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By Henry M. Howe

The brilliant and very original matter in Professor Jeffries' discussion† should rank not only as an independent paper, but as a most important one. In particular, the explanation which it gives of the remarkable Sauveur phenomenon, over which so many of us have puzzled long and hard, is so clear, complete, and cogent as to go far toward establishing Professor Jeffries' hypothesis. The very leatures of Professor Sauveur's photographs which fit this hypothesis so exactly are reproduced in Chap-pell's photographs of steel coarsened under somewhat different conditions.' The ideas developed by these discoveries are so novel that convenicnce of language seems to call for new conventional terms for expressing them. In what follows here I propose certain terms for this end, for criticism and improvement, and I attempt to generalize from Professor Jeffries' hypotheses. Generally speaking, a given set of grains which undergo no growth in the cold will, when the temperature is raised progrcssively, start to grow on reaching a certain temperature, and will continue growing at all higher temperatures. The "germinative" temperature is that at which growth begins, quite as the conditions which cause a seed to grow are "germinative." We have then an inert temperature range below the germinative temperature, and a growth range above it, the germinative temperature being the limit between these two ranges. So, too, a germinant grain is one which is at its germinative temperature, and hence beginning to grow, while inert grains are those below their own germinative temperature, and the term "growing grains" includes those which are germinant and those which are above their germinative temperature. These last could be called " supergerminant" if the distinction should be needed. "Germinative temperature" seems better than "critical temperature

Jan 1, 1917

By S. W. Kennedy, M. Cohen, L. D. Calvert

A high-temperature X-ray diffraction method has been used to study the composition and the kinetics of formation of oxide scales at 800 °C on iron and pure iron-nickel alloys containing 25.6, 75, and 84 pct Ni. This technique has been combined with chemical analysis, and metallographic examination, and determination of weight-gain time curves. The 75 and 84 pct Ni alloys form a three-layer scale consisting of porous NiO next to the metal, a spinel layer, and a -Fe203 on the outside. The 25 pct Ni alloy produces a scale of spinel and Fe,O,, in which, however, traces of FeO and NiO are observed near to the metal. On all the nickel alloys the Fe20, is orieqted with the (107) plane parallel to the surfaces. The exposed surface of the Fe20, is in the form of needles whose axis is perpendicular to the specimen surface. Although the alloys show nonuniform oxidation rates as determined from weight-gain measurements, the X-ray data indicate that the total scale and individml scale layers grow uniformly and parabolically. Deep subscale formation is observed in the 25 pct Ni alloy only. This appeared to be associated with cracking of the scale and penetration of the oxygen along the grain boundaries. ALTHOUGH film formation has been investigated by high-temperature electron-diffraction techniques, for example by Gulbransenl and Hickman,' there have apparently been no investigations of scaling by methods permitting study of the scale during formation at the reaction temperature. Methods involving quenching of scales are based on the working assumption that no significant changes take place on cooling. In general, however, compounds may disproportionate, and the different thermal expansions of constituents may cause disruption of the scale on cooling. In particular, some scales cannot be quenched without spalling. These difficulties are avoided by X-ray diffraction examination at the temperature of formation. High-temperature diffraction procedures also provide a method of determining the kinetics of formation of each phase separately in a multicom-ponent scale. The scaling of binary iron-nickel alloys Containing up to 30 pct Ni at a temperature of 800°C has been studied by Benard and Moreau using cooled specimen~,~ whilst Foley, Druck, and Fryxel14 made an electron-diffraction study of cooled oxide films formed on an iron 42 pci Ni alloy. In the present work the scaling of three iron-nickel alloys containing 25.6, 75, and 84 pct by weight of nickel, at 800°C in oxygen at atmospheric pressure was investigated by X-ray diffraction techniques using a Norelco Geiger-counter diffrac-tometer. The oxidation of iron was investigated for comparison. In addition normal metallographic examinations and chemical and X-ray analyses were made, and weight-gain time curves obtained. EXPERIMENTAL Materials Used—The analyses of the alloys were as follows: Percent by Weight Nickel 25.6 pct 75.4 pct 83.2 pct Aluminum 0.004 None found 0.002 Cobalt — 0.05 0.05 Chromium — — — Silicon — 0.01 None found Carbon All less than 0.05 pct The chemical analysis of the iron was: Al— 0.002 i 0.001 pct, C—0.007 pct, Cr less than 0.001 pct, Cu—0.002 ± 0.001 pct, Mn—0.003 ± 0.001 pct, N—0.0002 pct, 0-0.013 pct, P—less than 0.0002 pct, Pb—not detected, S—0.0017 pct, Si—0.0095 pct, Sn—none detected. This iron was the same as that used to make the alloys and was obtained from the same source-Vacuum Metals Corp. One specimen of pure iron from The British Iron and Steel Research Association was used for preliminary investigation. Specimens were machined to shape from cast rod, polished (the final polish being with 600 Sic paper), degreased in trichlorethylene, washed, and etched. The etching and neutralizing procedure adopted by

Jan 1, 1960

By Milton E. Wadsworth, W. Martin Fassell, William H. Dresher

A study of the rate of dissolution of molybdenite (MoS2) in alkaline solution was carried out under carefully controlled conditions. Effects of temperature, oxygen over-pressure, and KOH concentration were evaluated. Studies were made in the temperature range 100°C to 175°C and in the pressure range 0 to 700 psia of oxygen. Under these conditions molybdenite was found to leach according to a linear mechanism. Both oxygen over-pressure and KOH concentration were found to control the rate of leaching. The mechanism has been explained in terms of adsorption of oxygen at the molybdenite surface followed by configurational rearrangement of the adsorbed molecules. The hydroxyl ion dependency is believed to be diffusion-controlled. Laboratory batch studies have shown that molybdenite can be readily dissolved in alkaline solutions under moderate conditions of temperature and pressure. Commercial application of this process to the production of ferro-molybdenum and molybdenum chemicals is promising in view of the ease of dissolution of molybdenite and the relatively noncorrosive conditions involved in the process. HIGH temperature-high pressure techniques have long been used to great advantage in the organic chemical industry, the petroleum industry, and the paper industry. Only recently, however, have these methods been used to extract metals from their ores on a commercial scale. The Chemical Construction Corp., together with interested producers of nickel and cobalt, has done much to develop methods of producing nickel and cobalt powders by the use of high temperature-high pressure techniques.' The Howe Sound Co. is currently operating a plant near Salt Lake City in which the new Chemical Construction Corp. technique is applied to cobalt-arsenic sulfide concentrates. In this method the concentrates are leached in a dilute solution of sulfuric acid under air pressure at a high temperature. Near Edmonton, in Alberta, Canada, the Sherritt Gordon Co. is also using the new method in conjunction with its ammoniacal leach process.' National Lead Co., at Fredricktown, Mo., is operating a process similar to that of Howe Sound. In spite of the rapid growth of high temperature-high pressure hydrometallurgical processes, there has been very little work done on fundamental principles involved in this type of process. Conse- quently the literature lacks any significant data in this field. Oxidation of pyrite,3 phalerite,4 galena,5 and recently molybdenite" in alkaline solutions has been reported to some extent. This investigation was initiated, therefore, to broaden the application of high temperature-high pressure hydrometallurgy and also to contribute some insight into the basic mechanisms of oxidation in an aqueous medium under these conditions. In addition to the immediate consequences of these processes much valuable information remains to be learned about fundamental reactions when they are carried out at temperatures and pressures slightly higher than those normally encountered. Leaching of molybdenite by alkaline solutions under oxygen pressure has recently been reported in the Russian literature by E. S. Usataya,8 who found that leaching rate increased with an increase in the pH of the solution—the strongest effects being observed at a pH of 10—and also with an increase in temperature. Usataya also has reported the formation of a protective film on the surface of the molybdenite when the leaching solution was weakly alkaline, neutral, or acidic. He believes that this oxidation process explains the migration of Mo+ + in the oxidation zones of molybdenite ore deposits and the subsequent impoverishment of the ores. Equipment: The high temperature-high pressure reaction unit used in this work was especially designed for kinetic studies of this nature, emphasis being placed on accuracy of measurement and precision of control. As details of the unit's construction and operation have been discussed elsewhere,7 Only basic features and principles of operation will be discussed at this point.

Jan 1, 1957

By S. F. Emmons

"The obscurity which still veils from us the true nature of veins will become more acid more cleared up when they can be considered in connection with the geological structure of the regions in which they occur." 1 THESE words, according to Lossen, the biographer of the late Dr. A. von Groddeck, of Clausthal, were the last received by him from that eminent man, perhaps the most far-sighted and carefully progressive of recent writers on ore-deposits. They seem to me to form a fitting text for what I am about to say ; since I find that many of the conclusions at which I have arrived by my own study of the structural relations of ore-deposits,or, in other words, of the structural and dynamic geology of the regions in which they occur in this country, have been similarly determined by hint within recent years in Europe, and especially in his home field of work, the Harz. I shall not enter upon a detailed account of how far other workers may have arrived at similar conclusions with myself, since these questions of priority are of little interest, except to those immediately concerned; but will briefly present the methods by which, in my work in this country, I have arrived at certain generalizations, and will point out the practical bearing which they may have upon the work of mining engineers. In my first thorough and systematic examination of an important group of ore-deposits, viz., that of Leadville, Colo., I was enabled, through the generous facilities afforded me by the then Director of the Geological Survey, Clarence King, to

Jan 1, 1913

By P. L. Hendricks, J. W. Spretnak

The interstitial atom principally responsible for the yield point and strain aging in electron-beam-melted tantalum is identified by analysis of the kinetics of the return of the yield point after an increment of plastic deformation. Two sets of specimens contained two levels of oxygen with very low hydrogen contents and the third set had comparable oxygen and hydrogen contents. The activation energy for the return of the yield point agrees well with that for diffusion of oxygen for the first two sets of specimens. For the third set of specimens, the activation-energy value lies between those for diffusion of hydrogen and for diffusion of oxygen. The advent of the dislocation model of plastic deformation in metals has revitalized interest in the yield point and strain aging in bcc metals containing a certain minimum content of interstitial solute elements. Much theoretical and experimental work has been performed in recent years to elucidate the detailed mechanism of these phenomena. The purpose of this investigation is to attempt to identify the principal interstitial element responsible for the yield-point phenomenon in electron-beam-melted tantalum by analysis of the kinetics of the return of the yield point after an increment of plastic deformation. Some of the earlier theories of the yield-point phenomenon proposed a grain boundary film of iron carbide. Such models could not satisfactorily explain all features of strain aging and the yield-point phenomena. The most widely accepted explanation is that of Cottrell,1 later extended by Cottrell and Bilby.2 Strain aging is ascribed to "locking" of dislocations by interstitial solute "atmospheres". The yield-point phenomenon results when the dislocations are torn away from their atmospheres. The strain-aged condition is re-established after sufficient time to allow the interstitial atoms to diffuse to the dislocation lines and re-establish the locking atmospheres. Clearly, the Cottrell-Bilby model is concerned with the bulk of the grain and does not specifically involve the grain boundary. The recent modification of the Cottrell-Bilby model is a redirection of attention to the role of the grain boundary and the possibility of multiplication of a limited number of free dislocations rather than unlocking all of the dislocations. Theories have been advanced by Hahn3 and conrad4 which are modifications of the Cottrell-Bilby theory. The model proposed by Hahn indicates that, although the possibility of un- locking anchored dislocations is not excluded, it implies that unlocking is not necessarily required to explain yield drop. Locking of dislocations during the aging treatment is a necessary part of the theory; however, it assumes that dislocations once locked remain locked. It is suggested that the yield drop observed is a result of the following factors: 1) the presence of a small number of mobile dislocations initially, 2) rapid dislocation multiplication, 3) the stress dependence of dislocation velocity. In the case of bcc metals, locking is considered to be the means by which dislocations are immobilized. Cold working of the metal results in the generation of larger numbers of new dislocations and the stress dependence of the dislocation velocity accounts for yield drop observed. Conrad' has proposed a model similar to the one just described which applies to strain aging of iron and steel and which logically could be extended to other bcc metals. This model also does not require large-scale unlocking of dislocations. It is proposed that, during initial loading of a specimen below the upper yield stress, a few dislocations are torn free of their Cottrell atmospheres at regions of stress concentrations. With an increasing stress, some multiplication of dislocations occurs by a double cross slip mechanism, thus giving a preyield microstrain. At some critical stress represented by the upper yield stress, sudden profuse multiplication of dislocations occurs, enabling plastic flow to proceed at a lower stress. In this model, microstrain, preyielding, and flow represent the movement of free dislocations. It should be noted that this model also requires the locking of dislocations by interstitial solute atoms for the occurrence of a yield point; however, unlocking of large numbers of dislocations is not required. If it is assumed that the yield point will return when some fraction of free dislocations produced during pre-straining are pinned, the number of solute atoms required to pin unit length of a dislocation line can be calculated when prestrain and reloading are done at the same temperature and strain rate. Since the migration of solute atoms back to the stress fields of dislocation lines is controlled by the diffusion rate of interstitial solute atoms, it is to be expected that the activation energy for strain aging would be identical to the activation energy for diffusion. It would also be expected that the strain aging observed will be controlled by the fastest diffusing species capable of producing locking over the temperature range investigated. The rate of yield-point return has been found to be adequately expressed by an empirical rate equation of the form: rate=Ae-Q/RT [1] where A = constant, Q = activation energy, R = gas constant, and T = absolute temperature. Cottrell and Bilby2 have expressed the number of atoms per unit length of dislocation line which arrive

Jan 1, 1967

As 1970 develops and industrial minerals stand at a crucial point in their progress, research and development programs appear to be the key needed to open up new uses for each mineral's future growth. Radically new processes are needed for making a host of new synthetic products from mineral raw materials which will more nearly meet the demanding specifications required for high performance in space, nuclear and defense applications. Consumer applications for high temperature environments will be needed and are important for continuing the nations economic mineral position. In addition, an acute materials problem limits the effectiveness of some of the newer concepts for controlling ail pollution. What is needed then, according to a report printed by the National Academy of Sciences, is the carefully planned development of a limited number of major centers at universities to provide for both basic research and training of personnel; the nurturing of interdisciplinary mechanisms for research and problem solving within these centers; the achieving of a better balance between physics and chemistry within research, emphasizing the chemical aspects of the material sciences; and the enhancement of a broader professional identity by unifying the various disciplines involved into a possible federation of existing societies which have an interest in the problems. [EE] presents its 1969 annual industrial minerals review, where individual authors evaluate the status of each industrial mineral and recount the major developments which occurred during the year.

Jan 1, 1970

By F. E. Harris

IT has been said that carbon is "ubiquitous" with reference to iron alloys. Certainly at temperatures where carbon and iron form the solid solution, austenite, it may be readily added to, or removed from, steel surfaces. Differences in concentration potential are the sole requirements for carbon flow. To measure the rate of carbon flow, a proportionality factor, D, is arbitrarily expressed in units of (length)2 X (time)-1. If the term used for carbon concentration is weight pct C, as is customary, then a factor must be found, changing this term to one of weight per unit volume when the diffusion coefficient, D, is used in flow formulae. The determination of D values for carbon is complicated since D varies with the concentration itself. The Matano method has often been employed for systems involving a variant D. This method expreses an evaluation of unsteady flow whereby .0 is given a relationship with the numerical value of C-X slopes. The author contends that this solution is incorrect, except when D is invariant. The primary purpose of this paper is to support this contention. Here diffusion is controlled under two conditions of flow. The first part deals with the steady state; the second part considers unsteady flow under definite restrictions. Beginning with the fundamental concept, the development is continued until equations for C-X curves are obtained. The solution is then subjected to experimental data. It is realized that a great amount of reliable data is required for a rigorous proof. No such research is claimed. Instead an attempt is made to set forth the physical significance of the diffusion mechanism, and particularly to express the factors which influence the flow of carbon in austenite. Of equal significance is the implication that gaseous media may be employed with reasonable accuracy in making these determinations. THE STEADY STATE DIFFUSION OF CARBON IN AUSTENITE The fundamental experiment defining diffusion in solid metals may be readily performed for carbon in gamma iron.1 For this experiment a thin plate of medium carbon steel is chosen. The surfaces of this plate may be taken as two parallel planes which may be considered infinite for points well in the center of the planes. These two planes are held at different concentrations of carbon at a constant temperature. This temperature, 1700°F for example, is one where the single phase, carbon in solution with gamma iron, exists. When these conditions are held for a sufficient time the concentration of carbon of the different points of the solid settles down towards its steady state value. At points well removed from the ends, the concentration will remain the same along planes parallel to the surfaces of the plate.

Jan 1, 1947

By F. D. Rosi

The plastic properties of extended silver and copper crystals of varying purity were studied as a function of crystal orientation in the early stages of flow. Variations in the gross shape of the shear stress-shear diagram and in the properties of critical Variationsshear stress and shear-hardening coefficient were correlated with changes in slip-band developments. The phenomenon of work hardening is discussed in terms of the existing dislocation theory. IT appears certain from the early studies on the deformation characteristics in metal crystals1-3 that plastic flow takes place in a preferred crystallo-graphic slip system which is determined by the geometry of the crystal (law of maximum shear stress), and that the value of shear stress for this system is independent of crystal orientation (law of critical shear stress). Experimentally, it has been demonstrated further that the law of critical shear stress can be extended to include extensive plastic flow.&apos; Thus, the shear-hardening coefficient, which is defined as the slope of the shear stress-shear curve, also is considered to be independent of orientation. It is noteworthy that deviations from this empirical shear-hardening law have been reported in cubic crystals whose initial orientation favors slip on more than two systems.&apos; Moreover, this law appears to have been derived from stress-strain data relating to relatively high values of shear strain (0.5 to 4), where widespread slip and complex distortions can be expected, regardless of crystal orientation. Since existing data indicate that the strain inhomogeneity in a crystal is manifested particularly in the early stages of flow, it would appear that a more exacting test as to the fundamental nature of the shear-hardening law would be to investigate systematically the shape of the stress-strain curve as a function of crystal orientation in the earlier stages of deformation. With regard to the general form of the shear stress-shear curve for cubic crystals, early studies show a parabolic hardening law, where the shear 1 stress is proportional to the square root of the shear-strain. Since this law was predicted theoretically by Taylor" in his original dislocation model for hard- ening, it has been accepted widely as a fundamental flow characteristic of cubic metals. However, it was recently pointed out by Masing6 hat the parabolic law is not the elementary form of hardening in cubic crystals, but instead is a consequence of complexities in the flow process (e. g., deformation bands and unpredicted secondary slip). Thus, in the very early stages of deformation (< 2 pct extension) where the occurrence of such complexities is unlikely, a different strain-hardening behavior might be anticipated. This view is supported by the recent work of Rosi and Mathewson7 on high purity aluminum where a linear law was obtained for extensions up to 2 pct. A linear hardening over a wider range of deformation also was reported by Rohm and Kochendorfer8 ho deformed aluminum crystals under conditions approximating pure shear. Even more pertinent is the recent evidence of Masing and Raffelsieper9 on high purity aluminum crystals. It was found that for crystals having initial orientations near a <l00> or <1ll> axis, a high hardening was obtained, whereas crystals with a <110> orientation exhibited a low and linear hardening curve followed by a region of more rapid hardening. Since much still remains obscure concerning the details of strain hardening as well as slip-band formation in face-centered-cubic crystals in the early stages of deformation, the present study was undertaken to evaluate the effect of crystal orientation on these two important manifestations of glide. It is important to note here that at the time of this study, Lucke and Lange11 presented information on the orientation-dependence of the shape of the strain-hardening curve in aluminum of various purities. Their work, which essentially represents an extension of that of Masing and Raffelsieper, in many respects is parallel to that of the present study. Experimental Procedure Production of Single Crystals: Single crystals of silver and copper of varying purity were used in

Jan 1, 1955

By W. H. A. Timm

Lake Dufault Mines, Limited, is located ten miles north of Noranda, Quebec, Canada. Following discovery of a copper-zinc orebody late in 1961, metallurgical investigations of diamond drill core were conducted by Lakefield Research Limited during 1962 and 1963. These were followed by pilot-plant tests in May and June of 1964, utilizing underground development ore. Milling operations commenced on August 16, 1964, and reached rated capacity of 1300 tpd by October 1, 1964. Since that time, tonnage was gradually increased to a maximum of 1400 tpd and since January 1, 1968, gradually decreased to the present rate of 1100 tpd due to an increase in the hardness of the ore. The ore milled from start-up until January 1968, was mainly massive sulfides, consisting of a complex mixture of iron, Copper, zinc, and minor amounts of lead sulfides with important associated values in gold, silver and cadmium (average specific gravity of 3-8). From January 1968 until the present, the ore being processed is described geologically as a boxwork of sulfide stringers of chalcopyrite, pyrite, and pyrrhotite with some local dissemination in siliceous rhyolite (average specific gravity 2.9) supplemented by the massive copper-zinc ore. The limited size of the orebody and the mining method employed (open stoping by blasthole and slash benching methods) would have

Jan 1, 1970

By A. D. McMaster, M. L. Gimpl, N. Fuschillo

Low-power, high-speed, radiation-resistant, monolithic thin-film integrated circuits require thin-film resistors of high sheet resistance which are compatible with the processing requirements for monolithic silicon devices. For this purpose the structure and electrical resistance as a function of temperature were investigated for Nichrome-silicon monoxide cermet films on passivated single-crystal silicon substrates. A suitable material was found to be a mixture of 50 vol pct Nichrome-50 vol pct silicon monoxide. This mixture, when evaporated onto 300°C substrates. showed a low temperature coefficient up to 400°C, at both 270 and 1100 ohms per square. Resistors deposited on room-temperature, 300°, and 500°C substrates were heat-treated at 600°C in air for short periods of H- seed, low-power, radiation-re sis tant, monolithic thin-film integrated circuits&apos;-3 require thin-film resistors of high sheet resistance and low temperature coefficients of resistance which are compatible with the processing requirements for monolithic silicon active devices. The present investigation is directed towards the replacement of the Nichrome in the sandwich-type SO2-Nichrome-SiO resistors, currently used for DTL monolithic thin-film integrated circuits, with codeposited Nichrome-SiO cermet resistors. These Nichrome-SiO resistors are provided with an overcoat of SiO and are deposited onto thermally oxidized silicon wafers used in monolithic mi-crocircuit technology. The cermet resistors are shown to provide a lower temperature coefficient of time totaling up to 45 min. Electron nzicrogvaphs and diffraction patterns were taken of the as - deposited and heat-treated films. These results were then compared with electrical-resistance measurements for each condition. The room-temperature and 300°C substrate films showed a large decrease in resistance. The 500°C substrate film remained stable throughout the entire cycle. Electron-microscopy results show that the increased stability after heating to 600°C is largely due to crystallization of the films which begins in the vicinity of 400°C. The slight oxidation of the films when heated in air had a negligible effect on the resistance. The resistance of the film was a function of the substructure. resistance and a more versatile compatibility with silicon monolithic processing. Previous work3, on chromium-SiO coevaporated cermet resistors on glass and ceramic substrates without overcoats of SiO has been reported. For the present application, the thin films should possess the following ideal requirements: a) a temperature coefficient of resistance as near zero as possible up to 300°C; b) have a sheet resistance higher than 200 ohms per sq to conserve space on the chip; c) be easy to evaporate; d) be oxidiation- and radiation-resistant; e) show long-time stability at 100°C; } be stable in N2 atmospheres up to 600°C for short periods of time (5 to 45 min). Requirements a to e are well-known. The last requirement was optional and was due to a mask elimi-

Jan 1, 1967

By W. T. Weller

In Part I, a study of pressure build-up curves calculated for conditions under which both oil and gas flow led to the conclusion that the presence of a dispersed free gas phase in an oil reservoir must be taken into consideration to estimate accurately average reservoir pressure and permeability from build-up curves. Familiar methods based on the assumption of no free gas can be extended to the two-phase case by using total compressibility and mobility in place of single-fluid compressibility and mobility. These methods give correct values for average pressure and permeability when gas saturation is small. Errors become larger as the gas saturation increases. However, for the use to which the results will be put, the methods are satisfactory for reservoir engineering purposes. An improved method of calculating the performance of depletion-type reservoirs is presented in Part 2. Because the mathematical relationships describing simultaneous flow of oil and gas are quite involved. simplifying assumptions are made to provide means of obtaining approximate solutions of reasonable accuracy. One such approximate method now in use is the constant-GOR solution. It involves the assumption that at any instant, the ratio of total gas flow rate (both free and disolved) to oil flow rate is the same at all points in the reservoir. The approach is not applicable unless the free gar saturation in the reservoir is everywhere greater than the critical gas saturation. This paper presents a modification which, by avoiding the constant-GOR assumption, makes the method applicable to all reservoir conditions, and so far appears to be more accurate than the constant-GOR solution and to he comparable in required compuctation time. PART I— BUILD-UP CURVE ANALYSIS INTRODUCTION Pressure build-up characteristics of shut-in wells have been used for many years by engineers to evaluate average reservoir pressure, effective permeability thickness of the pay section, effectiveness of well completion (skin effect) and reservoir size. A number of methods of analysis have appeared from time to time."" Without exception, these methods are based on the assumption that the reservoir contains but one fluid of constant small compressibility and constant mobility. It has been suggesteda" hat these single-fluid methods may be applied to data from reservoirs containing both oil and gas by substitution of some effective total properties of the multiphase system in place of the corresponding single-phase properties. The present investigation was undertaken primarily to evaluate this approach. METHOD A number of theoretical build-up curves were calculated for conditions of two-phase flow, under the assumption of certain reservoir and fluid properties, and were analyzed by single-fluid methods with appropriate total compressibility and total mobility values for the corresponding single-fluid properties. Results of the analyses were compared with the assumed conditions. The theoretical build-up curves were completed by procedures similar to those of West, Garvin and Sheldon." Since these calculations require a considerable amount of computer time, an attempt was made to derive an approximate calculation method. The attempt was unsuccessful for calculating build-up curves, but the effort did result in a new approximate method of calculating the performance of solution gas drive reservoirs, which appears to be an improvement over the constant-GOR method" used previously (see Part 2). The West, Garvin and Sheldon calculations involved the following assumptions: (1) the reservoir is circular and completely bounded, with a completely penetrating well at its center; (2) the porous medium is uniform and iso-tropic, with a constant water saturation at all points; (3) gravity effects can be neglected; (4) compressibility of rock and water can be neglected; (5) the composition and equilibrium are constant for oil and gas; (6) the same pressure exists in both the oil phase and the gas phase; and (7) no afterproduction occurs, i.e., the well is shut in at the sand face for build-up. These assumptions make it possible to describe two-phase flow of oil and gas by the partial differential equations:

Jan 1, 1967

By R. Ebeling, M. F. Ashby

The paper is in two parts. The first develops the formulae and method needed to calculate the size, nu)nber, spacing, and volume fraction of hard or inert particles in the interior of a specimen from measurernents made on an extraction replica; throughout, the spread of- particle sizes in a single specimen is taken into account, and the extraction efficiency of the replica is considered. A method for testing whether the particles are randotnly distributed in space is described, and the spacing of randomly distributed particles is discussed. The second Part describes the application of the method to copper containing spherical particles of silica; the description includes an estimate of the errors involved, and a comparison of this with alternative methods. All parameters except uolume fraction can be determined satisfactorily, and the method offers advantages over other electron-,rzicroscopic techniques when dealing with hard particles in a softer matrix, or inert particles in a chem-ically less inert matrix. 1 HE experimental measurement of sizes and numbers of discrete particles of a second phase embedded in a matrix material from opaque, plane sections has been considered by many authors, notably by Fullman.&apos; It is assumed that, when the specimen is sectioned, the particles are also sectioned, so that the diameters of the circles of intersection of particles with the plane of the cross section ("surface diameters") are measured. It is difficult to derive the distribution of true particle diameters ("volume diameters") from measurements of the distribution of "surface diameters" on a plane section. The measurement of size and numbers of small second-phase particles by transmission electron microscopy through thin foils of matrix containing the particles has been described by Cahn and ~uttin~&apos; and by ~illiard.~ Because of overlap and the fact that particles which intersect the foil surface may be sectioned whereas those in the bulk of the foil are not, it is again difficult to measure the true distribution of particle sizes. The use of replicas for this sort of measurement has not been analyzed in detail. A replica made from an opaque cross section, thus replicating the circles of intersection of particles with the plane of section, is analyzed by Fullman&apos;s method and suffers from the same difficulties. Under certain circumstances, however, extraction replicas can be used, and offer a special advantage in that they make the determination of the true distribution of particle diameters particularly simple. It is the purpose of this paper to describe this extraction replica method. Consider the example of an alloy consisting of SiOz particles, whose mean diameter is about 1000A, dispersed in a copper matrix. When the alloy is sectioned and mechanically polished, the particles are not sectioned, because they are much harder than the matrix, and so will be either left in the surface or pulled out whole, and because the particle size is smaller than the abrasive size of even the finest abrasive. The particles are chemically inert in solutions which chemically etch or electropolish the matrix, so that chemical treatments do not section the particles either. (Experimental measurements of particle shape in this alloy confirm this—truncated particles are never seen.) Small, hard or inert, particles are therefore not sectioned when the specimen is sectioned and polished. An extraction replica taken from this polished surface shows the true "volume" diameter of each extracted particle; the distribution of diameters seen on the replica is the surface distribution of true "volume" diameters, and the volume distribution of true "volume" diameters is easily derived from it. The extraction replica method is not subject to the difficulties associated with sectioning of particles, and avoids the problem of overlap from which the transmission method suffers. The method is well-suited for studying hard particles in a soft matrix. Examples are provided by internally oxidized alloys, oxide-dispersion strengthened metals like T.D. Nickel, and carbides, nitrides, and strong intermetallic compounds in metals. It should be possible to adapt polishing techniques in alloys containing softer but inert particles to avoid sectioning the particles (say by electropolishing or etching). The method is tested and illustrated in Sections 8 and 9 by applying it to a dispersion of spherical SiO2 particles in a copper matrix. I) SYMBOLS Symbols are defined where they first appear in the text. Volume fractions of particles are denoted by the symbol f, particle diameters by x, center-to-center particle spacings by D, and numbers of particles by N. Mean particle diameters and standard deviations about these means are denoted by x and a. Both arithmetic (subscript A) and geometric (subscript G) means are employed. In this paper we measure the distribution of true diameters of particles which touch or pass through a random-plane section of the specimen. We may want to know the distribution of particle diameters in the

Jan 1, 1967

By A. G. Spillette, R. L. Nielsen

The purpose of this paper is to further the understanding of reservoir response to hot-water injection by desuribing a two-dimensional, mathematical model of the process. Key assumptions are that no gas phase is present, and that the injected fluid reaches thermal equilibrium instantaneously with the reservoir fluids and sand. The resulting system of three partial differential equations is solved simultaneously through the use of a "leap-frog" application of standard alternating direction implicit methods for the solution of the mass-balance equations and the method of characteristics for solution of the energy-balance equation. The utility of the mathematical model is demonstrated by comparing numerical and analytic temperature distributions for hot-water bank injection and by comparing calculated with observed field behavior. Additional calculations show that hot waterfioding can recover significantly more oil than cold waterflooding, and that a hot-water bank recovers, with less energy input, nearly as much oil us continuous injection. Introduction Consistent field success with hot fluid injection processes requires good reservoir description and a thorough understanding of recovery mechanisms. The latter is fostered by a combination of well designed experimental studies and physically sound mathematical modeling. The purpose of this paper is to further the understanding of reservoir response to hot-water injection by describing a two-dimensional mathematical technique, indicating its validity, and demonstrating its utility for studying the effects of reservoir and operating parameters. Published experimental studies of hot fluid injection processes are few." Even if extensive data were available, two considerations discourage exclusive reliance on laboratory or field work. First, because of the severity of scaling requirements," laboratory results must be interpreted with care. Second, because of the one-shot nature of field experiments — injectivity/productivity tests and pilot floods—results seldom are available over the desired range of operating conditions. These factors emphasize the need for devoting attention to mathematical modeling to complement laboratory and field work. Through the use of mathematical models, scaling uncertainties can be bridged and response can be predicted for unique combinations of reservoir and operating conditions. Numerous mathematical models developed during recent years enable us to calculate temperature distributions, thermal efficiency (or conversely, fraction of heat lost), and oil recovery behavior for hot fluid injection. Ramey" and Spillette&apos; recently have provided reviews of these methods. Most models have concentrated on predicting temperature distributions and thermal efficiency; few have been directed at predicting oil recovery.&apos;."1° Although these techniques are useful for estimating effects of reservoir parameters and operating conditions on process performance, results are limited by the assumptions made and by the methods of coupling independently solved fluid-flow and energy-balance equations. A computer-based method is presented for predicting total reservoir response to hot-water injection that obviates most simplifying assumptions. The model simulates fluid flow and heat transfer in two dimensions within a vertical cross-section spanning the oil sand and adjacent unproductive strata. Known numerical procedures are used to solve the governing partial differential equations. The mathematical model handles the effects of reservoir heterogeneity, gravity, capillarity, relative permeability and temperature-dependent fluid properties. In addition, a wide range of operating conditions can be modeled, including hot-water followed by cold-water injection. Mathematical Description of Hot-Water Injection Key assumptions in the mathematical model for hot-water injection are that (1) no gas phase is present and (2) the injected fluid reaches thermal equilibrium instantaneously with the reservoir fluids and sand. Relative permeability and capillary pressure are assumed independent of temperature. Darcy&apos;s law for multiphase fluid flow relates the velocities of the oil and water phases to the phase pressure gradients by the following relations:

Jan 1, 1969

Jan 1, 1923

By E. H. Bunce, E. C. Handwerk

The inherent difficulties of zinc smelting arise from the fact that metallic zinc is volatilized at the reducing temperature of zinc oxide and thus is liberated in the form of a vapor. This vapor must be subsequently condensed to obtain metallic zinc, first in molten and eventually in solid form. Zinc vapor is sensitive to oxidation not only by air but by combustion gases containing carbon dioxide. It is, therefore, necessary to carry out both the reduction and the condensation operations in a closed system consisting of an externally heated muffle with attached condenser from which extcrnal oxidizing agencies are excluded. However, the reoxidation of zinc vapor cannot be entirely prevented by excluding external sources of oxidation. Internal sources of oxidation are necessarily present when oxidic zinc ores are reduced by a carbonaceous reducing agent. The reduction reactions themselves involve, first, the production of carbon monoxide in an amount at least equal in volume to the zinc vapor produced in the reaction, and, second, the formation of carbon dioxide. Not all of the carbon dioxide is reduced again to carbon monoxide by the excess carbon in the time available, and the slightly oxidizing condition, which results, seriously affects the efficiency of the condensation of the zinc vapor to the metallic state. In the past the difficulties arising from these causes have limited practical zinc smelting on an industrial scale to the use of small retorts equipped with small condensers. The retorts had to be small, because a closed refractory container capable of excluding oxidizing gases from the heating chamber surrounding the retort could not be built in large dimensions. The size was also limited because ordinary refractories when thin enough to conduct heat readily are not capable of sustaining a heavy load of charge at high temperature. Moreover, a loose charge of zinc ore and carbonaceous reducing material such as fine anthracite coal or coke breeze is a poor conductor of heat, thus limiting the cross section of the retort. The operation of these small retorts requires arduous

Jan 1, 1937

By W. M. Weigel

The general term "sand" applies to a multitude of similar materials consisting of fine granular mineral. As usually understood, it means the ordinary natural product used for structural purposes and made up largely of grains of quartz. Quartz sand constitutes by far the greater bulk of the production, but there are other grades used for industrial purposes, such as molding sand, glass sand and many others, that may be grouped under the general name of special sands. Under this general group would fall filter sand, sand-blast sand, engine sand, potter&apos;s sand, abrasive sands of all kinds, sand for pulverizing, roofing sand, flooring sand, fire or furnace sand, standard sand, burnishing sand, sand for magnesium oxychloride cement-plasters and sand for chemical and metallurgical purposes. Sources of Supply Sand is a widely distributed natural product and even the better grades are low-priced commodities. For these reasons development has occurred near points of consumption where sand meeting the requirements is available. Some special grades, however, cannot be prepared from any sand bed and shipments are often made over considerable distances when the only developed deposit is remote from the consuming center. This is true of filter sand, sand-blast sand, sand for pulverizing and some of the others when chemical purity or grain size, coupled with the need of a properly equipped plant for preparation, are required. New Jersey is a large producer of filter, engine, sand-blast, fire, and pulverizing sand. Pennsylvania, and West Virginia produce special sands for pulverizing, fire sand, abrasive sand, engine sand and sand for chemical and metallurgical use. Ohio produces much sand-blast, fire and abrasive sand, and some filter sand. Illinois and Minnesota produce

Jan 1, 1926

By Michel T. Halbouty

The area for which oil and gas development is reported for 1938 in this paper is larger than that covered by the report for 1937, in that besides Duval, Jim Hogg, McMullen, Starr, Webb and Zapata Counties, comprising the Laredo district, this paper also includes the South Corpus Christi district, which is composed of the following counties: San Patricio, Nueces, Jim Wells, Kleberg, Kenedy, Brooks, Willacy, Hidalgo and Cameron, all heretofore included in A.I.M.E. Gulf Coast reports. In the map, Fig. 1, the area known as South Texas is represented by the counties south of the heavy black line. Production in the South Corpus Christi district, which covers an area that extends inland for 50 miles and follows the coast line, is primarily in zones ranging from the Catahoula, through the Frio sands, into the Vicksburg horizon. General exploration is done mainly with geophysics because in this district production is directly dependent upon structural conditions. In the Laredo district most of the production is from sand lenses; therefore, because these shallow sand lenses represent old shore lines which are monoclinic in character, the most satisfactory method of exploration in the Laredo district is drilling. This type of production centers around Duval County and follows a northeast-southwest trend along the Mirando district. Although drilling operations showed a decline from the preceding year, 1938 was highly successful as far as new discoveries and developments were concerned, and results of the year&apos;s operations should have an important effect on the near future trend of exploration and drilling. Besides the discovery of several new fields and many new sands in established fields, 1938 saw the discovery of a new Vicksburg sand trend and the first marine drilling off the South Texas Gulf Coast. Many new fields were discovered during the year, but only a few were subjected to an extensive drilling program. Several already established fields, especially in the Laredo district, received a large amount of drilling as new sands and extensions enlarged the producing areas, a

Jan 1, 1939

By Michel T. Halbouty

The area for which oil and gas development is reported for 1938 in this paper is larger than that covered by the report for 1937, in that besides Duval, Jim Hogg, McMullen, Starr, Webb and Zapata Counties, comprising the Laredo district, this paper also includes the South Corpus Christi district, which is composed of the following counties: San Patricio, Nueces, Jim Wells, Kleberg, Kenedy, Brooks, Willacy, Hidalgo and Cameron, all heretofore included in A.I.M.E. Gulf Coast reports. In the map, Fig. 1, the area known as South Texas is represented by the counties south of the heavy black line. Production in the South Corpus Christi district, which covers an area that extends inland for 50 miles and follows the coast line, is primarily in zones ranging from the Catahoula, through the Frio sands, into the Vicksburg horizon. General exploration is done mainly with geophysics because in this district production is directly dependent upon structural conditions. In the Laredo district most of the production is from sand lenses; therefore, because these shallow sand lenses represent old shore lines which are monoclinic in character, the most satisfactory method of exploration in the Laredo district is drilling. This type of production centers around Duval County and follows a northeast-southwest trend along the Mirando district. Although drilling operations showed a decline from the preceding year, 1938 was highly successful as far as new discoveries and developments were concerned, and results of the year&apos;s operations should have an important effect on the near future trend of exploration and drilling. Besides the discovery of several new fields and many new sands in established fields, 1938 saw the discovery of a new Vicksburg sand trend and the first marine drilling off the South Texas Gulf Coast. Many new fields were discovered during the year, but only a few were subjected to an extensive drilling program. Several already established fields, especially in the Laredo district, received a large amount of drilling as new sands and extensions enlarged the producing areas, a

Jan 1, 1939

By R. S. French

THE purpose of this paper is to present data that have been obtained during the past two years concerning the effects of prior cold-work and temperature and time of anneal upon the recrystallization and grain growth of 70-30 cartridge brass. It was desirable to study certain of these phases so that an accurate picture of the principles of the subject could be shown. The work is not intended to provide explicit annealing data, but to provide material examples that may help to clarify analogous problems concerning this alloy. Specifications often set limitations upon the grain size of annealed materials because of the importance of grain size upon subsequent manufacturing operations. It was, therefore, worth while to study the variables that affect the recrystallized grain size of this material. C. H. Mathewson and A. Phillips,1 W. R. Webster,2 and others have presented annealing characteristic curves of this alloy. A recent typical curve presented by R. S. Pratt3 is shown in Fig. I. The tensile properties and grain sizes are shown as functions of the annealing temperature. Such curves serve as a useful guide in determining the physical properties of annealed material, but as they are made generally under carefully controlled laboratory conditions they do not indicate the performance of metal annealed in a mill muffle, where conditions are different and the amounts of metal require necessarily longer heating times and temperatures. Study of the effect of time and temperature upon grain growth and subsequent recrystallization was made with a coil of metal having the following analysis: 70.04 per cent copper; 0.007 lead; 0.007 iron; 0.00 tin; 0.00 silicon; 0.001 nickel; 0.000 phosphorus; balance zinc. The sample coil was obtained from metal that had been rerolled from hot-rolled mill stock, and was received at 0.228-in. gauge, soft, with a grain size of 0.125 mm. This material was then rolled 43.5 per cent to 0.125-in. gauge and annealed to a 0.053-mm. grain size. In this condition, samples were cut and used in all of the experimental work reported in this paper. TIME The first study was of crystal growth at a constant temperature over a moderate length of time. Material was cut from the stock coil at 0.129-in. size and rolled 75 per cent hard to 0.032-in. gauge. From this piece small samples were cut ½ by 2 in., suitable for grain-size determinations. Twelve samples were placed in an electric furnace uniformly across the width, approximately an inch from the floor, A thermocouple was wired to the center sample, so that the approximate metal temperature could be followed. At various

Jan 1, 1944

By S. B. Twiss, P. R. Basford

The relationship between areas of iron powders, briquettes, and sintered compacts and tensile strength has been determined. It has been found necessary to distinguish between two types of areas which exist in such powders—a macroscopic area due to the shape and size of particles and a microscopic area due to pores and cracks in the surface. Only the macroscopic area, specifically the area due to particle irregularity, contributes to tensile strength; the microscopic area cannot be forced into contact with adjacent particles ond does not participate in bond formation. Of the two methods of area measurement employed in this study—permeability to liquids and gas-phase adsorption—only the former is useful for determining the roughness factor. A measure of this roughness, (area measured by permeability to liquid) -f- (orea of powder with the same size distribution, but made up of spherical particles), is shown to be uniquely related to tensile strength at constant density. The other important factors in determining the strength of sintered-metal compacts are the density and presence or absence of surface oxide. THE manufacture of metal parts by the process of powder metallurgy is an important and rapidly growing industry. Progress has been rapid and continuous, largely because of the excellent research in the field. Nevertheless, the process remains inherently complex and empirical. Several investigators have shown that the properties of the final compact must depend on many variables; namely, shape,&apos; size distribution,"-" nd compositiona of the original particles, the pressure necessary to compress to the desired density, the density of the compact, the time and temperature of sintering, and so on. Through the application of some new techniques to the study of powders and compacts, and the correlation of a number of observations of known variables, the present paper attempts to clarify and simplify the underlying theory of the powder-metallurgy process. Any theory must start with the obvious fact that the strength of a compact, its most useful property, is due to the formation of welded areas between adjacent particles, and attempt to deduce what effect other variables will have on (a) the area and (b) the intrinsic strength of these welds. Such welded areas can be demonstrated by electron micrographs, as in Fig. 1. It was believed that (a) could be most directly studied by means of surface-area measurements on the original powders and on the compacts made from them; the area decrease should be related closely to the welded area. A representative group of eleven iron powders from commercial sources, and made by a variety of processes, was chosen for this study. In addition to the surface-area measurements, correlations were established between the tensile strength and all the known variables which might possibly affect it. The results are quite unexpected. They indicate that the situation is much simpler than the authors had anticipated. The strength of the sintered compact is determined, indeed, by no more than three variables; viz., the irregularity of the original particles, the density of the compact and, in exceptional cases, the amount of surface oxide. All three had been recognized previously as having some effect on the tensile strength, but in the absence of the special techniques and interpretations to be developed here, there could be no suspicion that they were the only relevant variables. Materials and Methods Material—All the iron powders were commercial products obtained from the Amplex Division of Chrysler Corporation. Powders A, B, C, and J were very pure electrolytic iron. Powder D was made from oxidized scrap reduced by heating with an excess of cast iron. Powder E was a high-grade iron ore reduced by hydrogen. Powder I was prepared by atomizing molten cast iron in an air blast, quenching the droplets in cold water, and crushing the coarse powder. Mill scale (oxide) is added and the mixture heated to reduce the high carbon content. The other powders were all prepared by reduction of iron oxides, such as mill scale. They

Jan 1, 1959