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By A. B. T. Werner, J. J. Schanz

A survey of the world's sources and markets for natural graphite and some predictions of future trends are presented here. The authors feel that there is no indication of major changes in sources of graphite over the next few years, but it is possible that the importance of domestic graphites as opposed to foreign carbons may increase in the more distant future. U.S. consumption of natural graphite, which has been in general decline for the past six years, and will probably continue downhill with the virtual disappearance of some markets. However, other markets such as bearings, brake linings and crucibles will probably grow. Natural graphite is the name given to all the naturally occurring mineral forms of carbon that crystallize in the hexagonal system. Natural graphite~ are generally divided into three broad classifications that are based on physical rather than chemical differences — crystalline flake, Ceylon amorphous and other amorphous. Crystalline flake graphites occur as thousands of small individual flakes disseminated throughout the ore and closely resemble shiny black fish scales. Ceylon amorphous graphite is mined from narrow veins of almost pure mineral. It is produced in lump form and often has a coarse platy or needlelike structure. Other amorphous graphites include all those that are extremely fine-grained and have a crystalline structure that is not visible under normal circumstances. In the primary raw material markets, the graphite's country of origin is also important. Crystalline flake graphites may, for example, be of the Alabaman, Bavarian or Madagascan types; Ceylon amorphous graphite may have originated in Montana or Ceylon; and other amorphous graphites may come from Mexico, Hong Kong or Korea. The distinctions between the graphites from each particular locality are small yet important, for the country of origin will signify certain inherent physical characteristics and will often give an idea of the amount of graphitic carbon contained in the shipment in question. .In certain instances, however, even this is not enough, since the actual mine at which the graphite is produced may have to be known before its true commercial value can be ascertained. Thus, the Madagascar flake graphite shipped from the Sahalambo mines of the Societe des Graphites de la Sahanavo is a thick flake which is known to be especially suited for use in crucibles, while the dull black earthy amorphous material formerly mined at Cranston, R.I., was ideal for stove polish. Synthetic, artificial, electric furnace and manufactured are terms used to describe graphites made from coke. These graphites will be considered in this paper only to the extent that they enter competition with natural graphite. DOMESTIC SOURCES OF NATURAL GRAPHITES Natural graphites have been produced from mines in Alabama, Alaska, California, Georgia, Montana, New Jersey, New York, North Carolina, Pennsylvania, Rhode Island, Texas and other states. The exception is the crystalline minerals resembling Ceylon graphite that have come from Montana and the amorphous meta-anthracites from Rhode Island. All the products mined have been flake graphite. In 1960, production was reported only in Texas and Pennsylvania. The Alabama graphite deposits of flake in quartz-mica schists are found southeast of Birmingham in a narrow belt that extends for about 60 miles southwest from Delta in Randolph County to Verbena in Chilton County. Since the long-run prospects for Alabama graphites appear to be fairly bright, especially if regular production of high quality output becomes possible, regional ore reserves of all kinds, including indicated and inferred, are estimated to be of the order of 25 million tons. Of this amount, 14 million tons are of the weathered variety. Alabama graphites are favored by their relative ease of mining, and by the fact that special methods of milling have been developed at the larger properties. In addition, the steady rise in ocean freight rates for Madagascar graphites, the tendency among crucible manufacturers to use flakes of a smaller size, and the possibility of producing other salable byproducts in addition to the graphite are favorable to Alabama producers. Against

Jan 1, 1962

By George S. Rice

STUDIES of ground movement and subsidence caused by mining necessarily chiefly deal with causes and effects of making extensive excavations underground with spans beyond the strength of the un- supported or temporarily timbered roof or hanging wall. Perhaps no other phase of engineering is so de- pendent for results upon the assemblage of what may be called "experience data." That this is the case is cot surprising when one considers the number of variables involved in any at- tempted mathematical formula to determine the angle of draw or the angle of permanent slope of the rocks in any particular case. It is not like dealing with construction materials in which, through testing of. small specimens, in conjunction with the tests of large built- up specimens, relative stresses and strains may be deter- mined and formulas closely approximated for still larger constructions.

Jan 1, 1931

By Howard N. Eavenson

TWO months ago, just after the coal code hearing in Washington, one of our leading liberal weeklies printed a study of the coal industry made by an economist in the Administration, and on the outside cover bad it featured as "Coal-A Dying Industry." There are, of course, different opinions as to the accuracy of this characterization and I want to present some of the facts about the outlook for the bituminous industry for a short time ahead. In view of what has happened in the industry within the recent past it would be futile to attempt to make any prophecy about what is likely to occur in the future. We all know that a prophet is not without honor save in his own country, but it is likely that anyone undertaking this role about this industry would soon find himself in no man's land. One can, with some slight degree of safety perhaps, outline present conditions and tendencies and draw some inferences as to what the future may hold.

Jan 1, 1933

By J. S. Marsh

AN incomplete statistical analysis performed wearily on the morning after Thursday, Feb. 12, indicates that the unavoidable items of conversation among steelmen were the current shortage of sleeping time and the "Normandie." No analysis is needed, however, to be certain that many thousands of valuable words were uttered, both in and out of technical sessions, concerning matters of deep interest to members of the Iron and Steel Division. The opening session consisted mostly of papers that have appeared, or will appear shortly, in Metals Technology. One, however, that was not finished in time to be printed in any form, but that aroused great interest, was by E. L. Ramsey and L. G. Graper (Wisconsin Steel Works). Its subject was the production of high-sulphur steel by treatment with sulphur dioxide derived from anhydrous sodium sulphite or bisulphite added to the ladle or to the mold. The sulphide distribution in the finished steel is such that increased machinability and longer tool life result. Both items are of obvious importance in these days of mighty production.

Jan 1, 1942

By Philip S. Mathews

THE tremendous stimulus given to the mining industry by the gold and silver policy of the present administration has found the capital market for mines ill prepared to afford practical means of financing. Particularly has this been true of the host of abandoned high-cost producers and prospects which increased gold and silver prices have made potentially profitable. In a comparatively short time, experience has demonstrated abundantly that valuable properties have frequently failed to secure capital, while questionable properties have drawn to themselves and their promoters more of the public moneys than their prospects justify. Singularly enough the fault is usually attributable to faulty financing. Discussion and study of this problem are vital to the industry.

Jan 1, 1936

By William N. Poundstone

To forecast the future of coal intelligently, one must first consider the market outlook. Coal can be used for many purposes, but currently about 25% of it goes into metallurgical coke, while 75% serves as fuel. Coal for metallurgical coke should show a modest growth for at least the next decade, primarily because of increased exports, but the important factor in the coal outlook is energy. Today, this country faces a serious shortage of energy, and its requirements are growing at an almost unbelievable rate. Last year the United States consumed 68 quadrillion Btu, or double the energy it consumed in 1950, and, if projections are correct, this figure will grow to 150 quadrillion Btu by 1990. Thus, in one working lifetime, the nation's energy consumption is expected to increase by roughly five times. The future of coal hinges on its degree of participation in meeting this energy need. The Federal Power Commission predicts that coal consumed by electric utilities will increase about 4-576 per yr, reaching 472 million tons by 1980 and 615 million tons by 1990. If this projection proves correct, 1980 consumption will be double that of last year and, even more startling, the utility industry alone will use more coal in 1990 than the entire coal industry produced in 1970. This is a tremendous increase, but in view of the projected energy growth, it is difficult to see how this country's needs can be satisfied with- out a coal contribution of this magnitude. Unless some new source such as solar energy is discovered, it must be assumed that the projected energy will come principally from the present-day sources-oil, gas, nuclear materials and coal.

Jan 1, 1971

By E. H. Snow, B. E. Deal

Instability effects in semicanductor devices have long been attributed to the motion of charges on or within oxide layers on the surface. These effects are of critical importance in metal-insulator-semiconductor MIS) field-effect devices. For this reason, the capacitance-voltage or the conductance-voltage characteristic of these devices can be used as a sensitive detector to study charge transport and polarization effects in the oxide or insulator. A review is given of the results of such studies of thermally grown SiO2 as well as of other insulating films of importance in silicon technology. Three types of effects are distinguished. The first of these is the drift of mobile cations within the dielectric, examples being thermally grown SiO, which is often contaminated with sodium ions, and a variety of other glasses in which the mobile ions are a part of the glass composition. The second effect is a dipole-type polarization which occurs in phosphosilicate glass films obtained by reacting P2O5 with thermally grown SiO2. The third effect involves the transfer of charges between the dielectric and the silicon electrode. This occurs in silicon nitride and other deposited dielectrics. It is concluded that MIS studies have provided a powerful technique joy the study of charge transport and polarization effects in insulating films. The knowledge gained from these studies has led to an understanding of surface effects on conventional transistors and diodes as well as making possible stable MIS transistors. THE metal-insulator-semiconductor field-effect transistor is conceptually the oldest type of active semiconductor device.' The earliest attempts at making this device were frustrated because of high surface state densities at the interface between the semiconductor and the gate insulation.' However, by using a silicon substrate with thermally produced silicon dioxide as the gate insulation, this problem was solved and metal-silicon dioxide-silicon devices with good characteristics were made as early as 1960. 3 Yet it was still over 5 years before these devices became a commercial reality. This delay was largly due, not to surface states, but to stability problems associated with polarization effects within the insulating layer which caused the threshold voltage of the device to drift under temperature and bias treatments. The solution to these problems has not only made possible stable MIS devices, but it has added immensely to our understanding of failure mechanisms in conventional bipolar transistors and has added to the reliability of ali types of planar devices. In this review, we shall first describe the effects of various types of polarization phenomena on MIS device characteristics. Then, since thermally grown SiO, is by far the most important insulator used in these devices, we shall review historically the type of instabilities which have been observed in thermal oxides, the attempts at understanding and eliminating them, and the present status of the problem. We shall then turn our attention to the various deposited insulators which have been used, including lead glasses, phosphosilicate glass, vapor-deposited silicon oxide, and silicon nitride. Interestingly enough, many of these materials show polarization effects which are quite different from those generally observed in thermally grown SiO2. THE EFFECTS OF POLARIZATION PHENOMENA ON MIS CHARACTERISTICS The simplest MIS device and the one which has been most frequently used in the study of polarization effects is the MIS capacitor. Two modifications of this structure with single- and double-layer dielectrics are illustrated in Figs. l(a) and (b), respectively. The capacitance of this structure as a function of voltage applied to the metal gate electrode is plotted in Fig. 2 for the case of an n-type silicon substrate. When the silicon surface is accumulated (positive bias) the measured capacitance is just that of the insulating layer C. When the surface is inverted (negative bias), the capacitance is that of the insulator and a silicon depletion layer in series CoCs/(Co + Cs). Indicated on the horizontal axis of Fig. 2 is the voltage VT at which the silicon surface becomes strongly inverted. This voltage corresponds to the threshold or turn-on

Jan 1, 1969

By A. L. Engel

STRICTLY speaking, ore-dressing does not commence until after the ore is in the mill bins, but where complex ores are treated and their minerals separated to make the best commercial concentrate with the lowest economical tailing, ore-dressing problems begin and often center in the mine itself. This does not refer to the grade of the ore, but rather to the frequent condition in which metallurgical results radically different from customary are obtained because of changes in the character of the ore treated. Different varieties of ore can usually be identified as coming from well-defined depths or zones in the mine, or from known sections of the orebody. Varying degrees of alteration of the ore, inclusions of harmful gangue material, or variations in the quantities of component metallic minerals are often causes of temporarily bad metallurgical results in otherwise successfully operated plants, especially those employing differential flotation to. recover several valuable minerals contained in the ore.

Jan 1, 1931

By Joseph E. Pogue

THERE are two methods employed in the development of oil pools. The older and dominant method is one in which the primary object is the protection of the underground deposit from drainage through competing wells, and considerations of efficiency of extraction and cost of production are subordinated thereto. The newer and less prevalent method is one in which maximum efficiency and minimum cost are the first objectives and developments to these ends may proceed undisturbed by the exigencies of competitive drainage. The second method has developed mainly in pools under single ownership and the term "unit operation" has come to be applied to this procedure. A single ownership, however, is not essential to the method, for unity of operation may be achieved by agreement under split ownership, or even by a concert of enlightened purpose. There are examples of unit operation where neither the ownership nor the management is a unit, but merely where unity of procedure has been attained, as is the case of the Yates pool. .Throughout this paper unit operation is used in its broad sense without implying sole ownership or single management, although unit operation is more conveniently attained where these conditions are present.

Jan 1, 1930

By C. R. Dale

IT IS the purpose of this paper to point out a number of the most common causes of crooked holes; to outline methods of drilling and straightening which to my personal knowledge have proved successful in numerous cases; to describe some of the characteristics of holes which, though not crooked in an exaggerated sense, may still cause serious mechanical trouble if not recognized and properly remedied; and to define clearly the part of oil-well surveying in the concerted effort operators generally are making to keep their wells straight from spudding to completion

Jan 1, 1931

By Bradley Stoughton

AT THE meeting of the Board of Directors on May 20, the resignation of Bradley Stoughton as Secretary of the Institute was presented and regretfully accepted by the Board. The letter of resignation follows : Gentlemen: About two years ago, I indicated to the President and some members of the Board my belief that the office of Secretary of the Institute should not be a permanent one. It is my observation of events, not only in our own Institute, but also in several sister societies, that too long a tenure of office by the Secretary inevitably leads to a situation which is not good either for him or for the society. After submitting this in writing to the Directors on February 17, 1920, I was overpersuaded by members of the Board to defer resignation until a more convenient time for the

Jan 1, 1921

By G. D. Rieck, M. M. P. Janssen

Chemical diffusion coefficients and heats of activation for diffusion in the NizAh fy), NiAl (6), and Ni3A1 (E) intermetallic phases and the solid solution of aluminum in nickel (( phase) were calculated from layer growth experiments. No finite diffusion coefficient for the NiAl3 ((3) inter metallic phase could be calculated. The values of the diffusion coefficients are dependent both on the method of calculation and the type of diffusion couple. The heat of activation for diffusion in the y phase was found to be 47 kcal per mole in the temperature range oj 428" to 610°C. Heats of activation of 41, 12, and 48 kcal per mole were found for diffusion in the 6, E, and ( phases, respectively , in the temperature range of 655" to 1000°C. Experiments with markers in the diffusion zone demonstrate a very pronounced Kirkendall effect. It appears that only aluminum atoms take an active part in the diffusion process during the formation of the 0 and y phases at temperatures of about 600°C. During the formation of the 6, E, and < phases at higher temperatures only nickel atoms are moving. It is suggested that the great stability of the intermetallic compounds in the Ni-A1 system governs the Kirkendall effect. SOME factors controlling layer growth during inter-diffusion in the Ni-A1 system (phase diagram, see Fig. 1) were studied by Castleman and Seig1e.l&apos;~ They found the NiA1, ((3) and NiAl3 (y) intermetallic compounds to appear in the diffusion zone of Ni-A1 couples at annealing temperatures of 400" to 625°C; the NiAl (6) and Ni3A1 (E) intermetallic compounds appeared in y-Ni couples at annealing temperatures of 800" to 1050°C. These authors carefully examined metallographically Ni-A1 couples after 340 hr annealing at 600°C. Besides the (3 and y phases they found very thin layers of the 6 and E phases. ~n~erman~ and Castleman and Froot4 observed a much more rapid growth of the 5 and E phases at 600°C in Ni-A1 couples in case a crack was present at the /3-A1 interface. Numerous layer thickness measurements carried out by Castleman and Seigle on the y phase prove that the layer growth of this phase obeys the parabolic law after a certain transient period. From this they concluded that the layer growth of the y phase is controlled by volume diffusion. The growth of the 13, 6, and E phases appeared to be volume-diffusion-controlled also. The authors estimated that at 600°C and at atmospheric pressure Dp was 1.8 x lo-"ll sq cm per sec, D, 9.1 x 10" ™ sq cm per sec, Qp 27 kcal per mole, and Qy 31 kcal per mole. The present work was carried out to obtain more quantitative data about the kinetics of growth of the phases of the Ni-A1 system and the reactions that occur during the formation of these phases. Because in this system the diffusion process results in the formation of several distinct intermetallic compounds, the current term reaction diffusion is used in the title of this paper. In order to obtain layers of the fl phase compound of uniform thickness, a new technique for preparing diffusion couples was developed. The kinetics of growth of the y phase in 6-Al, E-Al, and Ni-A1 diffusion couples was studied at different temperatures. The kinetics of growth of the 6, c, and ( phases in Ni-y, Ni-6, and Ni-c diffusion couples was also studied at different temperatures. The calculation of the diffusion coefficients Dp and Dy by Castleman and Seigle are critically considered in this paper; by means of a revised method of calculation more reliable val-ues of , and Dg were found. These values are in good agreement with the values of the diffusion coefficients obtained by the method of Boltzmann-Matano. From the temperature dependence of the diffusion coefficients the heats of activation for diffusion were calculated by means of an Arrhenius-type equation. The investigation of the Kirkendall effect has been used to obtain information about the ratio of the intrinsic diffusion coefficients of the separate atoms5 and the mechanism of diffusion. Moreover porosity as a result of a distinct Kirkendall effect would be of practical importance in connection with the bonding of diffusion coatings. The analyses of the diffusion couples were carried out by metallographic methods. The values of the concentrations at the phase boundaries and the concentration profile in each of the phases, which are needed for the calculation of diffusion coefficients, were obtained by electron-pro be X-ray microanalysis. EXPERIMENTAL PROCEDURE A) Materials for Diffusion Couples. The intermetallic compounds 6 (50 at. pct Ni) and E (74 at. pct Ni) were prepared from the pure metals by high-frequency induction melting in argon atmosphere. Use was made of aluminum wire (99.99 wt pct Al) and nickel sheet (99.95 wt pct Ni). The 6 and E phase melts and the nickel shiet (thickness 0.1 and 0.5 mm) used for preparing diffusion couples were annealed for 64 hr at 1200°~ for homogenization and grain coarsening (final crystal size 1 to 3 mm). composition and homogeneity of the intermetallic compounds were checked by mi-crohardness measurements and X-ray diffraction. From the 6 and E phase melts discs of 0.5 mm thickness were prepared by means of a water-cooled rotat-

Jan 1, 1968

By Benjamin Lustman, Robert F. Mehl

The study of the high-temperature oxidation of pure metals, intensively pursued experimentally since the pioneer work of Pilling and Bedworth1 and supplemented by the recent theoretical work of Wagner2 is now well advanced. The important field of low-temperature oxidation—i.e., oxidation extending only through the temper color range of thicknesses with the formation of thin oxide layers in the range from 0 to 1000-2000 ?ngstroms—has not, however, reached so satisfactory a state, owing largely to the experimental difficulties that attend the formation and study of thin films; most of the work has been performed on abraded specimens whose surface irregularities approximated the thickness of the films formed. It has been pointed out that the rates of oxidation of different crystal faces are different and that the difierence may be related to the orientation relationships that obtain between the metal crystal and the superimposed oxide crystal; it has also been suggested that this orientation dependence should manifest itself in rates of oxidation and perhaps also of corrosion in aggregates bearing preferred orientations.3&apos;4 An attempt to measure the rates of oxidation of different crystal faces of alpha iron demonstrated this difference in rate,4 but the dependence of rate on orientation was not simple; the method of measuring thickness, consisting of a color comparison with barium stearate multi-films of known thickness, was not wholly satisfactory. For these reasons it was felt that a study of the rate of oxidation of single crystals prepared with surfaces as smooth as possible, using a sensitive method giving true film thickness, should be profitable. Copper was chosen because of the ease of reduction of the primary oxide film and because the orientation relationships between metal and oxide and the composition of the oxide films formed at low temperatures are known; for thin films formed at low temperatures, Cu2O alone occurs.22-24 Experimental Procedure Various methods of surface preparation were attempted in order to obtain a surface that would oxidize uniformly and repro-ducibly. Electrolytic polishing by the method of Jacquet5 and electrolytic and mechanical polishing followed by annealing in vacuum and in purified hydrogen at various temperatures were tested. The procedure finally adopted consisted in a fine metallographic polish followed by an anneal in purified hydrogen at temperatures of 900° to 1000°C. for 12 hr. or more. The surface so produced was very bright and smooth, with no trace of specular etching (though some grain-boundary etching was observed); indeed, fine scratches produced by the final polish were entirely removed by the high-temperature anneal. After this treatment, the specimens were cooled in hydrogen to room temperature and placed in the oxidation furnace, where

Jan 1, 1941

By Benjamin Lustman, Robert F. Mehl

The study of the high-temperature oxidation of pure metals, intensively pursued experimentally since the pioneer work of Pilling and Bedworth1 and supplemented by the recent theoretical work of Wagner2 is now well advanced. The important field of low-temperature oxidation—i.e., oxidation extending only through the temper color range of thicknesses with the formation of thin oxide layers in the range from 0 to 1000-2000 ?ngstroms—has not, however, reached so satisfactory a state, owing largely to the experimental difficulties that attend the formation and study of thin films; most of the work has been performed on abraded specimens whose surface irregularities approximated the thickness of the films formed. It has been pointed out that the rates of oxidation of different crystal faces are different and that the difierence may be related to the orientation relationships that obtain between the metal crystal and the superimposed oxide crystal; it has also been suggested that this orientation dependence should manifest itself in rates of oxidation and perhaps also of corrosion in aggregates bearing preferred orientations.3&apos;4 An attempt to measure the rates of oxidation of different crystal faces of alpha iron demonstrated this difference in rate,4 but the dependence of rate on orientation was not simple; the method of measuring thickness, consisting of a color comparison with barium stearate multi-films of known thickness, was not wholly satisfactory. For these reasons it was felt that a study of the rate of oxidation of single crystals prepared with surfaces as smooth as possible, using a sensitive method giving true film thickness, should be profitable. Copper was chosen because of the ease of reduction of the primary oxide film and because the orientation relationships between metal and oxide and the composition of the oxide films formed at low temperatures are known; for thin films formed at low temperatures, Cu2O alone occurs.22-24 Experimental Procedure Various methods of surface preparation were attempted in order to obtain a surface that would oxidize uniformly and repro-ducibly. Electrolytic polishing by the method of Jacquet5 and electrolytic and mechanical polishing followed by annealing in vacuum and in purified hydrogen at various temperatures were tested. The procedure finally adopted consisted in a fine metallographic polish followed by an anneal in purified hydrogen at temperatures of 900° to 1000°C. for 12 hr. or more. The surface so produced was very bright and smooth, with no trace of specular etching (though some grain-boundary etching was observed); indeed, fine scratches produced by the final polish were entirely removed by the high-temperature anneal. After this treatment, the specimens were cooled in hydrogen to room temperature and placed in the oxidation furnace, where

Jan 1, 1941

By Robert H. Richards

The extent to which sizing by sieves should be carried, as a preliminary to the separation, by jigging, of minerals of different specific gravities, has been a matter of controversy for many years. The subject has been investigated by several authorities, yet the ground does not seem to have been completely covered, nor are the questions involved entirely settled. For my present purpose I shall refer to but three investigators—Rittinger, Munroe, and Hoppe. In seeking additional light, I have gone over part of the old ground which has been considered satisfactorily settled; and since these preliminary tests have thrown light on some points, they have been included in this paper. In the investigations here described, I have confined myself, for several reasons, wholly to small sizes—grains of 0.1 inch in diameter and less. Rittinger&apos;s work was mainly done upon larger sizes, and there is much need among millmen of information concerning the smaller sizes. Moreover, these sizes brought the investigation within the means at my disposal. The laws that have been claimed as the laws of jigging by the several authorities are: 1. The law of equal-settling particles. 2. The lam of interstitial currents. 3. The law of acceleration. 4. The law of suction. The first of these has been considered by investigators, generally, to be the most important of all, and the larger part of the work of jigging is thought to be governed by it. But that it does not cover the whole of jigging is clear to all; and to account for the increased efficiency which we may call the extra jigging-catch, the other three laws have been advanced. The investigation described in this paper was undertaken to determine, as far as possible, to what extent each of the four laws con-

Jan 1, 1895

By R. S. Dean

REQUIREMENTS for war materials have led to large scale experimentation upon metallurgical innovations. It is of interest to inquire what this may contribute of permanent value to our existing technology, as innovations adopted during war are apt to be discarded promptly at its end. This is because utilization of substandard ores usually requires a new technology for ore treatment, and a new use-pattern for employment of the products. Thus two very different problems are involved: first, devising a process; then, adopting its products by industry, with readjustments of the use-pattern if necessary. A new process may be as good or better than an old one, but the readjustments required for use of its products may prevent its general adoption if this implies scrapping existing plants and investing much additional capital. Metallurgical innovations are of three kinds: I. The use of substandard material in processes already established; 2. The grading-up of substandard material to render it more suitable for established processes; 3. The adjustment of technology and use-pattern to the raw materials that we have.

Jan 1, 1945

By C. K. Leith

THE interdependence of nations in regard to mineral supplies has grown apace with the expanded needs of industry, with depletion of reserves, and with advances in technology. This increased mutual dependence raises many questions of foreign economic policy of special importance in our postwar planning. Realization of the urgent need for the development of a general mineral policy broadly based on national requirements led to discussions of the problem between officials of the Department of State and myself, as a result of which it was suggested that I make an informal and unofficial canvass of the views of mineral specialists of the country on foreign mineral policy.

Jan 1, 1946

By Anthony William Deller

MAJOR battles in the present war have been fought in American research laboratories. Without the outstanding contributions made by our scientists, engineers, and technologists in mining and metallurgy, many of our achievements in the present war would have been impossible. All recognize the fact that modern research has found the answer to problems which seemed insuperable. For the duration, many of these inventions must be maintained as war secrets. But aside from these, the record of accomplishment in peace and war, especially in the past few decades, known to all, demonstrates what scientific and industrial research can accomplish. It may be regarded as axiomatic that the development of modern industry is based principally upon research devoted to making inventions and discoveries. We have come a long way from the sixteenth century, when Agricola published his classical "De Re Metallica:" With our vastly increased knowledge we are now commercially producing dozens of metals entirely unknown at that time. Further, with our modern methods of research and development, a large number of invaluable alloy compositions have been produced. These include numerous age-hardenable alloys, cupronickels, "Everbrite", "Everdur", "Duralumin", "Elinvar", "Hastelloy", "Inconel", "Invar", "Monel", "Ni-chrome", "Ni-Hard", "Ni-Resist", "Permaloy", "Silcrome", stainless steels and irons and other alloy steels, "Stellite", and zinc die-casting alloys.

Jan 1, 1945

By A. E. Jenkins, L. A. Baker, N. A. Warner

Rates oj decarburization of levilated Fe-C droplets conlaining 5.5 to 0 pct C have been measured at 1660°C. Gas mixtures of 1, 10, and 100 pct 0, with helium diluenl were used at velocities of 12.5 and 62.5 cm per sec. Rates were independent of carbon concentration in the mell and in good agreement with the calculated rule of oxygen diffusion through the gas boundary layer. The effects of flow rale and total pressure are as predicled and the rates are approxitnalely 2.5 times those with CO2 as oxidant. The mass-transfer correlation used incorporaled the efject of natural convection as well as forced conrection. Graphile spheres are shown to oxidize at the same rate as Fe-C droplets under the same experimental codlions. It is concluded that, for high carbon concentrations in the melt, the rate of- decarburizalion is controlled wholly by the rate of gaseous diffusion. Rate measurements with pure CO, are reported for low carbon concentrations where CO bubbles nucleate within the droplet. Under these circumstances the decarburi-zation decreased with carbon concentration and it is proposed that carbon diffusion is significant in conlrolling the decnvburization rate. In an earlier paper1 decarburization rate measurements were reported for levitated Fe-C alloys at 1660°C but with CO2 as the oxidant. The decarburization rate was found to be independent of carbon concentration in the melt but slightly affected by total pressure. The authors were unable to explain the slight pressure effect but in all other respects the results were consistent with control by diffusion in the gas boundary layer. Subsequent work has been directed at finding the reason for the slight pressure effect and whether the kinetics with oxygen as oxidant parallel those with CO2. Recently Ito and Sano2 have shown that with water vapor-argon atmospheres the decarburization rate is gaseous diffusion controlled until an oxide film appears on the surface. In this work the melts were contained in crucibles. MASS TRANSFER IN THE GAS PHASE In the earlier analysis1 only forced-convection mass transfer was considered. Subsequent recognition of the existence of some free-convection mass transfer explained the observed small effect of total pressure on the decarburization rate. Steinberger and Treybal3 and Kinard, Manning, and Manning4 have developed correlations involving the linear addition of the contribution of radial diffusion, free and forced convection. Steinberger and Treybal&apos;s correlation was chosen as the most applicable to the present work since it correlated most of the data available in the literature and handled the low Reynolds number region exceptionally well. The correlation for (Gr&apos;Sc) < 108 is where Nu&apos; is the Nusselt number for mass transfer based upon the total surface of a sphere in an infinite medium, G&apos; is the mean Grashof number for mass transfer defined by Eq. [2], Sc is the Schmidt number (µ/pDAB)f, Re is the sphere Reynolds number (dpu,pf/µf), p is the viscosity of the gas (poise), p is the density of the gas (g cm-3), Dab is the binary diffusivity for the system A-B (sq cm sec-&apos;), dp is the sphere diameter (cm), u is the approach velocity of the gas (cm sec-I), and subscript f denotes the property value is computed at the film temperature Tf defined by Tf = +1/2(To + Tr) where To is the specimen temperature and T, is the approach gas temperature (oK). Natural convection occurs when inhomogeneities exist in gas density. These may be caused by concentration gradients, temperature gradients, or both. In the present work the temperature gradient between the sphere and the bulk gas was very large and in some cases, for example the runs with pure oxygen, the concentration gradient was also appreciable. The Grashof number defined by Mathers, Madden, and piret5 was used since it took account of both temperature and concentration gradients: where Gr&apos; is the Grashof number for mass transfer (p2fgd3|-yA-yA|/µ2f), Gr is the Grashof number for heat transfer (p2f gd3p|To - T,]/µ2fTf), Pr is the Prandtl number (cpµ/k)f, g is the acceleration due to gravity (cm sec-&apos;f, a is the concentration densification coefficient (1/p)(ap/ayA)T, yA is the mole fraction of component A at the gas-metal interface, yA is the mole fraction of component A in the bulk gas stream, cp is the heat capacity of the gas per unit mass at constant pressure (cal g-I OK-&apos;), and k is the thermal conductivity of the gas (cal cm-&apos; sec-1 OK-1). Mathers et al. tested this combined Grashof number

Jan 1, 1968

By Donald B. Gillies

WE HAVE come a long way since the time of the old steel master who declared that chemistry would ultimately bring the steel business to ruin. Yet I sometimes doubt whether even now we fully recognize the great debt we owe to the institutions that today are initiating young men into the fascinating mysteries of science and training them in the art of engineering. I am not sure that we recognize the importance of the contribution that the schools of applied science and the technical colleges are making to our industrial economy. That contribution is neither narrow nor restricted. It covers the whole range of industry. Dr. Compton, himself, has shown in his survey of leading American corporations that the engineer is twelve times more likely than the nonengineer to become president, five times more likely to become treasurer, and thirty times more likely to become an officer. So the hand of the engineer not only is all-powerful in the laboratory and in the drafting room but his control is increasing in all departments of management.

Jan 1, 1940