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By M. J. Mullikin, J. B. Conway

Several different equation forms were studied to determine the extent to which each particular equation type yielded an accurate representation of a given set of first-stage creep data. Specially developed least-squares computer programs were employed to obtain unique solutions for the creep-equation constants. In studies of creep data for lead at 14.5"C, nickel at 70OCC, and arc-cast tungsten at 2400°C consistently good representations were afforded by a third-degvee polynomial in t113. Other effective correlations were obtained with the Andrade, Cottrell-Aytekin, and de Lacombe equations along with a third-degree polynomial in t112. A newly proposed creep equation involving a hyperbolic-sine term in t1'3 was also found to yield very satisfactory results. This appears to be the first use of such a functional relationship in the analysis of transient creep behavior. In general, the deformation behavior of a material subjected to a tensile load is described in a strain-time plot. Experiments have shown that, following the instantaneous elongation which results on loading, the instantaneous slope (i.e., creep rate) of the strain-time curve decreases gradually with time and approaches what appears to be a constant value. Equations, therefore, which are proposed to provide an analytical representation of such first-stage or transient creep behavior must be consistent with these observations. In other words, at time zero, these equations must yield a finite deformation value corresponding to the elongation on loading. Furthermore, the first derivative of these equations must exhibit a fairly high although finite value at time zero, and then values which decrease with time. It is also preferable, in general, that the derivative eventually assume a constant value at high time values. Although many studies of first-stage creep behavior have been made and numerous equation forms have been proposed for expressing this type of deformation behavior, it is still not possible to state with any assurance which functional relationship will be adequate for a given set of measurements. Parabolic relationships have been employed most extensively although logarithmic expressions have been shown to be applicable in some instances. Combined forms1 have been studied in considerable detail and have on occasion been found to be very effective. One such expression is that of iXndradea and involves a modified parabolic expression: where 1 is the instantaneous length, lo is the length immediately following load application, t is the time, and p and k are constants. Another combined form has been proposed by weaver3 as follows: where E is the instantaneous strain, is is the linear creep rate, t is the time, and a and b are constants.

Jan 1, 1967

By Henry Ferguson

THIS paper is a preliminary statement, intended to present the more important results of the recent studies of the ore deposits of the Alleghany district in advance of the publication of the complete report, now in preparation. The Alleghany district (Fig. 1) has been a producer of gold since the early days of California gold mining. As in other California gold camps, placers yielded the bulk of the earlier production, but during the last 30 years lode deposits have been the only important source of output. The district differs from other California gold-quartz districts in that nearly all the production is from small shoots of high-grade ore. The mining camps of Alleghany and Forest are on the western flank of the Sierra Nevada range about 20 miles west of the crest. The gently sloping lava-covered plateau which controls the upland topography has been trenched by deep canyons of the westward flowing streams, which are cut to depths of as much as 2000 ft. below the crests of the ridges. The district is about 18 miles from Nevada City but the automobile road which connects the two places is 31 miles long. The senior writer first visited the district in 1913 and published a short description of the lode deposits.1 The increasing importance of the district made further study desirable. A detailed topographic map was therefore made by W. B. Upton, Jr., of the U. S. Geological Survey, in the spring of 1924, and the senior writer spent parts of the field seasons of 1924 and 1925 in the district. For the second field season the Geological Survey was fortunate in securing the services of R. W. Gannett, who had already done geologic work in the district for several of the mining companies. Owing to the death of Mr. Gannett in October, 1925, just before the close of his field work, the work of preparation of the entire report fell to Mr. Ferguson. He takes this opportunity of acknowledging how deeply he is indebted to Mr. Gannett for his excellent work in the field, and his realization of how greatly the completion of the report on the district has suffered from lack of Mr. Gannett's assistance in the office. In October, 1.928, after the completion of the first draft of the manuscript, Mr. Ferguson made a short visit to the district.

Jan 1, 1929

CONTENTS PAGE SOUTHWARD, GLENN B.-Coal Mining by the V System. Discussed by Glenn B. Southward, Howard N. Eavenson, Edward B. Raiguel, Thomas de Venny, J.. J. Rutledge, Graham Bright 1 ARMS, RAY W.-Dry Cleaning of Coal. Discussed by Ray W. Arms, S. A. Taylor, Howard N. Eavenson, W. R. Crane, F. F. Jorgenson, G. R. Delamater. 6 EAVENSON, HOWARD N.-Data About Labor Employed in Various Bituminous Coal Mines. Discussed by Howard N. Eavenson, George H. Ashley, E. A. Holbrook, S. A. Taylor, R. V. Norris 14 Coal Mining by the V System Discussion of the paper of GLENN B. SOUTHWARD presented at the New York Meeting, February, 1924, and issued as Paper No. 1300-C, with MINING AND METALLURGY, February, 1924. MEMBER.-How do you pay your men for loading? GLENN B. SOUTHWARD.-Everything is on time basis. MEMBER.-How many men do you have loading across one of the diagonal faces? GLENN B. SOUTHWARD.-From four to five, depending on the length of the face. Our loaders are so arranged that each will give about twenty-five tons per loader a day. MEMBER.-How much timber do you use? GLENN B. SOUTHWARD.-A little more than will be used in room-and-pillar work, but not a great deal more. We have not attempted to recover much of our timber. MEMBER.-IS the mine union or non-union? GLENN B. SOUTHWARD.-Non-union. HOWARD N. EAVENSON, Pittsburgh, Pa.-I went .through that mine some weeks ago, and think that the author has been very conservative in his statements about the amount of loadings, etc. EDWARD B. RAIGUEL, Huntington, W. Va. (written discussion).¬Page 7 shows 60 men employed in day and night shifts, inside the mine, producing 750 tons per day. Let us reduce these figures to a man-hour basis, for comparison with Mr. Eavenson's figures on West Virginia mines, as follows:

Jan 6, 1924

By James P. Kimball

Sulphur is always present in mineral coal of every variety. In the oxidized state it may exist as sulphuric acid in combination with a base. In the unoxidized state it exists in combination with iron as bisulphide of iron. It is also supposed by some chemists to exist in unknown combinations with the organic elements of the coal. This supposition requires the demonstration as a fact that certain coals yield more sulphur than what may exist in a free state, or what belongs to recognized combinations, not only with the accompanying iron but with other inorganic bases abundantly occurring in coals, but which unfortunately are very rarely estimated. This practically as well as theoretically important question it is at present impossible to decide, simply for want of available thorough ultimate coal analyses including the ash. Such analyses, at the best imperfect, are luborious and intricate, and therefore seldom made, the much simpler proximate analyses, so-called, being resorted to by most chemists for technical purposes, and commonly substituted for more scientific work even in the laboratories of government surveys. And it is unfortunate enough that few ultimate analyses are extended to the composition of the ash, much less to its relation to the original constitution of the coal. Sulphur chiefly occurs in most coals in the form of yellow pyrites (pyrite) and white pyrites (marcasite), both minerals, characterized by differences in crystalline form and in physical properties as well as in color, but having the same chemical composition (FeS2). No coal is entirely free from one or both of these dimorphous forms of bisulphide of iron. It may be disseminated through the mass so as to be invisible, in plates or scales between the laminæ of the coal, or in conspicuous segregations or nodules, sometimes of considerable dimensions. Coals greatly differ as to the proportion of sulphur which they contain. They also differ as to the relative proportion in which its several forms of combination occur. Such qualitative and qnantitative disparities arc scarcely, if at all, more marked in separate coal seams of a uniform type than in different parts of one and the same coal seam, whether it be considered locally as constituted of several

Jan 1, 1880

By George H. C. Norman

A NUMBER of methods have been developed for the determination of the dust concentration in air, some of which have been reported as very efficient and for research may be more satisfactory than the method about to be described. In practical mine use, however, the accurate research equipment is unwieldy and requires a high degree of technical skill to manipulate it. Also, it gives less general practical information to the operator in the same length of time than the method described here. Moreover, it is doubtful whether at the present stage of affairs the results obtained from the precise methods have any more practical significance than those obtained with simpler and more portable apparatus, which can rapidly give a sufficiently reliable indication of the relative dust hazard. HISTORY OF DUST DETERMINATION IN ONTARIO The first record of mine-dust determination in Ontario is given in an article by Dr. J. H. Elliott,' in which he records a few dust counts made with the Palmer spray apparatus. There were insufficient data from which to draw any definite conclusions or reasonably compare with present-day counts using the konimeter. The first konimeter dust sampling was started in the Porcupine district in 1926, using light-field counting without adhesive and with no sample treatment before counting. A method of semidark-field counting was used from about 1928 to 1931 and dark-field illumination was adopted permanently about December 1931. The konimeter has been continued as the principal means of dust sampling in the mines of Ontario, where South African practice has been adopted because in South Africa most careful study has been given the problem of silicosis, and very complete records of work done there are

Jan 1, 1937

By Pekka S. Särkkä

The method of interactive dimensioning is based on the computation of the loading-deformation curves caused by country rocks on the pillars with numerical methods. The comparable loading-deformation curves of pillars with different shapes are determined with small-scale model tests in a servo-controlled testing machine. The equilibrium points, i.e. the stability of the different pillar-country rock systems are determined by matching these curves adequately scaled. A case from a Finnish mine is presented together with the stoping results.

Jan 1, 1984

By John D. Sullivan, Edwin J. Rogers, Chester R. Austin

THE problem of making a building unit combining the necessary physical and mechanical properties and good thermal insulation has been foremost in the minds of architects and ceramic and construction engineers for many years. This paper presents the results of studies on thermally expanding shales or clays to produce light-weight cellular products suitable for making building units. An expanded clay block suitable for building purposes should be large enough so that substantial savings may be effected in labor costs in laying the wall. The permeability should be low and it should have sufficiently good "dry-wall" characteristics to permit exposing the exterior surface to the elements, and to permit plastering directly the inside wall surface. The thermal conductivity should be low and the mechanical properties should be adequate. Obviously, a unit possessing satisfactory qualities for constructing an outside wall would be satisfactory for interior walls and for back-up purposes. The results of studies on bloating various shales or clays† and the properties of the expanded products are reported. In another paper1 basic factors involved in bloating of clays are discussed. Manufacturers of ceramic products, particularly structural clay, may encounter bloating of the ware during burning, and precautions must be followed to avoid this phenomenon. About 1927 the C. F. Burgess Laboratories, Madison, Wis., while carrying on an investigation for the American Face Brick Research Corporation, conceived the idea of intentionally bloating clay while holding it in a restrained condition, with the hope of producing a unitary cellular mass. Work was carried on until about 1931, when studies were terminated because of business conditions. These studies were continued later by The Western Brick Co., Danville, Ill., which developed a process of "inwardly expansive bloating." The major purpose of the latter investigation was to produce back-up tile to compete with concrete blocks made from Haydite or cinder aggregate. Haydite is a light-weight aggregate formed by heating certain clays or shales rapidly in a rotary kiln. While the investigations at the C. F. Burgess Laboratories or at Western Brick Co. were not carried far enough to lead to the commercial production of material for the construction of walls, particularly outside walls, they showed that certain clays could be thermally expanded and that it was possible to produce a material of low permeability with a large percentage of the total voids or cells closed. Commencing in 1939, the Ozark Chemical Co. sponsored a research program at Battelle Memorial Institute for the purpose of determining whether it is technically feasible to make thermally expanded building units, and specifically to get answers to the following questions:

Jan 1, 1942

By H. A. Koch, R. L. Slobod

This paper discusses a new oil recovery process called the "miscible slug process." This process involves the injection of propane or LPG into the reservoir prior to gas injection. The operating conditions are maintained so that the slug is miscible with both the reservoir oil and the injected gas phase. Thus, a miscible phase displacement is achieved, and high recoveries are obtained from the area of the reservoir contacted. The most striking discovery of the laboratory study which included displacements from cores up to 123 ft in length was that relatively small slugs of LPG are effective over reservoir distances in the miscible displacement of oil. This makes possible the commercial application of the process. The important factors controlling the size of the slug are: (I) reservoir length, (2) reservoir fluid composition, and (3) reservoir pressure at the displacement front. Of lesser importance are the effects of injection rate and porous medium type. Questions which have not been completely answered deal with the effects of gravity and reservoir inhomogeneities on the process. INTRODUCTION One of the major problems facing the oil industry today is recovery of the large fraction of the discovered oil which will remain unrecovered unless some new processes are found. Water flooding has been one successful method used to increase recovery over natural depletion. But even successful water floods may leave 25 to 40 per cent of the pore space filled with residual oil. Recently a process which involves the use of thermal energy has been reported1,'*' which may prove useful in increasing recovery from shallow reservoirs containing highly viscous crudes. This paper deals with a new oil recovery process involving use of miscible phases to displace the oil from the reservoir. Miscible phase displacement oil has been an intriguing idea because the elimination of capillary effects in the reservoir leads to 100 per cent recovery in the areas contacted by the miscible displacing phase. The big deterrent in the past to the practice of miscible phase displacement has been the high cost involved in using large volumes of solvent in the process. The use of high pressure gas to achieve a miscible phase displacement of reservoir oil has been reported4,5 as one economically feasible method. However, this process calls for the maintenance of pressures above 3,000 psi at the dis-placement front. The process described in this paper is not restricted to high reservoir pressures; the only qualification being that the slug of material which is injected into the reservoir must be miscible with both the displaced oil 2nd the displacing phase. Two such cases are the use of an alcohol slug followed by water to achieve a mis-cable water flood, and the use of a low boiling hydrocarbon slug such as propane followed by gas to achieve a miscible gas drive. This paper will deal specifically with the propane dug process. This process will obtain a miscible phase displacement at pressures as low as about 1,200 psi at a reservoir temperature 01 150°F. The process is very simple. The propane displaces oil completely at one front because it is miscible with the oil, and gas displaces the propane completely at a second or trailing front because it is miscible with the propane. A small band of propane should thus remain wedged between the gas and oil phases. This idea has been called the "miscible slug process."6 Unfortunately, the propane slug will become diluted as it flows through the reservoir. This results from a mixing action since the fluids flow through a complex reservoir porous medium rather than simple capillaries. Fig. 1 diagrams a miscible slug displacement. The effects of some of

Jan 1, 1958

By R. E. Boni, G. Derge

SURFACE tensions of molten silicates are of metallurgical importance for many reasons. From a knowledge of their values, an insight into the problem of liquid slag structure can be gained. Also, such problems as separation of slag from metal, slag penetration of refractories, spreading of enamel coats on metals, bonding of cutting wheels, adsorption of gases, frothing of slags, and homogen-ization of slags are related to the surface tensions of the silicates. Because of the absence of a correlated review of the work that has been conducted in this field, the following survey is presented. It is not a complete summary of all the surface tension studies of silicates but only a review of the literature which is pertinent to metallurgical applications and research. Liquid Surface Tension The surface of a liquid differs from the interior in that its particles (ions, atoms, or molecules) are not

Jan 1, 1957

By S. Fróes Abreu

The importation of liquid fuels in Brazil amounts to about 1,300,000 tons; 30 per cent of this total being gasoline for automobiles and airplanes. Statistics show an increasing consumption of gasoline notwithstanding the use, daily greater, of fuel alcohol, a domestic fuel of low cost in the producing areas. The Brazilian market for petroleum products has shown a tendency to grow as the country has steadily developed— expansion of the industries in the areas already developed, and also the recent occupation and population of new zones. The war has brought many difficulties to Brazil. It has limited the importation of petroleum products, which came mostly from the United States, Venezuela and Mexico. During the first days of the present crisis automobile and truck traffic was vastly curtailed; but the national activity in the production of more fuel alcohol, and principally in the development of producer gas, has done much to provide a solution for the transportation crisis threatened at the beginning of the gasoline shortage. Many thousands of cars and trucks in Brazil are now burning producer gas made from charcoal. Producer gas for automobiles has been improved by Brazilian engineers and many new types have appeared. - Production There is only one producing oil field in Brazil—the one in the State of Baia, near the Baia de Todos os Santos. The first producing oil well was drilled in Lobato in 1939 by the Federal Government following studies carried on in that area by Oscar Cordeiro, S. Froes Abreu, G. Paiva and J. Amarai. The field and laboratory work done by these men was published in 1936 in a paper entitled " ContribuicBes para a Geologiado Petroleo no Reconcavo (Baia)," which indicated the potentialities of the area as an oil producer. After the discovery of the first producing well, the Brazilian Government issued a decree establishing an area, 60 km. in radius, as a National Reservation. This first well was drilled in Lobato. In no other locality in Brazil is any petroleum produced. Although many wells have been drilled in the southern part of Brazil, on the northeastern coast and in the Amazon Basin, they yield nothing. Actual production is below 1000 bbl. daily. The producing area covers Itaparica Island, Candeias and Arath, Joanes Island and Lobato. Since very little geological information was available, especially about subsurface structure, it was necessary to drill several wildcats in order to collect the data essential in the choosing of good locations. The United Geophysical Co. was contracted to perform a geophysical survey to clear up the major problems concerning the oil deposits in the Reconcavo beds. The best wells in Reconcavo are on Itaparica Island, where the daily flow amounts to about zoo bbl.; in other sectors production is considerably lower and most of the wells are pumping. In the Aratfi sector, near an area of very light oil, there is an important gas field, with wells producing about I0,000,000 cu. ft. daily.

Jan 1, 1944

By S. Fróes Abreu

The importation of liquid fuels in Brazil amounts to about 1,300,000 tons; 30 per cent of this total being gasoline for automobiles and airplanes. Statistics show an increasing consumption of gasoline notwithstanding the use, daily greater, of fuel alcohol, a domestic fuel of low cost in the producing areas. The Brazilian market for petroleum products has shown a tendency to grow as the country has steadily developed— expansion of the industries in the areas already developed, and also the recent occupation and population of new zones. The war has brought many difficulties to Brazil. It has limited the importation of petroleum products, which came mostly from the United States, Venezuela and Mexico. During the first days of the present crisis automobile and truck traffic was vastly curtailed; but the national activity in the production of more fuel alcohol, and principally in the development of producer gas, has done much to provide a solution for the transportation crisis threatened at the beginning of the gasoline shortage. Many thousands of cars and trucks in Brazil are now burning producer gas made from charcoal. Producer gas for automobiles has been improved by Brazilian engineers and many new types have appeared. - Production There is only one producing oil field in Brazil—the one in the State of Baia, near the Baia de Todos os Santos. The first producing oil well was drilled in Lobato in 1939 by the Federal Government following studies carried on in that area by Oscar Cordeiro, S. Froes Abreu, G. Paiva and J. Amarai. The field and laboratory work done by these men was published in 1936 in a paper entitled " ContribuicBes para a Geologiado Petroleo no Reconcavo (Baia)," which indicated the potentialities of the area as an oil producer. After the discovery of the first producing well, the Brazilian Government issued a decree establishing an area, 60 km. in radius, as a National Reservation. This first well was drilled in Lobato. In no other locality in Brazil is any petroleum produced. Although many wells have been drilled in the southern part of Brazil, on the northeastern coast and in the Amazon Basin, they yield nothing. Actual production is below 1000 bbl. daily. The producing area covers Itaparica Island, Candeias and Arath, Joanes Island and Lobato. Since very little geological information was available, especially about subsurface structure, it was necessary to drill several wildcats in order to collect the data essential in the choosing of good locations. The United Geophysical Co. was contracted to perform a geophysical survey to clear up the major problems concerning the oil deposits in the Reconcavo beds. The best wells in Reconcavo are on Itaparica Island, where the daily flow amounts to about zoo bbl.; in other sectors production is considerably lower and most of the wells are pumping. In the Aratfi sector, near an area of very light oil, there is an important gas field, with wells producing about I0,000,000 cu. ft. daily.

Jan 1, 1944

By Paul Tyler

THE ferroalloying elements are connecting links between the steel industry and the nonferrous metal industries. Although ferroalloys are distinctly nonferrous themselves, they serve the steel industry either in the manufacturing process or in modifying the product-in some cases so that it may compete in the markets with nonferrous metals. Of the 92 elements generally accepted by chemists as constituting the primary building blocks of matter, all but the very rarest have been investigated with a view to employing them in steel manufacture. The surprising thing is that so few have been found commercially acceptable. Despite the relatively small number of elements involved, the employ-ment of alloys in steelmaking is one of the most complicated and probably one of the least well understood of modern industrial enterprises. A great deal has been written regarding the action of individual elements and a profuse and somewhat acrimonious literature covers pretty much the whole field of ferroalloy ore supplies. In the middle ground between the miner and the steelmaker developments are less carefully watched by most observers, and except for an occasional description of the technique of some conversion process or the tariff hearings in Congress, very little is said about them. The purpose of the present paper is to describe in relatively nontechnical terms this highly complex industry and to study its relations to our national progress.

Jan 1, 1933

SEC. 1. This Institute is incorporated under the Membership Corporations law of the State of New York; its corporate name is American Institute of Mining and Metallurgical Engineers, Inc.; and its abbreviated title A. I. M. E. SEC. 2. The objects of this Institute, as set forth in its certificate of incorporation, are: "To promote the arts and sciences connected with the economic production of the useful minerals and metals, and the welfare of those employed in these industries by all lawful means; to hold meetings for social intercourse and the reading and discussion of professional papers, and to circulate by means of publications among its members the information thus obtained, and to establish and maintain a place for meeting of its members, and a hall for the reading of papers and delivery of addresses, and a library of books relating to subjects cognate to the sciences and arts of mining and metallurgy." ARTICLE II MEMBERSHIP SEC. 1. The membership of this Corporation shall include all those who on the third Monday in February, 1928, were members and all others subsequently elected and qualified in accord with the By-laws of the Institute at the time of such election. SEC. 2. The membership shall be divided into such classes as may be from time to time fixed by the By-laws. ARTICLE III DIRECTORS SEC. 1. The business, financial, professional, technical, scientific and social interests of the Institute shall be managed by a Board of Directors, elected annually by letter ballot in the manner specified in the By-laws, to serve for the terms as set forth in the Certificate of Incorporation. ARTICLE IV AMENDMENTS SEC. 1. Proposals to amend this Constitution may be made by resolution of the Directors or by written petition signed by at least ten members. Such proposals must reach the Secretary not later than October fifteenth. The Board of Directors shall consider them and, in case of petitions, the proposers shall be notified of the opinion of the Board in regard to them, when they may cither withdraw their proposals, or accept any changes suggested, or insist on the original form. All proposals when in final form shall be mailed to all members on or before January first, with the election ballots, and with a ballot in proper form for voting on the amendment in its original or amended form. Ballots shall be received by the Secretary until the second Tuesday in February. The Tellers of the election shall count these ballots,

Jan 1, 1929

By Joseph S. Malesky

The discovery and development of explosives mark one of the most important findings in the history of civilization. Without explosives our vast economic enterprise concerning the mining of coal, copper, iron, aluminum, and various other ores could not function. Explosives are used in all kinds of construction works, in the razing of old buildings, blasting of trenches, driving of tunnels, and in many other instances common to our everyday life. For these reasons explosives are rightfully referred to as the forerunner of progress. An explosive may be defined as a substance (usually a mixture) that, when flame or shock is applied, yields readily to rapid combustion or oxidation, accompanied by the formation of such relatively large quantities of gases as to produce much violence and pressure which, in turn, react against their surroundings and cause what is termed an explosion. By their very nature the action of explosives is destructive and disruptive of adjacent materials. Decomposition of explosives can occur through deflagration, which is rapid burning or combustion, as in the case of black powder, or through detonation, which is an almost instantaneous disruption, as in the case of dynamites and blasting agents. HISTORY OF BLASTING WITH EXPLOSIVES At one time workmen obtained stone blocks for building by grooving the rock with crude picks, driving wooden wedges into niches in the rock, and pouring water on the wedges; the swelling of the wood forced out the blocks. As late as the 17th century, fires were placed against the face of rock to crack it, and water was sometimes dashed on the heated rock to shatter it by sudden cooling. The progress of our country is synonymous with advancement of the improved manufacture and extended use of explosives. Coal had been

Jan 1, 1981

By N. A. Tiner, Saara Asunmaa

The early stages of nucleation of vacuunz-deposited gold coatings on electropolished surfaces of pure nickel and binary alloys of Ni-A1 and Ni-Ti have been studied, employing carefully controlled temperature and vacuum conditions. The preferential nucleation of gold on slip-plane edges on the crystal surfaces gave rise to a very pronounced decoration effect which was used in studying the morphology of the pain boundaries, etch pits, and slip planes on crystal faces. Characteristic surface patterns were observed with local dimensional variations. Most pronounced geometric patterns were ohserved in the pain boundaries of nickel and on the crystal faces of Ni-A1 alloy. The nucleation behauior of gold indicates contamination on the Ni-T1 alloy and the getter properties of titanium are presented as a tentative interpretation for the detected contamination. The markings and imperfections on cleavage surfaces of crystals have long been observed by optical microscopy.1,2 Surface-replica techniques are also used to detect the smallest steps and structural details on crystal surfaces by electron microscopy. Recently, Bassett3-5 and Sella, Conjeaud, and Trillat 6 have shown that, when gold is deposited onto a rocksalt cleavage surface, there is preferential nucleation at steps and slip-plane edges on the crystal surface. This gives rise to a very pronounced decoration effect which is invaluable for revealing the lattice steps on a cleavage surface. According to Bassett,3 gold atoms arriving during vacuum evaporation at the crystal surface have a certain mobility on the surface after arrival, particularly at elevated temperature. If a significant

Jan 1, 1964

By John R. Wynnyckyj

Results of correlations between strength-development and sintering shrinkage occurring during induration are presented. A mathematical treatment of the shrinkage kinetics is, next, given and is based on the use of semi-empirical equations. The discussion stresses the significance of kinetic constants and activation energies in the assessment of iron ore concentrates for pelletizing and induration. Next, starting with the assumption that there is a need for parameters to characterize the iron-ore concentrates and relate these parameters to shrinkage-kinetic constants and balling behaviour, results of compaction measurements and pore structure characterization (mercury porosimetry) are presented and discussed.

Jan 1, 1977

By J. W. Rutter, K. T. Aust

The temperature dependence of the rate of grain boundary migration was measured in bicrystals of zone-refined lead containing from 20 to less than 1 ppm by wezght of tin. The apparent activation energy in the temperature range from 320" to 200oC is markedly dependent upon the solute tin concentration and upon the orientation relationship of the grains adjacent to the grain boundavy. The quantitative experimental observat~ons are compared with the predictions of various theories of grain boundary migration. In previous work.&apos;?&apos; the mobility of individual grain boundaries was studied as a function of impurity concentration and type of boundary. Grain boundary migration occurred at the expense of dislocation arrays which were introduced into the specimen during solidification. Boundary mobility in zone-refined lead at 300°C was markedly decreased by small additions of tin. 0.004 wt pct being sufficient to decrease the rate of grain boundary migration by a factor of 1000. The mobility of grain boundaries having polar orientation relationships near 38 and 22 deg about <Ill>, and 28 deg about <100>, was much less sensitive to tin concentration in the range studied. As a result, these boundaries have relatively high mobilities. The present paper is a continuation of the above study. Data are now presented on the temperature dependence of the motion of individual grain boundaries in zone-refined lead as a function of solute tin concentration and orientation relationship of adjacent grains at the grain boundary. The experimental observations are compared with the predictions of a number of theories of grain boundary migration3-8 which, prior to the present experimental investigation, could not be critically evaluated. EXPERIMENTAL PROCEDURE The striation or lineage structure of melt-grown single crystals of zone-refined lead, containing various additions of tin, was utilized to provide a driving force for grain boundary migration, as previously described.1,2 Each grain boundary under study separated the striated single crystal from another grain which was introduced by localized plastic deformation and recrystallization of a small region of the sample. The speed of migration of grain boundaries in dilute alloys of tin in zone-refined lead was investigated as a function of 1) tin concentration from < 0.0001 to 0.002 wt pct, 2) temperature in the range of 200" to 320°C, and 3) orientation relationship of the adjacent grains at the grain boundary. The substructure driving energy available for grain boundary migration was estimated to be about 4000 ergs per cu cm, within a factor of two, from specimen to specimen.&apos; The specimen dimensions, and growth and alloying procedures for the preparation of striated single crystals of lead of known tin composition, were as described previously.&apos; Each bicrystal was carefully wrapped in aluminum foil, and annealed in a well-stirred salt bath consisting of 50 pct NaNO2 and 50 pct KNO3, for known periods of time at a series of constant temperatures (*2°C). The grain boundary positions, before and after each anneal, were determined by etching lightly in a solution of 5 pct nitric acid in methyl alcohol, in order to follow the motion of the boundary and determine its rate of migration. Thus, the rate of motion of the grain boundary in a single specimen was measured at various temperatures. The above procedure was carried out for each grain boundary in seventeen different bicrystal specimens.

Jan 1, 1960

By W. P. Sykes

SINCE Honda and Murakami1 in 1918 proposed their constitutional diagram of the carbon-free iron-tungsten system, considerable effort has been expended by several investigators in attempts to define more positively the structural features of the alloys. The existence of an intermediate phase corresponding to the formula Fe3W2 (68.7 per cent W) was proposed from evidence of a purely metallographic nature by one of the present authors2 in 1926. Since that time the identity of this phase has been confirmed by Arnfelt3 and by Takeda,4 both of whom employed X-ray methods as well as the microscope and the chemical analysis of isolated microconstituents. According to Arnfelt, Fe3W2, as crystallized from the iron-rich melts at a temperature above 1450&apos;C., contains by analysis 68.7 per cent W. The lattice of this phase is characterized by trigonal symmetry. Arnfelt, moreover, proposed a second intermediate phase formed at some temperature between 1450° and 1000° C. by a peritectoid reaction involving Fe3W2 and the iron-rich solid solution. A melt containing 25 per cent W was cooled to 1000° C. and heated for. 100 hr. The precipitated tungsten-rich constituent was separated and found by analysis to contain 62.6 per cent W. This composition agrees closely with that represented by the formula Fe2W (62.2 per cent W). Diffraction patterns from the concentrated precipitate showed a hexagonal unit cell. Takeda confirmed the data of Arnfelt regarding Fe3W2 but was unable to detect Arnfelt&apos;s second intermediate phase. While Takeda. failed to describe in detail the treatments employed, he stated that in alloys containing 40 per cent W which were quenched after heating at various temperatures between 1200° and 1450° C., no evidence of the second phase (Fe2W) was observed either in the microstructure or in the diffraction patterns of isolated residues. He therefore considered the existence of this low-temperature hexagonal compound as disproved.

Jan 1, 1932

By G. V. Woody, J. D. Price

Many producers of by-product coke have spent considerable time and given considerable thought to the use of a substitute for low-volatile coal as an admixture with high-volatile coking coal for charging high-temperature by-product coke ovens. Generally speaking, there are two principal reasons for this, one being occasioned by the lack, in certain localities, of low-volatile coal delivered at a cost sufficiently low to permit its use, and another being the desirability of finding a substitute product with a delivered cost lower than the cost of the low-volatile coal. It was for the first of these reasons that the Colorado Fuel and Iron Corporation was particularly interested in this subject. This paper deals with the experimental work and the results obtained by that company in producing and using low-temperature char. Overcoming Defects in Coke from Colorado Coals Colorado coking coals are all of the high-volatile type and were all laid down during the Cretaceous period, which makes them something like 80 million or so years younger, geologically, than eastern coals. They behave, when coked alone, something like the Pittsburgh-seam coals. They make a very brittle, highly cross-fractured, fingery coke of fair shatter value but quite low in resistance to abrasion. Mixed with a low-volatile coking coal such as Poca- hontas or certain Oklahoma coals, they make a coke that is equal to virtually any of the eastern cokes. The inferior quality of Colorado coke has long been recognized, and a considerable amount of time, effort and money has been spent upon investigations of means for improving its physical properties. While it has been found that some improvement in quality of coke can be secured by the adjustment and control of such variables as pulverization, moisture content, oven temperature and bulk density of charge, and through the addition of certain inert materials such as pulverized coke breeze, pitch, high-volatile noncoking or semicoking coal, the benefits so gained have been comparatively small. There are no low or medium-volatile coking coals available within a reasonable freight-cost distance. Therefore a substitute for low-vol-atile coal was developed through low-tem-perature carbonization—or, more correctly speaking, through the partial devolatiliza-tion—of high-volatile coals. The blending of this lower volatile char with the high-volatile coking coal distinctly improves the quality of coke made from Colorado coal. There is nothing especially new about this idea. In 1908 a Japanese patent was taken out by Kotaro Shimomura, whose claim was: The method of making a nonfingery coke out of bituminous coals, without using natural coals of low-volatile matter; according to which a certain coal is heated at a temperature between about 300°C. and about 600°C. so as to leave about 15 to 25 per cent volatile matter in the coal; this coal is mixed with the

Jan 1, 1944

By J. D. Price, G. V. Woody

Many producers of by-product coke have spent considerable time and given considerable thought to the use of a substitute for low-volatile coal as an admixture with high-volatile coking coal for charging high-temperature by-product coke ovens. Generally speaking, there are two principal reasons for this, one being occasioned by the lack, in certain localities, of low-volatile coal delivered at a cost sufficiently low to permit its use, and another being the desirability of finding a substitute product with a delivered cost lower than the cost of the low-volatile coal. It was for the first of these reasons that the Colorado Fuel and Iron Corporation was particularly interested in this subject. This paper deals with the experimental work and the results obtained by that company in producing and using low-temperature char. Overcoming Defects in Coke from Colorado Coals Colorado coking coals are all of the high-volatile type and were all laid down during the Cretaceous period, which makes them something like 80 million or so years younger, geologically, than eastern coals. They behave, when coked alone, something like the Pittsburgh-seam coals. They make a very brittle, highly cross-fractured, fingery coke of fair shatter value but quite low in resistance to abrasion. Mixed with a low-volatile coking coal such as Poca- hontas or certain Oklahoma coals, they make a coke that is equal to virtually any of the eastern cokes. The inferior quality of Colorado coke has long been recognized, and a considerable amount of time, effort and money has been spent upon investigations of means for improving its physical properties. While it has been found that some improvement in quality of coke can be secured by the adjustment and control of such variables as pulverization, moisture content, oven temperature and bulk density of charge, and through the addition of certain inert materials such as pulverized coke breeze, pitch, high-volatile noncoking or semicoking coal, the benefits so gained have been comparatively small. There are no low or medium-volatile coking coals available within a reasonable freight-cost distance. Therefore a substitute for low-vol-atile coal was developed through low-tem-perature carbonization—or, more correctly speaking, through the partial devolatiliza-tion—of high-volatile coals. The blending of this lower volatile char with the high-volatile coking coal distinctly improves the quality of coke made from Colorado coal. There is nothing especially new about this idea. In 1908 a Japanese patent was taken out by Kotaro Shimomura, whose claim was: The method of making a nonfingery coke out of bituminous coals, without using natural coals of low-volatile matter; according to which a certain coal is heated at a temperature between about 300°C. and about 600°C. so as to leave about 15 to 25 per cent volatile matter in the coal; this coal is mixed with the

Jan 1, 1944