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By J. H. Swisher, E. O. Fuchs

Rate equations were derived to describe the kinetics of internal oxidation of cylinders and spheres. The derived equations for cylinders were checked experimentally by means of sub scale thickness and electrical conductivity measurements on Cu-Cr alloy wires. The properties of the internally oxidized samples were examined with conductivity applications in mind. It was possible to produce uniform dispersions of Cr2O3 in copper with an initial chromium content as high as 3 wt pct. While electrical conductivities only a few pct less than that of OFHC copper were obtained, the Cr2Os particle size and spacing were too large for effective dispersion hardening. T.HE process of internal oxidation has been used widely in basic studies of the permeability of gases in metals. In a review article, Rapp1 has discussed the principles of internal oxidation in considerable detail. From a technological standpoint, internal oxidation is often considered undesirable, since it is a means by which inclusions can be introduced into an otherwise clean material. Another important aspect of internal oxidation is its use as a means of dispersion hardening a material. Broutman and Krock2 discuss this and other methods for making dispersion hardened alloys. The only internally oxidized material known to the authors which is commercially available is a Cu-BeO alloy.3'4 This alloy is made from Cu-Be alloy powder, using a so-called Rhines pack. It has a tensile strength of 80,000 psi and retains its strength at relatively high temperatures. The objectives of the present study were to derive rate equations for the internal oxidation of cylinders and spheres, to check the derived equations for cylinders experimentally, and to examine the structure and properties of internally oxidized Cu-Cr alloys. The Cu-Cr system was chosen for this study because uniform dispersions are obtainable at high alloy contents, which is a desirable characteristic in dispersion hardened materials. RATE EQUATIONS FOR VARIOUS GEOMETRIES A number of authors5--9 have derived equations to describe internal oxidation kinetics. These derivations differ somewhat in mathematical assumptions and approximations, and all except one of the derivations deal exclusively with the internal oxidation of plates. The exception is a brief treatment of cylindrical and spherical geometries given by Meijering and Druy-vesteyn9 as a part of a comprehensive paper on the general subject of internal oxidation. These authors did not obtain rate data to check their derivations, although they did show that the hardness profile across an internally oxidized sample is directly related to the rate of interface movement. For cylindrical and spherical geometries, a quasi-steady-state approximation is needed to circumvent mathematical complications in obtaining a solution to the basic differential equations. In using this approximation, we consider the concentration gradient of dissolved oxygen in the internally oxidized zone or sub-scale to be the same as the gradient which would be present if there were no movement of the subscale interface. The steady-state approximation introduces an error of about 1 pct in computing the rate of internal oxidation of an Fe-1.0 pct Mn alloy plate, if the present method is compared to the more exact method of Wagner.7'10 The details of the derivations of the rate equations for cylinders and spheres are given in the Appendix, and only the results of these derivations are given below. The final equations obtained by Meijering and Druyvesteyn9 can be shown to be equivalent to our Eqs. [1] and [2], although the two approaches are somewhat different. Cylindrical Geometry. [2] where r1 is the outer radius of the cylinder or sphere, cm, r2 is the radius of the unreacted core, cm, see Fig. l(a), D is the diffusion coefficient of oxygen in copper, cm2 per sec, %O is the concentration of dissolved oxygen at the surface of the specimen, wt pct, %Cr is the initial chromium concentration in the alloy, wt pct, and t is the reaction time, sec. Plate Geometry. The analogous rate equation for a plate has been derived previously for internal oxidation of Fe-Al alloys.8'11 For Cu-Cr alloys, we may write the same equation as follows: [3] where r1 is the half-thickness of the plate, cm, and r2 is the distance from the mid-plane to the subscale intherate is An analysis of Eqs. [1], [2], and [3] shows that for a plate the rate is completely parabolic. The initial

Jan 1, 1970

By M. H. Loveman

THE orebody described below has been rediscovered and developed within the last 3 years. It has, however, been known and worked by the Chinese for hundreds of years. When assay values and size are considered, it contains what is probably one of the largest single bodies of zinc and lead sulphides yet found. The tonnages developed at other places, as at Broken Hill, are much greater but the average zinc and lead sulphide contents are considerably lower than at Bawdwin. Bawdwin is situated in the semi-independent State of Tawng Peng, one of the numerous units which make up the Northern Shan States. These States are under British rule and are generally considered as a portion of Burma. They are governed as a separate administrative unit, however, under the Lieutenant Governor of Burma. Each State is under its own chief, or Sawbwa, who has considerable power over his own subjects. Bawdwin is approximately in latitude N 23°6', longitude E 97°20', about 50 miles south of the nearest point on the Chinese border and 450 miles north of Rangoon (Fig. 1). The period at which mining was first begun at Bawdwin is unknown. The most reliable records have been obtained by deciphering local Chinese inscriptions and from these it is concluded that the work dates back to at least the beginning of the 15th century. The first undoubted reference to the mines by a European is by Symes in 1795. Crawford in 1827 estimated the output of silver from the mines at $600,000 annually. At about the middle of the 19th century the rebellion of the Chinese Mohammedans in the neighboring Chinese province of Yunnan so weakened the power of the Chinese that the incursions of hostile tribes (Kachins) made work extremely dangerous. The mines were finally abandoned by the Chinese about 1868. The closing down of the mines was probably not entirely due to outside causes but may have been influenced somewhat by the increasing difficulty of handling the water, as the workings gradually descended below the water level of the district. Several attempts were made by the Burmese kings, Mindon Min and Thebaw, to resume operations, but because of a

Jan 12, 1916

OF the many categories into which scientific knowledge has been arbitrarily divided, the one that has proved most applicable in our attempts to gain an insight into the details of steelmaking processes is physical chemistry. To the young metallurgist who has only recently survived a college course in this subject, the application of its principles to reactions in liquid steel should not be difficult. The many excellent textbooks of physical chemistry1 provide ample material on the principles of this subject for the student of steelmaking processes; yet with- out exception those texts draw the greater part of their illustrative material from room-temperature data. It is the purpose of this chapter to provide a concise review of the principles of physical chemistry that have proved useful in studies of steelmaking and at the same time to present some of the data that are essential to the application of physical chemistry to reactions at high temperatures. Certain parts of physical chemistry require rather formidable mathematics for their complete development but in the main those applications in which we are here interested can be ex- pressed in fairly simple terms. Many of the equations are logarithmic, and we shall use the symbols In X and log X to represent respectively the natural and the common logarithm of X. The two are related by In X = 2.303 log X. Logarithms may be read from a good slide rule with sufficient accuracy for our purposes. In a few spots a knowledge of the calculus will be, helpfu1. MATTER Innumerable forms of matter may be recognized, and these may be converted by chemical processes into others, as ore, coke, and air are converted into iron, slag, and gas. Whenever such a change occurs there is a corresponding change in

Jan 1, 1951

By R. E. Miner, J. K. Jackson, D. F. Gibbons

Internal-friction measurements were made during isothermal aging treatments of 18 pct Ni maraging-steel wires between 420° and 612°C. A sharp initial drop in the internal-friction level was interpreted in terms of a rapid dislocation recovery reaction. The rate of the recovery was found to be independent of temperature. Truncation of the recovery reaction was apparent in those systems that exhibited the rapid age-hardening characteristics of the maraging steels. It is proposed that this initial hardening response is the result of a low activation energy preprecipitation reaction involving molybdenum. A gradual rise in the internal-friction level at longer aging times was associated with the precipitation of a molybdenum-containing precipitate. CONSIDERABLE research effort has recently been devoted to the mechanisms responsible for the high strength and toughness of 18 pct Ni maraging steels. These bcc martensitic alloys are found to harden during aging at temperatures between 400° and 600°C. The aging response is very rapid with more than half the total hardness increase occurring within the first few minutes of aging, Fig. 1. Precipitate particles have been observed in the later stages of aging by a number of investigators.'-' While the identity of the precipitates remains the subject of some controversy, one or more of the intermetallic compounds, Ni3Mo, Ni3Ti, and Fe2Mo, are almost certainly involved. Heterogeneous nucleation of precipitates at dislocations has been noted8 and cobalt is believed to enhance the formation of fine, homogeneously distributed particles by lowering the solubility of the alloying elements in the martensitic matrix.3,7 Transmission electron microscopy studies of the initial hardening behavior have not been fruitful. Strengthening mechanisms based on atomic ordering have not been generally supported by X-ray and neutron-diffraction experiments.9 In the present investigation, the aging reaction was studied using isothermal-aging internal-friction measurements. The marked sensitivity of internal friction to short-range diffusion and precipitation processes has provided a convenient tool for the elucidation of the strengthening mechanisms operative in the maraging steels. EXPERIMENTAL PROCEDURE An upright torsion pendulum was used to measure the internal friction of several maraging steels during isothermal aging. The pendulum was placed in an atmosphere of helium at a pressure slightly less than atmospheric. To permit measurement of internal friction during the first minutes of aging, the specimens were rapidly heated by passing a current through them in a manner similar to that described by Ang and Wert.10 Thermal gradients in the specimen were largely eliminated by using specially designed specimen grips11 which produced temperature variations of less than 1 pct over 90 pct of the specimen length and less than 3 pct over the entire length at aging temperatures up to 620°C. A proportioning strip-chart program controller was employed to maintain constant specimen temperature during treatments of up to 36 hr duration. A number of vacuum-melted laboratory heats having compositions near that of a typical commercial 18Ni-7Co-5Mo-0.4Ti alloy were investigated. The amount of cobalt was varied from 0 to 7 wt pct in five of the heats. Either molybdenum or titanium was omitted in the remaining two heats. The alloy desig-

Jan 1, 1967

By Charles L. Thomas

A novel, highly sensitive, and reproducible nzetlzod for the determination of hydrogen in solid materials is presented. The procedure requires equilibration of the specimen with hydrogen gas, rapid quenching, and hot vacuum extraction of the dissolved gas with subse-quent quantitative analysis by mass spectroscopy. Good linearity is obtained for the Arrl~enius plots of the investigated metals. The advantages in the use of this method over that of Sieverts aye discussed. The solubility data for copper are in reasonable agveewzent with a considerable number of other inuestigations, wllile those fov silver are considerably lower than previously reported. The first known solubility data for gold are presented. Solubility equations and heats of MUCH of the data which are available on the solubility of hydrogen in various metals and alloys have been obtained by the classical Sieverts method.' The method involves the measurement of a decrease in pressure of a gas in a calibrated system, and the calculated contraction in volume is attributed to the solubility of the gas in the metal sample. The procedure requires several corrections, such as the solubility of the gas in the container walls and the diffusion of the gas through these walls, as noted by Steacie and .Johnson2 and others. In addition, errors may be incurred due to reactions between metal surface impurities, such as oxides, and the saturating gas. The precise calibration of the measuring system where large thermal gradients exist can present additional difficulties. Also, accurate volumetric measurements of small quantities of gas are difficult. Many of the objections to the Sieverts method were overcome on solid materials by Ransley and ~eufeld,~ who first saturated the metal with hydrogen and performed a subsequent extraction and measurement of the gas by chemical means. Eichenauer and pebler4 and Eichenauer, Kiinzig, and pebler5 measured the diffusion coefficient and solubility by following the degasification of a sample as a function of a rate of increase in pressure in a previously evacuated system. Here again, however, the procedure involves many of the corrections of the Sie-verts method. The present investigation deals with the solubility of hydrogen in solid copper, silver, and gold by a technique which eliminates many of the aforementioned corrections and possible errors. This procedure requires equilibration of the specimen with gas, rapid quenching, and hot vacuum extraction of the dissolved gas with subsequent quantitative analysis by mass spectroscopy. EXPERIMENTAL Two completely separate systems were employed to accomplish first, the equilibrium saturation of the sample and second, the extraction of the dissolved gas. Saturation Apparatus. The saturation apparatus, illustrated in Fig. l, consisted of a vertically mounted quartz tube with a three-way valve for vacuum or hydrogen near the top and an outlet near the bottom leading to a butyl phthalate seal. The bottom end of the tube was terminated with a joint accommodating an O-ring sealed "Asco Stirring Gland" (The Emil Greiner Co.). This gland facilitated movement of the thermocouple without introduction of air into the system. The upper portion of the tube (above the furnace) was water-jacketed. A Welsh 1405-B mechanical pump provided the necessary system evacu-

Jan 1, 1968

THE refining period of an open-hearth heat blends imperceptibly into the finishing period, during which final adjustments are made in slag composition, in bath action and temperature, and in composition of the steel, in order to prepare it for casting into ingots. Operations must be governed by the consideration that alterations in the character of the heat during the finishing period must be held to a minimum. In a broad sense, the finishing and deoxidation period of a heat may be said to be- gin when the action of the last ore addition has ceased, and to end when the teeming of the ingots is completed. INGOT STRUCTLIRES A survey of the relative advantages and disadvantages of different types of ingot structure is required because deoxidation treatments during the finishing period control the amount of gas evolved during solidification and consequently determine the type of ingot structure. Four classes of ingots are recognized, de- pending upon the degree of deoxidation to which the steel has been subjected. These types are killed, semikilled, capped, and rimmed; typical examples of their structures are represented by ingots 1, 2, 5, and 7, respectively, of Fig 9-1. The actual ingots from which these cross sections were sketched were all poured to the same height (indicated by the dotted lines) in the same type and size of bottle-top molds. The eight drawings of the figure represent selected types of ingot structure in a continuous series from "dead killed" to "wild," resulting from variations in the total quantity of gas evolved, from none at all to copious amounts, during solidification of the steel in the mold. Killed and semikilled steels are adjacent at the "quiescent" end of the ingot structure series where only small amounts of gas are evolved. The term "quiescent" describes the action of the molten metal during and subsequent to the teeming of killed and semikilled steels. Capped and rimmed steels are adjacent at the

Jan 1, 1964

By E. C. Truesdale

IN recent years various problems in connection with research work on the preparation and properties of zinc-base alloys have required reliable information concerning the constitution of the zinc-rich portion of the iron-zinc equilibrium diagram. On numerous occasions rather positive indications were obtained that, for example, the solubility of iron in zinc was incorrectly represented on the current equilibrium diagrams. A careful study of all the available literature relating to the iron-zinc system led to the conclusion that much of the early work was unsatisfactory as measured by present standards of experimental accuracy, and as a result it was decided to redetermine the location of the liquidus curve and of adjacent portions of the diagram. Part I of this paper comprises a description of the experimental methods and a summary of the results by means of which the zinc-rich end of the iron-zinc diagram has been revised in the following ways: 1. Measurements of the solubility of iron in liquid zinc by several different sampling methods, leading to a relocation of the liquidus curve. 2. Microscopic, conductivity, and X-ray studies of the solid solubility of iron in zinc, which, together with thermal analyses, have resulted in new values for the solid solubility and the eutectic temperature and composition. 3. Heating and cooling curves, obtained by a refined differential method, leading to new locations for the two peritectic horizontals. In Part II of the paper the attempt is made to review all of the pub-lished work having a bearing on the constitution of the iron-zinc system, and to correlate the present results, and some recently published data

Jan 1, 1935

By G. Van Esbroeck, M. Van Weyenbergh

The copper mines of the Katanga region in the Belgian Congo lie along the same mineralized belt as those of Northern Rhodesia. There are two distinct types of deposits in that belt, the dolomitic and the quartzitic. In the dolomitic type the metallic minerals are found in a dolomitic limestone country rock. Through oxidation and enrichment, large deposits of high-grade oxidized copper ores were formed, some of which are being worked by the Union Minière du Haut Katanga. Such deposits are all in Katanga. The quartzitic deposits are found in Katanga and Northern Rhodesia. Here the primary mineralization occurred in sandstones and quartzites, in horizons stratigraphically lower than the dolomites. These rocks are not favorable to secondary enrichment and the oxidized zone is poorer than the sulphide zone, which alone contains the ore. There are also in Katanga a few ore-bearing veins. One of them is being worked in the Prince Leopold mine at Kipushi. Prince Leopold Mine The Kipushi ore body fills a fault vein and invades the wall rocks more or less extensively by metasomatic replacement. The vein strikes north-northeast and south-southwest and dips to the west. The variable dip averages 60' to a depth of 300 ft., and more uniformly 80' below 400 ft. In the upper section the average width is 200 ft. and below the width is about 150 ft. The length of the ore body is 2300 feet. The eastern side of the vein—the footwall—is dolomitic and contains irregular masses of ore sometimes extending 100 ft. or more from the main

Jan 1, 1940

By Clair Upthegrove, E. S. Rowland

The widespread interest in the alloys of beryllium with copper is due principally to the fact that certain compositions show very favorable precipitation-hardening characteristics and are, in fact, the stronges nonferrous alloys known at the present time. Investigations have been conducted by Masing and Dahl and others on the physical characteristics of ternary beryllium alloys, in an attempt to produce precipitation hardening effects with a smaller amount of beryllium than that required in the binary copper-beryllium alloys (2.0 to 2.5 per cent Be). The results of these investigations show that ternary alloys of beryllium with Cu-Sn, Cu-A1 and Cu-Zn, among others, exhibit promising improrcmc~nts in physical properties after precipitation-hardening treatment and, while the increases in properties obtained are not as high as those reahzed from the binary copper-beryllium alloys, excellent properties arc obtaincd with beryllium contents averagirlg about one-half the amount reqnired in the binary alloys. This paper presents the results of an investigation of the equilibriun relations of certain alloys containing copper, tin and beryllium. The alpha-phase boundary of the ternary system is given for alloys containing from 0 to 1 per cent beryllium. The equilibrium conditions beyond the alpha-phase boundary are presented for alloys containing up to 32 per cent tin and 1 per cent beryllium. The data were collected by means of quenching experiments, microscopic examination and thermal analysis The results of some powder-method X-ray determiniations on the alloys, conducted by Mr. William Mikulas and Prof. Lars Thomassen at the University of Michigan, are used as evidence in this paper. The con

Jan 1, 1935

By Aureal T. Cross

THIS paper is a review of the published literature on research in coal geology, principally exclusive of resource studies, which appeared or became available during 1950 and the latter part of 1949. This report is not to be construed as being complete. The papers referred to in the bibliography are those among many more, which were read either in full or in abstract. Undoubtedly other papers were published which either escaped the author's notice or were not available to him. Those which were seen in abstract only (about one fourth of those listed) were not available in time for the inclusion of more than a notice. An outline of all papers listed in the bibliography has been arranged by subjects and reasonable subdivisions with some papers cited under more than one subject. Most papers are indexed according to the principal subject of discussion or research only as to an unusual or noteworthy section of the entire report. There will likely be some disagreement as to the quality or merit of some of the papers selected and the specialist may be supercritical of the outline or organization of papers in his field. It may be that attention has occasionally been drawn to papers reporting old information or conclusions of questionable value. Conferences and Meetings One of the best indications of the growing interest in coal geology problems in the United States is the increasing number of times this field has been the focus of attention at conferences and meetings. Notable among these are the joint meeting of the Society of Economic Geologists and the Geological Society of America at El Paso, November 1949, at which the principal thesis was concerned with low rank carbonaceous fuel deposits, especially of western United States. Among the papers given which are already available were those presented by Barghoorn,'" Parry? Roe? and Parks."' At the annual meeting of the Botanical Society of America in New York, December 1949, a joint meeting of the Paleobotanical and Microbiological Sections was held for which a symposium on Microbiology in Relation to the Geologic Accumulation of Organic Complexes was organized. Publication of the six papers presented by Ralph G. H. Siu, Elso S. Barghoorn, Irving Breger, Claude E. ZoBell, James M. Schopf, and A. C. Thayson is anticipated. At the regular meetings of the Paleobotanical Section at the same time, several other papers of interest reported on coal ball studies, partial coalification of petrified wood, and floras. In Chicago, April 1950, a symposium on Applied Paleobotany was held by the Society of Economic Paleontologists and Mineralogists in conjunction with the American Association of Petroleum Geologists. The five papers presented at this meeting dealt with the use of Paleozoic plant microfossils for stratigraphic work, J. M. Schopf, Devonian-Missis-sippian fossils of the black shales, Aureal T. Cross, Mesozoic plants of stratigraphic value, Th. Just, plant microfossils of the Tertiary, L. R. Wilson, and studies of the Brandon lignite, Elso S. Barghoorn. Early publication of these in the Journal of Paleontology is expected. The Nova Scotia Research Foundation and the Nova Scotia Dept. of Mines sponsored an excellent 3-day conference in June 1950, which dealt with several aspects of coal geology. Papers on coal classification, P. A. Hacquenbard, structure and sedimentation problems in Nova Scotia, T. B. Haites, new techniques of thermal analysis, W. L. White-head, geochemical investigations of Nova Scotia coals, Irving Breger, the role of fossil plant spores in coal correlation and the stratigraphy of the coal-bearing strata of the Appalachian Region, Aureal T. Cross, were given. Some discussions of these papers by those in attendance were recorded, and the entire proceedings is being prepared for publication. In September 1950, an unusual 3-day field conference was held by the Ohio and West Virginia Geological Surveys under the sponsorship of the Coal Geology Committee. This study of the stratigraphy, sedimentation, and nomenclature of the Upper Pennsylvanian and Permian coal-bearing strata of southeastern Ohio, southwestern Pennsylvania, and northern West Virginia was augmented by two discussions on associated rocks (clays and shales) and stratigraphic nomenclature at Wheeling and Morgantown, West Va. An extensive guidebook was prepared, and transcriptions of the Morgantown meeting were made. As a follow-up of the September field conference, a round-table discussion was held on this general topic at a special open meeting of the Coal Research Committee in conjunction with the November meeting of the Geological Society in Washington. Short prepared statements to invite discussion were given on each of several topics by L. M. Cline, Carl 0.

Jan 1, 1953

By R. Ingerson

Bore surfaces of used guns commonly show a pattern of cracks in various degrees of development. It has been suggested that these cracks may aid erosion by providing channelways for the gases, eventually leading to the tearing out of blocks of metal. Under the general studies of gun erosion conducted at the Geophysical Laboratory it appeared desirable to consider this factor, and to determine the resistance to surface cracking offered by gun steel and by various other materials that might be used in the bores of guns. Method and Apparatus In order to make such a determination it is necessary to have (I) an arrangement in which the surface to be studied can be subjected to conditions similar to those in a gun with respect to temperature, pressure (developed by explosion gases), composition of the gases and length of time the surface is exposed to the gases; and (2) a specimen that can be examined readily after any number of shots, and then fired again, if necessary. The first of these conditions can be met by using an explosion vessel designed by H. S. Roberts of the Geophysical Laboratory. Fig I shows a cross-section of the apparatus. The "gun" G from which the charge is fired is made from the receiver of a caliber 0.30 army rifle, M1903, and the charges are prepared in caliber 0.30 cartridge cases. The test specimen S is held in place by a cone-shaped plug P and by a steel bridge B which is bolted to the outside of the explosion vessel on either side of the section shown. The plug, in turn, is held in place by a screw collar C. Maximum pressure is controlled by a brass rupture disk R. Part of the explosion gases flow past the two flat areas on S. Temperature and composition of gases, and the time before the rupture disk breaks, can be controlled by amount and kind of powder used, and pressure can be controlled by using rupture disks of different thickness. While the explosion vessel used was not designed so that temperature and pressure could be measured, in other vessels of closely similar size and shape containing proportionate charges of the same kind of powder as that used for standard testing procedure, values of 2700°K and 50,000 psi were obtained. Since the orifices past the flat areas on the plug are small compared to the rupture disk hole (I:I6), most of the gas goes out through the rupture disk when it breaks. The amount that goes by the plug depends on (I) the pressure attained before the rupture disk breaks and (2) the time it takes for this pressure to be built UP. The second condition (examination at will after any firing) is met by using for specimens short rods that have flat areas ground on opposite sides. These flat

Jan 1, 1949

By Eugene F. Broome, Hugh A. Walls

A diffusion measurement technique based on a shear cell comprised of only two segments is described. The diffusion boundary value problem for the finite capillary geometry is solved in general for any arbitrary initial concentration profile and is subsequently specialized for the modified shear cell problem. Effects of convection and mixing at the shear interface were found to be negligible. Mercury self-diffusion coefficients were determined from -25° to 252°C. These data are in good agreement with those found by Meyer. ALTHOUGH diffusion in liquid metals has been of interest for over two centuries, the need for measurement techniques of improved accuracy and precision has become increasingly apparent as additional data have been obtained and theory has become more refined. These conditions reflect the experimental difficulties inherent in liquid diffusion measurements, in which transport by other processes, such as convection, tends to mask the diffusive transport. Frequently the disagreement between several theoretical predictions is less than that found between different sets of data obtained for a system. Moreover, as has been shown by Nachtrieb,1 diffusion data are needed over much larger temperature ranges if the functional dependence on temperature is to be known. Thus, improved techniques must be devised if experimental data are to augment fundamental understanding of the liquid state and to meet technological needs. The available techniques have been discussed elsewhere.' Of these, only the capillary-reservoir, long capillary, and shear cell techniques will be discussed briefly in terms of experimental advantages and disadvantages. These methods served to establish design criteria for the modified shear cell described here. The capillary-reservoir technique of Anderson and saddington3 has been the most widely used method in recent years. The method offers experimental simplicity relative to other methods and has been employed for high-temperature measurements. Moreover, the mathematical relationship between the measured concentration ratio and the diffusion coefficient is such that smaller values of the ratio are achieved for a specified diffusion time relative to other methods. The amplified errors between the concentration ratio and the calculated diffusion coefficient are diminished at lower values of the ratio.' The method also permits multiple determination by the simultaneous use of several capillaries. Disadvantages of the capillary-reservoir method are primarily associated with the hydrodynamic ef- fects of convection and of placing the capillary in the reservoir. These effects are most pronounced in the region near the open end of the capillary and produce an ill-defined boundary condition between the capillary and the reservoir. Such effects are not amenable to experimental or mathematical correction2 (although this has been suggested4). The long-capillary method of Careri, Paoletti, et al.5-10 involves filling one half of a small capillary tube of 150 to 200 mm total length with material of one composition or radioactivity and the other half with the second part of the diffusion couple. This arrangement eliminates the adverse hydrodynamic effects associated with the capillary-reservoir technique; however, certain other experimental difficulties are encountered in this method. The more significant of these difficulties involve the melting, expansion, contraction, and solidification of the diffusion system. The dependence in some cases of the diffusion coefficient on the capillary diameter noted by Careri et a1.7 (termed the "wall effect") has been alternatively explained by Nachtriebl as a convection effect during solidification. In mutual diffusion measurements, the convection problems associated with melting and solidification are increased because of the differences in melting points and in expansion coefficients between the halves of the diffusion couple. However, the errors caused by convection effects within this method are usually less than those in the capillary-reservoir method. Furthermore, the concentration profile needed to determine concentration-dependent diffusion coefficients by the Boltzmann-Matano analysis can be obtained from this method. Of the previous attempts to use shear cells, only the cell used by Nachtrieb and Petit11,12 appears to have yielded good data. They reduced the mechanical complexity of the conventional shear cell by using a cell comprised of only four segments. Three of these segments were filled with ordinary mercury and the fourth with radioisotopic mercury in their determination of mercury self-diffusion coefficients. The average concentration (radioactivity) was determined in each segment following a period of isothermal diffusion. These concentration values were fitted to concentration profiles obtained from the Stefan-Kawalki tables, and the diffusion coefficients were evaluated. Thus, although the number of cell segments is reduced in their method, some information about the concentration profile can be obtained in terms of the Stefan-Kawalki analysis. Moreover, their cell is suitable for measurement of diffusion coefficients at elevated pressure, as they successfully demonstrated with mercury. Consideration of the design and experimental features of the methods discussed above suggested several criteria for the new cell: 1) a ''total" capillary system, as opposed to a capillary-reservoir system, should reduce adverse convection effects; 2) such a capillary system should avoid the problems en-

Jan 1, 1969

By J. W. Hickman, E. A. Gulbransen

One of the important factors that determine the resistance of a metal or alloy to further chemical reaction is the structure of the superficial oxide film. A thorough understanding of the physical and chemical structure as well as the stability of the oxide film formed on the surface as a function of time and temperature of the chemical reaction might furnish clues as to the nature of the reaction process and the protective nature of the film. A comprehensive program has been undertaken to study these phenomena. This paper summarizes the structure of the oxide films formed on the metals iron, cobalt, nickel, chromium and copper at temperatures up to 700°C. Before the introduction of the electron diffraction technique, it was necessary to use either direct chemical analyses or X-rav diffraction analyses to determine the nature of the oxide film formed on the metal or alloy. Chemical analyses yields information on the percentages of the several atomic species present in the film while X-ray diffraction analyses yield information on the atomic geometry. In special cases the information obtained may be identical, but in general both viewpoints are necessary. Much of the early work was carried out on the oxidation of bulk samples where thick films were obtained. The products were identified after cooling to room temperature by X-ray diffraction and chemical analyses. Although much useful information has been obtained in this manner. little could be learned about the character of the protective oxides during the period when the films were actually protective. Evidence concerning the chemical structure of thin oxide films has been made possible by the development of the electron diffraction reflection technique. In this method the most fruitful investigations have been made by carrying out the reaction in situ at the temperature at which the film is actually protective. Literature The oxidation of iron has been extensively investigated by X-ray and electron diffraction. Jackson and Quarrelll found that oxide films formed and examined at the same temperature differed considerably from those allowed to cool to room temperature. The results showed that below 400°C the oxide that was stable in intimate contact with iron was Fe³O4; between 515° and 900°C. the stable film was FeO. Above the upper change point of iron the oxide was found to be Fe³O4. From 400' to 515°C., FeO, Fe³O4 or a mixture of the two oxides was found. Recrystallization of the air-formed film below 400' and above 900°C. led to the formation of Fe3O4. In the range where thicker films consisted of FeO, the air-formed film was converted to a new hexagonal oxide not previously described.

Jan 1, 1947

By R. Ingerson

Bore surfaces of used guns commonly show a pattern of cracks in various degrees of development. It has been suggested that these cracks may aid erosion by providing channelways for the gases, eventually leading to the tearing out of blocks of metal. Under the general studies of gun erosion conducted at the Geophysical Laboratory it appeared desirable to consider this factor, and to determine the resistance to surface cracking offered by gun steel and by various other materials that might be used in the bores of guns. Method and Apparatus In order to make such a determination it is necessary to have (I) an arrangement in which the surface to be studied can be subjected to conditions similar to those in a gun with respect to temperature, pressure (developed by explosion gases), composition of the gases and length of time the surface is exposed to the gases; and (2) a specimen that can be examined readily after any number of shots, and then fired again, if necessary. The first of these conditions can be met by using an explosion vessel designed by H. S. Roberts of the Geophysical Laboratory. Fig I shows a cross-section of the apparatus. The "gun" G from which the charge is fired is made from the receiver of a caliber 0.30 army rifle, M1903, and the charges are prepared in caliber 0.30 cartridge cases. The test specimen S is held in place by a cone-shaped plug P and by a steel bridge B which is bolted to the outside of the explosion vessel on either side of the section shown. The plug, in turn, is held in place by a screw collar C. Maximum pressure is controlled by a brass rupture disk R. Part of the explosion gases flow past the two flat areas on S. Temperature and composition of gases, and the time before the rupture disk breaks, can be controlled by amount and kind of powder used, and pressure can be controlled by using rupture disks of different thickness. While the explosion vessel used was not designed so that temperature and pressure could be measured, in other vessels of closely similar size and shape containing proportionate charges of the same kind of powder as that used for standard testing procedure, values of 2700°K and 50,000 psi were obtained. Since the orifices past the flat areas on the plug are small compared to the rupture disk hole (I:I6), most of the gas goes out through the rupture disk when it breaks. The amount that goes by the plug depends on (I) the pressure attained before the rupture disk breaks and (2) the time it takes for this pressure to be built UP. The second condition (examination at will after any firing) is met by using for specimens short rods that have flat areas ground on opposite sides. These flat

Jan 1, 1949

By Anson Hayes, John Chipman

THE quality of sheet and strip products made of rimming steel is closely related to the structure and chemistry of the ingots. The variation in composition throughout the ingot, as affected by segregation, is of great importance, as are also the form and distribution of the voids that result from the gases evolved. It is because of this importance that the considerable literature in this field has accumulated. No attempt is made in the present paper to compile a bibliography of the excellent work that has already been done, as this has been adequately covered in the many excellent reports on the heterogeneity of steel ingots prepared by a joint committee and published by the British Iron and Steel Institute.1 From time to time, in any field of investigation new tools and new technique are developed, which make further progress possible. In the field with which this paper is concerned, this is true. The development of the vacuum-fusion method as a means of following oxygen segregation, and a technique for obtaining the volume and composition of the gases evolved during solidification, have opened the way to obtaining data by means of which some considerable progress has been realized in developing more of the detailed mechanisms of solidification and segregation in rimming-steel ingots. GENERAL THEORY OF SEGREGATION The basic cause of segregation lies in the fact that the impurities are less soluble in solid than in liquid iron. The solid that forms from the impure liquid is more nearly pure than the liquid itself. If solidification proceeds slowly enough, or if the liquid and solid phases are maintained in contact with one another for a sufficient time, a condition of equilibrium is set up, which may be represented by a phase diagram. Portions of the

Jan 1, 1938

By Roland Blanchard

ABSTRACT RECENT discovery at Mount Isa of copper mineralization in commercial amount at a depth of 1000 ft., coinciding with downward termination of ore at about the same depth within the larger silver-lead-zinc lenses that have been the standby of Mount Isa's production to date, has been cited as an example in support of mineral zoning. A previous paper by the author and Graham Hall1 furnished a detailed description of the geology of the ore at Mount Isa as exposed up to that time, but necessarily dealt mainly with the silver-lead-zinc mineralization. Most of the geologic facts that constitute the first half of the present paper were set forth in the previous one in much greater detail, with full supporting evidence for the facts cited. The large amount of underground development (approximately 20 miles) and the extensive exploration carried out by diamond drilling (100,000 ft.) at Mount Isa, added to extensive microscope work conducted over a period of years, both by the company's staff and by others, had made possible the calculation within fairly close limits of mineralogical composition of the principal mineralized block of ground down to 1000-ft. depth, and had established closely the mineral succession, with reasons for deposition of the various minerals in the patterns now occupied by them. The geologic facts as outlined in the previous paper remain as stated; but because substantial development within the new copper ore body and further exploratory diamond drilling within the new silver-lead-zinc area (Race-course) have taken place since that paper was written, statements and figures relating to those two areas in the present paper supersede those furnished in the previous one. The recent work likewise has established more clearly the paragenetic relationship between the chalcopyrite and galena. Evidence confirming the relationship is furnished in the present paper. The facts of ore occurrence at Mount Isa show [ACCEPTED ZONAL SUCCESSION Silver sulphantimonides Galena Sphalerite Tetrahedrite Arsenical sulphides Chalcopyrite Pyrrhotite MOUNT ISA SUCCESSION Chalcopyrite In the main but Silver sulphantimonides wholly Tetrahedriteably not Galenacontemporaneous Pyrrhotite Sphalerite Arsenical sulphides They show further: (I) that instead of the silver-lead minerals yielding to increased zinc in depth, the zinc yields to increased silverlead; (2) no dovetailing of the silver-lead-zinc sulphides into chalcopyrite takes place; (3) despite the large amount of pyrrhotite deposited in the district (estimated at upward of 100,000,000 tons), its deposition took place under moderately low temperature conditions; (4) no evidence has been found for increase in temperature of deposition, with depth, to deepest exploration in ore (1495 ft.). The anomalous condition at Mount Isa, both as to the unorthodox mineral succession and the largely unorthodox pattern of mineral distribution, is explained in the present paper,

Jan 1, 1943

By L. A. Rapoport, W. J. Leas

The original Burkley-Leverett theory has been extended and a more detailed formulation of the waterflood behavior in linear horizontal systems is presented. Particular consideration has been given to the evaluation of capillary pressure effects and differential equations permitting an explicit evaluation of these effects have been derived. On the basis of the developed theory it is recognized that the flooding behavior is dependent upon the length of the system and the rate of injection. At the same time it has been determined that systems of different lengths yield the same flooding behavior if the injection rates and or the fluid viscosities are properly adjrrsted or "scaled." It has also been found that the sensitivity of the flooding behavior with respect to rate and length decreases as any one of these {actors increases in value and that for sufficiently long systems and high rate.; of water injection the flooding behavior becomes independent of rate and length. or "stabilized." To such stabilized conditions the theory formulated by Buckley and Leverett is applicable. A number of laboratory flooding tests have been made and good agreement Iraq been found between theory and experimental observations. The experimental results are discussed and it is shown that under field conditions the flooding behavior is usually stabilized. As a result of these finding; a procedure is indicated for evaluating field performances either on the basis of tests performed with commonly available core samples or by means of calculations using relative permeability data INTRODUCTION In recent years the development of methods for evaluating oil recovery by waterflooding has been the object of considerable research. A theoretical analysis of the mechanisms involved in the displacement of immiscible fluids was originally established by Buckle!- and Leverettl and experimental investipatio~~s have been made by numerons workers." Many of the experimental results are in mutual agreement and bear out several significant features of the flooding mechanism as predicted by theory. Thus it lias been generally recognized that a flood corresponds to the movement of a steep saturation hank or "front" (primary phase), followed by additional gradual oil displacement (subordinate phase). It has also been found that for any porous medium the flooding behavior is largely dependent upon the oil-water viscosity ratio and that for increasing values of this ratio the relative importance of the primary displacement phase decreases while that of the subordinate phase becomes more pronounced. Although the studies to date have clarified certain aspects of the flooding process. they have given rise to observations of a somewhat contradictory nature that cannot he explained in terms of the original theory. These observations pertain mainly to the effect of injection rate or pressure gradient upon recovery. Some investigators report laboratory tests that indicate incresing oil recoverieq with increasing rates of water injectill, others find the flooding behavior to be independent of and other. mention lower oil recoveries with increased injection rates.3 The conflicting evidence indicated above creates considerable uncertainty with respect to laboratory testing procedures and the utilization of the resulting data for field evaluations. The principal purpose of this paper, then, is to resolve these Uncertainties by means of a comprehensive theoretical and experimental investigation of the flooding meanism. THEORETICAL DEVELOPMENT Derivation of Flooding Equations The mathematical description of transient flow phenomena is based upon the consideration of the various processes occurring during an infinitesimal time interval in an infinitesimal volume element and upon the correlation of these processes with those occurring in the adjacent elements. The volume elements are defined as being infinitesimal in comparison to the overall dimensions of the porous system, yet each sufficiently large so aS to encompass the full range of pore openings encountered throughout the system. If a porous system can arbitrarily be subdivided into an infinite number of volume elements all possessing the same distribution of pore openings and if this distribution is unformly continuous. the system may be said to be homogeneous. Such a homogeneous porous medium is considered in the present studivs. It is furthermore postulatecl that only oil and water are present in the pornu wediu. that they act a- totally incompressible and immiscible fluids. and that gravity effects are negligible. In n linear flow system of unit cross sertional area. as treated here. the infinitesimal volume element.; to he considered are cylindrical ".slices" of thickness dx. oriented perpendicularly to the direction of flow. The equations applicable to any such volume element. at my time. describe the movement. of oil and water across the element:

Jan 1, 1953

By Gerald Sherman

(San Francisco Meeting, September, 1915) THE ore deposits of the Warren district, in which the mines of the Copper Queen Consolidated Mining Co. are situated, have been described in a number of technical publications, and will not be-discussed here in detail. Certain of their characteristics, however, control -methods of underground transportation and hoisting of ore. In the Copper Queen mine, the majority of the ore has occurred in a zone encircling the west boundary of the porphyry intrusion of Sacramento Hill. It has a width varying from 800 to 1,200 ft., and a thickness of about 400 ft. It reaches the surface in the older part of the mine to the northwest, but dips to the southeast, where it is reached at 1,400 ft. below the Czar collar, in its farthest extension at present developed on Copper Queen ground. There is one major extension from the northwest end of the zone toward the west along the Czar fault, and others of minor importance. Individual orebodies are scattered through the zone in an eccentric manner, only matched by their own irregularities of form and size. Their most general characteristics are the softness of the ore and their great horizontal rather than vertical extent. It has been estimated that the average vertical thickness of ore in the Czar and Lowell divisions is between 30 and 35 ft. It is calculated by assuming it to be uniformly distributed over its horizontally projected area. In this zone, and for some distance above it, the ground has been .subjected to intense alteration and intense but irregular oxidation. It has resulted in an enormous quantity of earthy or clayey material, which may be either ore or waste, which when wet is both heavy and tenacious. Below alteration, the ground is fairly hard, and the limestones contain primary ores differing from those heretofore considered typical of the camp, and which have not yet been thoroughly exploited. The mine production has been drawn from many orebodies spread . over a great area. A diagram map (Fig. 1), of haulage drifts and loading stations, illustrates the situation in 1914.

Jan 9, 1915

By W. R. Shimer, F. O. Kichline

The investigation herein described was carried out for the purpose of studying, both by chemical and metallographical means, the extent of over-oxidation of steel that can be accomplished by excessive overblowing in a Bessemer converter. 111 addition there are appended some results of basic open-hearth and crucible steels. Remarks on Chemical Methods. The test block used was hemispherical in shape, 4.5 in. in diameter and 2 in. thick. Drillings for analysis were obtained by drilling through the entire solid part of the block, carefully avoiding all cracks and blow-holes and mixing these drillings thoroughly. Drillinga were carefully examined for scale and the finest were gone over with a microscope to be sure all scale from whatever source had been removed. Oxygen was determined by the well-known method of Ledebur, modified according to Cushman,1 with, however, the removal of the preheating tube, which was found unnecessary. This method has been found to give concordant results. Blanks run from 0.0003 to 0.0006 g. Duplicate determinations varied not more than 0.001 to 0.003 per cent. It seems to be generally supposed that the hydrogen method gives only that oxygen which is combined with iron. Whether this be true or not, the content of oxygen existing as iron oxide no doubt predominates sufficiently, so that the result obtained is sufficient to indicate whether the steel is over-oxidized or not. We are well aware that the oxides of manganese and chromium, when existing alone, are not reduced by hydrogen at a red heat. To learn of their action in steel the following work was carried out: A sample of ferro-manganese and of ferro-chrome were each exposed

Jan 1, 1914

By Charles Fettke

IN THE present day manufacture of glass nearly pure quartz sands are used almost exclusively as the source of the silica, which is the major constituent of all common varieties of glass. Ordinary soda-lime, such as bottle, common tableware, plate, and window glasses, contain from 65 to 75 per cent. of silica. OCCURRENCE Glass sands occur in nature either in the form of loose, unconsolidated sediments or in deposits in which the individual grains have been more or less thoroughly bound together by some cementing agent so as to form sandstones. While deposits of sand and sandstones occur both widely and abundantly distributed, deposits that are sufficiently free from other constituents than quartz grains, so that they can be employed in the manufacture of the better grades of glass, are, comparatively speaking, of rare occurrence. The major portion of the glass sand produced in the United States comes from sandstones. In order to be suitable for glass sand, they should be rather friable. The rock should break down readily along the cementing material between the grains and should not break across the grains rather than along the bond. Some of the sandstones used are so friable that only light shots of slow-burning dynamite are necessary to disintegrate them sufficiently for hydraulic mining, while others have to be passed through crushers in order to disintegrate the rock into its individual grains.

Jan 2, 1926