Search Documents

By Perry Harrison

THE mixing of fine ores with fuel and burning under induced draft is called sintering in iron-ore practice and either sintering or roasting in copper and lead metallurgy. The first development of sintering was the Huntington-Heberlein process, in which fine sulfide ores mixed with fuel were charged into a pot and burned under the action of an upcast current of air introduced at the bottom of the pot. Modern development has resulted in two types of machine; the continuous Dwight-Lloyd machine, which consists of heat-resisting grates and a moving beltlike type of hearth constructed of metal, in which air is drawn downward through the bed, and the stationary Greenawalt batch process, which operates in the same manner as the Dwight-Lloyd except that the hearth is stationary. The recent rapid increase in the use of sintering has been the result of two great advances in metallurgical process-flotation and the treatment of flue dust. The Dwight-Lloyd machine is used in many plants for agglomerating flotation concentrates and at the same time reducing the sulfur content to furnace requirements and it has become standard practice to treat iron blast-furnace flue dust by either the Greenawalt or Dwight-Lloyd machine, so that it can be recharged into the furnace. The mining of low-grade magnetite iron deposits and their beneficiating by grinding and magnetic separation resulted in a fine concentrate extremely detrimental to blast-furnace practice. These concentrates are sintered and made into ideal material for blast-furnace use. Incidentally, coke savings of about 400 lb. per ton of pig are reported.

Jan 1, 1930

By D. M. Warner, Samuel Daniels

In this paper are given the mechanical properties, determined by the Engineering Division, Air Service, U. S. A., of the 94 per cent. aluminum, 5 per cent. copper, 1 per cent. silicon alloy as 8and-cast and as heal-treated commercially to Air Service Specification No. 11,300. This particular alloy was tested both in the cast and in the heat-treated condition. Tension and tension modulus values were obtained from machined and from un-machined test specimens; while data for shear, compression, impact, torsion, and for Brine11 and Rockwell hardness were found from machined bars. Specific-gravity tests were made on sanded, un-machined specimens. The metallography of the alloy is useful as a control to heat treatment and presents some interesting peculiarities in regard to the two iron-bearing compounds. The demand for an aluminum alloy, suitable for sand castings, that may be heat treated to meet requirements of high strength, ductility, shock and corrosion resistance, and ready machineability has led to the commercial development of a proprietary material that contains from about 4 to 5 per cent. of copper, 1 per cent. of silicon, and such impurities as iron, up to a maximum of 0.75 per cent., and manganese, in quantity usually less than 0.1 per cent.' Magnesium is not generally present, for it tends to nullify the beneficial influence of the added silicon by forming magnesium silicide. The function of the silicon is to minimize casting difficulties and, structurally, to favor the precipitation of (insoluble) iron-bearing skeletons rather than the needles, which prevent full realization of tensile properties from heat treatment by stimulating intergran-ular fracture. The amount of silicon necessary to counteract the ill effect of iron is equal to or slightly more than the content of iron; the excess of silicon over this ratio, under certain conditions of heat treatment, enters with CuAl2, the principal hardening constituent, into solid solution and contributes somewhat to the strength of the alloy without appreciably impairing its ductility. The schedule of heat treatment of this alloy depends on the design (cross-sections) of the castings and on the nature of the tensile properties desired. Essentially, the process consists in heating the material at about 950" F., quenching in oil or in cold or boiling water, and artificially aging

Jan 1, 1926

By C. E. Nighman, R. S. Foster

The following is a description of the methods used in rescuing men and extinguishing the underground fire at the Pennsylvania mine, Butte, Mont. , This fire, which cost the lives of 21 men, began about 9 p.m., Feb. 14, 1916, at or near a ventilating fan on the 1,200 air-shaft station. This shaft at that time was downcast, while the main hoisting shaft was upcast. Owing to the proximity of the fire to the air shaft, the air in the latter soon became heated, and as the fan on the level was not running— the power having been cut off shortly after the outbreak of the fire—the air shaft became upcast to the 300 level. At this point a blanket of cold air from the surface caused the smoke and gases to be drawn in on that level and carried down again through the workings to the 1,200. A short time after the discovery of the fire, water was turned down the air shaft through a series of pipes around the collar of the shaft, which caused the smoke to recede below the 300, so that within 2 hr. it was possible to search that level for the missing men. From the above it will be apparent why the air shaft was upcast instead of downcast, as under normal conditions, and why men were suffocated at considerable distances from the seat of the fire. The smoke and gases that came up the main hoisting shaft did not diffuse through the workings to any extent. There are doors on all levels in the connections to the main hoisting and air shafts, but in the confusion and running around many of these doors were left open, and this undoubtedly caused the smoke and gases to spread more rapidly than they would otherwise have done. It was necessary for most of the men on the various levels to pass close to the air shaft in going to the hoisting shaft, and when they encountered the smoke and gases in that vicinity a number turned back and climbed down with the direction of the air currents and were then suffocated, while all those who passed through the pall of smoke to the main shaft were saved. There were 220 men in the mine that night, and all but 25 were hoisted to the surface within 30 min. after the discovery of the fire. Of the 25, five went out through the Tramway mine, and one through the Moun-

Jan 1, 1918

By Walter Crooke

Regenerative hot-blast stoves are now in general use in all parts of the world, and are so well understood and appreciated, that I need not take up your time with an account of their history and introduction into the United States. My object in writing this paper is to give you a short description of a stove that is now being very favorably received and adopted here (see drawing). The stove was first introduced into this country in 1887 by M'Clure & Shuler (now M'Clure & Amsler), who have the management of the patent right in the United States. The English design had to be modified to suit the exigencies of American blast-furnace practice, which, in many respects, widely differs from our English experience. In the first place, the fire-bricks used in America expand to an extent unknown in England, and it became necessary to make special provision for this by increasing the number of cross-walls, and by leaving a space at the top of the stove through which the lining could expand. The expansion laterally was, however, more difficult to provide for, as the combustion-chamber in the center, being the hottest part of the stove, must necessarily expand more than the outer walls, and therefore tend to squeeze up the flue-openings. On first introducing these stoves to American ironmasters, a feel ing seemed to prevail that a " four-pass " stove did not utilize the whole of its surface. They also had an idea that the " two-pass " stove let the burning gas go before all the duty had been extracted from it; so that it was found neceseary to design a stove of a special character to suit their wishes. Hence the "three-pass" chimney top stove now before your notice, the advantage claimed for which is that each stove is independent, requiring no underground chimney flue or stack, and can be erected at a very light cost. The working of these stoves has proved to be very successful wherever they have been introduced.

Jan 1, 1891

By John Birkinbine

Secretary's Note.—In printing this paper in the present volume, the figures given in the pamphlet edition have been brought more nearly up to date, the product of 1899 being in many instances inserted. Iron-Ore Resources. In a paper presented to the Institute in 1897,* I discussed the iron-resources of the United States as then developed, calling attention to some principal sources upon which other countries depended. The following statement will give a general idea of the amounts, as compiled from the latest official records, of ores won, and metal produced, in the nations which are important contributors to the world's output. Unfortunately these are not all contemporaneous, since in some countries the statistics do not appear until after one or more years. The statement covers not only pig-iron and iron-ore, but also manganese-ore —the manganese mined being principally used in the production of spiegeleisen or ferro-manganese, and these alloys being generally included in the pig-iron output. Table I, which epitomizes the present situation, shows respectively the countries and the quantities of iron-ore and man-

Jan 1, 1901

Following is the personnel of the various society and national committees on which the A I M E is officially represented United Engineering Society Officers of the Board, 1920 JOHN VIPOND DAVIES,, President CALVERT TOWNLEY, 1st Vice-president ALFRED D FLINN,, Secretary WALTER M McFARLAND, 2d Vice-president JOSEPH STRUTHERS, Treasurer Finance Committee House Committee WALTER M McFARLAND Chairman GEORGE H PEGRAM W L SAUNDERS

Jan 1, 1923

By Arthur Wade

The most important development in connection with the search for oil in Australia during 1940 was on the legislative side. Prior to 1939 legislative enactments in the various states with regard to prospecting for petroleum were such as to prohibit large-scale effort and to bar the major oil companies from operating. The preparation of the Wade Model Bill for the Commonwealth Government in 1939 and the acceptance of the Bill in principle by all States, has gone far to remove these obstacles. Amending Acts, largely based on the Alodel Bill, have now been passed by all States with the exception of New South Wales and Tasmania. In New South Wales an Amending Bill is being drafted, while the Govern-ment of Tasmania is preparing to introduce an Amending Bill provided there is any demand for it. Noteworthy developments followed immediately on the passing of these Amending Acts. The Shell Company (1)1 and the Superior Oil Company of California (2) too$ up large areas in Queensland and com-menced work during 1940. Caltex acquired a big tract of country in the Kimberley district of Western Australia (3) and has made application for an area in the Territory of Papua. An Australian company, The Phoenix Oil Extraction Co., has obtained a permit to prospect over an extensive area bordering the south coast of Western Australia (4). Other developments are foreshadowed. The Shell Company is making an intensive examination of its area in Queensland (I). Geological, geophysical and aerial surveys are in progress. Caltex has three geological parties in the held in Western Australia while Superior Oil Company of California has done some geological work in the interior of Queensland (2). None of these concerns envisages a drilling campaign in the near future. Much exploratory work is necessary. Further work has been done by the companies that were already operating in 1939, though an important Australian company - Oil Search—has abandoned the work of prospecting in Australia. This company has subleased its holdings, at North West Cape in Western Australia (;), to Caltex on a royalty basis. The company also maintains its holdings in, and connection with, the Australasian Petroleum Company Proprietary Limited, which is a combination of Standard Oil (New Jersey), Anglo-Iranian and Oil Search. This company is operating in the territories of Papua and New Guinea. Drilling Victoria.—Although a good deal of drilling was done in the LaBes Entrance Tertiary Basin of Victoria (7), no appreciable production of oil was obtained. In order to test the extent and possibilities of the oil-bearing sand in this region, the Commonwealth and State Governments jointly put down six scout boreholes to depths of between 1200 and I500 it. The results were nega tive. A deeper exploratory horehole put down by the Governments at Seacornbe, or 26

Jan 1, 1941

By Arthur Wade

The most important development in connection with the search for oil in Australia during 1940 was on the legislative side. Prior to 1939 legislative enactments in the various states with regard to prospecting for petroleum were such as to prohibit large-scale effort and to bar the major oil companies from operating. The preparation of the Wade Model Bill for the Commonwealth Government in 1939 and the acceptance of the Bill in principle by all States, has gone far to remove these obstacles. Amending Acts, largely based on the Alodel Bill, have now been passed by all States with the exception of New South Wales and Tasmania. In New South Wales an Amending Bill is being drafted, while the Govern-ment of Tasmania is preparing to introduce an Amending Bill provided there is any demand for it. Noteworthy developments followed immediately on the passing of these Amending Acts. The Shell Company (1)1 and the Superior Oil Company of California (2) too$ up large areas in Queensland and com-menced work during 1940. Caltex acquired a big tract of country in the Kimberley district of Western Australia (3) and has made application for an area in the Territory of Papua. An Australian company, The Phoenix Oil Extraction Co., has obtained a permit to prospect over an extensive area bordering the south coast of Western Australia (4). Other developments are foreshadowed. The Shell Company is making an intensive examination of its area in Queensland (I). Geological, geophysical and aerial surveys are in progress. Caltex has three geological parties in the held in Western Australia while Superior Oil Company of California has done some geological work in the interior of Queensland (2). None of these concerns envisages a drilling campaign in the near future. Much exploratory work is necessary. Further work has been done by the companies that were already operating in 1939, though an important Australian company - Oil Search—has abandoned the work of prospecting in Australia. This company has subleased its holdings, at North West Cape in Western Australia (;), to Caltex on a royalty basis. The company also maintains its holdings in, and connection with, the Australasian Petroleum Company Proprietary Limited, which is a combination of Standard Oil (New Jersey), Anglo-Iranian and Oil Search. This company is operating in the territories of Papua and New Guinea. Drilling Victoria.—Although a good deal of drilling was done in the LaBes Entrance Tertiary Basin of Victoria (7), no appreciable production of oil was obtained. In order to test the extent and possibilities of the oil-bearing sand in this region, the Commonwealth and State Governments jointly put down six scout boreholes to depths of between 1200 and I500 it. The results were nega tive. A deeper exploratory horehole put down by the Governments at Seacornbe, or 26

Jan 1, 1941

By I. A. Lesk

The various materials utilized in the construction of integrated circuits, and the resultant materials interfaces, are discussed with emphasis on a materials system that is compatible with all types of integrated circuits and minimizes the number of different interfaces. Problems with interfaces may originate in the silicon, on its surface, and between other materials within the integrated-circuit package independent of the silicon. ThE difference between integrated-circuit theory and practice may generally be spelled out in terms of the difficulties in fabricating a desired structure. There are, of course, problems in forming the requisite materials, of the necessary composition and geometry, where needed. A distinct class of problem, however, is associated with interfaces— generally between different materials, but occasionally between regions of the same material. We require that each interfacial system perform its proper electrical, mechanical, and thermal function, and do so in an unchanging manner with time under the most severe operating conditions. In a practical sense, we deal in nonideal systems, such that it is generally not possible to form an interface exactly the way it was intended, even if we allow for a knowledge of the practical limitations of the fabrication system. Another way of looking at this situation is to realize that, when we form a group of interfaces under apparently the same experimental conditions, there are often differences of important consequence between them. Very high-magnification pictures, such as are obtained by an electron microscope, reveal fine structure that often differs over the area of a given sample, as well as from sample to sample. Low-magnification pictures look better, but don't eliminate the problem. The trend towards integrated circuits, and away from circuits fabricated utilizing separate components, is very strong in many areas of electronics. A typical silicon monolithic integrated circuit, still in place in the wafer on which it was fabricated, is shown in Fig. 1. The increased reliability which is being experienced through the use of integrated circuits can, to a large extent, be credited to the reduced complexity of the interface system that is present in the electronic system. A glance at Fig. 1, however, with all of its epitaxial and diffused p-n junctions, and interconnect system, shows that interfaces have been far from eliminated. Fig. 2, depicting a schematic cross-sectional view of a (partial) typical integrated circuit, illustrates in detail the numerous interfaces that occur in this type of structure. Besides the individual circuit elements, there are interfaces for isolation, and, Fig. 3, even a crossover requires a series of interfaces. What has been accomplished, however, irrespective of whether or not the total number of interfaces in the circuit is increased or decreased, is that the variety of interfaces is very much reduced. This is because there are fewer materials involved. Since the expense incurred in an R & D program to improve reliability is pretty much directly proportional to the variety of interfaces involved, it is economically advisable to work with integrated circuits for highest reliability. That is not to say that circuits built using standard components could not be made as reliable as integrated circuits, but that the expense involved because of the more complex over-all interface system would be much greater. Although electronic performance utilizing integrated circuits with all silicon elements (i.e., transistors, diodes, resistors, capacitors) is adequate for many applications, there are numerous instances where thin-film passive elements must

Jan 1, 1965

By John Henderson

Densities of melts 0f the lime-iron oxide-silica system in contact with solid iron have been measured by the maximum bubble pressure method in the temperature range 1250° to 1440°C and the composition range 0 to 40 mol pct lime, 15 to 100 mol pct iron oxide, and 0 to 55 mol pct silica. Densities range from 4.65 g cm 3 for wustite at 1440°C to 2.75 g cm-&apos; at 1350°C for a melt containing 30 mol pct lime, 20 mol pct iron oxide, and 50 mol pct silica. The results are interpreted in terms of a postulate that the melts can be regarded as a random array of oxygen ions in which regions of local order exist to satisfy the coordination requirements 0.f the cations. An understanding of the nature of metallurgical slags is basic to the development of a sound theoretical description of heavy metallurgical extractive and refining processes. Because these liquids are complex, direct measurements of their properties has not thrown much light on their structure. This has led to the approach of measuring the properties of simpler liquids, and building up their complexity until slag compositions are reached. In this way the density of liquid iron silicates was measured in a previous study1 and the present work represents a further stage in this synthesis. EXPERIMENTAL The technique used in the measurement of density was the maximum bubble pressure method. Details of the apparatus and procedure were similar to those previously reported,&apos; with the exception that a constant voltage transformer was used to supply the power input to the furnace and six silicon carbide resistance elements were used in place of the molybdenum winding. With these modifications melt temperature could be maintained within 1 centigrade degree during the course of a run. The silica used to prepare the melts was washed natural quartz ignited at 1000°C; wustite was prepared by air-melting A.R. grade ferric oxide in an iron crucible and lime was prepared by air ignition, at 1000°C, of weighed quantities of A.R. grade calcium carbonate, previously air-dried at 110°C. The finely ground constituents were intimately mixed in a glass ball mill prior to melting. Temperatures quoted are accurate to * 5°C and the standard deviation of the density values, calculated by the method of least squares, ranged from 0.5 to 1.8 pet. However, replicate determinations of density on different melts of the same nominal composition at the same nominal temperature did not vary by more than 1 pct, Table I, and this figure has been taken as an estimate of the accuracy of the density results. The density of carbon tetra-chloride was also measured as a check on the absolute performance of the experimental method. At 20°C a value of 1.593 * 0.002 g cm"3 was obtained; this compares with the literature value2 of 1.595 g cm"3. Results of experiments designed to measure the dependence of the density of lime-iron oxide-silica melts, in contact with solid iron, on composition and temperature are shown in Table I. Because iron sometimes precipitated in the sample during quenching, the Fe203 chemical analyses were only poorly reproducible and should be taken as a guide rather than as absolute values. Fig. 1 shows the data from various sources for the density of liquid iron silicates and Fig. 2 shows isodensity contours at 1410°C for lime-iron oxide-silica melts, calculated by graphical interpolation of smoothed curves drawn through the experimental results, together with the 1400°C results of Adachi and ogino3 and Pope1 and Esin.4 Fig. 3 shows the isothermal variation with composition of the volume of melt per gram ion of oxygen at 1410°C and Fig. 4 shows regions in which the temperature coefficient of this volume is negative, positive, or negligible (<0.005 cm3 deg-I). DISCUSSION a) Disparity Between Reported Density Results. Consider the system iron oxide-silica, the results for which are summarized in Fig. 1. Although there is some difference in the temperatures at which the various densities apply, this difference is not sufficiently large to account for the observed discrepancies. The reliability of the present results for the low-silica region has been confirmed by measurement of the density of liquid wustite by three different techniques. At 1410°C the density measured by a balanced-column method was 4.55 g cm"3, by a combination balanced-column and gas-densitometer method 4.59 g emd3, and by a pycnometer method 4.53 g cm"3. Schenck, Frohberg, and Hoffermann&apos; have also reported a value of 4.55 g cm"3 for the density of liquid wustite at 1400°C. It must be concluded, therefore, that neither Pope1

Jan 1, 1964

By A. E. Dwight, A. F. Berndt

Binary and ternary alloys of uranium with transition metals were prepared with U2X stoichiometry. The compounds U2Tc, U2Rh, U2Os, and U2lr were formed by peritectic or peritectoid transformations, and were shown to be isostructural with U2Ru. The lattice constants are presented. Miscibility relationships obtained from the study of ternary alloys are graphically summarized in terms of an area-of-stability plot. The compound U2Re is not isostructural with either U2Ru or U2Mo. A series of compounds with stoichiometry U2X has been prepared in which X is technetium, rhodium, rhenium, osmium, or iridium. The only other U2X compounds, for which X is related to the above transition metals by proximity in the periodic table, are U2Mo and U2Ru. The structure of U2Mo is the tetragonal C11b type (MoSi2 type)1 and U2Ru is monoclinic, with a new structure type.&apos; This investigation was undertaken to determine if any of the above compounds are isostructural with either U2Ru or U2Mo and to find the range of occurrence of these phases. EXPERIMENTAL Alloys were prepared from stoichiometric amounts of electrolytic uranium (99.99 pet pure) and transition metals of 99.5 pet purity (98+ pet pure Tc), by arc melting on a water-cooled copper hearth under an Ar-He atmosphere. Weight losses were negligible. The buttons were homogenized at temperatures between 700o and 800°C (900°C for U2Tc) in evacuated capsules and air-cooled. The X-ray powder specimens were annealed briefly at the temperature of homogenization. Except in the case of the technetium alloy, metallographic examination was used to determine the number of phases present. The radiation hazard involved in handling technetium precluded the use of metallography to examine U2Tc. The temperature and mode of formation of the U2X phases were determined by heating the metallographic specimens to successively higher temperatures, until examination indicated the presence of chilled liquid or a peritectoid transformation. RESULTS The U2X compounds investigated were found to be formed under the following conditions: UzTc unknown U2Ru peritectic 897o ± 3°C U2Rh peritectoid 755o ± 5°C U2Re peritectoid3 below 750°C Uas peritectic4 920°C U2Ir peritectoid 775o ± 5oC Debye-Scherrer patterns for the above U2X phases were made with CuKa radiation (nickel filter). The similarities in the positions and intensities of the strongest lines in the front-reflection region strongly suggested that U2Tc, U2Ru, U2Rh, U2Os, and U21r are isostructural with only minor differences in the unit-cell dimensions. The known lattice constants and intensities of the Debye-Scherrer rings for U2RU2 were used as a guide in order to index the low-angle X-ray reflections of the U2TC, U2Rh, U2Os, and U2Ir powder patterns. Approximate lattice constants for these compounds were thus obtained and were used along with the intensities observed for U2Ru to index the strongest lines in the back-reflection regions. A sin2 2? correction term was included and the lattice constants were refined and standard deviations estimated by least squares. Comparison of observed and calculated values of Q(= 4 sin2?/?2) used in these calculations are given in Table I. In each case when the positions of lines could not be resolved on the films they were not measured. The final lattice constants, with their standard deviations, are given in Table 11, along with the unit-cell volume and X-ray density. The values of the atomic volume5 of the transition ele-

Jan 1, 1965

By Shirley Mason, L.G. Huntley

The predominant sedimentary formations in Colombia are those of Tertiary age. They form the floor of the Magdalena Rivcr valley and the coastal plain that borders the Caribbean Sea: this is also true of the southern part of the narrow coastal belt of the Pacific coast.

Jan 1, 1923

By Shirley Mason, L. G. Huntley

The predominant sedimentary formations in Colombia are those of Tertiary age. They form the floor of the Magdalena Rivcr valley and the coastal plain that borders the Caribbean Sea: this is also true of the southern part of the narrow coastal belt of the Pacific coast.

Jan 1, 1923

By W. B. Wise, H. D. Attra, W. M. Black

The purpose of this paper is to illustrate a comparatively new approach for solving a problem that has plagued oil producers for many years—how to make the most money with available field production capacity. In a very basic operation such as a top-allowable one-well field, a computer and staff of engineers are not required to determine that the best operation is to produce that well at its maximum for as long a time as it will produce. However, as the problem becomes more complex and the number of wells and number of reservoirs increase, it probably will be a wise choice to devote some engineering thought and calculation time to determine the best way to operate that field on both an ultimate and day-to-day basis. Continued developments in the field broadly referred to as "operations research" have led to a number of useful engineering analyses for optimizing field operational problems. One of these techniques, termed linear programing, is parlicularly interesting because of its potential applications to the study of complex oilfield operating problems. Linear programing is concerned with the problem of planning a complex set of interde~endenl activities in the best possible (optimal) fashion. A field application of linear programing is being used to maximize daily income from a multi-reservoir producing operation. The initial results of this study indicate that the linear programing technique (I) can be applied effectively to field problems, (2) can be used to detect unsuspected avenues for improving operations and (3) can effect a significantly improved means of controlling field operations through the use of the highspeed computer. INTRODUCTION The usual approach for studying complex field operational problems has been to look in detail at several basic plans suggested by judgement and experience and, then, to choose the best plan from those investigated. This approach is entirely satisfactory provided: (1) that judgment and experience alone will reliably pick the best or near the best program as one of the plans to be investigated; and (2), and most important, that the factors which control field production will not change. This paper deals with the large group of field operations which are at least one-step removed from a satisfactory solution using the conventional method of analysis. Problems such as pipeline- and gathering-system design, transportation studies, large field development projects and multi-reservoir producing operations fall in this latter category. To find the best program for handling these problems when the best program is not obvious, a complete optimization study is required, and high-speed computers are required to continually update the program once it is selected. Operations of this type have an extremely large number of possible solutions. However, only one will result in maximum economic return and, more important, this one program must be re-evaluated and adjusted constantly to accomodate such changing field factors as the number of producing days, the price of crude, the discovery of new reserves, declining reservoir pressure with subsequent decline in production and a host of other factors which characterize specific operations. One of the most widely used, direct methods of optimization is a numerical procedure termed "linear programing", which is designed to investigate systematically each of the possible solutions involved in a given problem, determining rapidly and uniquely the optimum answer. As implied by the name, linear programing requires that all field variables be either defined or expressed in a series of interdependent linear equalities or inequalities. These relationships are solved simultaneously, using a form of matrix solutions to determine the optimum values for each producing variable that will maximize net profits. The solution techniques used in a recent field case study is termed the "simplex method" and is discussed in full detail in Ref. 1.

By R. E. Cech, J. H. Hollomon

KURDJUMOV and Maksimova reported experiments with manganese steels and high carbon steels&apos; and with an Fe-Ni-Mn alloy&apos; in which mar-tensite was formed isothermally over a range of temperatures. They found in some cases that mar-tensite formation could be suppressed by rapid quenching to liquid nitrogen temperature. From their microstructural observations of martensite formed isothermally, they concluded that the rate controlling step is nucleation rather than growth. Kulin and Cohen,3 in an attempt to reproduce these experiments, found that with a steel having the same composition as that reported by Kurd-jumov and Maksimova, the transformation to martensite was essentially complete above the temperature range of Kurdjumov and Maksimova&apos;s isotherms. The possible reasons for this disagreement were not considered. Recent papers by Das Gupta and Lement4 and Kulin and Speich5 report the formation of isothermal martensite in a high chromium steel and in an Fe-Cr-Ni alloy, but neither paper can be considered a verification of the original Kurdjumov and Maksimova results. Further, in neither case were the authors able to suppress the formation of martensite entirely. Because of the important bearing the Kurdjumov and Maksimova results have to an understanding of the mechanism of martensite reactions it was felt that an experimental investigation directly concerned with checking the validity of their results was in order. This paper describes the results obtained on the isothermal transformation over the temperature range from —79" to —196°C of an alloy of iron, nickel, and manganese. Experimental Apparatus A 15 lb heat of an alloy containing 73.3 pct Fe, 23.0 pct Ni, and 3.7 pct Mn was melted by induction and cast under argon. The ingot was forged to 1-in. bar and a portion rolled to 1/16x1 1/2-in. strip. This strip was pack-homogenized 300 hr at 1100" in a helium-filled sealed iron tube. The composition after homogenization was 73.2 pct Fe, 22.94 pct Ni, 3.73 pct Mn, 0.05 pct C, and 0.015 pct N. The strips were cut to 1/2-in. width for dilatometer and metal-lographic specimens. Only the center portion of the 11/2-in. strip was used in the present investigation. The dilatometer employed was similar in design to one described by Flinn, Cook, and Fellows." A concentric fused auartz rod and tube assembly with hooks for holding the specimen was mounted so as to transmit the specimen dilation to a 1/10,000 in., 1/10 in. travel dial gage. The dilatometer proper was mounted by means of extension arms to a counterweighted sliding member on a vertical standard. This method of mounting permitted rapid transfer of the dilatometer from the austenitizing furnace to the quenching bath and low temperature chamber. A small electrical vibrator on the dilatometer kept frictional effects of the quartz members at a minimum. The austenitizing unit was a vertical, molybdenum-wound, hydrogen atmosphere furnace maintained at a constant temperature ±3°C by means of constant power input. A 12-in. stainless steel jacketed copper liner having 1/2-in wall thickness acted to equalize the temperature in the hot zone of the furnace. This liner, closed at the bottom end and open at the top to permit entrance of the dilatometer and specimen, was kept filled with dry nitrogen gas. A chromel-alumel thermocouple was placed inside the tube to determine the temperature. The 4-in. dilatometer specimens in the chamber varied less than 1/2° across the specimen length except for a 1 1/20 drop at the end nearest the open end of the furnace. The low temperature isothermal holding bath was a double Dewar arrangement similar to one described by Turnbull7. The outer bath was filled with a refrigerant at a temperature lower than the desired holding temperature. The inner bath was filled with Freon "11" or "12" or a mixture of both, depending upon the holding temperature. This inner bath which tended to be cooled by the outer bath was kept at a constant temperature by introducing a small amount of heat with a manually controlled electric heater. Stirring was accomplished by bubbling dry air through the bath. A Leeds and North-rup type K potentiometer was used to measure the inner bath temperature as indicated by a five element copper-constantan thermopile. The bath temperature was maintained within ±0.2°C of the desired temperature by occasionally adjusting the heater current so as to keep the Leeds and Northrup galvanometer at zero deflection with a constant setting of the potentiometer. Isothermal tests were usually continued for 300 to 400 min and another reading made at approximately 1000 min if the bath, unattended overnight, had not deviated in temperature more than 5°C. Transformation curves are drawn dashed (Fig. 1) through the time region where temperature was not controlled precisely. Experimental Procedure Dilatometer specimens of 1/2x1/16-in. strip were cut to 41/2-in. length and holes were drilled for the quartz hooks with proper spacing to give a 4-in. measured length. A thermocouple consisting of 0.012-in. diameter chrome1 and alumel wires was spot welded to the specimen and threaded between the dilatometer rods to binding posts near the dial

Jan 1, 1954

H. W. Turner, Portland, Ore. (communication to the Secretary*) :—Mr. Brown&apos;s paper on the complicated groups of veins exposed in the workings of the Bodie mine forme a valuable contribution to the literature of the structural features of ore-depoeits. It is much to be desired that managers should put into print the results of their observations of the mines under their charge. These observations, as well as data of production, kind of ores, etc., usually accumulate for years, and unless the mining geologists of the Geological Survey happen along before the mine is worked out, such data seldom get into print. About the year 1899 I went through the mines at Bodie with R. C. Turner, then superintendent, and made some notes on the veins and gangue-minerals, and collected some specimens. Mr. Brown refers to crystals of feldspar (albite) found on fragments of quartz on the surface. I collected a number of specimens of these crystals, mostly from Queen Bee hill, and

Jan 1, 1909

By Barry D. Lichter, Pierre Sommelet

High-temperature heat contents of InSb, GaSb, and AlSb were measured over the temperature range 400" to 1450°K using a diphenyl ether drop calorimeter. Smoothed ualues of the thermal properties, H$ - H:9s, have been derived and are tabulated at even temperature intervals. The heats of fusion of the three compounds were determined as, respectively, 5707 *100, 7780 * 100, and 9800 5 3011 cal per g-atorn at the determined melting points of 797" l°, 985" * , and 1330" * 5°K. The calculated entropies of fusion are, respectively, 7.16 0.12, 7.90 * 0.11, and 7.37 * 0.23 cal per deg per g-atotn. The heat capacities increase substantially on tnelting in contrast to the behauior of structurally related germanium and silicon. Deriations from the Kopp-Neumann rule are negative for solid compounds and positive for the liquid phases. Previously obsevrrd "post melting" in InSb is confirmed. The high-temperature thermal properties of 111-V compounds are presently not well-established, despite the technical importance of these semiconducting cbmpounds. Uncertainties in available heats of fusion and heat contents have seriously hampered thermo-chemical evaluations&apos; and thermodynamic analyses of phase equilibria2"" in these systems. This paper reports results of high-temperature heat content investigations of InSb, GaSb, and AlSb measured in the range 400" to 1450°K employing a diphenyl ether drop calorimeter. Similar measurements for InAs and GaAs will be reported in a following publication.~ EXPERIMENTAL PROCEDURES Samples. High-purity samples of the compounds InSb and GaSb were supplied in the form of crushed crystal fragments by Dr. Carl Thurmond of the Bell Telephone Laboratories and in the form of single crystals by Dr. A. Strauss of the M.I.T. Lincoln Laboratory. Single-crystal samples of semiconductor-grade AlSb were supplied by Dr. W. P. Allred of the Bell and Howell Research Center. Chemical analyses indicated that all compounds were stoichiometric to *0.1 at. pct, which is within the experimental uncertainties of the analyses. Samples were crushed, weighed, and encapsulated in evacuated, thin-walled, fused silica capsules. The capsules were nearly identical in external shape, 2 cm by 2 cm diam, but varied in weight due to differences in wall thickness. One sample of AlSb was contained in a thin-walled, high-purity alumina cup encapsulated in silica and used for heat content determinations of liquid AlSb. The capsule materials showed no visual evidence of reaction with any of the compounds. The sample and capsule weights are given in Table I. Calorimeter. A Bunsen-type calorimeter, similar in design to a previously described instrument6 but employing diphenyl ether (C6H5)&apos;0 as the calorimetric substance, was used for measurements of heat contents above 300.0°K, the melting point of diphenyl ether. Heat input to the calorimeter caused isothermal melting of diphenyl ether, and the resulting increase in volume was measured by displacement of mercury from the calorimeter into a 200 cm horizontal, calibrated capillary, 1.25 * 0.01 mm diam, or into a weighed beaker. The advantages of diphenyl ether over water have been previously pointed out7 and include: i) an increase by a factor of 3.5 in sensitivity as measured by the ratio of the volume change to the enthalpy change on fusion, ii) the smaller required extrapolation from the melting point to the standard temperature of 298.17"K, and iii) the positive volume change on fusion of diphenyl ether in contrast to the contraction which occurs on fusion of ice. Diphenyl ether was purified by fractional crystallization to 99.95 mol pct as determined from the melting point depression with fraction crystallized. During assembly of the calorimeter, the ether was repeatedly outgassed under high vacuum to remove dissolved air. The calorimeter receiving vessel consisted of an 8-in.-long by 1:-in.-diam copper tube with twelve horizontal 3-in.-diam radiator "fins" for dissipating heat to the surrounding mantle of diphenyl ether. Before forming the mantle the chamber surrounding the receiving vessel contained 3300 cu cm of liquid diphenyl ether above 250 cu cm of mercury which was

Jan 1, 1970

By Robert Glass Cleland

FROM the time of its organization down to 1917, a period of more than eighty years, Phelps, Dodge & Co. was seldom involved in what could be called a major labor difficulty. Behind this remarkable record lay both a philosophy and its practical application. The philosophy was an attitude toward society called the Golden Rule. That philosophy had been a living principle in the lives of the founders of the company, Anson Phelps, Daniel James, and William E. Dodge. Their successors, William E. Dodge, Jr., and Daniel Willis James, accepted the same philosophy. Dr. James Douglas governed his life by it. All of these men and their families had given tangible expression to that conviction in benefactions of great magnitude and variety-churches, hospitals, educational institutions, libraries, missionary undertakings, and other organizations for human betterment, such as the Young Men&apos;s and Young Women&apos;s Christian Associations, and the development of model communities about their mills and factories. According to the best standards of their generation, they had sought to improve the condition of labor,

Jan 1, 1952

By C. Graeme-Barber, R. L. Bell, T. G. Langdon

An analysis is made of the formulas and ,methods used to estimate the contribution of grain boundary sliding to the overall strain of a polycrystal. The errors involved in the approximations and/or ,mistakes in earlier work are assessed quantitatively so as to make possible the critical use of previously published data. SINCE it has been found that, under conditions of very slow creep, the strain due to grain boundary sliding (?gb) may contribute as much as 80 pct of the total creep strain,1,2 it is obviously important to have reliable methods for estimating this grain boundary strain. In two recent papers Stevens3,4 has drawn attention to the pitfalls encountered in assessing ?gb. He criticizes 1) the assumptions made in the derivation of some of the formulas for ?gb, and 2) the indiscriminate averaging procedures used for obtaining the quantities substituted in these formulas. These and further criticisms of earlier work are mostly valid. Unfortunately the only formulas and procedures recommended are either impossible or very difficult to apply in practice. Furthermore no attempt is made to assess the errors involved by the earlier approximations or mistakes, and so it is not possible to make critical use of any of these early dab. The present article attempts to improve on these shortcomings by reference to empirical verification of easily applied formulas whose theoretical derivations involve some otherwise unjustifiable assumptions, and by a quantitative assessment of the errors in previous work. DEFINITIONS First it is necessary to define the terms and symbols to be used. The choice of symbols preferred here is a logical combination and extension of the v introduced by McLean5 and the u by Brunner and rant.&apos; In Fig. 1 the two grains X and Y are displaced by the sliding vector AC. u is the component of sliding resolved along the stress axis, v is that measured perpendicular both to the stress axis and to the specimen surface, and w is that measured perpendicular to the stress axis but in the plane of the surface. Two angles define the orientation of the grain boundary: 8, between the stress axis and the surface trace of the boundary, and +, the internal angle on a longitudinal section cut perpendicular to the surface. In computing the strain resulting from the boundary displacement at all the in- dividual boundaries in a polycrystal the components u, v, or w are sometimes averaged along a longitudinal line (i.e., parallel to the stress axis), sometimes along a transverse line, and sometimes at randomly chosen boundaries. Averages obtained in these three ways are given subscripts 1, t, and r, respectively. Stevens rightly calls attention to the possibility of non-equiaxed grain shapes either at the start or at the end of deformation. In this article all values of numbers of grains per unit length will refer to measurements made before deformation. The subscripts 1 and t will be used for the number of grains per unit length obtained along longitudinal and transverse lines, r for that obtained by averaging along a number of randomly directed lines. FORMULAS FOR ?gb ?gt, as a Function of u. An obvious truth is that cgb can, in principle, be obtained by summation of all the v components at the boundaries intersected by a longitudinal line of known length I, viz.: where nl is the number of grains per unit length, parallel to the stress axis, in the unstrained specimen. There are assumptions in the analytic derivation of Eq. [I] due to Brunner and rant&apos; but ~achinger&apos; arrived at Eq. [la] by a rigorous method. Unfortunately the experimental procedure required by Eq. [ la] proves very difficult as boundary migration tends to obscure the points at which the longitudinal line meets the grain boundary and the errors on such measurements tend to be large, see Fig. 2. For example, on a specimen of Magnox AL 80 at a creep strain of 9.7 pct, 300 measurements of u obtained from the points of intersection of a longitudinal line with the grain boundaries gave ul = 8.95 ± 3.58 pm, or an error of ±40 pct, at the 95 pct confidence limit. These large errors due to migration may be avoided by measuring u from the separation of the segments

Jan 1, 1968

By M. B. Holt

At this time, when electricity in its various applications is attract- ing so much interest, and with such good reason, it has been suggested to me that, as the Aspen Mining and Smelting Company, of Aspen, Pitkin county, Colorado, was the first mining company in America to employ electrical power for hoisting, a record of what has been accomplished by this company would be of interest. Early in the year 1888 the question of power for the development of the ore-horizon lying below the level of the tunnel through which the property is worked, became one of importance. The conditions under which it was proposed to use power were as follows (See Fig. 1): The company&apos;s mines lie upon the northwestern slope of a mountain, the ascent of which is at an angle of 28&apos; from the horizon. The ore, consisting of argentiferous galena and other silver-bearing mineral, is found at or near the plane of contact of a superincumbent mass of blue limestone, with an underlying bed of dolomite. This contact plane dips north 30° west, at an angle of 60&apos; with the horizon. A tunnel 1000 feet in length, driven south into the mountain near

Jan 1, 1892