Search Documents

By S. Yukawa, M. J. Sinnott

A high resolution autoradiographic study of the diffusion of a nickel isotope (NP3) into copper in the temperature range of 650° to 925°C, with particular emphasis on grain boundary diffusion, has been made. The extent of grain boundary diffusion is a function of the grain boundary angle and the diffusion temperature. The ratios of the grain boundary diffusion coefficient to the lattice diffusion coefficient ranges from 104 to 105. The activation energy for grain boundary diffusion decreases with increasing grain boundary angle. STUDIES and reviews&apos;-8 of metallic diffusion have indicated that grain boundary diffusion is a common phenomenon but quantitative studies of the many variables involved are not numerous. The present work was concerned with determining the influence of the crystallographic orientation of the grain boundaries and the temperature on the extent of boundary diffusion of nickel into copper. The study involved essentially three steps: 1—the production of grain boundaries of known crystallographic orientation, 2—the determination of the extent of diffusion into the boundaries, and 3—the analysis of the resulting data in terms of the usual diffusion concepts. The grain boundaries investigated approximated the simple tilt variety having l° of freedom. They were produced by controlling the solidification from a melt of Cuprovac (a high purity vacuum-melted copper obtained from Vacuum Metals Corp.) of a pair of seed crystals so that the bicrystals of copper produced had a common <100> axis. By rotating one seed crystal relative to the other, a simple tilt boundary was produced. The angle of rotation between the two crystals is the grain boundary angle 8, or what is sometimes termed the misfit angle. In all, some 16 boundaries ranging from 2" to 72" in 5" to 10" steps were investigated. The crystallographic orientations were measured with the use of both X-ray and optical goniometric techniques. The <100> axes in the crystals were found to be parallel within 2" to 3" with the exception of one crystal (8 = 12") in which the axes were 6" from being parallel. All bicrystals showed evidences of sub-grain structures. Laue analyses showed that these subgrains differed in orientation up to a maximum of 2". Because of these variations, and some curvature in the boundaries, the grain boundary angles listed are actually average values and deviate from the 1 o of freedom boundaries. The stripping film technique of high resolution autoradiography was used to detect the diffusion of the nickel isotope into the grain boundaries of the bicrystals of copper. Kodak experimental permeable stripping film with an emulsion layer 5 u thick

Jan 1, 1956

By John M. Bostwick

Bitumen is a general term for a group of materials composed of mixtures of hydrocarbons that are fusible and soluble in carbon disulfide. Included in the group are petroleum, asphalts, asphaltites, and mineral waxes. Asphalt is a dark-colored, cementitious solid or semisolid, which generally softens on heating and resumes a more viscous or solid state when cooled (personal communication). It is found in native form in fissures and pore spaces in rocks and as lakes. It is also obtained from the residues produced in petroleum refining. Asphaltites are black, naturally occurring solid bitumens. They are generally shiny and break with a conchoidal fracture. Common asphaltites are gilsonite (uintahite), grahamite, and glance pitch. Mineral waxes are solid or semisolid, relatively nonvolatile bitumens of various colors, having an unctuous feel and waxy luster. Of the native waxes, ozokerite is the best known. Montan wax is also classed as a natural wax, although it never occurs in the pure state and must be extracted from lignite or cannel coal (Ladoo, 1920). Mineral waxes may also be obtained by pyroprocessing of petroleum, lignite, and peat. Pyrobitumens are dark-colored, solid hydro- carbons that are infusible and relatively insoluble in carbon disulfide. They are so-called because they will yield liquid and gaseous hydrocarbons only when heated. Asphaltic pyrobitumens are defined as "substantially free of oxygenated bodies" and include wurtzilite (elaterite), albertite, and impsonite (Thrush, 1968). Nonasphaltic pyrobitumens contain oxygenated bodies; examples are coal and peat. The nonasphaltic type will not be discussed further. Petroleum Asphalts Asphalts refined from crude petroleum have almost completely replaced the native types. Refineries can produce asphalts in every desirable grade more economically and in greater quantity than the native types and with a variety of properties that meet the requirements of the various manufacturers using them. For all practical purposes, it is estimated that more than 95% of the asphalts consumed in the United States are refined from crude petroleum (private communication).

Jan 1, 1975

By R. C. Edwards, Will Mitchell, T. G. Kirkland

THREE years ago, when the Process Research Laboratory at Allis-Chalmers Manufacturing Co. sought a remedy for the increasing cost of disposing of great quantities of spent sands from foundries, R. C. Edwards developed a continuous inclined paddle scrubber which removed a substantial amount of the charred coatings from the grains with a surprisingly small amount of degradation of the sand itself.1 The satisfactory results obtained on foundry sand, using this piece of equipment in conjunction with classification, suggested that a similar procedure could probably be applied to the cleaning of other sands, such as those required by the glass and chemical industries. This paper describes the flowsheet and the results of tests performed on impure natural sands. The four materials tested were silica sands obtained from widely separated geographical areas. Three of the sands tested contained various amounts of iron oxide and the fourth an excessive amount of calcareous bonding material. The iron oxide was present predominantly in the form of grain coatings, which were scuffed by the paddle scrubber, and in all cases a product was manufactured which would meet one of the sets of specifications imposed by the glass industry&apos; The Edwards paddle scrubber used in these tests consists of a rubber-lined steel cylinder 18 in. in diam and 48 in. long, mounted on a frame so that its slope can be varied 5 ° to 35º from horizontal. This variable slope permits controlled flow of material through the machine. Rubber paddles rotate inside the cylinder and are secured to a center shaft 2 in. square, which extends through the entire length and is turned at both ends so that it can be supported by sleeve bearings centrally fixed in the end plates of the shell. At the upper or feed end it extends through the bearing on the end plate into a sheave, to which the motor drive is connected by means of Texrope transmission. The four sets of paddles mounted on the shaft, two in each set, are made of rubber belting, 1/4 in. thick, 9 in. wide, and 16 in. long. The two paddles in each set are secured on opposite sides of the square shaft, but in the same longitudinal position along the shaft axis. In other words, the two paddles in the set operate 180° apart. Each successive set is mounted 90º from the preceding one. One end of each paddle is bolted to the square shaft and the other weighted by a steel bar, 1x1 ½ x9 in. long, which is attached about 1/ 2 in. from the outer tip of the paddle. By centrifugal force at proper shaft speed, these weights force the paddle surface to rub smoothly against the rubber lining of the cylinder. During operation, the sand forces its way between the paddle face and the surface of the cylinder, providing the necessary abrading action as the pulp flows by gravity down the length of the cylinder. The capacity of the machine is limited by the amount and the hardness of the coating material and by the quality of product desired. The degree of scrubbing is governed by the retention time in the scrubber, which in turn may be changed by varying the feed rate, water content of the feed, and

Jan 1, 1952

By L. H. DeWald

During the examination of various commercial brands of copper wire bars, which had exhibited different degrees of adaptability for being drawn into fine gages of wire by the present-day high speed machine, it was found that each brand had a more or less characteristic crystal macrostructure. The extremes of these macrostructures are similar FIG. 1.-EFFECT OF METAL TEMPERATURE IN CASTING ON CRYSTAL MACROSTRUCTURE OF BAR. Reading from left to right, metal temperatures were 1166" C., 1149" C., 1132" C.. 1121" C., 1093" C. to the maximum variation shown in the photomacrographs reproduced in Fig. 1. As the various brands did not differ materially in chemical composition, it was concluded that the differences in structure were the result of variations in casting technique.

Jan 1, 1931

By R. C. Edwards, T. G. Kirkland, Will Mitchell

A scrubber of new design has been invented for the beneficiation of glass and chemical sands. The machine is described and its capacity and metallurgical efficiency compared with the performance of other sand cleaning devices. THREE years ago, when the Process Research Laboratory at Allis-Chalmers Manufacturing Co. sought a remedy for the increasing cost of disposing of great quantities of spent sands from foundries, R. C. Edwards developed a continuous inclined paddle scrubber which removed a substantial amount of the charred coatings from the grains with a surprisingly small amount of degradation of the sand itself.&apos; The satisfactory results obtained on foundry sand, using this piece of equipment in conjunction with classification, suggested that a similar procedure could probably be applied to the cleaning of other sands, such as those required by the glass and chemical industries. This paper describes the flowsheet and the results of tests performed on impure natural sands. The four materials tested were silica sands obtained from widely separated geographical areas. Three of the sands tested contained various amounts of iron oxide and the fourth an excessive amount of calcareous bonding material. The iron oxide was present predominantly in the form of grain coatings, which were scuffed by the paddle scrubber, and in all cases a product was manufactured which would meet one of the sets of specifications imposed by the glass industry.&apos; The Edwards paddle scrubber used in these tests consists of a rubber-lined steel cylinder 18 in. in diam and 48 in. long, mounted on a frame so that its slope can be varied 5" to 35" from horizontal. This variable slope permits controlled flow of material through the machine. Rubber paddles rotate inside the cylinder and are secured to a center shaft 2 in. square, which extends through the entire length and is turned at both ends so that it can be supported by sleeve bearings centrally fixed in the end plates of the shell. At the upper or feed end it extends through the bearing on the end plate into a sheave, to which the motor drive is connected by means of Texrope transmission. The four sets of paddles mounted on the shaft, two in each set, are made of rubber belting, 1/4 in. thick, 9 in. wide, and 16 in. long. The two paddles in each set are secured on opposite sides of the square shaft, but in the same longitudinal position along the shaft axis. In other words, the two paddles in the set operate 180" apart. Each successive set is mounted 90" from the preceding one. One end of each paddle is bolted to the square shaft and the other weighted by a steel bar, lx1 1hx9 in. long, which is attached about Yz in. from the outer tip of the paddle. By centrifugal force at proper shaft speed, these weights force the paddle surface to rub smoothly against the rubber lining of the cylinder. During operation, the sand forces its way between the paddle face and the surface of the cylinder, providing the necessary abrading action as the pulp flows by gravity down the length of the cylinder. The capacity of the machine is limited by the amount and the hardness of the coating material and by the quality of product desired. The degree of scrubbing is governed by the retention time in the scrubber, which in turn may be changed by varying the feed rate, water content of the feed, and

Jan 1, 1953

By R. C. Edwards, T. G. Kirkland, Will Mitchell

A scrubber of new design has been invented for the beneficiation of glass and chemical sands. The machine is described and its capacity and metallurgical efficiency compared with the performance of other sand cleaning devices. THREE years ago, when the Process Research Laboratory at Allis-Chalmers Manufacturing Co. sought a remedy for the increasing cost of disposing of great quantities of spent sands from foundries, R. C. Edwards developed a continuous inclined paddle scrubber which removed a substantial amount of the charred coatings from the grains with a surprisingly small amount of degradation of the sand itself.&apos; The satisfactory results obtained on foundry sand, using this piece of equipment in conjunction with classification, suggested that a similar procedure could probably be applied to the cleaning of other sands, such as those required by the glass and chemical industries. This paper describes the flowsheet and the results of tests performed on impure natural sands. The four materials tested were silica sands obtained from widely separated geographical areas. Three of the sands tested contained various amounts of iron oxide and the fourth an excessive amount of calcareous bonding material. The iron oxide was present predominantly in the form of grain coatings, which were scuffed by the paddle scrubber, and in all cases a product was manufactured which would meet one of the sets of specifications imposed by the glass industry.&apos; The Edwards paddle scrubber used in these tests consists of a rubber-lined steel cylinder 18 in. in diam and 48 in. long, mounted on a frame so that its slope can be varied 5" to 35" from horizontal. This variable slope permits controlled flow of material through the machine. Rubber paddles rotate inside the cylinder and are secured to a center shaft 2 in. square, which extends through the entire length and is turned at both ends so that it can be supported by sleeve bearings centrally fixed in the end plates of the shell. At the upper or feed end it extends through the bearing on the end plate into a sheave, to which the motor drive is connected by means of Texrope transmission. The four sets of paddles mounted on the shaft, two in each set, are made of rubber belting, 1/4 in. thick, 9 in. wide, and 16 in. long. The two paddles in each set are secured on opposite sides of the square shaft, but in the same longitudinal position along the shaft axis. In other words, the two paddles in the set operate 180" apart. Each successive set is mounted 90" from the preceding one. One end of each paddle is bolted to the square shaft and the other weighted by a steel bar, lx1 1hx9 in. long, which is attached about Yz in. from the outer tip of the paddle. By centrifugal force at proper shaft speed, these weights force the paddle surface to rub smoothly against the rubber lining of the cylinder. During operation, the sand forces its way between the paddle face and the surface of the cylinder, providing the necessary abrading action as the pulp flows by gravity down the length of the cylinder. The capacity of the machine is limited by the amount and the hardness of the coating material and by the quality of product desired. The degree of scrubbing is governed by the retention time in the scrubber, which in turn may be changed by varying the feed rate, water content of the feed, and

Jan 1, 1953

By R. C. Edwards, Will Mitchell, T. G. Kirkland

A scrubber of new design has been invented for the beneficiation of glass and chemical sands. The machine is described and its capacity and metallurgical efficiency compared with the performance of other sand cleaning devices. THREE years ago, when the Process Research Laboratory at Allis-Chalmers Manufacturing Co. sought a remedy for the increasing cost of disposing of great quantities of spent sands from foundries, R. C. Edwards developed a continuous inclined paddle scrubber which removed a substantial amount of the charred coatings from the grains with a surprisingly small amount of degradation of the sand itself.&apos; The satisfactory results obtained on foundry sand, using this piece of equipment in conjunction with classification, suggested that a similar procedure could probably be applied to the cleaning of other sands, such as those required by the glass and chemical industries. This paper describes the flowsheet and the results of tests performed on impure natural sands. The four materials tested were silica sands obtained from widely separated geographical areas. Three of the sands tested contained various amounts of iron oxide and the fourth an excessive amount of calcareous bonding material. The iron oxide was present predominantly in the form of grain coatings, which were scuffed by the paddle scrubber, and in all cases a product was manufactured which would meet one of the sets of specifications imposed by the glass industry.&apos; The Edwards paddle scrubber used in these tests consists of a rubber-lined steel cylinder 18 in. in diam and 48 in. long, mounted on a frame so that its slope can be varied 5" to 35" from horizontal. This variable slope permits controlled flow of material through the machine. Rubber paddles rotate inside the cylinder and are secured to a center shaft 2 in. square, which extends through the entire length and is turned at both ends so that it can be supported by sleeve bearings centrally fixed in the end plates of the shell. At the upper or feed end it extends through the bearing on the end plate into a sheave, to which the motor drive is connected by means of Texrope transmission. The four sets of paddles mounted on the shaft, two in each set, are made of rubber belting, 1/4 in. thick, 9 in. wide, and 16 in. long. The two paddles in each set are secured on opposite sides of the square shaft, but in the same longitudinal position along the shaft axis. In other words, the two paddles in the set operate 180" apart. Each successive set is mounted 90" from the preceding one. One end of each paddle is bolted to the square shaft and the other weighted by a steel bar, lx1 1hx9 in. long, which is attached about Yz in. from the outer tip of the paddle. By centrifugal force at proper shaft speed, these weights force the paddle surface to rub smoothly against the rubber lining of the cylinder. During operation, the sand forces its way between the paddle face and the surface of the cylinder, providing the necessary abrading action as the pulp flows by gravity down the length of the cylinder. The capacity of the machine is limited by the amount and the hardness of the coating material and by the quality of product desired. The degree of scrubbing is governed by the retention time in the scrubber, which in turn may be changed by varying the feed rate, water content of the feed, and

Jan 1, 1953

By R. C. Edwards, Will Mitchell, T. G. Kirkland

A scrubber of new design has been invented for the beneficiation of glass and chemical sands. The machine is described and its capacity and metallurgical efficiency compared with the performance of other sand cleaning devices. THREE years ago, when the Process Research Laboratory at Allis-Chalmers Manufacturing Co. sought a remedy for the increasing cost of disposing of great quantities of spent sands from foundries, R. C. Edwards developed a continuous inclined paddle scrubber which removed a substantial amount of the charred coatings from the grains with a surprisingly small amount of degradation of the sand itself.&apos; The satisfactory results obtained on foundry sand, using this piece of equipment in conjunction with classification, suggested that a similar procedure could probably be applied to the cleaning of other sands, such as those required by the glass and chemical industries. This paper describes the flowsheet and the results of tests performed on impure natural sands. The four materials tested were silica sands obtained from widely separated geographical areas. Three of the sands tested contained various amounts of iron oxide and the fourth an excessive amount of calcareous bonding material. The iron oxide was present predominantly in the form of grain coatings, which were scuffed by the paddle scrubber, and in all cases a product was manufactured which would meet one of the sets of specifications imposed by the glass industry.&apos; The Edwards paddle scrubber used in these tests consists of a rubber-lined steel cylinder 18 in. in diam and 48 in. long, mounted on a frame so that its slope can be varied 5" to 35" from horizontal. This variable slope permits controlled flow of material through the machine. Rubber paddles rotate inside the cylinder and are secured to a center shaft 2 in. square, which extends through the entire length and is turned at both ends so that it can be supported by sleeve bearings centrally fixed in the end plates of the shell. At the upper or feed end it extends through the bearing on the end plate into a sheave, to which the motor drive is connected by means of Texrope transmission. The four sets of paddles mounted on the shaft, two in each set, are made of rubber belting, 1/4 in. thick, 9 in. wide, and 16 in. long. The two paddles in each set are secured on opposite sides of the square shaft, but in the same longitudinal position along the shaft axis. In other words, the two paddles in the set operate 180" apart. Each successive set is mounted 90" from the preceding one. One end of each paddle is bolted to the square shaft and the other weighted by a steel bar, lx1 1hx9 in. long, which is attached about Yz in. from the outer tip of the paddle. By centrifugal force at proper shaft speed, these weights force the paddle surface to rub smoothly against the rubber lining of the cylinder. During operation, the sand forces its way between the paddle face and the surface of the cylinder, providing the necessary abrading action as the pulp flows by gravity down the length of the cylinder. The capacity of the machine is limited by the amount and the hardness of the coating material and by the quality of product desired. The degree of scrubbing is governed by the retention time in the scrubber, which in turn may be changed by varying the feed rate, water content of the feed, and

Jan 1, 1953

By Luther Lennox

THE purpose of this article is not to compare one type of grinding machinery with another and to conclude from a series of tests that one particular machine is superior to all others. Neither is the reader asked to tire himself with the details of many tests to prove the statements herein made. The Chilean mill stands today almost, in outcast from the milling world. It ranks with the applicant for a job who has been given a trial along with others and condemned because he was not able to perform the definite task assigned as well as the others, and was forever eliminated. The judges did not tarry long enough to try this aspirant in a field of a slightly different nature. Even though it has been condemned, the writer contends that the published records will indicate that the trials were never shifted into the field of greatest efficiency for the Chilean mill. Those of us who cling to this outcast as a fine grinder in our milling operations do not wish, naturally, to be condemned along with the machine, and yet we feel that we are classed as behind the times, at least in this phase of our milling judgment. Hence there is considerable personal feeling in our efforts. During the last few years there have been published several papers on the relative merits of the various grinding machines. In two of these articles a comparison was made between Chilean mills and cylindrical grinders. In each case the Chilean mill came out second best from about all standpoints. The outstanding feature in these comparisons would seem to be the decided attempt to keep all conditions the same, so that each machine could be judged on its merit. As Mr. David Cole states, "We are inclined to regard a direct comparison of grinders arranged side by side, and making a product that affords as nearly as possible the same screen measure, as the Supreme Court in these grinding matters." The writer agrees that this is the very best method for true comparison between machines. The results in the two detailed tests should give the relative merits of the two grinders in doing the work assigned. And they probably do. The conclusion drawn in each case was adverse to the

Jan 9, 1919

By W. F. Hosford

A series of aluminum single crystals was subjected to axially symmetric flow by drawing through dies. The orientation dependence of the drawing stress, which indicates the resistance to this type of flow, compares reasonably with predictions of Taylor and of Bishop and Hill. Measured lattice rotations likewise are generally consistent with theory. The most successful analyses of the plastic behavior of polycrystalline metal and its relationship to single crystal behavior are those of Taylor1-3 and of Bishop and Hill.4-6 The purpose of this paper is to provide a critical test of some of the basic assumptions involved in these theories. Both treatments apply to fcc metals and assume the shape change of each grain in a polycrystal to be the same as that of the polycrystal as a whole. Thus for a randomly oriented polycrystal extended under uni-axial tension each grain is assumed to undergo axially symmetric flow. dey = dez = -1/2dex, deyZ = dezx = dexy = 0 [l] where x, y, and z are a set of orthogonal axes, x being the tensile axis. Although [011.] oriented grains in bcc and fcc metals may depart markedly from this ideal behavior,7,8 the assumption is probably quite reasonable for most grains. Under a uniaxial tensile stress, ox, the work dW per unit volume expended in producing an increment of axial strain dex is, dW=oxdex [21 Since this work is expended in slip, dw =STi dyi 131 where Ti and yi are the shear stress and shear strain on the active slip systems. In both analyses Ti is taken to be the same on all slip systems, and dependent only on the total prior shear strain on all systems, so dw = Tdy [41 where t is the shear stress required for slip and y is the sum of the shear strain yi on all slip systems. Combining 121 and [4] and defining M = oX/T The ratio M is a generalized Schmid factor. It relates the tensile stress required for axially symmetric flow, ox, to the basic shear stress, 7, and it also expresses the ratio of crystallographic strain, y, to the tensile strain, Ex It depends only on the orientation of the crystal. Taylor evaluated M for various orientations by finding the least value of dy/dEx which could satisfy the shape change. Bishop and Hill, on the other hand, found M by considering the relative work (1/T)dW/dEx expended by stress states which could activate enough slip systems to produce the shape changes. The results of both methods appear to be equivalent, although certain omissions were made in Taylor&apos;s original work. The orientation dependence of M, calculated by the second method,9 is shown in Fig. 1. Taylor used the average 2= 3.06 for all possible orientations to predict the tensile stress-strain curve (oxvs Ex) for a random polycrystal from the shear stress-strain curve (t vs y) of a single crystal. Changes in M from lattice rotation were neglected so points on the ox vs ex curve were simply taken at ox = 3.06t and e = y/3.06 from corresponding points on the t vs y curve. Recent extension of the analyses of Taylor and of Bishop and Hill to crystallographically textured metals has been used to relate plastic anisotropy to textures, and to predict the potential texture hardening that could result from texture control.9 Unfortunately there have been relatively few experimental tests of the underlying theory. Taylor found that the tensile stress-strain curve of polycrystalline aluminum did agree reasonably well with that predicted from a single-crystal T-y curve. Had the single crystal undergone easy glide, how-

Jan 1, 1965

By Thomas T. Read

It is natural, in reviewing the progress that has been made in mineral industry education during the three quarters of a century that has elapsed since the American Institute of Mining Engineers was organized in 1871, to seek to establish some significant correlation. Earnest endeavor along such lines, however, produces nothing more in the way of fundamental relationship than a technical economic interest in mineral production and utilization in the United States, which had been steadily increasing since 1800. This is a sound correlation, since it is unquestionable that organized and systematic mineral industry education had its origin in Germany, more than 150 years before 1871, in an economic interest in producing minerals for use with the maximum of recovery at a minimum of cost. Mineral industry became the originator* and creator of systematic technical education because of the political and economic fact that in all European (and most other) countries, prior to 1800, precious metals belonged to the ruling power, no matter upon whose land they were discovered. The practical way of working under this system was to grant to a discoverer the right to work the deposit on payment

Jan 1, 1947

By Leonard D. Jaffe

IN recent years, the advantages of tempered martensite as a microstructure for steel parts have been well established. For parts that must not fracture brittlely when loaded at high rates, at low temperatures, or under conditions of combined stress, tempered martensite is especially desirable. One of the factors that determine whether a steel part will have a martensitic structure after heat treatment is the hardenability of the steel. Despite the large amount of recent research, there are still many unsettled basic questions concerning hardenability and its relation to chemical composition, and, indeed, considerable disagreement among investigators in the field. Much of the uncertainty that beclouds the existing knowledge of hardenability arises from the fact that hardenability is still a wholly empirical concept, and has not been quantitatively related to the more fundamental knowledge of isothermal decomposition of austenite. Hardenability is, essentially, a measure of the time required for small percentages of austenite to decompose, during continuous cooling, to pearlite, bainite, proeutectoid ferrite, or proeutectoid carbide. In the practical heat-treatment of steel, also, the decomposition of austenite is usually not isothermal but rather during cooling, or, in general, is not at a single constant temperature. Thus, both hardenability and practical heat treatment involve anisothermal decomposition of austenite. In a previous publication1 the author and his collaborators outlined the principles that govern the relations between isothermal and anisothermal decomposition of austenite, and reviewed the experimental information available in 1945. To avoid repetition, familiarity with that article (Paper 1) will be assumed, and attention given primarily to work carried out or published since 1945. The method generally employed was explained in Paper 1: anisothermal transformation is studied through investigation of the effect of holding austenite at one temperature upon its subsequent decomposition at another temperature. Both temperatures are below the stability range of the austenite. This paper is confined to studies in which only a small amount of transformation occurred at the first temperature. This is the only case of importance in practical heat treatment when an essentially martensitic structure is sought. MATERIALS AND PROCEDURE It was necessary to use different steels for the studies involving proeutectoid ferrite and for those involving proeutectoid carbide, because the two constituents have not been found to form in the same steel. Several steels were tried and rejected

Jan 1, 1947

By F. C. Miller

The metallurgical fuel of Colorado, Utah, and New Mexico has been a Veiny tardy member in the caravan of western industrial progress. The history of western coke has naturally been closely related to the development of the metallurgy of iron and steel and the precious metals, in the State of Colorado. It was at Leadville, with a population of 300 in 1877, that the Sentinel was published by Richard S. Allen. The Sentinel gave very full accounts of the various mineral discoveries at the new town of Leadville, which found their way to the more widely circulated journals of the East, and attracted the attention of many people. At the close of 1878, a census slowed a total of 5040 persons. The first smelter was established in 1877, at Malta, two miles from Leadville, by A. R. Meyer, but was not successful. It was succeeded by the Harrison Reduction Works, in 1878. The La Plata began with one furnace in June, 1878, and in 1879 had four furnaces in active operation. These furnaces used charcoal for fuel, and, because of hot tops, suffered a tremendous loss in lead and silver. This difficulty was overcome by the erection of 50 single-bank 10-ft. beehive ovens at Crested Butte, Colo., in 1880. The slack coal sent to these ovens was very pure, and yielded a coke carrying as little as 4.5 per cent. ash. Among the pioneers in the Leadville district were Grant, Eddy, James, Billings, Eiler, and Dickson. To these men the West owes the present expansion of its mining industry, and the erection of metallurgical processes for the treatment of precious metals. On Mar. 1, 1876, Pueblo was connected to the Atchison, Topeka & Sank Fe by the Pueblo & Arkansas Valley branch. The first smelter was erected in Pueblo by Mather and Geist. This modest plant grew into the immense Pueblo Smelting and Refining Co., now a part of the American Smelting and Refining Co. Coke for these small furnaces was made from unwashed Engleville coal, in 186 single-bank 12-ft. ovens at El Moro, in the Trinidad district, and it was not uncommon for the percentage of ash to exceed the percentage of fixed carbon in the coke. On Jan. 23, 1880, the Colorado Improvement Co. consolidated

Jan 1, 1920

By Edward Chapman

IN the Leadville district toward the close of the "intermediate mesothermal period" of mineralization, there occurred a stage of ore deposition marked by a rather complex mineral association. As bismuth minerals formed in many places during this period, it is here called the "bismuth stage" for convenience of description. The minerals so far identified with this stage, listed roughly in the order of prominence, are: chalco-pyrite; several varieties of galena, differing slightly from one another in their small contents of silver, bismuth and tellurium; altaite; hessite; galenobismutite; alaskaite; aikinite; gold; tennantite; argentite; and perhaps sphalerite and arsenopyrite. With the exception of gold, the age relations of these minerals are difficult to determine. As shown in their descriptions, they all appear contemporaneous and hypogene. Gold may be in part contemporaneous, but most of it is distinctly later. Where minerals of this stage occur so that they can be mined alone, as at the Tucson mine, they constitute high-grade ore. Elsewhere their presence in small amounts has served to increase greatly the value of what otherwise would be low-grade pyritic or zinc-lead sulphide ore. The distribution of the bismuth ores corresponds closely to the distribution of gold ores, though not so general. It seems probable that most of the gold in the district was deposited during the "bismuth stage." These ores occur relatively near the supposed centers of mineralization in Breece and Printer Boy Hills or deep down along the Tucson-Maid fault, which is one of the well recognized channels of mineralization in the Iron Hill and Graham Park areas- Consideration of the high-grade nature of this mineralization and the fact that it appears to be found relatively close to the source of mineralization suggests that prospecting along some of the known channels, even deeper than they have yet been prospected, may offer hope of commercial success.

Jan 1, 1939

By S. A. LoPilato, J. T. Smith

SEVERAL techniques have been evaluated for cooling the throat area of rocket-nozzle inserts to prevent erosion or fracture of the inserts during exposure to high operating temperatures and pressures. Self-cooled composites, such as infiltrated tungsten, have shown considerable promise for these applications. These composites can be fabricated by infiltrating the refractory matrix with a lower-melting metal or non-metal which is insoluable in tungsten. During firing, the lower-melting substance undergoes a series of continuous endothermic phase changes which absorb sufficient heat to maintain the nozzle matrix material at or below a safe operating temperature. At present, the state-of-the-art has reached a point where the refractory matrix density and microstruc-ture have been established as the critical parameters to be controlled for optimum self-cooled performance.&apos;" Nondestructive testing has been utilized to ensure that porous tungsten billets were of uniform density and free from cracks or other defects prior to fabrication into rocket nozzle inserts. Ultrasonic-velocity techniques have been employed because of their reliability and reproducibility. The purpose of this note is to present and interpret the test data developed for porous tungsten matrices. For evaluation purposes, tungsten powders with Fisher subsieve sizes of approximately 4 and 18 p have been obtained for study from four commercial sources: the General Electric Co., Wah Chang Corp., Fansteel Metallurgical Corp., and Kennametal, Inc. Porous tungsten matrices were fabricated from the powders by hot pressing in induction-heated graphite die assemblies. Typical billets ranged from 3 in. diam, 2 in, high to 5 in. diam, 5 in. high. The ultrasonic-velocity measurement technique employed was through transmission, pulse echo at a frequency of 1.0 mc using matched barium titanate crystal transducers. The testing equipment included a pulsed ultrasonic generator, an amplifier, a specimen holder, and an oscilloscope, as shown in Fig. 1. The porous tungsten thickness was measured to i 0.0005 in, with precision micrometers while the oscilloscope achieved 0.02 psec time measurement accuracy. The time for a sound wave to pass through the billet, the bulk wave velocity, was calculated to 0.5 pct using Eq. [l]: V-} where V = bulk wave velocity, in. per psec, T = specimen thickness, in., and / = time, psec. To develop inspection standards, the bulk density of a porous tungsten billet was determined by the ASTM water-immersion technique.3 The ultrasonic-velocity measurements were completed at seventeen positions for each billet and averaged to develop a characteristic standard velocity for a particular tungsten powder at several density levels. A plot of ultrasonic velocity vs density is presented in Fig. 2 for six different tungsten powders. This graph has been established as

Jan 1, 1967

By Larry D. Patts

Section 317(e) of the Federal Coal Mine Health & Safety Act of 1969 directed the Secretary of the Interior to prepare standards under which all working places in a mine shall be illuminated by permissible lighting while persons are working in such places. Section 317(e) further provides that such working places shall be illuminated within 18 months after such standards are promulgated. In accordance with this section of the Act, there was published in the Federal Register for December 91, 1970, a notice of proposed rulemaking which prescribed the illumination to be provided in the working places of underground coal mines. In light of written comments, suggestions, and objections to this proposed rulemaking, the proposedstandards were withdrawn and reproposed in the Federal Register for Wednesday, October 27,-19h. In light of further comments, suggestions, and objections, a public hearing was held on April 4, 1974, and standards were again reproposed and published in the Federal Register for April 1, 1976. Promulgation of the final lighting standards took place on October 1, 1976, which means that the underground coal mining industry must comply with face illumination requirements by April 1, 1978. As mentioned previously, the first proposed rulemaking for illumination of underground coal mines was published in the Federal Register on October 27. 1971. In early 1972, Consolidation Coal Company (Consol) and the United States Bureau of Mines agreed to a cooperative study of underground face illumination: Consol felt that expertise is this field would become increasingly important. Consol&apos;s initial efforts in illumination were aimed at investigating practical lighting systems for underground face equipment. We were concerned with installing unobtrusive lights which provided sufficient face illumination for safety, but at the same time were readily maintainable, electrically reliable, and physically sheltered from damage. We believe that our initial lighting systems did provide sufficient face lighting for safety, but because only prototype components were available for field testing, the resultant poor system reliability and maintainability necessitated drastic improvement before face lighting could become practical. Final Lighting Standards Deem Early Lighting Installations Out Of Compliance On April 1, 1976, the Federal Register contained the final version of the illumination standards (as they were later promulgated in October). When these illumination regulations and measurement techniques were defined and measuring instruments were available, Consol checked their lighting systems underground and determined that the systems were not in compliance with these final illumination standards. More Lighting Hardware Added In An Attempt To Achieve Compliance. After determining that all of our face lighting systems were not in compliance, we began adding additional lighting hardware in order to meet compliance with published regulations. Unfortunately, to date, we have not been able to meet compliance with practical lighting systems. We have determined from our field installations that the required additional lighting hardware, (to meet compliance) with its increased vulnerability and decreased reliability, renders the lighting systems impractical, if not impossible, to reasonably maintain. Our attempts to provide 0.06 footlamberts have also produced adverse operator reaction to the glare and to illumination systems in general. BCOA Members Ask MESA To Demonstrate Practicability Of Compliance With Regulations Industry concern about meeting the impending lighting regulations was mounting, and in May of 1976 a meeting between MESA and BCOA members was held to discuss lighting compliance problems. At this meeting, BCOA offered to work cooperatively with MESA in testing the practicability of various lighting systems mounted on underground mining equipment. Field tests were to be conducted by United States Steel Corporation, American Electric Power Service Corporation, and Consolidation Coal Company. The purpose of this underground field testing was to develop capability to provide adequate face illumination in a safe, workable manner which would not detract from efficiency of operation. BCOA members involved in this cooperative study were to submit necessary machine drawings, sketches, etc. to MESA in order that MESA could perform a "black-box" study and specify the type and location of luminaires to be installed on the test machines. MESA was confident that they could specify lighting systems that would be in compliance and would be practical so as not to detract from efficiency of operation. Consol was first to install lighting hardware under the BCOA/MESA cooperative agreement. As per MESA specifications, Control Products HgV luminaires were installed on a Joy 2BT-2H boring machine at the Williams Mine of Northern West Virginia Region. As of mid-October, 1976, Consol had approximately eight weeks operating experience with the lighting system on this boring machine underground and had drawn the following conclusions: The lighting system installed at Williams Mine (1) does not meet compliance with lighting standards as originally proposed by MESA, (2) does not provide illumination in a safe workable manner, and (3) will detract from efficiency of the mining operation due to operational delays. Although Consol has rearranged lights on this boring machine in an attempt to reduce operator objections, a practical lighting system which is "in compliance" has not been arrived at as of this writing.

Jan 1, 1979

By F. L. Sizer

The mining regulations of British Columbia and Mexico present some features which might well be copied in the United States, if we are to have a complete revision of the laws governing mining titles. 1. First and foremost is the "squarc" location, which would mean the abolition of extralateral rights. This is a condition in both of the countries above named which has seemed to work no hardship upon any one, and certainly the limitation of underground rights by vertical planes through all lines makes a locator&apos;s rights clear. In view of the long and costly litigation which has involved so seriously many of our most important mining districts, it would seem to be the part of wisdom to avoid a repetition of similar trouble on titles of lode mining claims, by the enactment&apos; of a law similar to that in force in British Columbia. Objections have been raised by .representatives of English companies to the investment of large amounts of money in mining operations in the United States, because of the insecurity of title under the &apos;present apex law; and the statement has been made to me personally by one of the largest English operators, that he would .never again consent to the purchase of mines in the United States, preferring Mexico with all its revolutionary troubles to the danger of encroachment upon his underground rights by an unscrupulous neighbor. Without going into further argument as to the desirability of the I(square location," it should be sufficient to say to those who are inclined to "let well enough alone" and still stick to the "law of the apex" that there have never been any serious objections raised to this feature of the square location in either British Columbia or Mexico. There are well founded and logical reasons for abandoning the doctrine of extra-lateral rights since it is so difficult of interpretation; the most natural substitute being a law similar to that of British Columbia, giving to each locator an area 1,500 ft. square. I would advocate the right to locate adjoining claims of equal extent on either side of the discovery claim, on the strike of the lode, subject to a seasonable requirement in the matter of work upon them; and in the case of a vein dipping flatter than 45&apos; from the horizon, or in case of a

Jan 1, 1915

The following resolution was passed by the Military Engineering Committee of New York on April 12, 1917. Copies are being sent to each member of Congress and to each of the five members in every State forming the committee representing, the five National engineering societies which carried on the industrial census under the direction of Howard Coffin. The Committee is urging every man to wire his Congressman and his Senator, asking him to do everything in his power to obtain favorable action by Congress on this resolution: Whereas in any large army to be created for the war, engineer troops will be needed in large numbers, and Whereas they should be officered by skilled engineers only, and Whereas the composition and training of such troops differ so much from the composition and training of non-technical troops that they should be organized under one central authority rather than under many scattered authorities. Now, therefore, be it resolved: That the members of the Senate and House of Representatives be requested to insist that all new units of engineer troops be organized and maintained by the War Department and not by the individual States.

Jan 6, 1917

By Ralph C. Flow

In Cleveland County, North Carolina, 1 ½ miles south of Kings Mountain, Foote Mineral Co. operates an open pit for the production of spodumene, feldspar, mica and commercial stone. Spodumene concentrate is sent to Foote Mineral&apos;s Sunbright, Va., plant and to other customers. Exton, Pa. and New Johnsonville, Tenn., plants produce lithium com- pounds sold to the oil industry for multipurpose lithium-base greases, to the metal industry as welding flux, to the air conditioning market and to the glass industry. Ceramic-grade spodumene, feldspar, and mica concentrates go to other processing companies from the Kings Mountain plant. Waste amphibolite is delivered to a neighboring quarry operation. Geology and exploration of the deposit have been described by T. L. Kesler, Chief Geologist of Foote Mineral Co., in the September 1961 MINING ENGINEERING. Measured ore reserves as published at that time were 20.7 million tons. The ore deposit consists of a series of lithium-bearing pegmatites enclosed in amphibolite and mica schist wall rocks. The general strike of the pegmatites is northerly, and in the southern part of the pit, they dip slightly towards the west. The largest body being mined has a fairly uniform thickness of about 200 ft. Other pegmatites in the pit area range from 20 to 100 ft in thickness. Minerals in the pegmatites are 20% spodumene, 32% quartz, 6% muscovite, 41 % feldspar and 1 % trace minerals.

Jan 10, 1962

By M. C. Flemings, F. R. Mollard

Two-phase Pb-Sn alloys, ranging in compositiotz from 12 to 26 at. pct Pb, were unidirectionally solidified in a convection-fvee system, with thermal gradients in the liquid of up to 480°C per cm. Plane front solidification Loas achieved in all alloys at sufficiently steep gradient and slow growth rate. Conditions causing breakdown of the interface to a cellular or dendritic structure were roughly as predicted by a sinlple constitutional supercooling criterion. Structures of alloys of near-eutectic composition, solidified with plane front, exhibited a lamellar structure; the alloys furthest from the eutectic exhibited a rod-like morphology. Assumptions used in a previous paper for calculations of solute redistribution in two-phase plane front growth are shown to be reasonable for Pb-Sn alloys. Results of calculations are in good agveement with experiment. These show that variations in growth rate during solidification of the composite produce marked changes in average composition of the solid. IN a previous paper, Part I,&apos; conditions necessary for plane front solidification of two-phase alloys were discussed and calculations given on solute redistribution in this type of solidification. This paper, Part 11, describes experiments on Pb-Sn alloys, designed to check the assumptions of the analyses presented, and to demonstrate their applicability to a given alloy system (Pb-Sn). APPARATUS AND PROCEDURE General. A vertical crystal growing unit was built for the study as described below, and "normal solidification" employed throughout (i.e., the ingot was completely melted except for a portion near the bottom end and then solidification initiated). The furnace was designed to permit achieving very low interface velocities, and steep gradients, in essential absence of convection; it is sketched in Figs. 1 and 2. Simple heat flow considerations indicated choice of a small-diameter specimen (ingot) to achieve high thermal gradients; ingot size chosen was 0.3 cm in diam. The ingots were held inside silica tubes 0.06 cm wall thickness. The requirement for an essentially convection-free system was met by use of the vertical furnace with the heat source over the heat sink, as well as by use of the small diameter ingots. In addition, by selection of tin-rich Pb-Sn alloys, the diffusion boundary layer (lead-rich) was denser than the bulk liquid and would not cause convection. The only apparent driving force for convection in this system was the small transverse temperature gradient resulting from heat flow into the samples from the furnace. Such convection must have been small, however, since 1) no temperature fluctuations in the melt were noted in the recordings, which would have indicated turbulent convection, and 2) experimental results obtained and described below could not have been achieved in presence of significant convection. Ingot Preparation. Pb-Sn alloys ranging from 12 to 26 at. pct Pb were prepared from high-purity lead and tin (99.9999 pct pure metal). Each alloy was prepared by first melting the pure metals in the proper ratio in air, in a Pyrex container. The melt was then stirred thoroughly with a graphite rod and cast into a preheated graphite mold. Ingots were then prepared from these castings for use in the actual experiments; each ingot consisted of a rod of alloy, 15 cm long in a 25-cm-long transparent fused-silica tube, 0.3 cm ID and 0.06 cm wall thickness. One chromel-alumel thermocouple, made with 0.004-in.-diam wire and protected by a two-hole alumina tube, was inserted into each ingot. The 1.5 cm of the thermocouple nearest the bead were protruding from the alumina tube and were coated with a very thin layer of boron nitride paste which provided electrical insulation while allowing good heat conduction. The electrically welded junction size was about that of each wire and the cross section of the two wires represented about 0.3 pct of the sample cross section. Including the coating, the thermocouple cross section still represented less than 0.5 pct of the ingot cross

Jan 1, 1968