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By Leo J. Vogel, E. D. Hummer

INTRODUCTION by E. D. HUMMER An efficient refuse-disposal system is a necessary part of the modem cleaning plant. The large-scale refuse system and disposal area, engineered for the lifetime of the plant, has become more important due to the greater tonnages of refuse produced from increased quantities of mechanically mined and prepared coal. Laws and increased government regulations have affected the design and operation of disposal systems. THE EFFECT OF MINE AND PLANT OPERATION Refuse disposal starts at the mining face. The mining system, the type of roof support, the machinery used, and the degree of discipline at the face contributes to the amount and type of refuse that must be removed through the disposal system. Economies gained through modification of the mining system or mining machinery may be partially offset by increased dilution of the mined coal with impurities from associated rock formations. In some cases the change in the mining system and equipment has reduced the dilution. In all cases the ratio of impurities that must be removed from the raw-coal feed to the plant not only affects the maintenance and operating costs of the plant, but greatly affects the design of the refuse disposal system. The design of a mine and plant should include the location and the estimated capacity of the disposal areas for the life of the property or plant. Complete evaluation of the disposal system and an estimate of its annual cost of operation over the life of the property or plant should be incorporated in the plant and mine evaluation. Plant design should be as simple as possible, consistent with the efficient production of clean coal. Material transfer points, crushing, screening and pumping operations should be kept to a minimum to reduce degradation and the subsequent increased difficulty and cost of refuse removal. The maintenance of good process control by operating management will result in a minimum of misplaced material in both refuse and clean coal. Reduction of misplaced float material in the plant refuse is an important factor in preventing combustion in the refuse storage pile. THE REFUSE DISPOSAL AREA Combustion in refuse piles occurs when air enters the pile in sufficient quantity to support oxidation. At certain rates of air in-filtration, the heat produced by the oxidation process is not dissipated and temperature rises.

Jan 1, 1968

By John L. Lamont, Walter Crafts

AN investigation has been made of the multiplying factors for some of the more common alloying and deoxidizing elements for use in calculating hardenability of steel according to Grossmann's method.1 The factors for manganese, silicon, and aluminum that were reported in an earlier communication2 have been confirmed by microscopic determination of the half-martensite structure rather than on the basis of an empirically determined hardness corresponding to a half-martensite structure. Measurement of ideal critical diameter by microscopic examination was found to he necessary for other alloying elements, and multiplying factors for nickel, chromium, molybdenum, zirconium, vanadium, titanium, and boron have been determined. The nature and order of magnitude of the multiplying factors reflect the effect of the alloying elements on the structural character of the steel. Except for nickel and vanadium, the multiplying factors agree fairly well with previously published results. Good correlation between actual and calculated ideal critical diameters has been found in developing the multiplying factors and in checking the results against fairly simple steels. However, some discrepancies have suggested the need for a more thorough study of low-carbon and complex steels. TESTING PROCEDURE The investigation was conducted principally on steels made at the Union Carbide and Carbon Research Laboratories, Inc., in high-frequency induction furnaces using Armco iron and standard alloying materials. However, a few open-hearth steels were used in establishing the effect of nickel, and the hardenability factor for boron was based primarily on open-hearth steels. All bars were normalized prior to the machining of Jominy hardenability specimens. The Jominy test was carried out under conditions standard for the test.3 Austenitizing temperatures judged to-be-appropriate for the composi¬tions of the steels were used., Chemical analysis was determined on a sample taken adjacent to the Jominy specimen. Residual amounts of phosphorus, sulphur, nickel, chromium, molybdenum, and copper were determined on only one heat of each group made with the same materials during the same period. "Acid-soluble" aluminum and zirconium rather than total amounts were determined, as it is considered probable that the acid-soluble amount is more representative of the effective alloy. As tin was present to the extent of only 0.002 per cent, its effect was neglected. The method used to determine boron in the steels shown in Table 9* was developed by Galen Porter, Vincent Napoleon, and Thomas R. Cunningham,of the Union Carbide and Carbon Research Laboratories, Inc., and is. a modification of J. Naftel's procedure for boron in soils

Jan 1, 1944

By Paul J. Sirkegian

The problem of properly controlling the movements of underground trains in the Emma Nevada and Morris Brooks workings of the Consolidated Coppermines Corporation of Kimberly, Nev., became more complex as the rate of production increased. Ore from these mines, which are connected through a 7000-ft. single-track haulageway (Fig. I), is hoisted through the Emma Nevada shalt. All production to date has been from one level. Because of heavy ground, even on the main haulage horizon, experience has shown that it is necessary to have a minimum cross section in the drifts, thus making it impractical to have a double track system. In 1937, production was 3000 tons per day; in 1938 it was increased to 6000 tons per day and in 1940 to 9000 tons per day. Each increase necessitated a revision in the method of controlling the underground traffic. In 1937 the tramming signal system consisted of a few signal lights in the main haulage drift. These lights were two 100-watt bulbs in a metal box that had one green and one red lens on each side. The box was mounted on the underside of a drift cap timber and could be seen For a considerable distance. The lights were so arranged that all boxes showed either red or green at the same time and all were controlled by a magnetic contactor at the entrance to each lateral drift. When the lights showed green, the main haulage was clear of traffic and a train could enter it. As the motor entered the main haulage drift, the motorman pulled the cord of the magnetic contactor switch, thus changing all the main haulage lights to red, which indicated that no other train could use the main haulage until the first train had turned into a lateral drift. When a train left the main line, its motorman pulled the cord connected with the magnetic contactors, causing the haulage lights to show green again. This arrangement permitted only one train at a time to use the main haulage and thus limited the number of train trips per shift, but it was satisfactory when the ore handled was only 3000 tons per day. Second SystEM Installed With a gradual increase in production it became necessary to place a train dispatcher in charge of all trains. He controlled their movements orally, giving his orders direct or by mine phone, instructing them where to load, when to leave for the station and when to return. His objective was to group several trains traveling in the same direction. Because of the human element involved, some mistakes were made. The danger of a serious collision was always possible. There was a 90° turn and curve in the underground haulageway, therefore travel in this section was always dangerous if mistakes were made in directing traffic. To protect the train crew, particularly the rear switchman who rode the last car or caboose, a two-way push button and flash-signal system was installed on the

Jan 1, 1946

By D. C. Ganow, N. J. Grant, I. R. Silver, A. R. Chaudhuri

The structural changes that result when a metal is "cold worked" lead to higher values of yield and tensile strength on subsequent deformation at room temperature. Further it has been shown that the beneficial effects of cold work are, to some extent, maintained even at elevated temperatures. The strength improvements from prior cold work decrease as the temperature is raised and are a function of grain size, amount of cold work, and strain rate (or time of test). If recrystallization occurs during test, the cold-worked material may even show weaker stress-rupture properties than the annealed material. A question that arises is whether there is a significant effect on the subsequent creep behavior if the prior deformation is performed under creep conditions at high temperatures not too different than the test temperature, but at significantly different strain rates and for various amounts of strain. An answer to this question was sought in the work described in the present paper. PROCEDURE Two materials were used in this work, high-purity aluminum and a solid-solution A1 2 pct Mg alloy. The compositions are shown in Table I. The grain size in the two materials was 0.2 to 0.3 mm. The deformation for both the prestraining and for the creep tests was at constant stress. The procedure adopted was to prestrain a specimen to the desired elongation, remove the load, and cool to room temperature rapidly by spraying. the test bar with cold water. The specimen was then placed in a creep machine, held at the test temperature for less than 5 min, and loaded. Less than 15 min was required to bring the specimen to temperature. The creep stress was based on the diameter resulting from the prior strain, and values of elongation at fracture listed in the tables do not include the respective elongations resulting from the prestrain. The choice of the stresses for the prestrain and for the creep tests was made so that the tests could be completed in relatively short times to maximize any effect of prestrain. The specimens had a gage length of 1 in., the pure aluminum specimens having a diameter of 0.150 in. and the alloy specimens a diameter of 0.125 in. For pure aluminum, prestrain was at 400' and 600°F with testing at 500°F; for the alloy, prestraining was at 700°F and testing at 600°F. RESULTS The prestrain conditions for the aluminum and the alloy specimens are shown in Tables I1 and IV. In addition to showing the time required to achieve the desired prestrain, the expected rupture Lives are given which would have resulted had the creep prestrain been continued to fracture. The prestrained and the annealed specimens were then tested in creep to fracture; the temperature and stress for the pure aliminum specimens being 500o F and 1800 psi and for the alloy, 600' F and 3400 psi. The creep curves for the prestrained and the annealed specimens of pure aluminum showed all three stages of creep; hence in addition to the effect of prestraining on the rupture life, it was also possible to determine the effect of prestraining on the minimum creep rate, and on the time and elongation at the end of each of the three creep stages. The results are shown in Fig. 1 and Table 111.

Jan 1, 1960

By Parke A. Dickey

Potential differences between strata of shale and sandstone have been recognized for about 15 years, and they form the basis of the electrical logging of oil wells. Hitherto these potentials have been ascribed solely to electro-¦ chemical reactions caused by the disturbing effects of the water in the drill hole through which they are generally measured. Observations by the author in wells empty of water and in a mine shaft suggest that potential differences between sandstones and shales are natural and specific properties of the rocks, although they are moditied in measurement by the disturbing effects of the water in the drill hole. The cause of these potentials probably is to be sought in the relative polar adsorptive capacities of quartz and clay particles. Introduction The existence of potential differences in the surface of the earth has been known for some time, and their measurement has facilitated the discovery of geological discontinuities such as ore bodies. The technique of measurement has been well established.1-3 In measurements in oil wells, it has been found that the potential of shales with respect to some arbitrary reference is very nearly constant in any one well, at least below the zone to which meteoric water has gained access. Sandstones and some other types of sedimentary rocks have a difference of potential with respect to shale that is negative arid may attain a value of 200 millivolts or more. The difference of potential, as usually measured commercially with water in the hole, is distributed over about one foot vertically at the top and bottom contacts of the sandstones. The sharpness of the curve at the formation contacts can be improved by using a short electrode that is close to the wall of the hole' These potentials generally have been ascribed to the disturbing effects of the water in the drill hole. Potentials have been found, however, in wells in which no water was present. In the course of experiments in electrical logging in pennsylvania, carried out by the pennsylvania Geological Survey, observations were made of several phenomena that hitherto have not been described, to the author's knowledge, ill the published literature. The potential differences across the contacts of sandstone and shale are called ill this paper "natural potentials," as distinguished from the potentials caused by electroendosmosis (electrofiltration) and concentration differences, which will be discussed subsequently. Potentials in Cored WeLl In the spring of 1942, the author measured the potentials in an exploratory well (Day 13, near Grand Valley, Pa.) which had been cored With diamond tools. The potentials were first measured with fresh water in the hole. * null balance potentiometer was used in this and all the other measurements described in this paper. One nonpolarizing porous pot electrode, containing copper sulphate solution and

Jan 1, 1946

By Parke A. Dickey

Potential differences between strata of shale and sandstone have been recognized for about 15 years, and they form the basis of the electrical logging of oil wells. Hitherto these potentials have been ascribed solely to electro-¦ chemical reactions caused by the disturbing effects of the water in the drill hole through which they are generally measured. Observations by the author in wells empty of water and in a mine shaft suggest that potential differences between sandstones and shales are natural and specific properties of the rocks, although they are moditied in measurement by the disturbing effects of the water in the drill hole. The cause of these potentials probably is to be sought in the relative polar adsorptive capacities of quartz and clay particles. Introduction The existence of potential differences in the surface of the earth has been known for some time, and their measurement has facilitated the discovery of geological discontinuities such as ore bodies. The technique of measurement has been well established.1-3 In measurements in oil wells, it has been found that the potential of shales with respect to some arbitrary reference is very nearly constant in any one well, at least below the zone to which meteoric water has gained access. Sandstones and some other types of sedimentary rocks have a difference of potential with respect to shale that is negative arid may attain a value of 200 millivolts or more. The difference of potential, as usually measured commercially with water in the hole, is distributed over about one foot vertically at the top and bottom contacts of the sandstones. The sharpness of the curve at the formation contacts can be improved by using a short electrode that is close to the wall of the hole' These potentials generally have been ascribed to the disturbing effects of the water in the drill hole. Potentials have been found, however, in wells in which no water was present. In the course of experiments in electrical logging in pennsylvania, carried out by the pennsylvania Geological Survey, observations were made of several phenomena that hitherto have not been described, to the author's knowledge, ill the published literature. The potential differences across the contacts of sandstone and shale are called ill this paper "natural potentials," as distinguished from the potentials caused by electroendosmosis (electrofiltration) and concentration differences, which will be discussed subsequently. Potentials in Cored WeLl In the spring of 1942, the author measured the potentials in an exploratory well (Day 13, near Grand Valley, Pa.) which had been cored With diamond tools. The potentials were first measured with fresh water in the hole. * null balance potentiometer was used in this and all the other measurements described in this paper. One nonpolarizing porous pot electrode, containing copper sulphate solution and

Jan 1, 1946

By Francis Cameron

Gloomy predictions that domestic mineral reserves are approaching exhaustion are unwarranted and may be harmful, this author contends. Specific mineral forecasting errors in the Paley Report are cited to support this contention, and steps that can be taken to insure a progressive mineral industry capable of keeping pace with the major raw material needs of the nation through advancing technology are suggested. Mining is both exciting and rewarding —although at times somewhat frustrating— and we all can have real pride in our industry, in its people, and in its accomplishments. It is, however, with concern that I have noted a deterioration in this Country in what might be called mining's stature and in the growth of a belief in many quarters that our mineral reserves are rapidly approaching exhaustion. In other words, there is a popular image that we are fast becoming a "have not" nation in many respects and that the domestic mining industry can no longer be considered, in the vernacular of Wall Street to offer much in the way of "growth potential." I do not subscribe to this hypothesis, nor do I be-li4ve that the record of the mining industry bears this out. However, let me add that we can, in time, talk ourselves into this frame of mind and we can hasten the day when this very well might come about by unnecessary and unwise legislation or regulation. My remarks today are basically designed to give my reasons for refuting this negative philosophy and to review our record. With your help, I know we can improve our image, and the public's recognition of our industry's peculiar problems. The progress of our civilization over the centuries has been fundamentally based upon proper use of raw materials, both agricultural and mineral, and upon energy, human or otherwise. As the standard of living has progressed century by century, the demands for mineral raw materials have increased in an irregular, but steadily rising progression. Fortunately, those minerals on which we depend most, i.e., iron, coal, petroleum, copper, aluminum, lead, and zinc have been neither too difficult to find nor to process into useful form. Iron, the most useful of all metals, is present in various amounts in most rock types and soils. Gold, seemingly the most generally desired (but certainly not the most useful of all metals), occurs in sea water in a far greater total tonnage than has been won from all of the world's known gold mines. If the latter is true, then why do we not see large installations treating sea water for the recovery of its gold content? The answer, of course, is that even the French, who seem, from their recent actions, to value gold above all else, have not devised a way of doing this at a profit. Theoretically, it is possible, but not with today's technology at a cost which would justify the effort. Man has exploited only those mineral concentrations which accidents of nature have placed within his so far limited means of finding and utilizing. What we geologists and engineers refer to as an orebody is nothing more than a concentration of minerals, exploitable with available knowledge, that will yield a value greater than the value attached to the energy and capital required to produce it. What is "ore" and what is not "ore" is, in the end, a matter of economics. The economic problem stems from the physical and chemical character of mineral deposits. The good Lord stacked the cards heavily in favor of rising costs by limiting the amount of the higher grade ores easily available. As the best and most accessible ores are depleted, it becomes necessary to work harder and with greater ingenuity to produce more from less accessible and lower grade resources. The quantity of mineral raw materials we can have in the future will be determined largely by what we can afford to pay for them in terms of human effort, capital outlay and production energies. We will always have the problem of cost with us and our only real means of keeping ahead of rising costs is by continually improving our technical abilities. We, in this country at least, no longer have open to us large and unexplored virgin wildernesses in which a pick-and-shovel prospector might uncover an untouched mineral bonanza. The rest of the world also has few conventional frontiers left in which the explorer-prospector is free to roam. We do, however, have enormous land areas unexplored, and untouched po-

Jan 1, 1969

By C. H. Mathewson, W. R. Hibbard, Robert Maddin

A satisfactory mathematical relationship between shear, elongation and change of orientation in the axial straining of a single crystalline rod or wire may be based on a simple model in which blocks, representing glide lamellae, glide over one another and rotate so as to maintain the original fixed position of the axis as the wire elongates.' Obviously such a model gives no information concerning strain-hardening or the atomic adjustments at the sliding surfaces and their influence on the internal structure of the blocks. Moreover such an operation could be conducted with rigid blocks only by using self-aligning grips or a flexible attachment which would permit the adjacent blocks to freely assume their changing orientations. There are many unsolved problems (see Andrade2) concerning the manner in which nature departs from the simple model in permitting the essentials of slip, rotation and elongation to occur along with strain-hardening and the appearance of glide lamellae of various dimensions and special characteristics, not fully appreciated at the present time. This paper describes part of an extensive investigation on the development and characteristics of glide ellipses in single crystalline alpha brass rods and is especially concerned with the observation of cross-slip in crystals oriented wholly within the range of slip on a single system according to the generalizations first presented by Taylor and Elam in 1923.³ Experimental Procedure Half-inch rods of alpha brass (nominally 70 pet Cu, 30 pet Zn)* were converted into single crystals by melting and gradual solidification in a graphite mold according to the Bridgman method.4 In order to remove any coring, the crystals were homogenized at 800°C for 16 hr and tested by etching with a 50 pet nitric acid solution. The back-reflection Laue technique as described by Greninger6 was used for determining the orientations of the crystals. Standard stereographic operations were employed to locate the specimen axis in a triangle of the Taylor and Elam3 projection so that the slip plane and direction could be predicted. The lineage structure reported by Buer-ger6 was present in the crystals used in this investigation. However, only crystals were used in which the internal differences in orientation did not exceed two degrees. Very little is known concerning the effect of the presence of a lineage structure on the detailed mechanism of plastic deformation.

Jan 1, 1949

By C. H. Mathewson, Robert Maddin, W. R. Hibbard

A satisfactory mathematical relationship between shear, elongation and change of orientation in the axial straining of a single crystalline rod or wire may be based on a simple model in which blocks, representing glide lamellae, glide over one another and rotate so as to maintain the original fixed position of the axis as the wire elongates.' Obviously such a model gives no information concerning strain-hardening or the atomic adjustments at the sliding surfaces and their influence on the internal structure of the blocks. Moreover such an operation could be conducted with rigid blocks only by using self-aligning grips or a flexible attachment which would permit the adjacent blocks to freely assume their changing orientations. There are many unsolved problems (see Andrade2) concerning the manner in which nature departs from the simple model in permitting the essentials of slip, rotation and elongation to occur along with strain-hardening and the appearance of glide lamellae of various dimensions and special characteristics, not fully appreciated at the present time. This paper describes part of an extensive investigation on the development and characteristics of glide ellipses in single crystalline alpha brass rods and is especially concerned with the observation of cross-slip in crystals oriented wholly within the range of slip on a single system according to the generalizations first presented by Taylor and Elam in 1923.³ Experimental Procedure Half-inch rods of alpha brass (nominally 70 pet Cu, 30 pet Zn)* were converted into single crystals by melting and gradual solidification in a graphite mold according to the Bridgman method.4 In order to remove any coring, the crystals were homogenized at 800°C for 16 hr and tested by etching with a 50 pet nitric acid solution. The back-reflection Laue technique as described by Greninger6 was used for determining the orientations of the crystals. Standard stereographic operations were employed to locate the specimen axis in a triangle of the Taylor and Elam3 projection so that the slip plane and direction could be predicted. The lineage structure reported by Buer-ger6 was present in the crystals used in this investigation. However, only crystals were used in which the internal differences in orientation did not exceed two degrees. Very little is known concerning the effect of the presence of a lineage structure on the detailed mechanism of plastic deformation.

Jan 1, 1949

By A. U. Seybolt, R. A. Oriani

The pressure and composition of the solid solution of nitrogen in chromium has been investigated as a function of temperature. The partial molal heat of solution, the activity of nitrogen in solid solution, and the partial molal free energy have been computed. The enthalpy of three reactions is summarized: N + 2Cr(3) = Cr2N(4), H° = —28,500 cal per mol 1/2N2(p) + 2Cr(8) = Cr2N(3)1 ?HO = —23,500 cal per mol 1/2N2(p) = N, ?H° = 5,000 cal per mol. WORKERS who have investigated the problem of the preparation of ductile chromium have been concerned with the effects of minor amounts of impurities upon this refractory metal. In particular, gaseous impurities such as oxygen and nitrogen have been suspected of causing trouble because of many known cases where brittleness in transition elements has been definitely traced to these elements. In order to evaluate the possible effects of the nitrogen impurity in chromium, it appeared desirable to learn something of the dependence of the nitrogen solubility upon temperature and pressure. Previous Work Maier3 in 1942 in his treatise on sponge chromium reviewed the thermodynamics of the chromium nitrides Cr2N and CrN, both of which are well-estab- lished compounds, but which apparently have not been studied in much detail. Maier presented some free energy-temperature expressions for the reactions 2 Cr,N = 4 Cr + N2 [1] and 4 CrN = 2Cr2N + N2 PI based mainly on the work of Satoh2 and Sano." Pearson and Ende3 in 1953 briefly reviewed the thermodynamics of Cr-N using the same data available to Maier, and also derived a free energy-temperature expression for reaction 1. Of the two nitrides mentioned previously, the present investigation was only concerned with Cr,N, since this nitride is in equilibrium with the metal phase, at least over most of the temperature range, Blix4 in 1929 established the structure of Cr2N (close-packed-hexagonal) by X-ray diffraction methods, and indicated that its homogeneity limits extend from 11.2 pet to 15.1 wt pet N. At a temperature of 1200°C, 38 mm Hg from the Maier expression and 43 mm Hg from the Pearson

Jan 1, 1957

By W. H. Bassett, C. Davis

Although brasses and bronzes have been made for ages, a systematic study of their physical properties has been carried out only during the years of the present century. Among these properties may be included those which are to be detected by means of microscopic examination; in other words by the science of metallography. The earlier workers in this field, both in this country and abroad, gave their attention to steel. When the senior author explored the situation in 1902, there was little encouragement to be found in undertaking the study of the non-ferrous alloys. A start was made, and the metallography of the brasses and bronzes, as well as of the copper-nickel-zinc alloys developed materially under his direction. Annealing experiments were begun in 1902, and in the succeeding years the effect of temperature, and the influence of previous working, on the grain size of brass were studied. The conclusions so well known and widely published today were largely reached during those earlier years. In 1905 the first complete annealing series were made. By this it is meant that brass and copper sheet, 5 B & S Nos. hard, was machined into tensile test specimens, then annealed under accurate control for 30 min. at temperatures up to the melting point of the material. Various determinations were made, including tensile strength and elongation in 2 in. There rapidly followed similar series on all of the copper-zinc alloys from 100 to 60 per cent, copper, on the bronzes, cupronickels, and on copper-zinc-nickel alloys. At this point there was published by Grard, in October, 1909,' the very comprehensive and complete work on the tensile properties of cartridge brass, 90-10 copper-zinc, and electrolytic copper. The excellent photomicrographs in that paper illustrated the changes in structure produced by cold rolling as well as by annealing at different temperatures, but where Grard's work was confined to copper and to two alloys, the investigations in this laboratory have been over the entire fields of the commercial copper-zinc alloys, copper-tin alloys, representative copper-nickel and copper-nickel-zinc alloys as well as aluminum bronzes and others of a more special nature.

By A. S. Nowick, C. Y. Li

It is deMonstrated that quenching from an elevated temperataupe accelerates the grain boundary relaxation in two solid solutions (aAg-Zn and a Cu-Al). This result is consistent with the proposal that, in solid solutions, grain boundary relaxation occurs by a mechanism of' self diffusion. Nevertheless, an alternative possibilitg, that quenching introduces vacancies into the boundary itself, must also be considered. THE phcnomenon of grain boundary relaxation has been well known for many years,1,2 yet the mechanism of this process is very poorly understood. One of the most interesting suggestions which relates to the mechanism of grain boundary relaxation was that of Ke,3 who claimed that the activation energy for grain boundary relaxation and for lattice self diffusion were essentially the same. The implication is therefore that the elementary step in the two processes is the same. This suggestion is particularly startling in view of the fact that activation energy for self diffusion along a grain boundary is very significantly lower than that for volume self-diffusion. Later evidence5-7 showed that there really are two grain boundary peaks, one which appears in high-purity metals, and the other (which develops at a higher temperature than the first) which appears in solid solutions beginning at solute concentrations in the range of 0.1 pct. Data for silver6 show that Kg's hypothesis is surely incorrect for the grain boundary peak in the high-purity metal, since it has an activation energy of only 22 kcal per mole, but that the hypothesis may still be correct for the grain boundary peak in various silver solid solutions, for which activation energies in the range 40 to 50 kcal per mole are observed. If the elementary step in the grain boundary relaxation process were the same as that for self-diffusion, it would be expected that the relaxation process could be hastened by quenching, 2.c. by introducing a non-equilibrium excess of lattice vacancies. Such a quenching effect has already been demonstrated in the case of another anelastic relaxation process, viz., the Zener relaxation effect. The Zener effect, which occurs in essentially all solid solutions, may be attributed to the reorientation of pairs of solute atoms in the presence of an applied shear stress,' and therefore must take place by means of a volume diffusion mechanism. The hastening of this process through quenching9 has been one way of demonstrating that atom movements in the lattice take place through a defect mechanism, presumably single vacancies. In order to see if the grain boundary relaxation is affected by quenching, it is particularly convenient to compare the grain boundary relaxation with the Zener effect, by choosing a specimen for which both relaxation effects appear. Specifically, a fine-grained sample of a solid solution shows in the curve of internal friction vs temperature, first a peak due to the Zener effect, then a second rise (and eventually a peak at substantially higher temperatures) due to the grain boundary relaxation. The same phenomena are also observable in static anelastic measurements, such as creep at very low stress levels. Thus, for the same fine-grained solid solution, the creepstrain, when plotted against log time, falls on a sigmodial curve with a sharp inflection point, due to the Zener effect, which is followed by a second rise and inflection resulting from the grain boundary relaxation. To look for a quenching effect, static measurements are preferable to the dynamic internal friction measurements, due to the fact that quenching effects tend to anneal out too rapidly at the temperatures at which the internal friction is measured.9 RESULTS AND DISCUSSION Creep experiments in torsion were carried out in an apparatus similar to that described by Ke1, whereby a wire is held under constant torque and its angular displacement is observed as a function of time. The alloy Ag-30 at. pct Znwas selected because of the large Zener relaxation that it displays. The two samples used were a "coarse grained" wire with a mean grain size about twice the diameter of the wire (diam = 0.032 in.), and a "fine-grained" wire which had several grains across the diameter. In Fig. 1 a comparison is made of the creep curves at 160°C of these two samples after they had been cooled slowly from 400°C. Curve A, which represents the coarsegrained sample, shows a unique relaxation process due to the Zener relaxation, with a relaxation time, T , in the vicinity of 100 sec. Curve B, which represents the behavior of the fine-grained sample, on the other hand, shows first the same relaxation process as that in A, followed by a turning up of the curve which corresponds to the onset of a second overlap-

Jan 1, 1962

By B. H. Caudle, R. E. Watson, I. H. Silberberg

The production history of an inverted nine-spot injection pattern was studied with a porous plate model similar to Habermann's. Colored fluids were used so the boundary movements could be photographed. By varying the production rates of the side and corner producing wells, the optimum pattern sweep efficiency can be obtained. Results of the laboratory tests indicate that interpolation of the pattern sweep and conductivity ratio data will permit application of the data to predicting fluid injection operations with mobility ratios between 0.1 and 10 and production rate ratios between I and the optimum values. INTRODUCTION The inverted nine-spot injection pattern in Fig. 1 has some unique advantages over other regular injection patterns (five spot, line drive, etc.) used in secondary recovery operations. It has three producing wells for each injection well, while the five-spot and line-drive patterns require an equal number of injectors and producers. Futher-more, of the eight producing wells surrounding each injection well, four are of the "side well" type which lie nearer the injection well than the remaining four "corner wells". This allows the production rates of these two types of wells to be adjusted independently of each other to obtain better pattern sweep efficiency. This latter advantage may well be the reason why the nine-spot patterns have not been studied as extensively as the patterns containing only one type of injection or producing well. The pattern sweep efficiency of the inverted nine spot is affected almost as much by operating with different producing rates of the comer and side wells as by differing mobility ratios. Possibly because of this added operating parameter, published studies of nine-spot systems have been limited in their coverage of the pertinent variables.'-' The model studies reported here covered the mobility-ratio range normally found in waterflood operations, as well as the variation in well production rates necessary to achieve optimum pattern sweep efficiency. Conductivity ratios — a measure of the change in total flow at constant pressure difference — were obtained during each model run. A porous-plate model with miscible fluids representing the in-place and injected fluids was used in this study. This model technique is the same as that used in both X-ray shadowgraph" and visual techniques4 described in the literature. Using miscible fluids eliminates residual oil in the model, and the permeability to the injected fluid is the same as to the in-place fluid. Thus the mobility ratio in the model is given by the ratio of the viscosity of the displaced fluid to the viscosity of the injected fluid. Because of the non-linear nature of the viscosity vs composition curve for two miscible liquids, the mobility change across the boundary between the two fluids is reasonably sharp. This technique thus represents the displacement of a region of one fluid mobility by a region of possibly different mobility in an isotropic system under steady-state flow conditions. Table 1 shows the dimensionless similarity groups used to scale the model conditions and results to

Jan 1, 1965

By R. V. Smith

The theory for unsteady radial flow of gas, as simplified by Aronofsky and Jenkins, has been reviewed and compared with actual well performance. This study indicated that the theory should be modified by the introduction of an empirical "rate of flow" function "Y(q)". The expansion of the theory on the flow of gas to include a Y(q) term bridges the gap between the theory of unsteady-state flow of gas and actual gas-well behavior. Apparently, the Y(q) term is a function only of the rate of flow for a given well. The completion factor or skin effect is associated with the Y(q) function in such a manner that at least two or more sets of drawdown or pressure build-up tests are needed to separate the Y(q) function and the completion factor. Since the Y(q) function used in this report represents an energy loss dependent on rate of flow near the well-bore of a gas well which is in addition to the loss required by Darcy's law, the Y(q) function is related to the exponent of the back-pressure curve for a gas well. Techniques and equations are presented which permit the estimation of stabilized and "short-time" deliver-abilities. INTRODUCTION The published theory of radial unsteady-state flow of gas through porous media may be divided into papers1-" which use Darcy's law as a premise and other papers4-7,16-10 which recognize that Darcy's law may not hold for flow into gas wells. Miller8 compared theory based on Darcy's law with actual gas-well behavior and concluded that flow into gas wells deviates from Darcy's law. Houpeurt4,5 in a thorough investigation of flow into gas wells concluded that the flow rate into a gas well is proportional to the difference between the squares of upstream and downstream pressures elevated to a power between 1.0 and 0.5. Houpeurt also concluded that the deviation from Darcy's law is caused by irreversible, kinetic energy exchange between the flowing gas and the porous media. Tek9 presented a complete evaluation of the flow problem in gas wells. Several investigators state that the inclusion of gas compressibility into flow equations based on Darcy's law does not begin to explain the flow problems suggested by gas-well behavior. For many years, natural-gas engineers have realized that gas wells by actual test exhibit behavior which cannot be explained entirely by Darcy's law. Many tests on gas wells have indicated that a value of 0.85 for the exponent in the back-pressure equation is a fair average for many wells. However, Darcy's law either for steady or unsteady-state conditions indicates that the exponent should be 1.0. The purpose of this paper has been to examine this deviation from Darcy's law and to present a reasonable mathematical means of evaluating the deviation. The method presented in this paper combines previous theory with an empirical function to provide a description of gas-well behavior. All equations in this report are for constant terminal-rate-of-flow conditions. While present methods of testing wells usually are not based on this concept, they are believed to approach the constant terminal-rate conditions closely in many tests. However, several gas wells were tested by holding the rates of flow constant in order to approach more closely the constant terminal rate of flow; the results confirm the concepts presented in this paper. REVIEW OF THEORY FOR UNSTEADY-STATE FLOW OF GAS The basic partial differential equation for the flow of natural gas has been given in technical literature; the equation for a cylindrical reservoir with the well in the center is

By J. B. Conway

Stress-vuptuve data for several of- the refractory metals are frequently found to yield a linear relationship between the Larson-Miller parameter and the logarithm of the applied stress. In such cases linear stress-rupture isotherms result with slopes bearing a definite relationship to the temperature. It also follows that the stress to produce rupture in a certain period of time will be linear in temperature. Data for several refractory metals have been reviewed and excellent linearity is shown in this type of isochronal plot. In addition, the af ore - mentioned lineavity leads to a linear relation between the log of the stress to produce rupture in a certain time and the homologous temperature. This has been illustrated for the Group VI-A metals, tungsten and molybdenum. EXTENSIVE use has been made of the Larson-Miller' parameter in the interpolation and extrapolation of stress-rupture and creep data. In those cases where this particular parametric approach is applicable a convenient and fairly straightforward procedure is made available for the correlation of experimental stress-rupture data. It is quite common to employ this parameter in the form of a master rupture plot in which the parameter, T(C + log tr), is expressed as a function of log stress. In many cases this functional relationship in log stress is linear within acceptable accuracy and hence the following relation results: where P is the parameter, C is the Larson-Miller constant, T is the absolute temperature, t~ is the rupture time, a is the stress, and a and b are constants. Examples of such a relationship are contained in the work of Green, Smith, and 01son2 dealing with high-temperature rupture behavior of molybdenum and in the work of Green' dealing with the high-temperature behavior of tungsten. In addition, pugh4 has shown a similar linearity for some fairly low-temperature data for molybdenum. It can be shown that when the relationship in Eq. [I] is exhibited certain generalizations can be made concerning the form of the stress-rupture isotherms. For example, rearranging yields: For a given material (constant C) at a given temperature the first term on the right-hand side of Eq. [2] is a constant and hence this equation defines a straight line when log stress is plotted as a function of log-rupture time. This is recognized as the standard form usually employed in this type of data presentation. Such linearity then suggests the linear form of the Larson-Miller parameter. Or, in other words, the linear parametric relationship in Eq. [2] results only when the stress-rupture data are linear on a log-log plot of stress vs rupture time. Another interesting observation can be made in regard to Eq. [2]. It can be noted that the slope of the stress-rupture isotherms is given by - T/b and hence a direct calculation of the constant b is available. It also follows that since the value of b is the same for all temperatures the slopes of the various isotherms on the log-log stress-rupture plot cannot be the same. Indeed, the existence of the relationship in Eq. [2] precludes a system of parallel lines on this common stress-rupture plot. As a matter of fact it further specifies that in addition to being nonparallel the slope of these isotherms must decrease (i.e., become more negative) with increasing temperature. Such a condition is indeed found to exist in the case of the stress-rupture data reported for molybdenum.' As a corollary to the above, it may be stated that stress-rupture data which do not lead to a linear log-log stress-rupture plot or whose isotherms do not exhibit a decrease in slope as the temperature increases will not yield the linear relationship of Eq. [I]. Applying Eq. [2] to two different temperatures and solving for C yields: Eq. [3] affords a simple and rapid method for calculating the Larson-Miller constant from the log-log stress-rupture plot. The slope of a given linear isotherm is measured and the value of "b" calculated based on Eq. [2] as: slope = - -Tb Then at an abscissa value of 1.0 hr (making log tr in Eq. [3] equal to zero) read the stress corresponding to rupture for two different temperatures. Substitution in [3] yields: A value of the Larson-Miller constant can thus be calculated from a few simple mathematical procedures employing data read directly from the log-log plot of the stress-rupture data. Of course, it is not to be overlooked that the above reasoning has been based on the linear relationship of Eq. [I] being applicable. However, if as mentioned above the log-log plot is

Jan 1, 1967

By J. D. Sullivan, Chester R. Austin, J. L. Nunes

IT is characteristic of most shales and surface clays that a bloated or vesicular structure is produced by burning to a sufficiently high temperature, usually about 150° to 200°F. above the normal maturing temperature used when making common brick of the same material. Early investigators recognized this phenomenon and attributed it to the release or expansion of gases in the vitrified piece. A number of theories have been advanced on the source of the gas and the manner in which it is evolved, but none has been proved conclusively. T. E. Jackson's1 early theory that bloating was due to oxygen evolved by ferric oxide in forming ferrous oxide or ferrous silicate was never substantiated by experimental work. Orton2 thought this explanation unlikely, as all clays should bloat at the same temperature, if this were true. He found that clays bloated in the range from 1100° to I700°C. Also, many clays containing iron did not bloat at all, but fused. Orton also stated that oxidation of different types of carbon was a source of gas during burning of clay and should be expelled before vitrification was reached. Seger3 said that he had dissolved ferric oxide in glass with no apparent evolution of gas. Matson4 came to the conclusion that ferruginous clays burned to vitrification in an oxidizing atmosphere did not have the iron in a ferrous form. According to Wilson,5 the gases responsible for bloating might be entrapped air, water, sulphur dioxide, carbon monoxide, oxygen, and hydrocarbons. He spoke of two causes of bloating: (I) incomplete oxidation below the vitrification temperature, and (2) decomposition of compounds and evolution of gases above the vitrification temperature. Decomposition of calcium sulphate was given as the principal example of the latter. Bleininger and Montgomery6 stated that if any time after vitrification began the evolution of gaseous matter was rapid enough so that pressure was produced within the clay, bloating was certain to take place, and a vesicular structure would be formed. They recognized that initial structure, rate of heating, kiln atmosphere, and many other variables affected bloating. Work done by the Emergency Fleet Corporation7 indicated that clays suitable for bloating should be high in compounds of metallic oxides, carbon, sulphur, sodium, potassium, or other equivalent compounds, which either act as a flux or give off gas. Orton2 studied the chemical status of the carbon, iron, and sulphur in clays during various stages of burning, using a Huron shale that bloated under oxidizing or reducing conditions. He found that only a small amount of sulphur remained in the clay and that it could be detected only by dissolving the clay in hydrofluoric acid,i.e., the sulphur was in combination with the silica. Orton said that this sulphur was probably in the form of iron sulphide dissolved in the glass phase. The iron sulphide was not broken down by heating, but was dissolved in the basic slag or glass,

Jan 1, 1942

By George Sachs

I deeply appreciate the honor of being selected to deliver the twentieth Annual Lecture of the Institute of Metals Division. The subject of my paper is extremely involved and voluminous, therefore I shall discuss only some more recent experimental material and speculate somewhat on the physical and mechanical fundamentals of these changes. The flow and the rupture of a solid material are rather different phenomena. It is therefore surprising that up to a rather advanced stage in metallurgical science these two fundamental phenomena have been simultaneously treated and forced into the general conception of the "failure " of solid material. Only in this century, and particularly during the last 20 years, have the very different physical meanings of flow and rupture been clearly recognized. Several hundred of the more recent publications deal with these subjects.l Law of Similarity The basic values commonly considered responsible for the mechanical behavior of any material are the stresses. From this standpoint both a large and a small article made from the same homogeneous metal and of geometrically similar shapes should behave identically, i.e., they should deform geometrically in a similar manner, if subjected to the same stress values at corresponding points. This "law of similarity" was introduced about 60 years ago simul- taneously by Barba2 and Kick3 and was derived from the classical theory of elasticity. As far as the plastic behavior of a metal is concerned, this rule appears to be valid. The conventional properties of large and small tension or compression test bars, machined from larger sections, are identical; while the force required to deform a section is proportional to its cross-sectional area and the work consumed in deforming geometrically similar articles in a geometrically similar manner is proportional to its volume. The general trend of the stress-strain diagram of a metal is independent of the section size (Fig. I). No exceptions from this rule are known. However, if the deformation of a metal is continued until rupture occurs, and the breaking stress or the work consumed is measured, a test bar of large cross section appears to fail before or at lower stresses than does one having a small cross section. Thus, the specific impact energy has been often found to decrease with increasing size of the test specimen, particularly for materials with a limited ductility.4 Another exception from the rule of similarity is offered by fatigue-strength values, which usually decrease with increasing section size.6'6 The conclusion must be drawn from these experimental facts that the ductility of a homogeneous metal decreases with increasing section size (Fig. I). This effect has been actually confirmed by Docherty,7 who observed that in static notch bending tests large specimens failed earlier and in a more brittle fashion than small specimens ma-

Jan 1, 1941

By George Sachs

I deeply appreciate the honor of being selected to deliver the twentieth Annual Lecture of the Institute of Metals Division. The subject of my paper is extremely involved and voluminous, therefore I shall discuss only some more recent experimental material and speculate somewhat on the physical and mechanical fundamentals of these changes. The flow and the rupture of a solid material are rather different phenomena. It is therefore surprising that up to a rather advanced stage in metallurgical science these two fundamental phenomena have been simultaneously treated and forced into the general conception of the "failure " of solid material. Only in this century, and particularly during the last 20 years, have the very different physical meanings of flow and rupture been clearly recognized. Several hundred of the more recent publications deal with these subjects.l Law of Similarity The basic values commonly considered responsible for the mechanical behavior of any material are the stresses. From this standpoint both a large and a small article made from the same homogeneous metal and of geometrically similar shapes should behave identically, i.e., they should deform geometrically in a similar manner, if subjected to the same stress values at corresponding points. This "law of similarity" was introduced about 60 years ago simul- taneously by Barba2 and Kick3 and was derived from the classical theory of elasticity. As far as the plastic behavior of a metal is concerned, this rule appears to be valid. The conventional properties of large and small tension or compression test bars, machined from larger sections, are identical; while the force required to deform a section is proportional to its cross-sectional area and the work consumed in deforming geometrically similar articles in a geometrically similar manner is proportional to its volume. The general trend of the stress-strain diagram of a metal is independent of the section size (Fig. I). No exceptions from this rule are known. However, if the deformation of a metal is continued until rupture occurs, and the breaking stress or the work consumed is measured, a test bar of large cross section appears to fail before or at lower stresses than does one having a small cross section. Thus, the specific impact energy has been often found to decrease with increasing size of the test specimen, particularly for materials with a limited ductility.4 Another exception from the rule of similarity is offered by fatigue-strength values, which usually decrease with increasing section size.6'6 The conclusion must be drawn from these experimental facts that the ductility of a homogeneous metal decreases with increasing section size (Fig. I). This effect has been actually confirmed by Docherty,7 who observed that in static notch bending tests large specimens failed earlier and in a more brittle fashion than small specimens ma-

Jan 1, 1941

By R. W. Winson

Asbestos is the generic name given to a group of fibrous mineral silicates found in nature. They are all incombustible and can be separated by mechanical means into fibers of various lengths and cross sections, but each differs in chemical composition from the others. The commercial grades of asbestos consist of a spectrum of lengths and sizes and are not definitive as are most organic fibers. It is generally recognized that there are two main groups of asbestos. The first only contains the fibrous serpentine called chrysotile and comprises about 94% of the world production of asbestos. The second group contains five minerals in the amphibole series+rocidolite, amosite, anthophyllite, tremolite, and actinolite. The latter two have no commercial importance. Properties Physical The structures of asbestos fibers have been studied intensively over a number of years. X-ray diffraction patterns have been used as a means of identification and classification. Low angle X-ray scattering techniques have shown that chrysotile fibers are "hexagonally close packed" and parallel to each other, having cross-sectional diameters varying from 18014 to 300A units, while the amphibole fibers are many times larger in cross section. Electron micrographs of the more common types of as- bestos are shown in [Figs. 1-4]. [Fig. 1] illustrates the softness and flexibility of chrysotile which make it suitable for textile-type products. For a number of years there was considerable controversy over the exact nature of chrysotile fiber, but the photographic evidence in [Figs. 5-7] clearly show that it is tubular in structure. The curvature is the result of the mismatch in the dimensions of the silica [Si,O,l and brucite [Mg(OH),] layers which are on the inside and outside, respectively, of a double sheet. This curvature had been predicted by Pauling (1930) years ago based on the molecular dimensions of the two component structures.

Jan 1, 1975

By E. R. Stover, J. Wulff

A tentative 870°C isothermal section, the solidus equilibria, and the solubility of Tic and graphite in the nickel solid solution have been determined with arc-cast specimens. Each of the Ni-Ti intermetallics forms two-phase fields with Tic; only Ti,Ni has a measurable solubility for carbon. A quasi-binary eutectic exists between Tic: and a titanium-rich nickel solid solution; ternary eutectics occur on either side, with TiNis or with graphite. Graphite is in equilibrium with a nickel solid solution containing a ratio of Ti/C which increases below the solidus. DURING the past decade, titanium-carbide cermets containing nickel or cobalt alloy binders have been widely studied for high-temperature and wear-resistant applications. Recent work has emphasized control of the carbide grain size and distribution2's and the thermal exparision match between the phases/ The present study was initiated to determine the phase compositions during the sintering or infiltration process, and during subsequent heating. Although the effects of additives and impurities in commercial compositions are important, it was necessary to consider first the pure ternary, Ni-Ti-C. Emphasis was placed on the nickel corner, since the nickel solid solution is the continuous phase in compositions having highest strength. Early metallographic work by Zarubin and Molkov- showed that solid solubility at either end of the section Ni-Tic is small. Edwards and Raine reported that nickel dissolves between 3 and 5 wt pct Tic at 1250° C, on the basis of microstructures of annealed, vacuum-melted powder mixtures. Although the solubility of nickel in Tic has not been measured, Tic formed by the menstruum process in liuid-iron solution contains as little as 0.06 wt pct Fe. BINARY SYSTEMS The most recent determinations of the three binary systems are summarized in Fig. 1. Titanium carbide (6) is predominant among the binary phases, and it melts above the boiling point of nickel. The Ni-C binary is based on separate liquid solubility' ) and solid solubilitylo measurements. The eutectic temperature, 1328OC, is taken from the solidus determination described below. However thermal analysis data by Morrogh and williams also show eutectic arrests in this vicinity in the absence of supercooling. The Ni-Ti binary is taken from the work of Poole

Jan 1, 1960