Search Documents

By Oliver Smalley

EXCEPT for the work of Guillet, who conducted a systematic investigation on the zinc-replacing value of nickel in brass, and extended his investigation with a view to developing commercial high zinc content nickel brasses, the author does not know of any systematic research on the subject. The most promising commercial alloys and their physical properties obtained by Guillet are given below: Maximum Elonga- Reduction Copper Zinc Nickel Stress, tion, of Area, Brinell Tons Per Per Cent. Per Cent. Sq. In. 55.0 41.0 5.0 24.4 46.5 94 Sand cast. 22.6 27.0 90 Chill cast. 56.7 39.74 3.35 30.0 43.0 51.7 97 Casting annealed 2 hr. at 750° C. 33.9 33.0 50.7 144 Cold-drawn bar. 55.15 42.3 2.24 29.8 33.0 116 Casting annealed 2 hr. at 750° C. 32.3 29.0 151 Cold-drawn bar. These test results scarcely justify the use of such quantities of so expensive a metal, and could have been obtained from ordinary commercial brass. For purposes of comparison, the physical properties of ordinary brasses, ranging from 70 per cent. to 50.1 per cent. Cu in both the cast and normalized1 conditions are included in Table 1. These incidentally furnish a useful standard of the properties of castings and of rolled, extruded and forged brass when correctly annealed. A close study of some of the well-known special brasses containing nickel reveals a series of alloys which bewilder by their complexity, and one can only hazard a guess at the function and commercial value of each of the many elements used.

Jan 10, 1925

By W. H. Bassett, J. C. Bradley

In considering the effects of reducing gases on hot solid copper the following conclusions have been reached. (I) Depth of deoxidation of copper heated in reducing gas is grealer the smaller the amount of cuprous oxide originally present in the copper, the range studied being from 0.015 to 0.136 per cent. oxygen. It is suggested that the reason for this diflerence in depth of deoxidation is thai, when the copper is low in cuprous oxide, the reducing gas is diluted less by the gas that is formed in the reaction than when the copper is high in cuprous oxide; and the greater the concentration of the reducing gas the deeper the deoxidation. (2) The rate of deoxidation is much more rapid at the beginning of exposure than at the end, a condition especially noticeable at temperatures around 900" C.; that is, deoxidaion is retarded as the depth penetrated by the reducing gas increases. (3) Within the accuracy of the experiments arsenic in copper up to 0.5 per cent. has no tendency to increase or decrease the action of a reducing gas on the cuprous oxide presenx in the copper. In 1912 pieces of 0.365-in. hard copper rod 1/2 in. long were heated in a porcelain tube in an electric furnace, while illuminating gas was passed through. An approximate analysis of this gas is: Hydrogen 38 per cent., carbon monoxide 30 per cent., illuminants 13 per cent., methane 10 per cent., ethane 3 per cent., carbon dioxide 3 per cent., nitrogen 2 per cent., oxygen 0.4 per cent. After heating for various lengths of time at various temperatures, samples were quenched

Jan 1, 1926

By C.F. Pascoe, H.J. Roast

The object of this investigation was to compare the arsenical antimony-lead alloy with some of the regular bearing-metal alloys. With this end in view, the following tests were made: 1. Chemical analyses to show the composition. 2. Thermal analyses. 3. Macroscopic examination of fractures. 4.Microscopic examination. 5. Tensile tests. 6. Crushing tests. 7. Scleroscope tests.' 8. Brinell tests, at temperatures from 80' to 400' F. Tests 3 to 8 were conducted on both sand-cast and chill-cast specimens. For the purposes of this paper the alloys have been numbered from 1 to 6; their composition is as follows: Lead. ' Antimony, Tin, CoppeR ARSEnic, NumBeR PeR CENT. PER CENT. PeR Cent. PeR CeNt. PeR Cent. 1 82.64 12.95 4.40 0.01 none 2 27.54 9.04 59.87 2.65 none I 3 none- 0.13 ------------1.47 4 82.95 16.85 none 0.20 none 5 83.78 15.35 none 0.05 0.82 6 0.15 7.87 . 84.13 7.85 none The analysis, in the case of the antimony, was made by solution in sul-furic acid and titrated with permanganate. For tin, the ferric-chloride method was used; for copper, the alkaline separations, and the thio-cyanate methods; for arsenic, volatilization of arsenic and titration with iodine. The lead, with the exception of alloy 6, was taken by difference. With the exception of No. 5, the alloys were taken as received from the manufacturer. About 40 lb, were melted in a graphite crucible and recast into small ingots to insure uniformity of composition; samples

Jan 1, 1923

By C. F. Pascoe, H. J. Roast

The object of this investigation was to compare the arsenical antimony-lead alloy with some of the regular bearing-metal alloys. With this end in view, the following tests were made: 1. Chemical analyses to show the composition. 2. Thermal analyses. 3. Macroscopic examination of fractures. 4.Microscopic examination. 5. Tensile tests. 6. Crushing tests. 7. Scleroscope tests.' 8. Brinell tests, at temperatures from 80' to 400' F. Tests 3 to 8 were conducted on both sand-cast and chill-cast specimens. For the purposes of this paper the alloys have been numbered from 1 to 6; their composition is as follows: Lead. ' Antimony, Tin, CoppeR ARSEnic, NumBeR PeR CENT. PER CENT. PeR Cent. PeR CeNt. PeR Cent. 1 82.64 12.95 4.40 0.01 none 2 27.54 9.04 59.87 2.65 none I 3 none- 0.13 ------------1.47 4 82.95 16.85 none 0.20 none 5 83.78 15.35 none 0.05 0.82 6 0.15 7.87 . 84.13 7.85 none The analysis, in the case of the antimony, was made by solution in sul-furic acid and titrated with permanganate. For tin, the ferric-chloride method was used; for copper, the alkaline separations, and the thio-cyanate methods; for arsenic, volatilization of arsenic and titration with iodine. The lead, with the exception of alloy 6, was taken by difference. With the exception of No. 5, the alloys were taken as received from the manufacturer. About 40 lb, were melted in a graphite crucible and recast into small ingots to insure uniformity of composition; samples

Jan 1, 1923

By C. A. Stetefeldt

In May and June, 1885, I was engaged in examining the goldores of Las Minas, in the State of Vera Cruz, Mexico, with a view of finding a cheap and efficient method for extracting the gold. The following minerals could be plainly seen in the ore : magnetite, pyrites of iron, pyrites of' copper, quartz, and garnet. Neither galena nor zinc-hlende mere visible, but the ore contained a trace of lead, and in some samples of ore from the Muertos mine, 1.19 per cent. of zinc mas found. Antimony and arsenic were not present. Native gold could scarcely be seen in specimens of' the ore, and it only appeared—mainly in extremely fine particles—after pulverizing and washing. Magnetite was in every instance the most prominent mineral, its quantity varying between 43 and 67 per cent. Determinations of copper and sulphur showed that from 3.5 to 7 per cent. pyrites of copper, and from 3 to 22 per cent. pyrites of iron were present. The gold-value of the ore varied between 0.3 oz. and 0.8 oz. per ton. I do not speak of specimens, but of average samples of large quantities of ore put through the battery. In ore that had been crushed through a No. 40 screen, the gold appeared, in part, as free gold, the rest being thoroughly mixed with the magnetite and pyrites, both minerals containing about the same percentage of gold. If this free gold was brought in contact with pure quicksilver it (lid not amalgamate readily, even if the quicksilver was charged with sodium amalgam.

Jan 1, 1886

By Glenn C. Waterman, Scott Hazen

3.1-1. Purpose. Development drilling is directed towards determining the grade, volume, and three-dimensional outline of a mineralized zone previously located by exploration. It is distinguished from exploration or reconnaissance drilling, which has as an objective the discovery of new mineralized areas. A development drilling and bulk sampling program should furnish the following information: 1. Geology of the mineralized zone. 2. Quantitative data on grade and tons of material within pertinent cutoff limits. 3. Physical size and shape of the deposit. Areas underlain by waste as well as ore. 4. Mineralogica1 and metallurgical characteristics of the ore. 5. I1hysical characteristics of the ore. 6. Hulk samples for metallurgical testing and grade check. 7. Data on other factors that could affect mining operations, such as ground water, ground conditions, etc. 3.1-2. Procedures. There are numerous methods and techniques that are used to acquire pertinent data on a potential ore deposit. The total cost and accuracy of a development program depends on significant evaluation of the geology, proper selection of a drilling method, thorough analysis of sample data, and accurate evaluation of all the information. Knowledge of the geology of the mineral deposit is important in planning the development testing program and in evaluating the data obtained from such a program. Exploration work usually provides some significant information on the general size, shape, thickness, grade, and geology of the deposit. In some cases no further data are needed; in many cases geological complexities suggested by the preliminary work require further geological study. Of considerable importance may be the following:

Jan 1, 1968

By W. J. Feuerstein

STRUCTURAL imperfections in crystals, in recent years, have received the attention of metallurgists concerned with single-crystal properties. Certain etching solutions cause local variations in the rate of etching at dislocations.' Dislocations are expected to be preferred segregation sites for impurities' and Dash" has shown that precipitation of copper occurs preferentially at edge-type dislocations in silicon. Diffusion rates along dislocations are probably higher than rates through more perfect crystalline regions.' These and other phenomena which may be influenced by dislocations may be studied by revealing dislocations as etch pits. This study was undertaken to develop an etch solution for silicon crystals to reveal low-angle grain boundaries associated with dislocation arrays and also etch pits with good contour definition. Additional etches have been reported by Dash," Vogel and Lovell.T rystals were sectioned on crystal lographic planes at various angles from the growth direction for microscopic examination of the etch pits. Experimental Crystals of 75-100 g mass and 3 cm diam were oriented and cut on crystallographic planes. Crystals were grown by Czochralski technique from a quartz crucible. Lapped wafers were chemically polished in a modified CP-4 etch for 1 min (bromine was deleted from the etch solution). The polished wafer was then etched* at room temperature for 5 min. The use of larger amounts of H2O and/or CH2COOH slows the reaction. The Cu(NO3),.3H2O was added to increase the reaction rate and give more definition to the etch pits developed. Some pertinent features concerning the attack of this etch on silicon can be summarized as follows:

Jan 1, 1959

By K. D. Jacob, W. L. Hill

THE bulk of natural phosphates is comprised of calcium phosphates, which are usually apatites;1 calcium aluminum phosphates such as pseudowavellite;2 and aluminum phosphates, which occur in extensive deposits, notably on Grand Connetable Island.3 Nearly all deposits of current commercial value are apatite, often with admixed material of other classes. In the trade coarsely crystalline material, mainly fluorapatite of igneous origin, moves as apatite, whereas the fine-grained material of sedimentary origin is marketed as phosphate rock. The latter classification includes the phosphate shales in western North America. Although several genetic varieties of phosphate rock are recognized,4 most known reserves are of marine origin. Calcium phosphate is concentrated from Florida land pebble and Florida hard rock deposits and from Tennessee brown rock deposits. Phosphate Rock as a Fluorine Carrier: More than two decades ago Reynolds and Jacob surveyed the fluorine content of commercial phosphate rock from various parts of the world.3,5 Later these samples were reanalyzed by a new and more reliable method of determining flourine.6,7 The revised results with interim additions of new samples, published a few years ago in a brief summary,' are shown in Figs. 1-3. Through the points representing the respective varieties of rock medial straight lines are drawn. In some instances the lines are well defined by the points; in others, where scattering renders the position of the best line uncertain, the greater weight is given points near the end of the covered range. Wherever distinct varieties are not recognized among regional deposits the custom is to identify the sample with the geographical location of the deposit.

Jan 10, 1954

By Sidney A. Swensrud

The writer has been interested for some time in trying to appraise our industry's prospects for gasoline consumption over the next half dozen years or so. Anyone who has even approached the problem knows the intimate relationship to it of the number of automobiles in use— by automobiles I mean both passenger cars and trucks. Probably at least 90 per cent of our gasoline is used in automotive vehicles. Some recent estimates secured from the Department of Commerce show the following breakdown: Per Cent Passenger cars............................................ 60.0 Trucks................................................... 27.4 Busses................................................... 2.9 Taxicabs................................................. 2.2 Subtotal............................................... 92.5 Aviation, motor boats and railroads......................... 0.5 Agricultural: farm tractors, etc.............................. 3.3 Balance (manufacturing, government use, construction, etc.)... 3.7 100.0 Up to the beginning of the depression there was, of course, a constant annual increase in the number of automobiles in use, for each year the industry added to the total inventory or ''population" more new units than were being scrapped, as may be seen in Fig. 1. Few of us in the oil industry needed to give much attention to the detailed figures, although the automobile industry seemed to interest itself in all sorts of calculations of replacement demand vs. new car demand, the average life of the car, the number scrapped, and the like. Probably many people in the oil industry, as well as outside it, were surprised at the way in which automobile registrations and gasoline consumption held up during the early years of the depression. Nor were they greatly perturbed when, as in the last two years, both registrations and consumption began to fall somewhat. That was natural enough; it

Jan 1, 1933

By E. J. Schmitz

This section was obtained last year during an examination of the iron-ore resources of the Rich Patch Mountain region and along Craig's creek valley. The geological members below the Oriskany and Lower Helderberg are exposed along the gap in a beautiful arch, while the higher formations appear in a more or less disturbed state on both sides of this arch, and are partly covered by dèbris. I have thought it of interest to the Institute to reproduce the drawing of this section at the gap which I made in my note-book at the time of my examination; those parts of the section, which lie at both sides of the arch, are only approximated. I give also a number of notes and measurements, referring to the Clinton formation and especially to the characteristics of the fossiliferous ore-seam opened in the various tunnels along the arch (see section). I. In Tunnel C: For the first 110 to 120 feet to second shute, we find the ore only here and there in small deposits, and interchanging with, or changing into, either a very siliceous limestone or a sandstone. About 10 feet beyond shute we have : Sandstone roof. Clay-slate, 211/2 inches Brown lean ore, 1 inch. Sandy clay, 3 to 31/4 inches. 1. Dark .brown ore, 3 inches. 2. Fossil-ore, changing into sandstone or very siliceous limestone, 2 inches. 3. Brown lean ore, 6 inches. Clay and slate below, 1 foot. 194 feet from entrance : Sandstone roof. Clay-slate, 4 inches. Clay 15 inches. Fossil-ore, 63 to 7 inches. Clay and ore, If inches. Lean brown ore, 2 inchea. Clay to bottom, 2 feet.

Jan 1, 1896

SUDBURY ore processed by International Nickel Co. of Canada Ltd. was recovered for many years as two mill concentrates, one primarily of copper, and the other mixed pentlandite-pyrrhotite, But, Since iron content of the nickeliferous pyrrhotite concentrate was ten times its nickel value, capacity of smelting was limited by the need for slagging the excess iron. A process for recovering the iron con- tent was developed after some years of research and a $20-million plant was constructed to employ the new method. Built near Copper Cliff, Ont., the plant started operation early in 1956, scheduled for separate treatment of 365,000 tons of pyrrhotite each year. It is only the first unit of an installation which will have a capacity of more than 1 million tons per year of pyrrhotite. By early 1958, production totaled more than 200,000 long tons of 68 pct Fe pellets containing 0.003 pct P, 1.5 pct SiO2, 0.01 pct S, and 0.15 pct Ni.

Jan 8, 1958

By Gregory L. Gullord

In September, 1975, production was begun at the new milling facility of ASARCO Incorporated, the Young Mill. The mill is located adjacent to the Young Mine 35 km (22 miles) east of Knoxville, Tennessee. The Young Mill replaced the obsolete Mascot Mill which had been operating since 1913. The basic flow sheet of Mascot was retained for the construction of the Young Mill, with a 20% increase in capacity included in the design. The Young Mill is capable of processing 7710 - t/d (8500 stpd) of crude ore from three underground mines (Young, Immel and Coy) yielding 300 - t/d (330 stpd) of 63% zinc concentrate. The Young Mill is unique in that 92.5% of the ore milled is recovered as saleable products, including zinc concentrate, construction aggregate, sand and agricultural limestone. Processing at the Young Mill is divided into five basic stages: two-stage crushing, heavy media separation, grinding-flotation, concentrate filtering and drying, and limestone by-products recovery. The ore bodies are located in the Knox formation, which consists of primary dolomite, secondary dolomite and limestone with silicas in the form of chert and jasperoid. The zinc mineralization occurs as an exceptionally pure sphalerite. The ore contains an occasional abundance of pyrite and traces of fluorite and barite. TWO STAGE CRUSHING Ore enters the crushing section from two points. The Young Mine ore is hoisted into a 816 ton (900 st) bin which feeds a 1.52m (60 in) conveyor via a 1.52 m (60 in) vibrating feeder. The Immel ore is trucked 10 km (6 miles) by an independent contractor and weighed on automatic recording truck scales at the entrance to the property.

Jan 1, 1977

By W. L. Crentz, E. E. Donath, D. Doherty

Maurice Rey—The influence of cyclone diameter upon the fineness of separation is an important point which, however, cannot be discussed adequately if the injection pressure or the rate of flow are not specified. Perhaps some light can be thrown on the matter by using the formulas derived by Dahlstrom. Let us consider several geometrically similar cyclones where the apertures e and b are equal and proportional to the diameter D and which are operated with the same pressure drop. Eq 8 of Dahlstrom's paper can be written: Q Q = K D'. " or. if F is constant: Q = K D18 K is a constant of proportionality. Introducing this value of Q in eq 13 gives elimination efficiency = K D0' " Elimination efficiency, in the terminology of Dahlstrom, means the diameter of particles, in microns, which divide equally between the underflow and the overflow. This denomination is regrettable and it would be preferable to call it diameter of separation or characteristic size or any other name connoting a size rather than an efficiency. Whatever the name used, the above equation shows a slow increase in the fineness of separation when the diameter of the cyclone decreases. For example, if a 14-in. cyclone gives a 400-mesh separation (37 microns), geometrically similar cyclones, having the same pressure drop will give separations at the sizes shown below.

Jan 1, 1951

By E. E. Donath, W. L. Crentz, D. Doherty

Maurice Rey—The influence of cyclone diameter upon the fineness of separation is an important point which, however, cannot be discussed adequately if the injection pressure or the rate of flow are not specified. Perhaps some light can be thrown on the matter by using the formulas derived by Dahlstrom. Let us consider several geometrically similar cyclones where the apertures e and b are equal and proportional to the diameter D and which are operated with the same pressure drop. Eq 8 of Dahlstrom's paper can be written: Q Q = K D'. " or. if F is constant: Q = K D18 K is a constant of proportionality. Introducing this value of Q in eq 13 gives elimination efficiency = K D0' " Elimination efficiency, in the terminology of Dahlstrom, means the diameter of particles, in microns, which divide equally between the underflow and the overflow. This denomination is regrettable and it would be preferable to call it diameter of separation or characteristic size or any other name connoting a size rather than an efficiency. Whatever the name used, the above equation shows a slow increase in the fineness of separation when the diameter of the cyclone decreases. For example, if a 14-in. cyclone gives a 400-mesh separation (37 microns), geometrically similar cyclones, having the same pressure drop will give separations at the sizes shown below.

Jan 1, 1951

By AIME AIME

THE report of the united. States Steel Corporation for the' year 1928 gives the, following ,figures of raw materials and' finished products . Raw materials, tons :

Jan 1, 1929

F. L. Clerc, Chicago, Ill. (communication to the Secretary): On page 681 in Mr. Winslow's paper, he refers to me as having "advocated the view that the ores were derived from the patches of Coal-

Jan 1, 1895

By J. P. Nielsen

When two grains in a polycrystalline specimen meet at a point in the course of grain-boundary movements, and the new boundary created at the point is one of relatively low specific free energy, a nonequilibrium boundary condition occurs. The nonequilibrium is enhanced if the other grain boundaries involved at the point of meeting are relatively high in specific free energy. The nonequilibrium results in a correction by growth of the complex grain (two subgrains) to a large size, sufficient in many cases for it to become a self-propagating unit, i.e., a recrystallization grain. This mechanism, herein called "geometrical coalescence," is proposed as a logical origin for recrystallization nuclei, particularly for secondary recrystallization. RECENT publications1-' indicate that considerable progress has been made toward a complete understanding of the three microstructural processes in metals: recovery, recrystallization, and grain growth. However, a major problem persists, namely, the origin of recrystallization nuclei. It is generally accepted that once a recrystallization nucleus, a secondary recrystallization nucleus particularly, has reached a certain size, it will continue to grow at the expense of its neighbors, simply as a consequence of grain-boundary free-energy considerations. What has remained obscure, however, is the mechanism whereby such a nucleus comes into being and grows to the self-propagating size. Recrystallization Nucleation in a Two-Dimensional Grain-Boundary System In the left portion of Fig. 1 is shown schematically the meeting of grains 1 and 4 on disappearance of boundary 2-3, i.e., the boundary that existed between grains 2 and 3, as might happen in the course of normal grain-boundary migration. If, by chance —and the probability is not necessarily small— grains 1 and 4 are close together in their mutual orientations, or in some other special way mutually oriented so that the new common boundary has relatively a very low specific free energy (hereinafter referred to by s), then the grain boundary arrangement as depicted in the figure is highly unstable. This is particularly so if boundaries 1-3, 3-4, 4-2, and 2-1 are high in their s values. Assuming, for the sake of argument, that boundary 1-4 has a s equal to zero, and the s's of all the other boundaries present are equal to each other and constant, then the boundary arrangement on the right in Fig. 1 will be

Jan 1, 1955

By C. H. Frick

Before presenting the main topic, as indicated by the title, this paper will give some of the high-spot history of the anthracite industry. Introduction The earliest recorded use of anthracite was in the year 1762, when a company of Connecticut pioneers discovered anthracite near the present city of Wilkes-Barre, Pennsylvania. In the early days of the industry, the coal was used only in large pieces, the smaller pieces being discarded to waste piles. As the output of the industry increased during the nineteenth century, uses were developed for somewhat smaller sizes down to and including pea coal. Early in the twentieth century, sizes smaller than pea, such as No. I and No. 2 buckwheat, were developed and used. Accumulations of piles from current mining operations were still increasing; that is, the smaller sizes were still being discarded. It was not until after World War I that preparation of the so-called steam sizes began commercially. This was largely No. 3 buckwheat, which is screened through a 3/16-in. round-hole screen and over a 3/32-in. or a 1/16-in. round-hole screen. Use of Smaller Sizes The earliest recorded experience in burning the small sizes of anthracite for steam production, other than in a previous small experiment, was in the year 1913, when a size known as "boiler fuel" was introduced—a mixture of rice and barley (No. 2 and No. 3 buckwheat). At that time, there was still no method known for burning the still smaller sizes. At the present time, various sizes down to and including No. 5 buckwheat are being prepared (Table I) from current mining and bank-reclaiming operations. The sizes of No. 4 and No. 5 buckwheat and smaller are generally being used for steam production in large boilers. The Pennsylvania Power and Light Co., following World War I, used 680,000 tons of anthracite per year, burned largely on stokers for production of steam, whereas for the year 1943 it used 1,940,000 tons of stoker sizes and 400,000 tons of smaller sizes for grinding and burning in pulverized form. This company has taken a very large part in the research and development of ways and means of burning these smaller sizes of anthracite, including the grinding of the very small sizes. This paper is particularly concerned with the latter feature.

Jan 1, 1949

By H. J. Engell, W. Frank, A. Seeger

SWISHER and ~urkdogan' have determined the solubility of oxygen in a iron. They found it to lie between 7 and 10.5 at.-ppm at 881°C. Using earlier work on the permeability of oxygen in bcc iron,' they arrived at the following expression for the diffusion coefficient of oxygen in bcc iron (k = Boltzmann's constant, T = absolute temperature): where The present authors3 have estimated the activation energy QD for the diffusion of oxygen in bcc iron in two different ways from various experimental data.2'4"6 In the first method QD + QS (QS = heat of solution for oxygen in bcc iron in thermodynamic equilibrium with solid FeO) was determined either from data on the reduction of FeO with hydrogen4 or from measurements of the internal oxidation of silicon in a iron.5 Using an estimate of QS from investigations of the oxygen solubility in 6 iron2 (in thermodynamic equilibrium with molten FeO) Q = 0.97 ev or Q~ = 1.06 ev were obtained. From the magnitude of these values it was concluded that oxygen migrates interstitially in bcc iron and that consequently the activation energy QD for diffusion of oxygen has to be identified with the migration energy E~ of the oxygen atoms. Therefore, for a second estimate of QD from the diffusion coefficient of oxygen in 6 iron at 1450" ~,~ we used the theoretical expression:3 (a = length of elementary cube edge, m = mass of interstitially diffusing atom, sM = migration entropy), applicable to diffusion via the octahedral interstices in bcc lattices. Taking sM = 3.8 k (migration entropy of carbon in a iron), one gets Q = 0.90 ev. Hence, in Ref. 3 Q = (0.98 *0.1) ev was proposed as a plausible value for the diffusion energy of oxygen in bcc iron. sM + 9 (9 = solution entropy for oxygen in bcc iron) can be determined from permeability measurements.4 Using the above-mentioned estimate for QS , the following expression for the solubility c (atomic concentration) of oxygen (in thermodynamic equilibrium with solid FeO) in bcc iron was derived: From [4] the solubility of oxygen at 881°C in a iron is calculated to lie between 0.6 and 12 at.-ppm. We see that the solubility determined by Swisher and

Jan 1, 1969

By Rustum Roy, E. F. Osborn

THE investigation discussed in this paper concerns phase equilibria in the alumina-silica-water system. Studies in this system are part of a re¬search project sponsored by the Geophysics Branch of the Office of Naval Research2 directed toward increasing knowledge of the stability relations of metamorphic mineral assemblages. Inasmuch as metamorphic rocks consist largely of aluminosilicate struc¬tures, many of them hydrated, the system alumina-silica-water is a logical starting point for the systematic laboratory study of metamorphic mineral systems. Although logical, this is not, however, an easy approach to the problem because of the very great difficulty of obtaining transformations among structures in response to changes in temperature, pressure, and con¬centration. Commonly equilibrium among the phases in this system is exceed¬ingly difficult to attain. New laboratory techniques are required to produce certain structural rearrangements, such as inversion of diaspore to boehmite or the transformation of alumina-silica mixtures to andalusite or kyanite. Phase equilibrium data for the alumina-silica-water system are consequently only partly complete, and only a summary progress report is presented here. Crystalline phases in the alumina-silica-water system are numerous and many are common minerals. The oxide components exist as: quartz, tridymite, cristobalite, corundum, water, and ice. Binary compounds occurring naturally are: sillimanite, andalusite, kyanite, and mullite in the alumina-silica system and gibbsite, boehmite, and diaspore in the alumina-water system. The most abundant among the ternary compounds is the composition A12O3.2SiO2.¬2H2O, existing in the four structural modifications, kaolinite, nacrite, dickite, and halloysite. The hydrated form of halloysite, A12O3.2SiO2.4H2O, is here called endellite. Pyrophyllite, A12O3.4SiO2.H2O, is the third ternary compound of natural occurrence. In addition to these minerals, two other ternary crystalline phases have been encountered in this study. The first is a structure resembling montmorillonite and corresponding perhaps to the pure aluminian end member of the beidellite series. The other has a composition approximating A12O3.2SiO2.H2O but its composition and structure are still in doubt. LABORATORY PROCEDURE In these laboratory studies, a starting material such as an alumina-silica gel or one or more of the crystalline phases is wrapped in platinum foil,

Jan 1, 1952