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By J. T. Norton, Pekka Rautala

The phases and equilibria in the W-Co-C system have been studied by X-ray diffraction methods, metallographic technique, and thermal analysis. In addition to the 7 phase, two double carbides, called 8 and have been revealed. The compositions correspond to CO3 W6C2 and Co3-W10C4. The reactions leading to these phases have been explained and tentative diagrams of stable and metastable equilibria proposed. The basic reactions in sintering cobalt cemented tungsten carbides are discussed. THE W-Co-C system is of fundamental importance in practical carbide manufacturing as well as for the understanding of the sintering mechanism. Surprisingly little is known about this system, for the probable reason that all the important alloys are of two-phase structure and that the diagram Co-WC has been treated as a quasi-binary. This obviously is incorrect, because WC decomposes before melting. One ternary phase, 7, of composition Co3W3C has long been known. It was first studied by Adelskold, Sundelin, and Westgren,1 although the isomorphous iron-tungsten carbide was known earlier. There have been in the literature several reports of two 7 phases.' " Also the 7 phase has been considered unstable by Takeda4 and Westgren.1 The Co-WC diagram has been studied by Wyman and Kelley5 and a quasi-binary diagram has been published by Sandford and Trent.2 Takeda has published a tentative Co-W-C diagram, considering both metastable and stable equilibria. However, the lines of two-fold saturation are shown only partially and it seems impossible to complete the diagram without violating the phase theory. Therefore it seemed desirable to examine the system in more detail. Experimental Procedure The alloys used in the present investigation were made of powders of tungsten, tungsten monocarbide, cobalt, and carbon and were of the grade used in manufacture of commercial cemented carbides. The powders were ground and mixed in small stainless steel ball mills, using balls of the same material. Benzene was used as a dispersing agent. The mixing period was 1 hr, since this was shown to give suffi- ciently good mixing of the powders without too great a contamination from the mill. After ball milling, the specimens were pressed in cylindrical or rectangular dies. No paraffin or other lubricant was used and the small compacts had sufficient green strength to be handled without difficulty. Several sintering furnaces were employed. The most satisfactory arrangement was a vacuum furnace based on the Arsem principle which employed a graphite helix as the resistance heating element. Specimens were placed on graphite stands and there was generally a slight carburization or decarburiza-tion of the specimen surface, depending on the carbon content of the alloy. The evaporation of the cobalt at a sintering temperature of 1400°C was not significant, but became severe at 1500°C and higher. The sintering time was 1 hr at 2000°C and 2 to 4 hr at lower temperatures. It was not possible to quench the specimens, but the cooling rates were rather fast, greater than 300°C in the first minute. In the system under investigation, the reactions are sluggish, and it is believed that the high temperature structures are satisfactorily retained. The principal method of investigating the sintered specimens was X-ray diffraction by the Norelco recording spectrometer. Approximate determinations of the phase boundaries were made by the disappearing phase method. Ternary Phases To study the phase formation in W-Co-C system, a series of specimens was sintered at 1400°C. In this experiment two ternary phases, called here ? and k were formed in addition to the well-known 7 phase. The 7 phase, which has been completely described by Westgren: showed a range of homogeneity from 7 to 20 pct C and from 38 to 48 pct Co. At 1400°C the 7 phase was found to be in equilibrium with monotungsten carbide, 8, tungsten, 8, #?, and liquid. The boundaries toward #? and liquid were difficult to determine and appeared to be very temperature sensitive. The other boundaries are believed to be well fixed. The homogeneity range of 7, as measured in this work, is considerably smaller than the one

Jan 1, 1953

By H. C. Casey, M. B. Panish

The roles of the phase diagram and the diffusion and solubility analyses in the selection of sources for the diffusion of zinc into GaAs are discussed. Isothermal sections of- the phase diagram are described at 1000°, 775°, 744°, and 700°. Below 744° the three solid phases, Zn3As2, GaAs, and ZnAsz, may be in equilibrium. In the composition regions where the three solid phases are in equilibrium, the partial pressures of the components do not vary with composition and there is no liquid phase. A diffusion source composition within that region containing 5, 50, and 45 at. pct Ga, As, and Zn was selected to yield reproducible diffusion profiles without surface damage. The 5/50/45 ternary source Provides a significant improvement in the reproducibility and planarity of- the zinc diffusion as compared with other zinc diffusion sources that result from starting with elemental zinc, dilute solutions of zinc in gallium, or various combinations of zinc and arsenic. Several experimental diffision profiles for the 5/50/45 diffusion source have been determined. The profiles are very steep in the region of the junction and produce devices that exhibit step junction behavior. The junction depth varies as the square root of time. Diffusion at 700°C for 4 hr gives a 5-µ junction depth and a surface concentration of 2.4 x1020 cm-3. The surface concentration is enhanced by a factor of three and the junction depth decreased by a factor of ten as compared with diffusion with a starting source 01- elemental zinc. The differences in dijyusion behavior with these two sources are due primarily to the approximately 10' greater equilibrium As4 partial pressure for the 5/50/45 source. ThE most common technique for the preparation of GaAs p-n junctions for diverse applications ranging from switching diodes to injection lasers has been to diffuse zinc into the solid from the vapor phase. The zinc impurity has generally been provided by introducing into a diffusion ampoule elemental zinc, dilute solutions of zinc in gallium, or various combinations of zinc and arsenic. For the purpose of eliminating surface deterioration, zinc has been diffused into GaAs through SiO2 films1 and from zinc-doped SiO2 films.2 During a study of the injection and recombination mechanisms in GaAs junctions, we found that these diffusion techniques either resulted in nonreproducible diffusion profiles and nonplanar junction interfaces or were extremely inconvenient to use. An unpublished report by Allen and pearson3 emphasized that an understanding of diffusion requires relating the diffusion conditions and system compositions to the ternary phase diagram. Recent studies have made it possible to relate the effect of starting source composition on the GaAs sample surface and diffusion profile reproducibility and, in addition, to estimate the expected surface concentration and zinc diffusivity. These studies include the Ga-As-Zn phase diagram,415 the determination of the incorporation reaction for zinc as a substitutional impurity,6 and the analysis of the concentration dependence of the diffusion coefficient.' In this paper the role of the phase diagram in the selection of the starting diffusion source composition is illustrated, and an application of the diffusion and solubility analyses is used to demonstrate their utility in the estimation of surface concentration and diffusivity for various starting source compositions. Consideration of the isothermal sections of the ternary phase diagram shows that below about 744° C a composition region exists where the three solid phases Zn3As2, GaAs, and ZnAs2 are in equilibrium without a liquid phase. In this region the partial pressures of the components do not vary with composition, and thus the surface concentration and diffusivity depend only on temperature. A diffusion source composition within that region containing 5, 50, and 45 at. pct Ga, As, and Zn was selected. As will be described in detail, this diffusion source yields reproducible diffusion profiles without surface damage, planar junction interfaces, and steep profiles that result in devices with step junction behavior. Only closed diffusion systems are considered. Open or flowing vapor systems require the maintaining of constant vapor pressures in the flowing gas and represent control problems outside the scope of this discussion.

Jan 1, 1969

By T. R. Armstrong

Total crude oil production in Mexico in the year 1941 is estimated at approxi- mately 41,000,000 bbl.; a daily average of 112,700 bbl. and a decrease of about 5 per cent as compared with the daily average of 120,000 bbl. produced in the year 1940, and nearly 11 per cent decrease as com-

Jan 1, 1942

By T. R. Armstrong

Total crude oil production in Mexico in the year 1941 is estimated at approxi- mately 41,000,000 bbl.; a daily average of 112,700 bbl. and a decrease of about 5 per cent as compared with the daily average of 120,000 bbl. produced in the year 1940, and nearly 11 per cent decrease as com-

Jan 1, 1942

By George C. Stone

AS most of you probably know, Australia has had many strikes. The two places that had the worst reputation were the Broken Hill mines and Port Pirie, where the smelter was located. About four or five years ago, the smelter changed hands. The new proprietors - immediately endeavored to get on better terms with the men and made such progress in that respect that, the men came to them and said, "There is no use giving us any more money. You have just raised our pay one- bob a day, but the store-keeper and the boarding-house keeper have raised their prices. The boarding housekeeper raised our board three bob a week and the storekeeper took the rest of it and we are no better off." Learning that what the men needed most was firewood wood the company bought the wood on a tract of ground across Spencer's Gulf and- sent men over to cut it. The wood was brought to the works and given to a man to cut up. He thought he had an easy job and loafed, but when the committee representing the men discovered that his loafing added to the cost of 'the wood, it promptly disciplined him and made -him work as he had never worked before. The next question that arose was the distribution of the wood. The committee got bids from several cartmen whose prices varied from about two to five shillings. It gave the work to the next to the lowest bidder. The fact that if delivering the wood cost more, the user would have to pay for it, was an entirely new idea to the men.

Jan 1, 1920

By Harold Vance

EMPLOYERS of engineers have not always been satisfied with the training that young graduates have received in the conventional four-year course. Specifically, employers of petroleum engineers for a number of years have believed that a four-year course does not allow sufficient time for the student to secure a fundamental engineering background plus the fundamentals of petroleum engineering. A group of California employers went so far as to set up a type of curriculum for a petroleum-engineering course, which was based on four years of undergraduate work and one year of graduate work, with most of the petroleum-engineering courses included in the graduate year.

Jan 1, 1944

By H. D. Hoskold

I. Instrument-Parts and Implements. Cross-hairs ; Stadia-measurement; Fineness of Graduation ; Cylindrical Gradu ation ; Nonius; Vernier ; One Vernier or two ; Leveling-Screws ; Troughton & Simms' Shifting Tripod-Head ; Hoskold's Shifting Tripod-Head; Hoskold's Extensible Tripod ; Electric Lamp ; Plumb-lines; Chain. II. Instruments. Compass (Mine-compaes of 1518, Compass of 1541, and Agricolals of 1556, Voig tel's Setz-compass, Circumferentor, Stanley's Hedley Dial, Compass on Tele scope, Hanging Compass, Lack of Precision) ; Plane-table; Octant and Quadrant; Theodolite and Transit (Evolution of the Theodolite, Scott's Tachymeter, Hoskold's Engineer's Theodolite, Angleometer, Precision of Mine-Theodolites). I. Instrument-Parts and Implements. Cross-Hairs.—Mr. Scott‡ says Lean's dial " might also have been provided with a diaphragm and cross-hairs; for Huygene discovered that any object placed in the common focus of the two lenses of a Kepler telescope (1611)- appeared as distinct and well defined as any distant body. Following this established theory, in 1669 Jean Picard, Marquis Malvasia and others crossed silken fibers in the mutual focus of their astronomical instruments." If by this Mr. Scott means that Huygens and Picard first devised and applied cross-hairs to the focus of the telescope, the writer cannot agree with him. Huygens did not describe " his telescope without tubes until 1684, in his Astroscopia Compendiaria."§ Moreover, it is recorded that the English astronomer, Gascoigne,?

Jan 1, 1902

By Albert Sauveur

IT is not without some hesitation, and even misgiving, that I venture into a discussion of the now classical Roberts-Austen Roozeboom diagram, lest I too fail, like so many other writers, in giving a satisfactory and logical explanation of these interesting curves. Roozeboom's original diagram is reproduced in Fig. 1. The generally accepted meaning of the various curves has been so often described before this Institute that it will suffice to recall it briefly before passing to my own interpretation of the changes involved.

Nov 1, 1906

Mansfield MERRIMAN,Lehigh University, South Bethlehem, Pa. (communication to the Secretary*):—The formulas established by Mr. Campbell require the use of tables in order to take into account the influence of manganese on the tensile strength of steel. On examining these tables I find that the quantities given therein may be expressed by simple algebraic forms, so that formulas for tensile strength may be written which can be used without the help of tables. Referring to the case where the carbon is determined by

Jan 1, 1906

By S. J. Swainson

PHOSPHATE ROCK is a low- priced commodity. This fact has influenced the choice of mining and beneficiating methods to a greater degree, perhaps, than in most other low-grade mining operations. The fact that many yards of everburden and matrix must be stripped and mined per ton of salable "rock" produced and sold has necessitated he development of relatively simple btneficiating plants having high capacity and low capital and operating costs. The law of diminishing returns must always be reckoned with in phosphate mining and washing, and often recovery must be sacrificed in favor of costs in order to achieve the highest over-all economic efficiency. The phosphate-bearing formation, known as "matrix," is composed of (1) phosphate pebbles, which are somewhat rounded in shape and which vary in size from 1-in, to micron sizes, (2) rounded quartz grains usually smaller than 10 mesh, and (3) clay, of varying "stiffness," which is the binder of the matrix. The phosphate pebbles vary in hardness. Their color, which varies from white to black, is not a reliable indicator of the Bone Phosphate of Lime (B.P.L.) content of the

Jan 1, 1944

By O. J. Hollister

Jan 1, 1888

By L., Ormsby

DRILLING and blasting practices in the Morenci open pit have undergone considerable modification in recent years. Changes in the character of the ground being mined, modifications of working conditions, and continuous experimentation have been the contributing factors.

Jan 1, 1950

By R. A. RAGATZ

THE preparation of specimens for microscopic examination from metal articles of relatively large cross-section offers no particular difficulty. It often happens, however, that articles submitted for examination are so thin that specimens satisfactory for microscopic examination can not be successfully pre- pared by the methods commonly employed when working with larger articles. Ordinarily, the preparation of metallographic specimens involves the following operations : (1) cutting the small specimens to be examined out of the larger mass of metal, (2) cleaning and electroplating, (3) mounting to furnish support during the grinding and polishing operations, (4) grinding and polishing to produce a scratch-free surface, (5) etching and drying. All of these operations must be carried out in such a manner that when the specimen is finally examined under the microscope, the structure seen is a true and well-defined representation of the structure that the larger mass of metal possesses at the place where the small specimen was removed. It is important that the deformation involved in cutting out the specimen be as slight as possible, in order that the subsequent grinding and polishing operations will completely eliminate the cold- working effects in the vicinity of the cuts. It is also important that the specimen never be allowed to attain a temperature high enough to alter its structure; the maximum permissible depends on the metal being handled. With some metals, zinc for example, consider- able care must be taken to avoid heating; with other metals, annealed steel -for example, no particular pre- cautions need be observed because there is no tendency for structural change to occur at relatively low temperatures.

Jan 1, 1929

By George A. Hill

WE of the oil industry, devoted to freedom of initiative, free competitive enter- prise, and free American institutions, applaud, with one voice, affirmation by the President of the national will and purpose to preserve and to protect, against all aggressors, "our American way of life with our individual and national freedom." We subscribe utterly and completely to this guiding declaration and seek its further definition as applied to the oil industry. Fortunately for all, the policy of the Government, after adequate study and deliberation, has been given precise definition. The National Defense Advisory Commission, with its patriotic, highly qualified, and distinguished personnel, has unanimously agreed to and adopted twelve general principles governing national defense contracts and also fair labor standard requirements. The President of the

Jan 1, 1940

By Russell C., Fleming

FOK, many years the officials of the Magma Copper Co. mine at Superior, Ariz., have had to contend with adverse conditions underground in the form of high rock temperatures, hot water, and high relative humidity. These conditions in the mine have been such that working the mine would have been impossible were it not for the constantly expanding and improved sys- tem of ventilation to produce bearable conditions in the working places. Results that have already been achieved make an interesting study of what can be done along those lines. From the time the mine was first opened in 1910 it has been hot. An idea of the conditions that have persistently been encountered can be obtained from parts of the mine that are not being worked at present or that do not yet have sufficient ventilation. Virgin rock temperatures as determined in drill holes at the faces range from 104° to 116°*. An observation made at the face of No. 5 West footwall drift on the 2800-ft. level.

Jan 1, 1930

By Theodore A. Blake

At the Chicago meeting of the Institute, May, 1884,I had the pleasure of announcing the introduction of a new machine for fine crushing, or The Blake multiple-jaw crusher, which, in combina tion with the ordinary Blake breaker, could be used in the reduc tion of ores or any hard and brittle substance to almost any degree of fineness. I am now able to give some practical results derived from its use on an extensive scale, on the gold ores of South Caro lina and the iron ores of Lake Champlain, together with some accurate and detailed statistics of the cost of crushing over one hundred thousand long tons of magnetic iron ores of the Chateaugay Ore and Iron Company at Lyon Mountain, Clinton County, N. Y., about thirty miles west of Plattsburgh. The construction of the multiple jaw-crusher, since the date of my first paper, is the same, except in the substitution of main swinging, instead of main sliding, or toggle jaw,—thus doing away with the upward thrust on the tension rods and the wear incident thereunto. (See Fig. 1.) It has also been found, in case of the fine crusher, that is, in machines of not over 4 inch width of opening, that the use of several small machines with a series of jaw openings, say 15 inches by 4 inch, is better than one large machine with a series of openings 24 by 4 inch, or 36 inches by 4 inch, as at first constructed. Many details of the method of holding in jaw-plates, etc., have been perfected. Without giving any details with respect to the different mills built upon the Blake 'system, let me state that, although it has proved possible to carry any hard and brittle material with crushers alone to a fineness such that all particles will pass a 30-mesh wire screen, still the economical limit of such crushing will be found somewhere between 14 and 20. If it is necessary to carry all the material to a fineness greater than this, the system must be supple

Jan 1, 1888

By Mazany, M. S.

THE Caletones copper smelter of the Braden Copper Co. is in the " Teniente" mining district about SO km. (49.7 mi.) southeast of Santiago, Chile. From the seaports of San Antonio and Tralparaiso, the property is reached via the Chilean State Railway (66-in. gage) to Rancagua, whence the Braden railroad (30-in. gage) leads to the smelting plant at Caletones, 60 km. away at 5100 ft. elevation, and continues on to the mine and concentrator at Sewell, at 7000 ft. elevation, 12 km. farther into the Andes. The smelting plant was completed and put into commission in February, 1922. At the start, it smelted daily 750 tons of concentrates produced at Sewell from 10,000 tons of ore; later, its capacity was increased to 900 tons of concentrates from 12,000 tons of ore per day; and it is now being increased to 1100 tons of concentrates from 15,000 tons of ore per day. The smelting plant production is governed chiefly by the

Jan 1, 1925

By Paul M. Tyler, Carle R. Hayward

DOES it pay to do really good work? Quite likely the practical millman will answer that it does not. The preparation of ores for market is primarily a business enterprise, and by and large the individual operator does not bother his head about squandering our national resources or making easier the job of the smelterman. Having accepted such ore as he may get fro111 the mine, his job is to make the best possible showing with his mill fro111 the standpoint of financial return. His success is measured in dollars and cents, and he has no rightful reason to expect more than scant acknowledgment of any other achievements from the stock- holders of his company who in the last analysis are his employers.

Jan 1, 1936

By C. C. CONCANNON

POTASH is an essential. It is necessary as an ingredient in fertilizers or as a plant food, and certainly one of the great problems, and one of increasing gravity, is the maintenance of agricultural fertility that we may have adequate food supplies. When one thinks of potash one thinks of Germany. The first and most important deposits of soluble potash salts were found in Germany, and it was through Ger- man research and the application of a highly developed knowledge of chemistry that the value of these deposits was recognized and appreciated in the field of agricultural fertilization. The Germans knew that they had something of great value in their potash resources, not only because of the advantage derived from the extensive use of it in their own intensive farming operations at home, but also because of the pressing need for it on the part of other countries. Appreciating the economic value of this in international trade, they fostered the industry to the fullest extent and devoted much attention to well organized propaganda designed to bring out the essential need for potash of German origin throughout the world. Thus every one came to believe that potash was an essential commodity of only German origin and as such it held an extraordinary position in world trade prior to 1914.

Jan 1, 1926

By W. S. CAYPLESS, H. O. Hofman, E. E. HARRINGTON

1. INTRODUCTION. AT the Lake Superior meeting, September, 1904, Messrs. A. Gibb and R. C. Philp presented a paper entitled " The Constitution of Mattes Produced in Copper Smelting,)' in which they concluded that ferrous and cuprous sulphides formed the chemical compound, 5 Cu2S, fee. They arrived at this inference from the observed fact that a matte containing Cu2S, 90.4, and Fee, 9.6 per cent (or, in round figures, Cu2S, 90, and Fee, 10 per cent.), did not contain any metallic copper, while one with more than 10 per cent of FeS readily dissolved copper, and with less than this amount retained copper in mechanical suspension. Although they determined the melting-points of five mattes containing from 32.6 to 80.1 per cent of copper, they did not draw a freezing-point curve, as the necessary apparatus was not available. A microscopical examination of 11 polished samples, gave them a grayish-black field of very uniform appearance, except that 5 of the specimens showed the presence of metallic copper. The object of the present investigation was to supplement the above paper by drawing the freezing-point curve of the series ferrous sulphide cuprous sulphide, and to see how the constitution could be further, revealed by microscopical work. The results obtained lead to conclusions very different from those of Gibb and Philp. While their paper bears the date 1904, it was published only in 1906.2 In the meantime, Bolles3 had presented his paper, "The Concentration of Gold and Silver in Iron Bottoms." The raw material which formed the basis of the research was a matte containing Fe, 61.68, and Cu, 11.20

Jan 1, 1907