Search Documents

By Charles S. Barrett

This paper is a progress report covering metallographic applications of the electron microscope that have been made during the past year at Carnegie Institute of Technology. An account is presented of the techniques that have been most satisfactory, the difficulties encountered, the resolution obtained, and the peculiarities that have been noted in the microstruc-tures. About 1200 exposures have been made during the year on the instrument, which is an RCA type B2 transmission microscope,' and a number of these have been selected to illustrate the results obtained. prints are also included showing the common types of falsities—to borrow a term from the biological field, the "artifacts." ln brief, the paper is a record of our attempt to determine the value of the electron microscope in the study of the structure of metals and alloys. In addition to comments on techniques and the quality of photomicrographs obtainable with them, the paper discusses the nature of the etch attack on a few metals, and the possible relation between the fine structure revealed by etching and the mosaic block structure of the grains, since numerous papers and reviews are available on the subject of imperfection in crystals, the comments here may be very brief; in fact, are restricted almost entirely to points having to do with recent theories relating the strength of metals to imperfections and to spacings of slip lines. Specimen Preparation and Photographs Mechanical polishing by hand was used throughout this work. Precautions that must be taken in microscopy at high magnification, which have been well explained by Vilella in his book on Metallographic Technique for Steel, are likewise important with the electron microscope. This applies particularly to the need for these polishing and etching (each successive polish becoming less severe and each etch lighter), since the fina1 etch should in general be no heavier than is used for oil-immersion optical microscopy and in many instances should be much lighter (compare Figs. 6a and 7a, 6d and 7b). An extremely light etch, of course, is incapable of cutting through a flowed layer of appreciable thickness. Unquestionably it would be very advantageous in each instance to compare the structures obtained by electrolytic polishing with those obtained by mechanical polishing, but difficulties with the electrolytic method have prevented this in the following collection of prints. The choice of etchant is important, of course; for example, picral proved superior to nital for tempered martensite. With the exception of Figs. Ib and 16, the replicas used were of silica, deposited upon polystyrene and floated from the polystyrene in ethyl bromide according to the method of Heidenreich and Peck.2 The samples were mounted in Bakelite, polished and etched, then the polished Bakelite

Jan 1, 1944

By Charles S. Barrett

This paper is a progress report covering metallographic applications of the electron microscope that have been made during the past year at Carnegie Institute of Technology. An account is presented of the techniques that have been most satisfactory, the difficulties encountered, the resolution obtained, and the peculiarities that have been noted in the microstruc-tures. About 1200 exposures have been made during the year on the instrument, which is an RCA type B2 transmission microscope,' and a number of these have been selected to illustrate the results obtained. prints are also included showing the common types of falsities—to borrow a term from the biological field, the "artifacts." ln brief, the paper is a record of our attempt to determine the value of the electron microscope in the study of the structure of metals and alloys. In addition to comments on techniques and the quality of photomicrographs obtainable with them, the paper discusses the nature of the etch attack on a few metals, and the possible relation between the fine structure revealed by etching and the mosaic block structure of the grains, since numerous papers and reviews are available on the subject of imperfection in crystals, the comments here may be very brief; in fact, are restricted almost entirely to points having to do with recent theories relating the strength of metals to imperfections and to spacings of slip lines. Specimen Preparation and Photographs Mechanical polishing by hand was used throughout this work. Precautions that must be taken in microscopy at high magnification, which have been well explained by Vilella in his book on Metallographic Technique for Steel, are likewise important with the electron microscope. This applies particularly to the need for these polishing and etching (each successive polish becoming less severe and each etch lighter), since the fina1 etch should in general be no heavier than is used for oil-immersion optical microscopy and in many instances should be much lighter (compare Figs. 6a and 7a, 6d and 7b). An extremely light etch, of course, is incapable of cutting through a flowed layer of appreciable thickness. Unquestionably it would be very advantageous in each instance to compare the structures obtained by electrolytic polishing with those obtained by mechanical polishing, but difficulties with the electrolytic method have prevented this in the following collection of prints. The choice of etchant is important, of course; for example, picral proved superior to nital for tempered martensite. With the exception of Figs. Ib and 16, the replicas used were of silica, deposited upon polystyrene and floated from the polystyrene in ethyl bromide according to the method of Heidenreich and Peck.2 The samples were mounted in Bakelite, polished and etched, then the polished Bakelite

Jan 1, 1944

MAY 17-The last bit of verbal sod had hardly come to rest on the grave of the coal industry-which grave was being eagerly dug with typewriters and microphones by administration hangers-on and even an operator or two-when its leaders gathered for the 1950 Coal Convention of the AMC in Cincinnati on April 24. Surprisingly, mourning clothes were not being worn but the boys had on their diggers preparatory to digging their way out from under the muck. High costs created by wage and welfare demands, together with work stoppages, have caused markets to shrink, but even so, an optimistic air still prevailed as new techniques were disclosed at technical sessions. The administration, however, came in for its share of knocks.

Jan 6, 1950

By B. H. Caudle, L. G. Davies, I. H. Silberberg

This paper presents a method of predicting the recovery and performance of a five-spot steam injection project, in which a realistic approach to pattern sweepout efficiencies is made. Published methods for radial systems were modified for the five-spot pattern by approximating the stream lines with straight lines radiating from the injection well and then converging to the producing well. In each radial segment, the position of the steam front and the temperature profile ahead of the steam front were determined by heat balance equations, which included an estimation of heat losses to surrounding formations. The location of the saturations behind the cold water front was determined from a Buckley-Leverett solution to the material balance equation. Results from this program show steamflood recovery in a five-spot pattern to be considerably less than that predicted for true linear or radial flow systems. For a specific reservoir containing 900-cp oil, a steamflood in a purely radial flow system was predicted to recover more than 75 percent of the original oil in place when 2 PV of water had been injected as steam. A five-spot steamflood with otherwise identical properties was predicted to recover 10 percent of the original oil in place when 0.15 PV of water had been injected as steam and to recover almost no oil thereafter. A cold water five-spot flood in this system was predicted to recover approximately W percent of the oil in place with I PV of water injected. For a five-spot pattern in an example reservoir with 10-cp oil, steam injection similarly showed lower ultimate recovery than water injection but no improvement in recovery rule. Introduction The thermal recovery method considered in this study is steam injection in a five-spot pattern. Pattern steam injection has been given little attention in the past, possibly because of some rather obvious disadvantages. Unless steam temperature is maintained throughout the entire swept area, the process will revert to simple waterflood with all heat being lost prior to reaching the oil bank. Also, the oil viscosity reduction takes place near the steam front and not around the producing wellbore, so that low producing rates must still be endured. This is the reason for the success of the steam stimulation, or cyclic injection, in which the fluids are produced from the same well used for injection. On the other hand, steamflooding can offer some advantages. Oil displacement is by four methods: (1) mechanical displacement by the condensed water, (2) viscosity reduction of the crude oil, (3) swelling of the crude oil, and (4) distillation of the crude oil in the steam zone. Although dependent upon the crude, laboratory experiments have shown displacements up to 80 percent by steamflooding. In addition, steam is a good heat transport medium, since it is cheap and has a high heat content. Previous Investigations Previous publications have reported methods for predicting recovery in a steamflood for linear and radial systems. Since no pattern sweep efficiency is taken into consideration, the recovery even from a radial system must be greater than from more realistic geometries such as the very common five-spot patterns. Probably the broadest coverage is given by Willman who reported experimental results and offered a method of predicting recovery for a radial flow system. They concluded that both hot water and steam injection recover more oil than an ordinary waterflood, and that steam injection could yield recoveries "as much as 100 percent greater than by water flood." They also concluded that both the heat requirements for a reservoir and the residual oil remaining in the reservoir after steam injection were independent of the amount of oil originally in place, that short exploitation times were desirable, and that a high percentage of net sand in the reservoir with a high initial oil saturation was desirable. The method assumes that the flood occurs in three concentric cylindrical zones: (1) an inner steam zone, (2) a central hot water zone, and (3) an outer cold waterflood zone. Displacement in the steam zone is based on laboratory-determined residual oil saturations while the hot water and cold water zones use the conventional Buckley-Leverett equations. Although the results shown by Willman et al. are for a radial system flowing out from the well to an assumed external circular boundary, their equations did

Jan 1, 1969

By Glenn A. Keep

THIS paper is not an announcement of the successful conclusion of the Cerro de Pasco Copper Corporation's pacos-pyrite problems, but merely a description of the commercial-scale, intermittent-roasting operations conducted by the writer, J. H. Lucas and others of the staff. It was prepared by request, for presentation at the February meeting of the Institute. The results obtained in Peru confirm the 1-ton-a-day experiments completed about three years ago at Kearny, N. J. by C. C. Gordon and Mr. Lucas, where it was first demonstrated that a mixture of about 80 per cent. pacos ore with 10 per cent. pyrite ore and 10 per cent. salt could be roasted intermittently in a small 1-ton-a-day Holt-Dern furnace without extraneous fuel, producing porous calcine that could be leached rapidly. Mr. Keep and his staff, by successfully introducing improvements in the construction of the commercial furnace and in their handling of material, have established beyond doubt a low cost for roasting. The other steps in the process of treating pacos and pyrite ores have not as yet been demonstrated as sufficiently conclusive to warrant their acceptance for a permanent plant. Cerro de Pasco Ores The ores of the Cerro de Pasco Copper Corpn. at Cerro de Pasco, Peru, are situated at an altitude of 14,000 ft. The town and mines are served by the Cerro de Pasco Railroad, which operates between Cerro de Pasco and Oroya, the site of the company's copper and lead smelters. Table 1.—Average Analysis of Cerro de Pasco Ores Pacos Ore Pykite Ore Silver, oz............................................... 10.3 12.0 Gold, oz................................................ 0.007 0.01 Lead, per cent........................................... 1.7 1.8 Copper, per cent......................................... 0.19 0.27 Zinc, per. cent........................................... 1.4 1.02 Iron, per cent........................................... 13.4 34.45 Silica, percent.......................................... 61.8 24.5 Alumina, per cent....................................... 2.5 0.62 Lime, per cent........................................... 1.5 0.20 Manganese, per cent..................................... 0.42 0.09 Sulfur, per cent,.......................................... 1.1 34.2

Jan 1, 1929

Jan 1, 1946

Jan 1, 1946

By Thirumalai, K.

Although the term "spalling" has long been known, Norton l first referred to its usage for the fracture or disintegration of materials subjected to rapid temperature changes. Spalling of ceramic materials at high temperatures has received attention in the past. Removal of the char formed during ablation in re-entry of space vehicles has been referred to as mechanical spalling. The first experiments to evaluate the process of rock fragmentation by thermal spalling were conducted by Stoces using a series of gasoline burners on the quartz veins of the Zinnwald deep mines in Germany. After the development of rocket-jet burners, the principles of 'thermal spalling combined with high fluid momentum found wide practical application in rocks. The well-known jet piercing process for drilling blastholes in taconite and for jet channeling in the quarrying of granite are among the more notable of these application^.

Jan 1, 1970

By Felix E. Wormser

REGISTRATION started bright and early Monday morning in the Silver Corridor at the Waldorf-Astoria with Mrs. W. H. Bassett as chairman. What a registration-over 200 ladies! Several joined us from as far away as California and Washington State. Apparently they enjoy our meetings so much that present travel inconveniences didn't discourage their coming. At noon the ladies joined the men at the All-Institute Luncheon and Monday evening we had our informal dance, which is separately reported. Tuesday morning was devoted to our annual meeting at which all Section annual reports were read. At noon we were all the guests of the W.A.A.I.M.E. at a luncheon at the Port Arthur Restaurant on Mott St. in Chinatown. Many of us rode down on the old 3d Ave. elevated railway-the last of four. It, too, is soon to be torn down. The luncheon was delightfully unusual, with huge dishes of delicious Chinese food on each table. Our chairman, Mrs. Read, who lived in China in her youth chose our menu, and she chose it well, for most of us indulged so heartily that as we arose from the table we felt we couldn't eat again for 24 hours. Someone donated sherry wine, and boxes of Chinese pencils as favors. We wonder who? All owe a big vote of thanks for this lovely party to Mrs. T. T. Read and Mrs. H. A. Prosser, chairmen, and Mrs. H. W. Hardinge, Mrs. R. Hursh, and Mrs. R. L. Lloyd, vice-chairmen.

Jan 1, 1944

By C. J. McHargue, J. C. Ogle

Lightly deformed columbiun single crystals which contained only parallel hoins or purullel and intersecting trains were annealed at 1000' and 1600"C. No re-crystallizntion occurred in specimens hawing only parallel twins. Only noncoherent twin boundaries nzipated at 1000°C but both coherent and noncoherent ones moved al 1600°C. Recrystallization occurred within a few minutes at twin intersections at 1000°C. The orientation 01 the recrystallized grains differed front that of both the matrix and deformation twins, but could he derired by (110) and/or(112) rotations. ALTHOUGH twinning in metals has been extensively studied, there have been no definitive studies of the annealing behavior of crystals containing deformation twins. Some effects observed after annealing deformation twins have been summarized by Cahn1 and Hall2. Any or all of these phenomena are observed: 1) The twins may contract so that the sharp edges of the lens become blunted, and eventually the twin may disappear entirely. 2) The twins may balloon out at an edge, giving rise to a large grain having the same orientation as the twin. 3) The specimen may recrystallize; i.e., new grains are nucleated and grow at the expense of the twins and the crystal immediately adjoining the twin. Such grains have orientations which are not present before. Contraction has been observed in iron,3 titanium,3, 4 beryllium,5 zinc,8, 7 Fe-A1 alloy,' and uranium.9 Long anneals at high temperatures are required to have any appreciable effect in these metals and only thin twins are absorbed. Lens-shaped twins are absorbed from the edges: the thin, almost parallel-sided twins are usually punctured in several places and each piece contracts independently. Absorption is very gradual and no sudden cooperative jumps have been observed. The expansion of a twin into a larger grain of identical orientation is unusual, but such growth has been observed in iron,"'" zinc,6 and uranium." Crystals which have been deformed simultaneously by slip and twinning recrystallize first in the area adjacent to the twin. New grains appear faster where the twins intersect: but isolated twins, especially if thick, can also give rise to new grains. This type of recrystallization occurs in zinc.6, 7, 12, 13 and beryllium.14 Reed-Hill noted, in a single crystal of magnesium, the nucleation of a recrystallized grain at a twin intersection which had the same orientation as the second-order twin and which grew into the highly strained matrix.15 Short-time annealing has been reported to cause no change in the deformation twins in vanadium,16 columbium, 17, 18 tantalum,19 tungsten,'' and zinc.7 The purpose of this investigation was to note the effects of annealing on the coherent and noncoherent boundaries of deformation twins in columbium and to locate the nucleating sites for recrystallization. The orientation relationships, which the new recrystallized grains have with the parent crystal and the deformation twins, were also determined. EXPERIMENTAL PROCEDURE Single crystals of columbium were obtained by cutting large grains from electron-beam-melted buttons which contained 10 to 50 ppm C, 10 to 100 ppm O,, 1 to 10 ppm H2, and 10 to 15 ppm N2. The crystals were hand-ground and chemically polished until all grain boundaries were removed. The specimens were mounted in an epoxy resin and a face of each crystal was mechanically polished on a Syntron polisher using Linde A and then Linde B polishing compounds. After all faces were mechanically polished, the crystal was electrolytically polished to remove all distortion due to cutting and grinding. Laue photographs were taken of all faces of the crystals to determine the quality and orientation of each crystal. The crystals were compressed about 10 pct at -196 C in a specially constructed compression cage with an Instron tensile machine. Each crystal was separated from the top and bottom anvils by teflon films which acted as a lubricant. With the specimen crystal in position, the entire cage was cooled to -196°C by being submerged in a Dewar containing liquid nitrogen. The crystals were compressed at a rate of 0.02 in. per min and the load was recorded on a strip-chart recorder. After deformation the crystals were mechanically polished on 600-grit paper and Pellon cloth with Linde A and Linde B polishing compounds. The crystal faces were chemically polished and then etched. The twin planes were identified metallographically from an analysis of the twin traces on two surfaces. Annealing was carried out by placing each crystal in a columbium bucket made from the same electron-beam-melted material as the crystal itself and suspending the bucket by a tantalum wire in a quartz tube. After a vacuum of 10-7 Torr was attained, a furnace at 1000" or 1600 C was raised into position and the crystals held for various lengths of time. The crystals were repolished and etched after annealing to remove any surface contamination. Approximately 0.010 in. was removed during this process. The resulting surface was examined metallographically for microstructural changes due to annealing. A microbeam Laue camera mounted on a Hilger Micro-focus X-ray unit was used to determine the Orientstions of the recrystallized grains. This X-ray micro-beam camera had a 0.002-in.-diam collimator and incorporated the ideas of both and and chisWik21 and Cahn.22

Jan 1, 1967

By H. Rush Spedden, A. M. Gaudin

IN the belief that a critical study of its operating problems might be a sound investment, the Cuban American Manganese Corporation initiated an ore-treatment research in cooperation with the Massachusetts Institute of Technology One of the early objectives of this research naturally became the relationship of the microscopy of the Cuban ores of the Corporation to their flotation treatment The operations in Cuba have already been described by F S Norcross, Jr 7 and the laboratory study of manganese oxide flotation goes back a number of years 4 Broadly speaking, the difficulties encountered in the flotation of manganese ores are that the consumption of reagents is extremely high, the concentrate contains more silica than is desirable and the tailing losses are relatively high An appreciable betterment on any of these scores would achieve a definite betterment in costs, quantity of minable ores, and quality of product The microscope study discussed in this paper was made on samples from the Quinto mine, from the Ponupo mine, and from mill products at various stages of passage of the ore through the mill The writers have had access to Company records and in particular to the petrographic studies made on thin sections of ore by the late Professors R J Colony and Philip Krieger, of Columbia University They acknowledge their debt to both of these men for the help derived from the reports Manganese oxides are black, friable, smudging It is therefore, very difficult to judge operations by inspection The mineralogy of manganese compounds seems to be confused, and the authors believe that many more minerals have been described than actually exist Much of this difficulty is due to the prevalence of the structural conditions that will be discussed further in this paper, namely, the porosity and the friability of the ores, and the extremely intimate association of minute manganifeous mineral crystals with impurities of various sorts By all odds the most important manganese mineral in Cuba is the one that in this paper is called "psilomelane " The name "psilomelane" has been used in so many different ways that the choice of it for this ore may not be approved by all However, it seems to be the best under the circumstances This mineral accounts for about 97 per cent of the manganese in the ores of the Quinto and Ponupo mines and in the mill feed The remaining odd 3 per cent consists mostly of pyrolusite together with minor amounts of other manganese oxide minerals DESCRIPTION OF PSILOMELANE Aggregate Structure In grains or lumps, psilomelane has a characteristic fibrous appearance and seems

Jan 1, 1942

By M. R. Campbell

Coal is the geological product of entombed vegetal tissues. This view of its origin led Stopes and Wheeler to define it as "mummified plants." They evidently intended this term to be used in a broad way and to mean the preservation of the organic material, as such, regardless of the means employed to accomplish the purpose. The term " coal" should be regarded, therrfore, as broadly generic, and applicable to all accumulations of vegetal tissues as soon as they are covered and protected either by water or by earthy material. In this sense peat should be regarded as the first stage of coal formation and the term coal should include the resultant products of transformation in all other stages of the process until they have lost all resemblance to the original matter from which they were derived. If this idea of the development of coal is accepted and it is admitted, as the geologists claim, that the forces which produced this transformation of the coal have been active since vegetation began to grow upon the land, and are still in operation, it is obvious that somewhere in the world there are all gradations of this material from peat just forming in the swamps of today to graphitic anthracite which presumably marks the most advanced stage that can be recognized with certainty as belonging to the series. Some of these coals, particularly those occurring in the upper part of the series, are fairly well known because they are the ones that are most widely distributed and have been mined and utilized most extensively. On the other hand, the coals in the lower part of the series are but little known because they are not so abundant and, owing to their relative inefficiency, have been only slightly exploited and utilized, especially in regions where the better coals are abundant. The result of these conditions is that much research work has been done on coals of the higher ranks and a great body of facts regarding their physical and chemical properties and the uses to which they are best adapted has been accumulated, but little information is available regarding the coals of the lower ranks. Many able scientists, particularly chemists, have attempted to bring some order of the chaos of coals of various compositions and uses by

Jan 1, 1930

By Paul D. V. Manning

MAGNESIUM is an exceedingly strategic material but the importance of its production at the time this war started was not realized. Our Government then suddenly became much alive to the need of a tremendous increase in magnesium output, and became a participator in the industry. In this paper an attempt will be made to given an over-all picture of the industry as it has been, and is being, developed. The present war is giving a great acceleration to the use of lighter metals. Development of facilities for production of great tonnages of aluminum and magnesium is bound to bring about some interesting changes in later peace times because costs will be low and production capacities high. As our knowledge of the metallurgy of magnesium alloys increases, this metal will become of vital peacetime importance and will be used in ways we do not now imagine. Household refrigerators, furniture, automobiles, even houses will all be lightened through the use of magnesium.

Jan 1, 1943

By Donald Barton

THE theory of gravitation is based on Newton's law that any two bodies exert a mutual attraction which is proportional to the product of their masses and inversely proportional to the square of the distance between them; i. e., A =KRM/R2 (1) where K is a constant, M and m are the respective masses of the two bodies, and R the distance between them. In the earth's gravitational system, the earth is one of the bodies; the other may be any body within or without the earth. In theoretical dis¬cussions and calculations in regard to gravity, that other body usually is taken as a unit of mass: in the C. G. S. system, a body of one gram in mass. GRAVITY AND LEVEL SURFACES Gravity is defined in geophysics as the force of attraction exerted by the earth, towards itself, on a body of unit mass. The intensity of gravity is usually expressed in dynes of force or in centimeters of acceleration. In geophysical work in America, most commonly it is expressed in dynes (per gram) with the "per gram" understood and not directly expressed. In geophysical work in Europe, most commonly it is expressed in centimeters per second per second (cm./sec.2) and less commonly merely as centimeter-gram-second units (C. G. S.). At sea level, the intensity of gravity amounts very nearly to 980 dynes. The vertical is the direction along which the attraction of gravity is exerted at any point. . In most cases, it is very nearly, but not quite, per¬pendicular to the earth's surface. The path that would be taken by a body falling freely through space toward the earth is vertical at each point and may be spoken of also as "the vertical," or as the line of the vertical, or as a line of force of gravity. At the earth's surface it com¬monly is very nearly, but not quite, a straight line.

Jan 1, 1928

By Edward L. Estabrook

This paper gives a brief account of the geologic and production problems encountered in the Grass Creek oil field, the methods used in their solution, and the beneficial results obtained from the work. The author wishes to acknowledge the assistance received from J. H. Pearson and Miss Ninettta A. Davis in the collection of the data and the preparation of the cross-sections. Permission for its publication was given by the officials of the Midwest Refining Co. and the Ohio Oil Co. The Grass Creek oil field is located in Ts. 98-99 W., R. 46 N., Hot Springs County, Wyo. The productive area includes about 2 1/2 mi. (4 km.) on the apex of a great anticlinal fold occupying more than 150 sq. mi. Fig. 1 shows the structural contours of the field. Oil was dicovered in the field in June, 1914; development proceeded rapidly and production rose to a maximum in 1918. The marketed production has been approximately as follows: Barrels Barrels 1915.................... 94,073.5 1918................... 2,946,774.27 1916................... 1,404,183.97 1919................... 2,000,584.84 1917.................... 2,780,697.51 1920................... 1,485,080.94 About 350 wells, 800 to 1500 ft. (243 to 457 m.) deep, have been drilled to reach the upper oil sands; two companies, the Ohio Oil Co. and the Midwest Refining Co., operate the entire field. The principal producing sands in the field are members of the Frontier Formation, a series of sands and shales occuring in the upper portion of the Colorado Group of the Upper Cretaceous seriee. These Frontier, or "Wall Creek" sands are also productive in the Salt Creek, Big Muddy, and Elk Basin fields and, therefore, are much the most important reservoirs of light oil in Wyoming. At Grass Creek, the sands in the Formation are more numerous than in the other fields and much less uniform in thickness and character. Usually, eight distinct beds are encountered and in some wells twelve sands have been reported. The formation above

Jan 1, 1923

By Edward L. Estabrook

This paper gives a brief account of the geologic and production problems encountered in the Grass Creek oil field, the methods used in their solution, and the beneficial results obtained from the work. The author wishes to acknowledge the assistance received from J. H. Pearson and Miss Ninettta A. Davis in the collection of the data and the preparation of the cross-sections. Permission for its publication was given by the officials of the Midwest Refining Co. and the Ohio Oil Co. The Grass Creek oil field is located in Ts. 98-99 W., R. 46 N., Hot Springs County, Wyo. The productive area includes about 2 1/2 mi. (4 km.) on the apex of a great anticlinal fold occupying more than 150 sq. mi. Fig. 1 shows the structural contours of the field. Oil was dicovered in the field in June, 1914; development proceeded rapidly and production rose to a maximum in 1918. The marketed production has been approximately as follows: Barrels Barrels 1915.................... 94,073.5 1918................... 2,946,774.27 1916................... 1,404,183.97 1919................... 2,000,584.84 1917.................... 2,780,697.51 1920................... 1,485,080.94 About 350 wells, 800 to 1500 ft. (243 to 457 m.) deep, have been drilled to reach the upper oil sands; two companies, the Ohio Oil Co. and the Midwest Refining Co., operate the entire field. The principal producing sands in the field are members of the Frontier Formation, a series of sands and shales occuring in the upper portion of the Colorado Group of the Upper Cretaceous seriee. These Frontier, or "Wall Creek" sands are also productive in the Salt Creek, Big Muddy, and Elk Basin fields and, therefore, are much the most important reservoirs of light oil in Wyoming. At Grass Creek, the sands in the Formation are more numerous than in the other fields and much less uniform in thickness and character. Usually, eight distinct beds are encountered and in some wells twelve sands have been reported. The formation above

Jan 1, 1923

By E. P. Pfleider, W. G. Pariseau

This paper reports the theoretical and experimental results of an analysis of ore pass drawdown as a problem in soil plasticity. The method of analysis developed appears to be a promising technique of investigating the mechanics of fragmented materials. A reconstructed plasticity theory brings experiment and theory into reasonable agreement, and hence may provide the foundation needed for rational ore pass design. The gravity-induced movement of broken rock through ore passes is an economical method of transporting fragmented materials through large vertical distances in underground mines, provided the ore pass is well designed. Unfortunately, the design procedures now followed do not very often result in ore passes that function properly. On the one hand, the huge accumulation of empirical data pertaining to the movement of materials in gravel bunkers, storage bins, deep grain silos and other structures that have features in common with ore passes remains uncorrelated. On the other hand, there is a dearth of experimental data substantiating theoretical models of material behavior. Consequently, reliable generalizations encompassing the broad spectrum of problems involved have not been forthcoming. AS an initial step towards improving the situation, a detailed case study of two-dimensional ore pass drawdown was made. The mechanics of the process were analyzed theoretically as a problem in soil plasticity and tested experimentally through observations of a laboratory ore pass model. THEORY Taylor1 defines a soil as a "mass commonly considered to consist of a network or skeleton of solid particles, enclosing voids of varying size." Broken rock in an ore pass is such a material. In plasticity theory this material is replaced by an idealized substance that deforms elastically up to some state of stress at which slip or yield occurs,2 For com-pressive states of stress, the Mohr-Coulomb criterion is a satisfactory yield condition. After the yield point is reached, the ideal soil deforms in accordance with the concept of plastic potential.4 Under plane strain conditions the governing equations separate into a system of stress equations and a system of velocity equations.' Only stress variables appear in the stress system. The velocity system, however, contains a stress variable. The two systems are, therefore, coupled. Both systems are hyperbolic, and each has two real, distinct families of characteristic curves that coincide according to the classical theory of ideal soil plasticity. The

Jan 1, 1969

By Luiz C. Correa da Silva, Robert F. Mehl

A. D. Le Claire and R. S. Barnes (Atomic Energy Research Establishment, Harwell, Didcot, Berks., England)-—This much awaited paper admirably confirms that the Kirkendall effect is a true diffusion phenomenon and likely to be found in all diffusing systems. The most likely explanation put forward so far to account for the shift of interface is that the two components of the system, diffusing in opposite directions, do so with unequal rates so that there is a net loss of material from that half of the diffusion zone rich in the more rapidly diffusing component. This loss is accompanied, and at least partly compensated for, by a closing up or decrease in volume of this latter half of the diffusion zone and an expansion of the other half so as to tend to keep constant the overall volume per atom. This is manifest as a movement of the original interface. If this is a true picture of what is taking place then there are at least two important matters requiring further study."1—The quantitative relating of the observed shift with the independently measured separate diffusion coefficients of the two diffusing species."2—A detailed study of the mechanism and characteristics of the closing up process."We would like first to make a few remarks pertinent to these topics. In connection with the first of these, it is a pity that more and detailed measurements were not made on the Au-Ag system, the only one for which the separate diffusion coefficients of the two species have been measured.'" One of us (A. D. Le C.) has calculated from Johnson's results the shift to have been expected in samples D.2 and D.3. Darken4 showed that the velocity v with which the markers move is related to the separate diffusion coefficients Dau, Dag, by the eauation:"dN"v = (Dag — Dau "dx"dN"where .is the concentration gradient at the mark-ax"ers. Under certain conditions,4, 20 it can also be shown that:"Xm"v = "2t"where x, is the total marker shift after time, t:"dN". . xm = 2t (Dag — Dau) [9]"dX"Johnson measured Dag and DAu in a chemically homogeneous alloy and so his reported figures represent the true or ideal diffusion coefficients"; the same quantities in eq 9 represent the actual diffusion coefficients as would be measured in the presence of a chemical concentration gradient, so we need to multiply Johnson's reported values of Dag and Dau by the"1 before insert-dlogN "ing them in eq 9. 7 is the activity coefficient of Ag at the concentration prevailing near the markers which we shall assume to be - 50 pct. The values of the thermodynamic factor for N = 0.5 and the temperatures at which D.2 and D.3 were annealed were obtained from thermodynamic data quoted by Darken.' aN/ax was computed from the coefficient of inter-diffusion of Au and Ag given by Johnson on the assumption that in the samples D.2 and D.3, the concentration distance curve could be represented by the standard equation:""No is the original difference in concentration between the two halves of the couple, and + is the error or probability function."aN/ax at x = 0 is then given by:"adN/dx "2/nDt"and we assume that this represents the concentration gradient at the markers, although it is probable that the figure is slightly high."When all the appropriate quantities are inserted in eq 9, we find that the expected shifts are: for D.2, 0.0134 cm and for D.3, 0.0119 cm."The agreement between these results and those

Jan 1, 1952

By AIME AIME

NINETEEN states have on their statutes laws requiring engineers practicing within their borders to be licensed sixteen other states have such laws under consideration. While mining engineers are not specifically referred to in every case, they are referred to by implication. In only a few states have mining engineers taken any active interest in this subject, either in support or in opposition, yet it is a matter of very grave importance to them. By some it is thought that it is now too late to take any active steps toward preventing or repealing a type of legislation for which there appears to be a growing demand from some source. And it is further thought that the best course for those who are interested is to endeavor to guide legislation so that the remaining states may enact laws containing as few objectionable features as possible.

Jan 1, 1921

By Charles Barrett

SINCE 1925, when the preferred orientations in compressed aluminum were first determined1, 2 the orientations have been described as a fiber texture in which a face diagonal, [110], of the face-centered cubic lattice is parallel to the compression axis. Subsequent experiments have seemed to confirm this texture,3-5 and a number of theories (recently summarized in references 6 and 7) have been proposed to explain it and to relate it to the behavior of single crystals during compression. 3,8-11 The experiments reported in this paper prove that the orientations are not adequately described as quoted above-i.e., as a [110] fiber texture-although this is a first approximation to the actual texture. They also show that the texture cannot be thought of as a stable orienta-tion that is reached and maintained after a sufficient amount of deforma-tion. The actual texture, when studied in detail at successive stages of compression, indicates that a hitherto unsuspected range of orientations is present, both in the polycrystalline metal as a whole and in various individual grains in its interior, and that a state of dynamic equilibrium exists within this range. The reasons for the failure of previous theories to predict the actual texture become obvious when the heterogeneous nature of the flow is considered. In addition to the deformation texture, the manner of its develop-ment, and its theory, this paper presents data on the following related subjects: the identity of strain markings in aluminum; the orientation changes in aluminum single crystals during compression and a com-parison of these with the conditions in individual grains of a polycrystal-line specimen; the origin of asterism in deformed single crystals, which heretofore has been regarded as a distortion localized at the surfaces of slip planes; and the relation of plastic strain in individual grains in an aggregate to the strain of the whole.

Jan 1, 1939