from the temperature dependence of the data of Weibke and Matthes. Thermodynamic data for the disordered alloys have been obtained by Assayag,5 and more recently by Schmahl and Minzl,6 by Myles and Darby,7 and by McCormack, Myers, and Saxer.8 The two latter sets of data7'' became available after the present study was completed. In the system Cu-0+ two oxides are stable at high temperatures, CuO and CuzO+ each having only minor deviations from stoichiometry. Equilibria in the liquidus temperature region of the system Cu2O-CuO have been studied by Roberts and systemsmyth,9'10CuzO-CuO by Vogel and ocher,I1 by Osterwald,12 and recently the the present authors.13 The system is of the eutectic type with a eutectic temperature of 1083.C The composition of the eutectic liquid corresponds to Xcu0 = °.44, and the oxygen pressure of the coexisting gas phase is Po2 = 0.55 atm.13 Equilibrium oxygen pressures for coexistence of solid CuO and solid Cu2O have been determined by Schmahl and Muller,l4 by Gadalla, Ford, and white,l5 by Bidwell,16 and recently by the present authors.13 There is reasonably good agreement among the various sets of data. Free energies of formation of Cu2O(s) from the elements have been derived by Tretyakov,17 by Bidwell,16 by Kiukkola and wagner,18 by Pal'guev and Neuimin," and by Steele and Alcock,20 There is particularly good agreement among the latter three1'-20 sets of data. THEORETICAL BASIS Consider a subsolidus isothermal section of the system Cu-Pt-0, as shown in Fig. 1. Two phase as-

Jan 1, 1970

By Charles F. Hickey, Eric B. Kula

Thermomechanical treatments applied to the maraging steels include a) cold working in the austenitic condition at 650°F, followed by transformation to martensite and aging, b) cold working in the murtensitic condition and aging, and c) cold working in the aged condition with and without subsequent reaging. The strength increases in these steels are very small compared to the increases observed in conventional carbon and alloy steels. The changes that are observed are compatible with the strengthening mechanisms operative during thermomechanical treatment of conventional steels, however. Differences are caused by the absence of a carbide precipitate and the low work-hardening rate in both the solution-treated and the aged conditions. ThE 18 pct Ni maraging steels represent a class of steels which are finding great interest for high-strength applications.1~2 They are essentially carbon-free, and contain 7 to 9 pct Co, 3 to 5 pct Mo, and 0.2 to 0.8 pct Ti. Although austenitic at elevated temperatures, they can be air-cooled to room temperature to form a martensite, which because of the absence of carbon is relatively soft. On subsequent reheating age hardening occurs and strength levels of 250 to 300 ksi yield strength can be attained. These steels appear to be particularly suitable for studying the response to various thermome-chanical treatments for additional reasons other than the obvious one of attempting to improve their already attractive properties. Thermomechanical treatments can be defined as treatments whereby plastic deformation, generally below the recrystal-lization temperature, is introduced into the heat-treatment cycle of a steel in order to improve the properties. With an absence of intermediate transformation products on air cooling the maraging steels have good hardenability and hence can readily be cold-worked in the austenitic condition prior to transformation to martensite. Further, they can be worked in the martensitic condition prior to aging, and even can be deformed in the fully aged condition. Finally, it is of interest to compare their re- sponse to that of the more conventional alloy and carbon steels, where the role of carbides is important in the strength increase by thermomechani-cal treatments. The thermomechanical treatment of conventional steels has been the subject of a recent review.' I) MATERIALS AND PROCEDURE The steel used in this investigation was a commercially produced vacuum-melt heat, which had been rolled to 0.090 in. and mill-annealed. The composition of the alloy was as follows: 0.02 C, 0.08 Mn, 0.10 Si, 0.009 P, 0.009 S, 18.96 Ni, 7.34 Co, 5.04 Mo, 0.29 Ti, 0.05 Al, 0.004 B, 0.01 Zr, and 0.05 Ca. Unless otherwise stated the heat treatments used were the standai-d solution treatment at 1500°F for 1 hr, air cool, followed by a 900°F, 3 hr age. In this condition, the material exhibited 232 ksi yield strength and 239 ksi tensile strength. Mechanical properties were determined by Vicker's hardness measurement (20 kg) and by tensile tests on standard 1/2-in.-wide, 2-in.-gage-length sheet tensile specimens. Notch tensile tests were run using the 1-in.-wide NASA type, edge-notched specimen.4 Fracture-toughness determinations were made on 3-in.-wide, center-notched, fatigue-cracked specimens, following the recommendations of the ASTM Committee on Fracture-Toughness Testing.4 An electric-potential technique was used for measuring the crack size at the onset of rapid crack propagation5 which is necessary for calculations of Kc, the critical stress-intensity factor under plane-stress conditions. The critical stress-intensity factor under plane-strain conditions KI, was also calculated, using the stress at which the first observable crack growth occurred. 11) RESULTS A) Cold-Worked in the Austenitic Condition. The reported M, temperature for the 18 pct Ni maraging steel is about 310°F.1 Therefore, a temperature of 650°F was selected as suitable for rolling in the austenitic condition. Specimens were solution-treated at 1500°F for 1 hr, air-cooled to 650°F, and rolled varying percentages from 0 to 60 pct, at 20 pct reduction per pass. Tensile and hardness properties after aging at 900°F for 3 hr are shown in Fig. 1. The tensile strength increases from 253 to 271 ksi and the yield strength from 247 to 265 ksi as a result of a reduc-

Jan 1, 1964

Jan 1, 1910

By Wallace E. Pratt

UNDER the stimulus of war psychology the American public has grown confused and jittery in its thinking on the subject of this nation's petroleum resources. This confusion arises from the failure of the average citizen, and even of many leaders in government, in our armed forces, and in the petroleum industry itself, to distinguish between our proved reserves of petroleum in the several oil-producing states and the total petroleum re- sources available to this nation. Leaders and public alike examine the accepted estimates of our proved reserves and thoughtlessly conclude that these estimates represent the total of our petroleum resources. Our fears are aggravated if we turn to the statistics on oil-finding and observe that the discovery of new reserves has waned decidedly in recent years. This confusion is dangerous because, under its influence, ill - considered policies spring up and flourish, choking out the most valuable fruits of the long experience of the American petroleum industry.

Jan 1, 1944

By Carl F. Cline, Richard R. Vandervoort, Willis L. Barmore

THE objective of this investigation was to determine the high-temperature plastic deformation behavior of stoichiometric uranium mononitride as a function of stress and temperature. Interest in the properties of this material stems from its potential use in high-temperature nuclear reactor systems. The creep of other refractory compounds containing uranium (e.g., U02, UC) has been studied by various investigators.1"4 Fassler et al.4 have studied the creep of UN in vacuum from 1100° to 1350°C at stresses of 6000 and 8000 psi. In the present work, the creep of stoichiometric UN was investigated from 1500° to 1800°C at stresses from 2000 to 5000 psi in a partial pressure of 200 mm of nitrogen. The specimens were prepared by hot isostatic pressing of UN powder into cylinders of $ in. diam by about 1 in. high. After pressing, the specimens were heat-treated in nitrogen at 1900°C for 50 hr. The densities of individual specimens were determined by the water displacement method. All specimens were theoretically dense, based on a value of 14.32 g per cu cm.5 Principal metallic impurities in ppm by weight were: Ca, 50; Cu, 5; Fe, 30; Mg, 5; Ni, 10; and Si, 20. Oxygen content was 400 ± 50 pprn and carbon content was 100 i25 ppm. The nitrogen content was 5.56 ±0.05 wt pct. The average grain size for five specimens, as determined by the intercept method, was 0.14 i 0.01 mm. One specimen had a grain size of 2.0 mm. This large grain size is an anomaly, since all specimens had the same chemical and thermal histories. Specimens of 1/4 in. diam by 1/2 in. high were creep-tested in compression in a clam shell furnace heated by W-25 pct Re sheet elements. Temperature was measured to ilODC by an optical pyrometer which had been calibrated by a standard source. The distance between fiducial marks on the specimen was measured before placement into the furnace. The furnace chamber was evacuated to 10-5 Torr and back-filled to 200 mm N2. After heating rapidly to temperature, the load was applied and controlled to ±2 pct by an Instron testing machine. Upon initial loading, the specimen was deformed until a constant crosshead rate was obtained, then quenched to room temperature, remeasured, and replaced in the furnace. Upon subsequent reloading at temperature, the crosshead rate was constant for the selected condition indicating steady-state creep.

Jan 1, 1969

By AIME AIME

THE annual fall meeting of the Institute of Metals and the Iron and Steel divisions, in conjunction with the American .Society for Steel Treating and the Metal Congress and Show, at Boston was from many standpoints the most successful we have had to date. While many faces were missing from the various gatherings, the Institute registration reached the high mark of 324 members and guests. Cooperating with the Steel Treaters were also the American Society of Mechanical Engineers, the Society of Automotive Engineers and the American Welding Society. ,The meeting was, as usual, a three-ring circus with technical sessions 'galore, plant .trips, visits to the Exposition, social events such as lunch- eons and dinners as well as entertainment for the ladies present.

Jan 1, 1931

By Serge L. Delinois

President Kennedy said that before 1970 this country will send a man to the Moon and get him back on Earth safely. Today, no one doubts that his promise will become reality. He who asks "What, then, is next for us in space?" is no longer considered a dreamer. And one of the very first things he discovers in trying to answer this question is that in whatever does come next, geologists and mining engineers will play a prominent role. This will be true not only in the conquest of the Moon, but also in that of the whole solar system. After 1970, it is very likely that a permanent lunar camp will be established. This beachhead, supplied entirely from Earth, in the beginning, will gradually develop into a research complex where virtually all scientific disciplines are investigated.

Jan 1, 1966

By Clarence O. Babcock

Model pillars of limestone, marble, sandstone, and granite, with length-to-diameter (LID) ratios of 3, 2, 1, 0.5, and 0.25 (0.286 for granite), were broken in axial compression to determine to what extent an increase in end constraint increased compressive strength. Radial end constraints of 13 to 23% of the average axial stress in the pillar, produced by solid steel rings bonded with epoxy to the ends of dogbone-shaped specimens, increased compressive strength somewhat above that of cylindrical pillars without ring constraint. However, when the results were compared with those obtained by other investigators for straight specimens of several rock types taken collectively, with LID ratios greater than 0.5, the resulting strengths were not significantly different. Thus, the amount of end constraint produced by the solid steel rings was about the same as that produced by the friction from the steel end plates. In other tests, a radial prestress of 3000 or 5000 psi was applied prior to axial loading by adjustable hardened steel rings to increase the constraint above that obtained for the solid rings. The average radial constraint stress, expressed as a percentage of the average axial pillar stress at failure for the 3000 psi prestress, was 54.3% for limestone, 40.3% for marble, 44.7% for sandstone, and 23.4% for granite. The average radial constraint stress, expressed as a percentage of the average axial pillar stress at failure for the 5000 psi prestress, was 74.2% for limestone, 51.2% for marble, 61.6% for sandstone, and 29.7% for granite. These constraints increased the compressive strength significantly above the strength of straight specimens and solid-ring constrained specimens. These results suggest that large horizontal stresses in orebodies mined by the room-and-pillar method should increase the strength of the pillars and allow an increase in ore recovery by a reduction of pillar size when major structural defects are absent. One important objective of the U.S. Bureau of Mines (USBM) mining research program is the rational design of mining systems. In the design of room-and-pillar mining operations, pillar strength is a fundamental variable. It is customary to estimate this strength from uniaxial compression tests of rock samples and to correct this value for the length-to-diameter (LID) ratio of the in-situ pillar. This method of estimating pillar strength corrects for pillar shape but does not consider the effect of a large horizontal in-situ stress field that sometimes exists in underground formations. The purpose of the work covered in this report was to determine to what extent the compressive strengths of model pillars of relatively brittle rock loaded in axial compression were affected by lateral end constraint. In previous work, Obert l used solid steel rings bonded to the ends of dogbone-shaped specimens to study the creep behavior of three quasi-plastic rocks -salt, trona, and potash ore - during a test period of 1000 hr. These rings provided radial constraint during the loading cycle of 20 to 50% of the axial stress for specimens with LID ratios of 2, 0.5, and 0.25. He concluded that (1) "for a quasi-plastic material the end constraint strongly affects the specimen strength, and (2) as D/L increases (length-to-diameter decreases), the specimens lose their brittle characteristics and tend to flow rather than fracture." He also concluded that model pillars constrained by rings were better for use in predicting the strength of mine pillars than either cylindrical or prismatic specimens. This conclusion appears to be valid where mine pillars, roof, and floor are a single structural element. In the present study, 460 specimens of four relatively brittle rocks — limestone, marble, sandstone, and granite - were tested to failure. The study consisted of two parts: (1) the effect on the compressive strength of end constraint produced during the axial loading cycle by solid steel rings bonded with epoxy to the ends of the specimens, and (2) the effect on the compressive strength of increased end constraint produced in part by a prestress applied prior to axial loading and in part by lateral expansion of the specimen during the loading cycle. The first part of this study was reported in some detail earlier.2 EXPERIMENTAL PROCEDURE AND EQUIPMENT Model rock pillars of the sizes and shapes shown in Fig. 1 were broken in axial compression when the ends were constrained as shown in Fig. 2. he straight specimens were broken without ring constraint. The specimens of dogbone shape were broken with (1) solid

Jan 1, 1970

By C. J. Bauer

WHEN the pipe lines from the Middle East to the Mediterranean are completed, the Middle East supplies will relieve the strain on Western Hemisphere petroleum resources, part of which are now shipped for Eastern Hemisphere use. A sketch of the world petroleum situation as it appears today and in the immediate future will help in understanding the future place of Middle East oil supplies. Anticipated 1951 world demand is slightly under four billion barrels. To meet this requirement, crude output and refinery runs throughout the world (including Russia) must be increased about two million barrels per day above the average of 1947. This increment, together with pipe lines, tankers, and other facilities, will require in excess of ten billion dollars of new capital in the next four years. We are, therefore, looking forward to the greatest expansion program in the history of the industry.

Jan 1, 1948

By Harold M. Feder, Robert V. Schablaske, Irving Johnson, Ewald Veleckis

The stoichiometry, structure, and stability of the internzediate phases formed between zinc and some of the rare earth (RE) metals were systematically exarnined by means of a recording effusion balance and X-ray diffraction analyses. In the La-, Ce-, PY-, Nd-, and Y-Zu systems, at or below about 600 C, the following sequences of phases (REZnx) were found: La, x = 1, 2, 4.0, 5.25, 7.3, 17/2, 11, and 13.0;' Ce, x = 1, 2, 3, 11/3, 4.3, 5.25, 7.0, 17/2,* and 11; Pr,x = 1,2, 3, 11/3 ,* 4.3, 5.3(?), 7.0, 17/2,* and 11; Nd,x = 1,2, 3,* 11/3,* 4.3, 6.5, 8.5,* and 11; Y,x = 1,2,3, 11/3, 4.5, 5.0, 17/2,* and 12.* The structure types of all these phases were classified. In addition, lattice parameters were obtained for the first time for the pluses denoted by asterisks. In the absence of de tectable valency or electronegativity effects the systesnatic trends in the results have been ascribed to the effects of' the lanthanide contraction. For example, the maximum number of zinc atoms in the coordination polyhedron surrounding the RE atom decreases from twenty-four to twenty-two to twenty as the size of the RE atom decreases. THE structures and compositions of a great many intermetallic phases (e.g., the Laves phases) are known to be based primarily, but not exclusively, on the space-filling efficiency of various modes of packing together atoms of different sizes. The valencies and electronegativities of the constituent atoms are, however, also influential. In extreme cases hypothetical intermetallic phases which fulfill the efficient spacefilling requirements may not be present in the constitutional diagram because of thermodynamic instability brought about by the operation of valency or electronegativity factors. Hence, for a detailed study of the influence of atomic size on alloy structure and composition, it would be desirable to minimize variations of valency and electronegativity. The intermetallic phases formed by the rave earths (RE) with some common partner offer an excellent opportunity for isolating the effects of size from those of valency and electronegativity. The rare earths exhibit a large, but smooth, decrease in size (the lanthanide contraction) in the series from lanthanum to lutetium when inter comparison is made for a common valence state, e.g., isolated atoms or trivalent ions. The elements yttrium and scandium are frequently included as pseudo rare earths; their sizes place them in the vicinity of dysprosium and lutetium, respectively. The electronegativities of RE elements vary by less than 10 pet. The trivalent state is the most common; however, the well-known tendency of cerium, praseodymium, and terbium to achieve higher valencies, and of samarium, europium, and ytterbium to seek lower valencies, requires that caution be exercised in the assumption of equal valencies. In the present study the existence, constitution, and structure of each of the numerous intermediate phases formed by zinc with lanthanum, cerium, praseodymium, neodymium, or yttrium were examined systematically and in detail. The investigation was conducted by a recording effusion balance technique and by X-ray diffraction analysis. The results enrich our knowledge of the phase diagrams of these systems. In addition, they present some clear-cut evidences of the operation of the size factor alone. EXPERIMENTAL PROCEDURE Apparatus. The mode of operation of the recording effusion balance and its application to phase studies have been discussed in detail elsewhere.' In this work, an effusion cell containing a finely divided alloy was suspended within an evacuated tube from the beam of an analytical balance. The tube was immersed in a massive molten salt bath whose temperature was controlled to within 0.5o C during each experiment. The loss in weight of the alloy owing to effusion of zinc* was continuously recorded. Two effusion cells, 1/2 in. diam by 1 in. high, were machined from tantalum rods. Two orifices were drilled laterally into the walls of each cell. The orifice areas were determined by calibration with pure zinc: cell A had a total orifice area of 6.5 x 10-41 sq cm, and cell B an orifice area of 9.8 x 10-3 sq cm. By appropriate choices of orifice area and temperature the wide range of volatilities from pure zinc to pure rare earth metal could be investigated. X-ray diffraction powder photographs were made at room temperature with a 114.6-mm Debye-Scherrer camera with both filtered CuKa radiation and filtered CrKa radiation. Lattice parameters were refined by a computer-programmed least-squares analytical treatment which incorporated appropriate extrapolation techniques.2 Frequent use was also made of a special computer program3 designed to generate a powder pattern from an assumed structure in order to verify structural assignments. Materials. Lanthanum, neodymium, and yttrium were purchased from the Lunex Co., cerium from the Cerium Metals Corp., and praseodymium from the St.

Jan 1, 1968

By AIME AIME

THE first meeting" of the Iron and Steel Division was held Tuesday afternoon, Feb. 17, with nearly 100 men present and C. B. Murray as chairman. This was a round table discussion of iron ore beneficiation and of its relation to blast-furnace operations, and only one paper was presented, by Clyde E. Williams. Mr. Williams discussed the future of the Lake Superior district in its relation to the iron and steel industry. He stated that although estimates had shown that the total life of the present known iron ore reserves of the Lake Superior district was 20 to 30 years and that many believed that as a result of this depletion foreign ores would be brought to the Atlantic Seaboard, thus causing a displacement of the steel industry to the East, he believed that the Lake Superior district would continue to be the important producer of iron ore used in this country for decades beyond the predicted time before the exhaustion of the present known reserves. He described the three general types of ores that required concentration and pointed out the needs for research and the proper methods to be used in processes for the beneficiation of these low-grade materials. He discussed the effects of fine concentrates and the use of agglomerated ores in the blast furnace. This general summary led to interesting and valuable discussion on the various economic, ore-dressing, and blast-furnace problems in large-scale development of beneficiation. Perry Harrison described recent developments in sintering and the properties of iron ore sinter. T. B. Counselman and W. H. Coghill discussed the merits of classification of iron ore previous to tabling. Robert Faulkner and J. E. Little described the beneficiation plant of the Bethlehem Steel Corporation.

Jan 1, 1931

By F. H. Deily, Jean M. Quets, Milton E. Wadsworth, John R. 222-000-000-012 Lewis, D. S. Rowley, R. J. Howe

Samples of synthetic magnetite were reduced in hydrogen-water vapor atmospheres in the temperature range 450o to 900oC. The reaction was always surface controlled, indicating the final products of reaction are nonfirotective. Three separate cases have been identified from the kinetic results: Case I, reduction of magnetite to iron below 570°C; Case II, reduction of magnetite to iron above 570°C; and Case 111, reduction of magnetite to wustite above 570 oC. In Cases I and 111 the kinetics have been explained by the formation of oxygen anion vacancies in the magnetite surface followed by associated diffusional processes. In Case 11 the observed kinetics have been related to the concentration of iron cation vacancies in the wustite layer formed, followed by associated steady-state diffusional processes. The concentration of cation vacancies in the wustite is maintained constant by the magnetite-wustite equilibrium. THE reduction of the oxides of iron has been a subject of study and interest for many years. However, few attempts have been made to interpret the results in terms of the mechanism of reduction of an iron oxide by either hydrogen or carbon monoxide. Stalhane and Malmberg' using CO, H2, and CO-Hz mixtures, developed the rate expression: where m = mass of oxide reduced, t = time, k = a constant, s = surface area, P = partial pressure of of CO or H,, and P, = partial pressure of the reducing gas at equilibrium. The rate of reaction per unit area was proportional to the difference between the partial pressure of the reducing gas and its pressure at equilibrium. Hansen, Bitsianes, and Joseph2 studied the reduction of pellets of hematite to magnetite with mixtures of CO-CO,. They concluded that below 450°C the reaction proceeded according to a model in which CO reacts with the hematite surface producing an oxygen ion vacancy. The rate controlling step was then assumed to be oxygen ion diffusion through vacancies resulting in the formation of magnetite. They derived an expression giving the rate of reduction proportional to the cO/CO, ratio. Recently McKewan3 published results for the reduction of magnetite spheres in atmospheres below 570°C. He explained his results by an equation of the form where K, is the equilibrium constant for wustite-iron equilibrium attributed to the formation of wustite as an intermediate in the reduction of magnetite. According to McKewan, Kp is an equilibrium constant for H, -HO adsorption in which oxygen is deposited on the surface from the H,Oand subsequently acts as a poison for reduction by hydrogen. Sample Preparation and Experiments. In this work the authors used the same apparatus and experimental procedure employed in the hydrogen reduction of magnetite. Sintered disk samples weighing approximately 1.5 g and measuring 1.2 cm in diameter and 0.25 cm in thickness were prepared by a method described previously.4 Partial pressures of hydrogen and water vapor were controlled by bubbling hydrogen through a series of flasks containing distilled and deionized water maintained at constant temperature in an oil bath. The total flow rate of the reacting gases—hydrogen and water vapor—was approximately 0.5 liter per min. The entire external system was maintained at a temperature above the oil bath to prevent condensation of water vapor. This was accomplished by wrapping electrical resistance elements over all surfaces. The glass column containing the weighing system-a McBain balance suspended from a gold chain-was enclosed in an aluminum tube heated by nichrome resistance wire enclosed in an insulating material. The temperature of the glass column was held constant by means of a series of thermocouples connected in parallel to a Leeds and Northrup temperature controller. This was necessary since variations in temperature resulted in expansion and contraction of the glass column and could be readily observed with the cathetometer. The spring extensions were measured through a window with a gaertner cathe-

Jan 1, 1962

"The mountains of Utah contain one of the largest deposits of high grade bituminous coal in the world. According to the United States Geological Survey, there are 13,130 square miles of land known to contain workable coal, and these extensive fields contain 196,000,000,000 tons of coal. More remarkable than the extent of the coal fields is the thickness of the coal beds. Over three-fourths of the output of coal in Utah is recovered from beds ranging from 8 to 17 feet in thickness, as compared to one-eighth of the output of the entire country from such beds. In 1917, Utah mined one-third of its coal from seams at least 16 feet thick, compared to one-half of one per cent of the total bituminous output of the country from like seams.Coal at Wales, in Sanpete County, and in the vicinity of Coalville, Utah, was, it is reported, the first discovered by white men in the state. Wales claims the distinction of having produced the first coal mined in Utah. Two men, who had been coal miners in Wales, learned of the coal from an old Indian chief who called it ""rock that would burn."" In 1857, the town of Wales was founded and coal mined, and in 1858 some coke was manufactured and hauled by ox team to Salt Lake City. South of Wales is Castle Valley, in Wasatch Plateau field. From 50 to 60 miles of the Old Spanish Trail from Santa Fe, New Mexico, to Monterey, California, lies in Castle Valley. The coal in this field may or may not have been known at the time the trail was used extensively. The first published reference to this coal, however, was made by a party of the Corps of Topographic Engineers in their journal for October 11, 1853.After the completion of the Union Pacific railroad in 1869, mining on a commercial scale was attempted. In 1876 the Utah and Pleasant Valley railroad commenced operations between Scofield, in Carbon county, and Springville, Utah county, and following the year 1878, when the Rio Grande Western railway began construction through the Carbon county field, development increased until in 1900, when large smelters commenced operations in Salt Lake valley and gave coal mining in Utah an impetus that first carried it to an annual output of a million tons. During the past fifteen years many new mines have been opened, and with the construction of the Utah railway, an exclusive coal road, from the properties of the United States Fuel company in Carbon and Emery counties to connect with the Union Pacific system at Provo, the state reached a maximum production of 6,005, l 99 tons in 1920."

Jan 1, 1925

NEW MEMBERS. The following list comprises the names of those persons who became members during the month of flay, 1913: Members. BASTIN, EDSON S., Geol U. S. Geological Survey, Washington, D. C BUCHERER, Louis, Cons. Engr Apartado 1471, Mexico City, Mexico. BURDICK, CHARLES A., Min. Engr 74 Broadway, New York, N. Y. CARR, HOMER L., Min. Engr 109 W. 88th St., New York, N. Y. CARTER, RUSSELL S., Mech. Engr. & Asst. Gent Mgr., Ingersoll-Rand Co., 11 Broadway, New York, N. Y.

Jan 6, 1913

By B. C. Allen

Grain-boundary gvoocing was studied irz chronziu?n. molybdenum, tungsten, and the solid-solution alloys, Cr-35Re. Mo-33Re, and W-25Re at 0.6 to 0.9 of the absolute liquidus temperature under an inevt atmosphere , foveign nzetal zlapor, and liquid metal. The controlling mechanism of matter transport was deduced frolr groove size and shape. kinetics of growth, and cotnparisoz with theoretical relatiotzships derived by Mullins. Grooves in chowzizon formed prittzarily by volume diffusion tkrongk kelium or argon at 1 atm pressure and by e1)apovation-condensatiotz in a static vacuum. Groozles in the other nzetals and alloys forrned priniarily by sirface diffusion, the coefficients of which were calculated. Carbon was found to decrease the acti7:ation energy for surface diffusion on molybdenun. Sitrface diffusizities weve sinzilav for iWo-0.0ZC and Mo-33Re. The presence of about 1 -?nm pressure of silver or tin vapor did not affect the neckanis)n of grooz;e formation. In liquid titz or silz:er, pain bolindary gvooves formed by zolume diffusion in the liquid. BASED on theories of ullins," the mechanisms of grain-boundary grooving have been determined for low-melting metals such as copper in an inert atmospheres or in liquid lead.4 The purpose of this investigation was to study grain-boundary grooving in the refractory Group VI-A metals, chromium, molybdenum, and tungsten, and the bcc solid-solution alloys, r-35e, 0-33e,= and -25e,' at 0.6 to 0.9 of included to see whether Mullins' theories were applicable to them as well. EXPERIMENTAL WORK The materials chromium, molybdenum, tungsten, Cr-35Re, Mo-33Re, and W-25Re were in the form of 0.050-cm-thick sheet assaying 99.98 pct or better. The nominal carbon level was generally 30 ppm. The oxygen + nitrogen + hydrogen content was -50 ppm. Mo-33Re and W-25Re were prepared by powder-metallurgy methods and supplied by Chase Brass and Copper Co. The remaining materials were arc-cast. Chromium and Cr-35Re were prepared at Battelle by arc melting, extruding, swaging, and rolling. Mo-0.003C was supplied by Climax Molybdenum Co., and Mo-0.02C and tungsten by Universal Cyclops Corp. As a source of liquid metals, tin and silver granules assaying 99.98 pct were used. Spectrographic analyses indicated the presence of -100 ppm each of iron and silicon. Vacuum melting reduced the combined gas content to c5 ppm (2.60,, 0.9N2, 0.4H2 in tin and l.602, 0.7N2, and c0.04H2 in silver). Specimens were prepared for grain-boundary grooving. Coupons 0.5 by 1.5 cm with a small hole in one end, or substrates 1.5 by 1.5 cm, were cut from sheet. The specimens were annealed in containers of the same material to provide a vapor-solid equilibrium as well as to protect them from gaseous impurities. Outgassing was done at 2 x 10"5 mm for 15 to 30 min at 1150°C for chromium and Cr-35Re, 1750°C for molybdenum and Mo-33Re, and 2600°C for tungsten and W-25Re. Then recrystallization to a stable grain size of about 0.5 mm was accomplished by annealing at least 1 hr at 1600°C for chromium, 1800°C for Cr-35Re, 2350°C for molybdenum, and 2300°C for Mo-33Re in a rhenium-element resistance furnace under 1 atm of static argon or helium. The atmosphere was gettered by tantalum radiation shielding. Tungsten and

Jan 1, 1967

By B. C. Mariacher

EXTRACTION of uranium from ores is being ac-complished by processes which. for the most part, subject the entire ore to acid or carbonate leaching. Ore deposits with a U 3 O 8 content below 0.10 pct U 3 O 8 are seldom considered suitable for treatment by leaching. A preliminary concentration that would enrich the uranium content of an ore by a simple, low cost process based on physical properties of the ore might result in some low grade deposits becoming commercial ores. In addition, the process might be employed in existing operations to reduce transportation and leaching costs and to increase capacity of existing leaching plants. A study to attempt the development of a preliminary concentration process for primary uranium ores was undertaken by the Colorado School of Mines Research Foundation under sponsorship of the U.S. Atomic Energy Commission. The objective of this work was to produce concentrates containing 0.25 pct U3O8 from the low grade ores tested. Ores Tested: The main effort was devoted to the low grade primary uranium ores from northwestern Saskatchewan. Samples were obtained from the Beaverlodge operation of the Eldorado Mining & Refining Ltd. Additional primary ores, obtained from deposits in Gilpin County, Colo., contained from 0.07 to 0.10 pct U3O8. Summary of Concentration Tests: The Beaverlodge ore was tested to determine amenability of the ore to concentration by magnetic, electrostatic, gravity, and scrubbing processes. None of these produced satisfactory results. Both gravity and magnetic processes produced fairly good concentrates when closely sized fractions of the ore were treated, but on the basis of treating the total ore, recovery was poor. Preparation of sized fractions and the low capacity of equipment for suitable concentration made these methods impractical. As flotation offered the advantage of treating the total ore without intermediate sizing, the main effort was in this direction. A flotation process was developed that fulfilled the concentration objectives as set by the AEC. Pilot plant testing was used to verify results obtained from laboratory batch testing. Mineralogy: A petrographic examination of the Beaverlodge ore included a study of polished sur- faces and identification of the radioactive mineral by autoradiograph and X-ray diffraction. Approximate quantitative mineral identification was as follows: quartz, 60 pct; orthoclase feldspar, 20 pct; chlorite, 10 pct; carbonates, 5 pct; and miscellaneous minerals, 5 pct. Included in this last group were plagioclase feldspar, pyrite, mica, chalcopyrite, pyroxene, sericite, magnetite, galena, and uraninite. The most general occurrence of uraninite was in the form of crusts and thin coatings on limonite-stained grains of pyrite, quartz, and pyrite-quartz intergrowth. At least 90 pct of the uraninite was still attached to other minerals in a 100 by 200-mesh size fraction. The uraninite crusts were as small as 10 to 20 µ diam, and 5 to 10 µ thick. The Flotation Process Petrographic examinations of the Beaverlodge ore had indicated the impracticability of attempting to concentrate the uranium by floating individual grains of uraninite. Liberation of the uraninite required grinding to sizes below those suitable for flotation. However, there was preferential association of the uraninite with some minerals while others were free of uraninite attachment. The approach to the development of a flotation process was, therefore, based upon an attempt to concentrate the uraninite by floating carrier minerals. The following paragraphs discuss the various stages of the process with regard to the factors tested and the conditions under which best results were obtained. Grinding: The most effective size range for flotation was —150 mesh + 13 µ. The —13 µ material in the final concentrate had a higher U3O8 content than the total ore, but not as high as the average concentrate; however, rejection of slimes before flotation was prohibitive because of the loss in uranium carried in the —13 µ fraction. Grinding techniques which contributed to a minimum production of fines, such as stage grinding, were then employed. Quartz and Silicate Depression: These minerals represented approximately 80 pct of the ore and were free to a large degree of uraninite attachment. Significant improvement in the grade of the concentrate was obtained by depression of these minerals with hydrofluoric acid or sodium fluoride. Promoter: Selective stage flotation of uraninite carrier minerals was simplified by development of a single promoter mixture. The mixture consisted of an emulsion of a fatty acid, fuel oil, and a petroleum sulfonate and was selected after a comprehensive series of tests. It contained three parts by weight of an oleic and linoleic acid such as Emersol 300,

Jan 1, 1957