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By Donald W. Mitchell

MINE operators have a choice of several classifications of mechanical loaders. Within each classification there are many types and makes available. Table I lists loaders on which manufacturing data as to operating characteristics are available. This paper discusses the conditions met in a mine as they affect these characteristics. It is assumed that management will provide satisfactory engineering, supervision, power, maintenance, loader service within a concentration of workings, and a balanced working cycle served by balanced production equipment. These are factors which affect the optimum operational efficiency of a loader. The conditions which determine loader choice are:

Jan 5, 1951

By Edwin M. Chance

During the last decade many conditions have been encountered that have materially increased the cost of the production of coal. As in most cases it has not been practicable to increase the selling price of such coal sufficiently to insure the necessary margin of profit, the mine management has been forced to avail itself of what might be termed unusual means that costs might be held at as low a figure as possible. The so-called efficiency engineer has been called upon, costly power plants have been built and machinery has been installed to replace manual labor wherever possible. Another aid used recently to secure economies through the more intelligent production of coal, is the chemist. As the coal industry, barring the production of byproduct coke, does not at once give evidence of its need of the services of the chemist, the writer will endeavor to point out a few of the services that this branch of the staff has been able to render. The preparation of coal in the past has been carried on entirely upon an empirical basis, that is, the criterion adopted has been an ocular inspection. Unfortunately, the appearance of a coal and especially of an anthracite, has but little relation to its fuel value, and as long as coal is purchased for the heat that can be obtained from it by its combustion, the quantity of such heat that is purchased must be one of the principal desiderata in selecting or preparing a coal. Were coals purchased for use as bric-a-brac or for exhibition in museums it might be both wise and just to purchase them upon their appearance. After 4 or 5 years of investigation the fact has been established that coals of very inferior appearance, and I now have special reference to anthracite, might and often did possess heating and burning properties superior to those possessed by bright coals which in the past had commanded considerable and uniform premiums in the market. This being the case the question arose as to whether the trade could be convinced of this fact. While at first some difficulty was experienced in establishing the quality of such dull coals, still it was found that the real obstacle to the sale of these materials in the past had been the fact that the coal producers' own sales departments felt convinced of the inferiority of this type of fuel and when complaints were registered they were given ready credence. Upon convincing the sales department of the quality of this type of fuel, but

Jan 1, 1917

By George Sachs

I deeply appreciate the honor of being selected to deliver the twentieth Annual Lecture of the Institute of Metals Division. The subject of my paper is extremely involved and voluminous, therefore I shall discuss only some more recent experimental material and speculate somewhat on the physical and mechanical fundamentals of these changes. The flow and the rupture of a solid material are rather different phenomena. It is therefore surprising that up to a rather advanced stage in metallurgical science these two fundamental phenomena have been simultaneously treated and forced into the general conception of the "failure " of solid material. Only in this century, and particularly during the last 20 years, have the very different physical meanings of flow and rupture been clearly recognized. Several hundred of the more recent publications deal with these subjects.l Law of Similarity The basic values commonly considered responsible for the mechanical behavior of any material are the stresses. From this standpoint both a large and a small article made from the same homogeneous metal and of geometrically similar shapes should behave identically, i.e., they should deform geometrically in a similar manner, if subjected to the same stress values at corresponding points. This "law of similarity" was introduced about 60 years ago simul- taneously by Barba2 and Kick3 and was derived from the classical theory of elasticity. As far as the plastic behavior of a metal is concerned, this rule appears to be valid. The conventional properties of large and small tension or compression test bars, machined from larger sections, are identical; while the force required to deform a section is proportional to its cross-sectional area and the work consumed in deforming geometrically similar articles in a geometrically similar manner is proportional to its volume. The general trend of the stress-strain diagram of a metal is independent of the section size (Fig. I). No exceptions from this rule are known. However, if the deformation of a metal is continued until rupture occurs, and the breaking stress or the work consumed is measured, a test bar of large cross section appears to fail before or at lower stresses than does one having a small cross section. Thus, the specific impact energy has been often found to decrease with increasing size of the test specimen, particularly for materials with a limited ductility.4 Another exception from the rule of similarity is offered by fatigue-strength values, which usually decrease with increasing section size.6'6 The conclusion must be drawn from these experimental facts that the ductility of a homogeneous metal decreases with increasing section size (Fig. I). This effect has been actually confirmed by Docherty,7 who observed that in static notch bending tests large specimens failed earlier and in a more brittle fashion than small specimens ma-

Jan 1, 1941

By George Sachs

I deeply appreciate the honor of being selected to deliver the twentieth Annual Lecture of the Institute of Metals Division. The subject of my paper is extremely involved and voluminous, therefore I shall discuss only some more recent experimental material and speculate somewhat on the physical and mechanical fundamentals of these changes. The flow and the rupture of a solid material are rather different phenomena. It is therefore surprising that up to a rather advanced stage in metallurgical science these two fundamental phenomena have been simultaneously treated and forced into the general conception of the "failure " of solid material. Only in this century, and particularly during the last 20 years, have the very different physical meanings of flow and rupture been clearly recognized. Several hundred of the more recent publications deal with these subjects.l Law of Similarity The basic values commonly considered responsible for the mechanical behavior of any material are the stresses. From this standpoint both a large and a small article made from the same homogeneous metal and of geometrically similar shapes should behave identically, i.e., they should deform geometrically in a similar manner, if subjected to the same stress values at corresponding points. This "law of similarity" was introduced about 60 years ago simul- taneously by Barba2 and Kick3 and was derived from the classical theory of elasticity. As far as the plastic behavior of a metal is concerned, this rule appears to be valid. The conventional properties of large and small tension or compression test bars, machined from larger sections, are identical; while the force required to deform a section is proportional to its cross-sectional area and the work consumed in deforming geometrically similar articles in a geometrically similar manner is proportional to its volume. The general trend of the stress-strain diagram of a metal is independent of the section size (Fig. I). No exceptions from this rule are known. However, if the deformation of a metal is continued until rupture occurs, and the breaking stress or the work consumed is measured, a test bar of large cross section appears to fail before or at lower stresses than does one having a small cross section. Thus, the specific impact energy has been often found to decrease with increasing size of the test specimen, particularly for materials with a limited ductility.4 Another exception from the rule of similarity is offered by fatigue-strength values, which usually decrease with increasing section size.6'6 The conclusion must be drawn from these experimental facts that the ductility of a homogeneous metal decreases with increasing section size (Fig. I). This effect has been actually confirmed by Docherty,7 who observed that in static notch bending tests large specimens failed earlier and in a more brittle fashion than small specimens ma-

Jan 1, 1941

By P. E. Phillips

INTRODUCTION Rocky Mountain Energy is the mining subsidiary of the Union Pacific Corporation, and has been active m uranium exploration since 1966. Since 1970, RME's uranium activities have been funded 50% by Mono Power, the fuels supply division of Southern California Edision. RME and Mono recognized the need for development of new methods for recovering low grade uranium deposits, and contacted Halliburton Services in regard to in situ leaching, because of Halliburton oil industry experience. As a result, a joint venture between the three parties was formed in 1974. BEAR CREEK The first ISL test was at the Bear Creek deposit in the Powder River Basin of Wyoming, about 60 miles north of Douglas. The mineralized sand is the tertiary Wasatch formation, which is an arkosic sandstone. The sand typically contains about 10% clay. The predominant clay being montmorillonite with some kaolin and illite. The roll front type trends occur along the flanks of old stream channels. This deposit was being considered for exploitation as an open pit mine. Routine amenability testing indicated it was quite amenable to a conventional acid leach, consuming about 50 lbs. of sulfuric acid per ton of ore in an agitation leach, while recovering more than 95% of the uranium. Hydrology testing indicated a permeability of about 1 darcy. The groundwater has a pH of about 8. 0 and TDS of about 1200. Test Facility The Bear Creek test was a summer-only operation, with no effort towards weather-proofing. Uranium was removed from the recovered leach solution by fixed bed ion-exchange columns. Loaded resin was eluted with strong sulfuric acid. The recovery plant was designed for simplicity of operation, with little concern for the grade or form of the yellowcake product. The plant was constructed of PVC piping and valves, fiberglass reinforced tanks, and stainless steel pumps. All waste streams were directed toward a lined evaporation pond. Wellfield The test pattern was a 30 foot radius 5 spot, with wells fully penetrating the 30 foot ore sand to a total depth of about 165 feet. The injection wells were three-inch PVC with slotted casing, while the producer was eight-inch I. D. , with a stainless steel screen. The eight-inch well was necessary in order to accommodate a six-inch stainless steel pump. Wells were cemented using cement baskets, at the top of the sand, to contain a latex acid resistant cement. Leach Conditions The lixiviant generally contained from five to seven gpl sulfuric acid, and about 0. 5 gpl hydrogen peroxide. The pH was generally 1.4 and EMF was usually -550 millivolts. Injection rates were rather variable from well to well, with a total injection rate between 12 and 25 GPM. Production rate was set at 25 GPM, since the production pump could not be throttled more than that. Approximately two pore volumes of solution were injected during the three-month test. Leach Results Injectivity was quite variable, but was generally rather poor, because of poor completion techniques. The problem stemmed from injecting before the injection wells had been completely cleaned of drilling mud. Pregnant solutions averaged about 50 ppm U308, with groundwater dilution varying from 10 to 50%, depending on the injection rate. Injectivity did decline with time, probably as a result of contamination of the well faces. A total of 1000 lbs U308 had been recovered when the test was shut down. This probably represented about 10% of the mineral under leach.

Jan 1, 1979

By AIME AIME

NO other man now on the Institute's Board has a record of long service to his professional society comparable with that of Karl Eilers. He joined in 1888; he was a Councilor as far back as 1909, a Vice-President as early as 1912, and for the last ten years has been continuously a Director and Treasurer. It seems fitting, therefore, that he is the only member of the present Board that is also an Honorary Member of the Institute. Karl Emrich Eilers was born near Marietta, Ohio, Nov. 20,,1865, which makes him 71 years old. Columbia School of Mines gave him his E.M. in 1889, after which

Jan 1, 1937

By A. H. Geisler, R. F. Mehl, C. S. Barrett

The mechanism by which the supersaturated solid solution of 20 per cent silver in aluminum decomposes has been reported in two previous publications.1'2 The analysis of streaks in Laue photograms showed that thin platelike particles (the so-called Guinier-Preston aggregates) form upon matrix planes in the early state of decomposition.1 The size of these particles is larger, the higher the temperature at which they form in accordance with nucleation theory;³ at all temperatures they increase in size with aging.2 When they have grown thick enough to afford three-dimensional diffraction, powder X-ray photograms show that the structure is not that of the equilibrium precipitate but that of a transition lattice . Sincc this is also platelike in shape and also lies upon the (III) matrix planes with the [IIO] direction in the matrix parallel to the [II.O] direction in it seems likely that the original platelet particles are merely in an early stage of formation, and thus finely dispersed. The atomic spacing and pattern on the (00.1) plane in y' are identical with those on the (111) matrix plane to which it lies parallel, and since comparable directions in the two planes are parallel, the lattices are thus coherent at the interface; an analogous coherence has been found in aluminum-copper alloys.3 The structures y' and y are both close-packed hexagonal and are oriented alike; they differ only in interatomic distances. Consequently, y' is regarded as y strained from its ordinary dimensions by the lattice coherency between it and the matrix.2 The lattice movements that transform the matrix to the equilibrium precipitate appear to be very simple.2 The mechanism of precipitation in this system is simpler and is more precisely known than that in any other system hence the system should be a profitable one for the difficult task of correlating property changes with structural alterations. The present report provides additional studies on powder X-ray diffraction from alloys of 10 per cent, 20 per cent and 30 per cent Ag, and presents the correlation of crystallographic changes with changes in microstructurc, Brinell hardness and electrical resistivity of the three alloys. Preparation of Samples and Experimental Procedure The preparation of the 20.2 per cent Ag alloy has been described2 Alloys containing 9.9 and 29.7 per cent Ag were prepared from 99.97 per cent A1 and 99.99+ per cent Ag using a similar procedure. Rolled

Jan 1, 1943

By R. F. Mehl, C. S. Barrett, A. H. Geisler

The mechanism by which the supersaturated solid solution of 20 per cent silver in aluminum decomposes has been reported in two previous publications.1'2 The analysis of streaks in Laue photograms showed that thin platelike particles (the so-called Guinier-Preston aggregates) form upon matrix planes in the early state of decomposition.1 The size of these particles is larger, the higher the temperature at which they form in accordance with nucleation theory;³ at all temperatures they increase in size with aging.2 When they have grown thick enough to afford three-dimensional diffraction, powder X-ray photograms show that the structure is not that of the equilibrium precipitate but that of a transition lattice . Sincc this is also platelike in shape and also lies upon the (III) matrix planes with the [IIO] direction in the matrix parallel to the [II.O] direction in it seems likely that the original platelet particles are merely in an early stage of formation, and thus finely dispersed. The atomic spacing and pattern on the (00.1) plane in y' are identical with those on the (111) matrix plane to which it lies parallel, and since comparable directions in the two planes are parallel, the lattices are thus coherent at the interface; an analogous coherence has been found in aluminum-copper alloys.3 The structures y' and y are both close-packed hexagonal and are oriented alike; they differ only in interatomic distances. Consequently, y' is regarded as y strained from its ordinary dimensions by the lattice coherency between it and the matrix.2 The lattice movements that transform the matrix to the equilibrium precipitate appear to be very simple.2 The mechanism of precipitation in this system is simpler and is more precisely known than that in any other system hence the system should be a profitable one for the difficult task of correlating property changes with structural alterations. The present report provides additional studies on powder X-ray diffraction from alloys of 10 per cent, 20 per cent and 30 per cent Ag, and presents the correlation of crystallographic changes with changes in microstructurc, Brinell hardness and electrical resistivity of the three alloys. Preparation of Samples and Experimental Procedure The preparation of the 20.2 per cent Ag alloy has been described2 Alloys containing 9.9 and 29.7 per cent Ag were prepared from 99.97 per cent A1 and 99.99+ per cent Ag using a similar procedure. Rolled

Jan 1, 1943

By H. C. Chang, N. J. Grant

Creep of very coarse grained high purity aluminum was studied at 400°, 700°, and 1100°F at initial stresses of 50 to 1200 psi. Local strain measurements were made across the grain boundaries and in different regions of various grains during creep, thereby permitting the drawing of component creep curves. The relative amounts of elongation as measured across a grain boundary and in the grains adjacent to the boundary depend on the temperature of testing. The significance of creep curve equations and activation energies is discussed. THIS paper presents some of the results of a research program devoted to the study of the mechanism of creep in high purity aluminum. Previous publications have dealt with the cyclic processes of alternating grain boundary sliding and migration, and the deformation in the grains caused by these processes;' the direction and the driving force of grain boundary sliding and migration;' the deformation in the grains and the restricting effects of the grain boundaries on this deformation." These previous papers were based mainly on either microscopic observations or X-ray data, or both. Sometimes creep curves across two closely spaced reference marks (about 0.6 to 0.7 mm apart) were also presented with a view to correlating the elongation values with the optical observations in general, and with certain deformation processes in particular. These curves shall henceforth be referred to as component creep curves. No attempts were made, however, to compare either the component creep curves which were obtained in different regions of a specimen, or those obtained from different specimens subjected to different creep test conditions. It is the purpose of this paper to present these component creep curves. Among the factors influencing the behaviors of these curves, those studied were stress, temperature, and grain arrangements in the specimens. It is proposed to show how greatly the deformation can vary from grain to grain and within an individual grain in a coarse grained specimen. The experimental technique and procedure have been presented.' It remains necessary to emphasize that the reference marks were produced by pressing a thin sewing needle into the surface of the specimen before the final annealing at 900°F for 24 hr and at 1150°F for 12 hr. The cold work around the needle indentations was therefore removed. The depth of these holes after electropolishing the annealed specimens was about 0.01 mm. This depth and area were negligible in comparison with the thickness of the specimens, 2.3 mm, and hence would not affect the creep behavior. Results Fig. 1 shows a development diagram of specimen P-8. The dots on the surface locate the needle point reference marks used to obtain the component creep curves. A curve obtained between two dots across a grain boundary measures not only the boundary deformation but also the deformation associated with boundary sliding occurring in the grains in the region between these indents. The original distance between two reference marks was about 0.6 to 0.7 mm. The maximum error of measurement was 0.01 mm, or in terms of percentage elongation, of the order of & 1.5 pct. Whereas the component creep curves shown in the figures to follow were drawn as a gross average of the points, in view of the fineness of some of the steps of grain boundary sliding and migration, as shown in the previous publications,¹,2 it appears logical to expect that some of the finer cycles of movement have not been delineated for the strain sensitivity of the measuring system. It seems justifiable to say that the curves are not as smooth as shown. 700°F Tests: Fig. 2 shows component creep curves across four of the grain boundaries in specimen P-8, tested at 700°F and 85 psi. These curves clearly show alternate cycles of increasing and decreasing

Jan 1, 1954

By F. H. Buttner, E. R. Funk, H. Udin

Gold wires, 5 mil in diam, are found to creep viscously up to approximately 5.5x106 dynes per sq cm around 1300°K. Beyond this point, an additional slip mechanism appears. The average coefficient in the viscous range at these temperatures is 18.9 ± 7x10 12 poises. This observation and other visual observations made during the experiments agree with Herring's predictions. EARLY creep studies by Chalmers on single crystals of tin produced some of the first experimental evidence to suggest that metals deform viscously under very light stresses. That is to say, over a small initial stress range up to 150 g per sq mm, the single crystals of tin elongated at a rate proportional to the stress. The proportionality constant between strain rate and stress is by definition the coefficient of viscosity. Chalmers named this range of proportionality the microcreep range. One of the first theoretical attempts to explain the microcreep phenomenon was given by Kauzman,' who applied Eyring'sQ eneral statistical mechanical theory of shear rates to creep data then available. From the rate theory, he deduced the general hyperbolic sine law for shear rate on the assumption that the distortion of the reaction path due to stress is negligible and that the system is an infinite continuum. In order to fit the available data to the equation, it was necessary to assume that creep occurs by shear of rather large blocks of material, rather than by an atomistic shear process as in diffusion. The size of the shear units was shown to increase with increasing temperatures and lower stress, or lower strain rates. In applying the hyperbolic sine law equation to the microcreep data of tin, it was shown by Kauzman that the unit shear blocks became quite small, which suggested to him that microcreep might be a self-diffusion process. Making this an assumption, Kauz- man reworked the rate theory and arrived at an equation where the shear rate is proportional to the stress. In the form of viscosity coefficient, the equation is: o- _ \LkT V = 2qAlA where u is the stress; S, the shear rate; X, the distance in shear direction moved by flow units relative to one another in the unit process; L, the distance between layers of units of flow; T, the absolute temperature; k, Boltzmann's constant; qAL, a constant proportional to the size of flow units; and kT A, the diffusion coefficient = ------kTe-Q/RT = K X2 h Kauzman applied the expression to molten lead with a fair degree of success, the calculated viscosity being low by a factor of four. For solid lead the result is 5000 times too high. Taking q = 1, and X = dA = L = 21 = nearest neighbor distance, Udin, Shaler and Wulff8 found the equation low by a factor of lo7 for solid copper. On the basis of the discrepancy in lead, Kauzman indicated that microcreep is probably not a simple diffusion process of molecular shear units, but one involving preferential diffusion paths, or even that diffusion in solids does not involve shear at all. Cottrell and Jaswon4 treat the microcreep phenomenon on the basis of slow moving dislocations and apply it to Chalmers' data on tin with fair success. Nabarro Suggested a microcreep model in which mass movement in the direction of pull is effected by the diffusion of holes. The tension on the crystal effectively creates a greater hole concentration at regions near the crystal surfaces perpendicular to

Jan 1, 1953

By Frank C. Greene

The wildcatting in northern and northwestern Missouri, which started in 1939, was continued in 1940. Two new gas fields were found and one discovered in 1939 was further extended. The total number of completions was 94, of which 5 were oil wells with about 48 bbl. initial production, 30 were gas wells with an initial open-flow capacity of 37,655,000 cu. ft., and 59 were dry holes. The outstanding discovery was the Polo gas field, T. 55 N., R. 28 and 29 W., in Caldwell County. A sand now believed to be a lens in the Bandera shale at a depth of 400 ft. yielded flows of more than 12,000,-000 cu. ft. In all, I0 wells with 31,490,000 cu. ft. of gas, were drilled. The rock pres-sure is 80 lb. At present no arrangements for an outlet have been made. In Platte County, the Prairie Point gas pool in sec. 7, T. 51 N., R. 33 W., and sec. 12, T. 51 N., R. 34 W., and the Lake-side pool in sees. 5 and 6, T. 50 N., R. 33 W., were further developed, and in the latter both oil and gas have been found, but data are not available for publication at this time. Drilling for gas continued in proven areas in Clay County, and for both oil and gas in proven areas in Jackson and Cass Counties. Table 1 summarizes the results of drilling in Missouri in 1940.

Jan 1, 1941

By Frank C. Greene

The wildcatting in northern and northwestern Missouri, which started in 1939, was continued in 1940. Two new gas fields were found and one discovered in 1939 was further extended. The total number of completions was 94, of which 5 were oil wells with about 48 bbl. initial production, 30 were gas wells with an initial open-flow capacity of 37,655,000 cu. ft., and 59 were dry holes. The outstanding discovery was the Polo gas field, T. 55 N., R. 28 and 29 W., in Caldwell County. A sand now believed to be a lens in the Bandera shale at a depth of 400 ft. yielded flows of more than 12,000,-000 cu. ft. In all, I0 wells with 31,490,000 cu. ft. of gas, were drilled. The rock pres-sure is 80 lb. At present no arrangements for an outlet have been made. In Platte County, the Prairie Point gas pool in sec. 7, T. 51 N., R. 33 W., and sec. 12, T. 51 N., R. 34 W., and the Lake-side pool in sees. 5 and 6, T. 50 N., R. 33 W., were further developed, and in the latter both oil and gas have been found, but data are not available for publication at this time. Drilling for gas continued in proven areas in Clay County, and for both oil and gas in proven areas in Jackson and Cass Counties. Table 1 summarizes the results of drilling in Missouri in 1940.

Jan 1, 1941

Executive HENRY A. BUEHLER, Chairman ERLE V. DAVELER EDGAR RICKARD JOHN M. LOVEJOY WILLIAM WRAITH J. V. W. REYNDERS, Consultant Finance HENRY KRUMB, Chairman E. E. ELLIS PAUL D. MERICA H. G. MOULTON, Consultant Admissions RALPH M. ROOSEVELT, Chairman GEORGE D. BARRON DONALD M. LIDDELL WILBER JUDSONW. D. B. MOTTER, JR.

Jan 1, 1934

By Robert A. Laurence

Ore deposits in the Southern Appalachians are ( 1) sedimentary or syngenetic, ( 2) epigenetic, and ( 3) residual. In general, deposits characteristic of high temperature and pressure are found in the Blue Ridge and Piedmont provinces and those of low and intermediate temperature and pressure, including the sedimentary ores, are found in the Valley and Ridge and Appalachian Plateaus provinces. Residual deposits are present throughout the area. Recognition of several periods of intrusion and metamorphism in the Appalachians has changed former concepts which held that most mineralization was of late Paleozoic age in a zonal pattern including all four provinces. Many deposits probably are of early or midPaleozoic age. Similarly, recent studies in geomorphology indicate that the formation of residual deposits is a continuous process and not related to specific cycles of peneplanation.

Jan 1, 1968

By J. W. Hickman, E. A Gulbransen

The physical and chemical structure of the oxide films formed on metals and alloys is of interest in our understanding of their protective properties. According to Pilling and Bedworth,¹ if the specific volume of the oxide is equal to or greater than that of the metal, a compact or continuous structure results; if the volume of the oxide is less, a cellular or porous structure forms. With the cellular type of coating the surface layer of oxide offers no impedance to oxidation; at a given temperature the rate of oxidation is quite constant. On the other hand, the compact type of coating acts as an effective barrier to oxygen and the rate of oxidation will follow a parabolic law. The recent work of Gulbransen2 and of Leontis and Rhines3 on the oxidation of magnesium indicates that it is not necessary for the volume of the oxide to be greater than that of the metal in order that the oxidation may follow a parabolic rate law. One exception to the rule of Pilling and Bedworth¹ is noted by Scheil;4 namely, tungsten. At 500° and 700°C long-time oxidations indicate a linear rate law with time. However, Dunn's6 0xidation measurements from 700°to 1000°C indicate that a parabolic rate law is followed. The oxide is mainly yellow WO a with a thin layer of the blue oxide. Preliminary results on the oxidation of tungsten6 in the temperature range 400° to 500°C indicate that the oxidation does proceed according to a parabolic rate law. Irrespective of the actual rate law that tungsten may obey, it is of interest to compare the results obtained on the oxidation of tungsten in the thin film region with those found when the metal is scaling. A time-temperature study of the oxides formed on both molybdenum and tungsten may indicate whether there exist any peculiarities in the oxide structures of the thin film region compared with those of the scaling region of oxidation. In a recent paper the authors7 presented an investigation of the structures of the oxide films formed on the metals iron, cobalt, nickel, chromium and copper. The results of these studies are presented in graphical form as existence diagrams of the oxides on a time-temperature scale. The existence diagrams of the oxides occurring on some of the metals are simple and show few chemical transitions, but there are many cases in which the physical state of the oxide surface changes as a function of time and temperature, as evidenced by the appearance or disappearance of orientation effects and sharpness of patterns. In general an increase in temperature results in an increase in

Jan 1, 1947

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

The physical and chemical structure of the oxide films formed on metals and alloys is of interest in our understanding of their protective properties. According to Pilling and Bedworth,¹ if the specific volume of the oxide is equal to or greater than that of the metal, a compact or continuous structure results; if the volume of the oxide is less, a cellular or porous structure forms. With the cellular type of coating the surface layer of oxide offers no impedance to oxidation; at a given temperature the rate of oxidation is quite constant. On the other hand, the compact type of coating acts as an effective barrier to oxygen and the rate of oxidation will follow a parabolic law. The recent work of Gulbransen2 and of Leontis and Rhines3 on the oxidation of magnesium indicates that it is not necessary for the volume of the oxide to be greater than that of the metal in order that the oxidation may follow a parabolic rate law. One exception to the rule of Pilling and Bedworth¹ is noted by Scheil;4 namely, tungsten. At 500° and 700°C long-time oxidations indicate a linear rate law with time. However, Dunn's6 0xidation measurements from 700°to 1000°C indicate that a parabolic rate law is followed. The oxide is mainly yellow WO a with a thin layer of the blue oxide. Preliminary results on the oxidation of tungsten6 in the temperature range 400° to 500°C indicate that the oxidation does proceed according to a parabolic rate law. Irrespective of the actual rate law that tungsten may obey, it is of interest to compare the results obtained on the oxidation of tungsten in the thin film region with those found when the metal is scaling. A time-temperature study of the oxides formed on both molybdenum and tungsten may indicate whether there exist any peculiarities in the oxide structures of the thin film region compared with those of the scaling region of oxidation. In a recent paper the authors7 presented an investigation of the structures of the oxide films formed on the metals iron, cobalt, nickel, chromium and copper. The results of these studies are presented in graphical form as existence diagrams of the oxides on a time-temperature scale. The existence diagrams of the oxides occurring on some of the metals are simple and show few chemical transitions, but there are many cases in which the physical state of the oxide surface changes as a function of time and temperature, as evidenced by the appearance or disappearance of orientation effects and sharpness of patterns. In general an increase in temperature results in an increase in

Jan 1, 1947

The following is an incomplete list of members and guests who called at Institute headquarters during the period Feb. 10, 1919, to Mar. 10, 1919. R. H. Allport, Cleveland, Ohio. R. R. Landon, Philippine Islands. I. H. Bergstein, New York. Alfred 0. Law, Cambridge, Mass. Capt. R. S. Burdette, San Antonio, Tex. James M. Little, Towanda, Pa. William R. Chedsey, State College, Pa. F. E. Marcy, Salt Lake City, Utah. L. R. Clapp, Philadelphia, Pa. H. F. Nash, Bartlesville, Okla. J. Murray Clark. L. S. Panyity, Columbus, Ohio. E. H. Claussen, San Francisco, Calif. W. C. Ralston, Reno, Nev. George E. Collins, -Denver, Colo. T. A. Rickard, San Francisco, Calif. George L. Collord, Sharpsville, Pa.. W. A. Rigby, Mt, Vernon, Iowa. William M. Corse, Mansfield, Ohio. H. H. Rowatt, Ottawa. Frank R. Crampton, Los Angeles, Calif. P. H. Royster, Pittsburgh, Pa. Capt. E. 0. Daue. Alan B. Sanger, Dorchester, Mass. A. E. Eddy, Butte, Mont. J. S. Shaw, Pittsburgh, Pa. N. H. Emmons, 2d, Lynchburg, Va. S. B. Shutts, Lynchburg, Va. E. W. Engelmann, Hayden, Ariz. Henry B. Smith, New Britain, Conn. F. A. Fahrenwald, Cleveland, Ohio. W. C. Smith, Roselle, N. J. 0. S. Finnie, Ottawa. Harry M. Spoor. John T. Fuller, Honesdale, Pa. D. M. Stackhouse, Johnstown, Pa. Major C. C. Griggs, Eureka, Utah. F. D. Stay,. Cleveland, Ohio. H. F. E. Gamm, Rutherford, N. J. D. B. Sterrett, St. Cyr, Que. A. W. Hackwood, Butte, Mont. R. H. Thayer, Yonkers, N. Y. C. L. Horne, Roanoke, Va. Kirby Thomas,. New York. B. B. Hood, Chrome, N. J. Henry Traphagen, Toledo, Ohio. R. E. Hore, Toronto Ont. H. D. Trounce, San Diego, Calif. Ross B. Hoffmann, Oakland, Calif. Henry J. Volkin, Ossining, N. Y. G. A. Joslin, Salt Lake City, Utah.. A. T. Ward, Bellefonte, Pa. John Johnston, Washington, D. C. Major L. W. Wickes. Paul S. King, Wilmington, Del. Horace V. Winchell, Minneapolis, Minn. E. William Kohl, Jr., Philadelphia, Pa. Fred L. Wolf, Mansfield, Ohio. W. H. Landers, San Francisco; Calif. J. Carson Adkerson, of the Stockwood Realty Corpn., Inc., of Woodstock, Va., writes that they are discontinuing their operations in Virginia on account of the conditions in the manganese market following the end of the war.

Jan 4, 1919

By T. Egleston

THE works of the Ore Knob Copper Company are situated in the county of Ashe in the northwestern part of the State of North Carolina, about ten miles from the Virginia line, at an elevation of 4600 feet above the sea. The nearest railroad station is at Marion, Smythe County, Virginia, about forty-five miles distant. The roads from the railroad to the works have been constructed by the company for the transportation of their material, and are very hilly, and in certain seasons of the year in bad repair. Transportation is therefore always limited and never easy, although it is done by contract at a very low price. The main difficulty with the transportation is not so much its cost as the fact that it puts a limit to the production of the works. These unfavorable conditions make it necessary for the owners of the mine to smelt their ores and to send to market nothing except the metal, which alone will bear the cost of transportation. The mine was opened previous to 1860, but has only been worked systematically during the last five or six years. The vein is a fissure vein from ten to twenty feet in thickness in the gneiss of the

Jan 1, 1882

By M. J. Pool, with Appendix by Larry Kaufman, R. W. Krenzer

Thermodynmic properties of the Cu-Mn system have been deterrrzined in the temperature range 973" to 1273°K by measuring the vapor pressure of manganese in equilibrium with alloys of compositions varying from 0.13 to 0.91 rnole fraction manganese using the Knudsen effusion technique. Activities of manganese calculated from the measured vapor pressures show large positive deviations. Calculated heats and entropies of mixing are positive with a maximum occurring at approximately 0. 7 mole fraction manganese. ThE investigation of thermodynamic properties of binary systems involving transition metals is of considerable interest at the present time. The incomplete subvalency electron levels of transition metals lead to unusual behavior in some alloys, and considerable information can be obtained by determining the thermodynamic characteristics of these systems and relating the thermodynamic behavior to observed physical properties. The Cu-Mn system, shown in Fig. 1,' provides an example of an alloy system in which the determination of the equilibrium phase diagram and various physical properties has received considerable attention, but very little work has been done on measurement of the thermodynamic properties. Elemental copper and manganese have comparable electronegatives, atomic sizes, and cohesive energies, but differ in crystal structure. They form a continuous series of solid solutions only at high temperatures and the structure varies in a continuous manner from fcc at the copper-rich end to fct at the manganese-rich end.' The purpose of this investigation was to measure the vapor pressure of manganese over a series of Cu-Mn alloys and from these values determine the thermodynamic properties of the binary system. Vapor pressure measurements were made in the temperature range 973" to 1273"K, remaining within the solid-solution region for each alloy studied. EXPERIMENTAL PROCEDURE The relative thermodynamic properties of solid Cu-Mn alloys were determined from vapor pressure measurements by means of the Knudsen effusion tech- nique. Several discussions of the theory can be found in the literature. In the case of copper and manganese, it is assumed that manganese is the only component subliming, so the vapor pressure of manganese over the various alloys can be determined directly by measuring the weight loss of the effusion cell. This is a valid assumption since the vapor pressure of manganese is about four orders of magnitude higher than the vapor pressure of copper in the temperature region of interest. The vapor pressure of manganese over the alloys at any given temperature is then related to the weight loss of the effusion cell per unit area per unit time. An upper limit of 1.5 x 10"s has been measured for the ratio of polyatomic to monoatomic molecules for manganese vapor in equilibrium with solid manganese at 1180°K, so it was assumed that manganese vapor is monoatomic. The effusion cells, fabricated from high-purity alumina, are 26 mm high, 18 mm OD, and have a wall thickness of 1 mm. Three different sized holes of 2.03, 2.54, and 3.18 mm diam were drilled in the lids from the inside face to minimize chipping, and the lids were then slip-cast onto the cells to provide a gas-tight seal. Alumina was selected for this particular application both because of its resistance to thermal shock and reaction with manganese vapor. In the ideal case, the orifice of the effusion cell should have a knife edge so that effusion through the orifice

Jan 1, 1970

By G. Thodos, E. M. Phillips

A reduced density correlation for the gaseous and liquid regions of ethane has been developed from all the experimental PVT data available in the literature for this substance. Saturated vapor and liquid densities reported for methane, propane and n-butane were utilized to establish the rectilinear-diameter line for ethane. This line was then used with the saturated-vapor data for ethane to produce the saturated envelope for this substance. Most of the saturated liquid data reported for ethane were found to be inconsistent with the saturated-liquid curve resulting from this study. The correlation covers the regions 0.65 < TR <6.0 and 0 < PR < 15. For regions for which no experimental data have been reported, the isobars of the correlation were extended by the use of the theorem of corresponding states. This correlation is presented both on rectilinear and log-log coordinates. INTRODUCTION At the present time, there is considerable interest in the exact PVT behavior of pure hydrocarbons. Matschke and Thodos12 recently have developed a comprehensive compilation of experimental vapor and liquid density data for methane. Similar studies have been conducted for other pure substances.4, 7 In the present study the density data available in the literature for gaseous and liquid ethane have been critically reviewed and utilized to develop a reduced density correlation for this substance. SATURATED LIQUID AND VAPOR DENSITIES The rectilinear-diameter rule proposed by Cailletet and Mathias5 states that the sum of the saturated liquid and vapor densities of a pure substance is a linear function of temperature which passes through the critical point. This law, although empirical, has been well established by continued verification since its conception in 1886. This rule has been applied to the saturated density data of methane,6 propane 17 and n-butane8 to produce the straight lines presented in Fig. 1 which pass through the critical point TR = 1.00, Pr = 2.00. The rectilinear-diameter relationship for ethane was established from the lines for the other substances in Fig. 1 by plotting the quantity p~, + PR against zc for different reduced temperatures. A critical analysis of the saturated vapor and liquid densities reported for ethane by Kuenen,10 Maass and McIntosh,11 and Sage, Webster and Lacey18 revealed that the values of PR1 + pr resulting from these studies were inconsistent with the rectilinear-diameter line obtained from the reliable density data of the other substances, as shown in Fig. 1. In the analysis of these data, reduced quantities were calculated using the critical con-