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By C. T. Young, J. L. Lytton

In recent investigations,1,2 the strength and thermal stability of dislocation substructures prepared by 5 to 25 pct room temperature tensile straining and recovery annealing at 120°, 160°, and 200°C have been studied in randomly oriented polycrystalline high purity aluminum. The techniques of transmission electron microscopy revealed that a major source of the strength and stability of dislocation substructures was the formation, during room temperature straining, of well-defined cells bounded by dislocation tangles which rearranged into nearly perfect dislocation networks during recovery, forming the boundaries of subgrains. The strength of such substructures increases with decreasing cell or subgrain size,2"6 and the formation of fine subgrain structures can provide thermally metastable strength at low temperatures and can favorably alter the course of primary creep at elevated temperatures.7'8 For maximum benefit, however, sub-grain growth should be reduced or eliminated. It was, therefore, decided to investigate the use of heterogeneous precipitation on dislocation networks as a means of imparting increased strength and thermal stability to subgrain structures through effective pinning. C.T. YOUNG, STUDENT MEMBER AIME, and J. L. LYTTON, Member

Jan 1, 1970

By Persifor Frazer

CONTENTS. PAGE 1. Committee House of Commons Report (1843).......521 2. Clark (1880).............521 3. Schröder and Schertel (1884).... . 521 4. Committee House of Lords Report (1887).......523 5. Vita (1890).............524 6. Irvine (1890-1)............524 i. Cramer (1891)............525 8. Bailey. Cohen. Tatham and Hartog (1891))......525 9. Morrison (1891)............525 10. Brunner (1891)............525 11. Bell (1892).............585 12. Oades (1892).............526 12a. Purcell (1892)............526 13. Sennett (1892)............526 14. Bulier (1892).............526 1.7. Wiesner (1892))...........526 16. Thomson (1892)............530 17. Fletcher (1892)............530 18. Committee Engineers' Club Report (1892).......530 19. Cohen and Hefford (1892)..........531 20. Discussion Soc. Chem. Ind. (1893). ..532 21. Reuss (1893).............532 22. Thomson (1894—5) ...........535 23. Clowes and Feilmann (1895). ...536 24. Callan (1895)...........536 2.5. Wright (1895)............536 25A. Mabery (1895)............536 26. Re- (1896). ..........536 27. Herman (1896)............ 537 28. Cohen and Russell (1896).......... 537 29. Dennstedt and A hrens (1896). ..537 30. Cohen (1897). ...........537 31. Drehschmidt (1897)........... 538 32. Pfeiffer (1898). .........538 33. Fritzche (1898)............ 540 34. Ost and Wehmer (1899)........... 540 35. Donkin (1899). .........541 36. Beilby (1899)............. 643 37. Berthelot (1900)............ 544

Jan 1, 1908

[†Aaronson, Alfred E., Oil Producer, Pres., Tuloma Oil Cc Tulsa, Okla. '18 ¦Abad, Leopoldo F., College of Min., Univ. of California Berkeley, Cal. '23 ¦Abadilla, Quirico A., Geol. Dept., Cia. Mexicans de Petroleo "EI Aguila," S. A., Edifico "El Aguila," Esq., Calles Aurora y Comercio, Tampico, Tamps., Mexico. '20 ¦Abbey, Robert Graham, Student, Case School of Applied Science Cleveland, 0. '21 Abbott, Clarence E., Gen'l Supt., Iron Mines Div., Tenn. Coal, Iron & R. R. Co., 1405 Minnesota Ave., Bessemer, Ala. '04] [ ]

Jan 1, 1925

Jan 1, 1970

By Dell P. Williams, Howard G. Nelson

The tensile behavior of magnesium single crystals at a temperature of 26º ± 2ºC was investigated at varying pressure levels from 760 to 8 X 10-8 tow. For crystals deformed at a constant linear strain rate of 0.061 min-1. there was no apparent effect of the vacuum environment down to 10-8 torr. However, from a vacuum of 10-5 torr down to the lowest pressure attained (8 x 10-8 tor,), the effect of the vacuum environment was to increase the strain at the end of the first linear (or easy-glide) stage and to decrease the slope of this stage; the magnitude of this effect was found to be dependent on pressure. The slope of the second linear stage was also decreased at the lower pressure levels; however, this effect appears to be caused primarity by the vacuum effect on the first linear stage. The magnitude of the vacuum-environmrnt effect was also found to be dependent upon strain rate. The reduction in flow stress at 5 x 10-8 torr, as compared to the stress in air, was obserced to be about 10 pct for a strain rate of 0.0250 min-' and 70 pct for a strain rate of 0.67 min-1. No systematic effect of pressure on the critical resolvled shear stress was observed. The data interpreted in terms of a modified form of Mott's work-hardening mechanism for hexagonal metals. It has long been known that surface conditions influence the mechanical behavior of materials. Roscoe 1 demonstrated the importance of surface conditions on mechanical behavior by testing cadmium crystals with oxide layers. He found that the "apparent" critical resolved shear stress for cadmium was increased approximately 2.5 times by the presence of an oxide layer 1000 atoms thick. The magnitude of this effect was dependent on film thickness with crystals having films less than 20 atoms thick still showing a definite increase. This observed strengthening could not be attributed to any strength of the oxide film because of 1) the thinness of the films and 2) an observed increase in the flow stress as deformation proceeded. Harper and cottrel12 obtained similar results on zinc crystals which had been etched and steamed to give artificially thick oxide films. However, in the course of this study, they also carefully examined the very early stages of plastic flow for zinc crystals which in one case had been electrolytically polished and in the other had been lightly etched to produce a thin film. They then found that the critical resolved shear stress for both surface treatments of the crystals was actually identical but that the etched crystal exhibited a much more rapid initial hardening rate. This had not been noted previously. This result indicated that, in fact, the film caused an increase in the stress for continuation of slip, rather than for the initiation of slip. Lipsett and King3 investigated the effect of evaporated gold films on the plastic behavior of cadmium single crystals. For large angles (=75 deg) between the specimen axis and the normal to the slip plane, they found that the stress-strain curve of the coated specimen always lies above that for a clean specimen. The shear strain at the end of the first linear stage was greater in clean specimens than in coated specimens and the slope of the second linear stage was

Jan 1, 1965

By C. Land, R. Hultgren

Heat contents of four Cr-Ni alloys were determined in a diphenyl ethev calorimeter. Aside from ferromagnetic effects, Kopp's law of additivity of heat capacities is approximately fol-lowed, in disagreement with earlier results of A. W. Foster. In 1934 Foster1 reported heat-capacity measurements of dilute solutions of chromium in nickel, primarily as a study of the effect of alloying on the ferromagnetic Curie temperature. He found that, apart from the Curie temperature effect, the general level of heat capacities was reduced 10 pct by the addition of 1 pct Cr; 20 pct by the addition of 2 pct Cr. His measurements of pure nickel essentially agreed with accepted values. These results indicate that small amounts of dissolved chromium cause an increase in the Debye temperature of nickel, presupposing a change of frequency of interatomic bonding vibrations which is much larger than should be expected. If Foster's results were verified, therefore, they would have important implications for bonding theory. The only other heat-capacity measurements in this system seem to be those of Taylor and Hinton,' who studied anomalies which they attributed to super-lattice formation at 25 at. pct Cr. At temperatures above the anomaly, Taylor and Hinton found heat capacities at this composition were quite normal, approximately obeying Kopp's law of additivity. EXPERIMENTAL WORK In order to verify or disprove the remarkable results of Foster, the heat contents of four dilute solid solutions of chromiunn in nickel were measured in a diphenyl ether calorimeter. This instrument, described elsewhere,, operates on the principle of the Bunsen ice calorimeter, but uses diphenyl ether as the working substance. Diphenyl ether melts at the convenient temperature of 26.S°C and supplies a more sensitive measure of heat than ice. The hot sample, in an atmosphere of argon, is dropped from a furnace at a measured temperature into a chamber which is surrounded by a mixture of solid and liquid diphenyl ether. The heat from the hot specimen melts some of the solid without chang- ing the temperature of the calorimeter. The amount of solid melted, and therefore the number of calories released by the specimen, is measured from the increase of volume of the mixture, which pushes mercury down a graduated capillary tube. The apparatus has been standardized against the known heat content of pure platinum. Heat loss during the dropping of the specimen was estimated by comparing the heat content of an empty platinum capsule with a solid platinum ball of the same radius and degree of polish of the surface. Repeated tests demonstrate the precision of measurement to be closer than *0.3 pct. Smoothed experimental results are listed in Table I. The tabulated values for pure nickel are taken from kelley, several measurements were made which agreed closely with this tabulation. For chromium, however, no similar agreement was found. The values tabulated were taken from a thorough study of chromium with the diphenyl ether calorimeter which will be published elsewhere.= Suitable plots of the data showed the expected ferromagnetic anomalies in the low-chromium alloys, while the 11 pct alloy shows no ferromagnetic anomaly, but a different, small anomaly below 900°K. This is perhaps the same anomaly found in CrNi, which was once attributed to superlattice formation,' but is probably due to some other cause, such as antifer-

Jan 1, 1960

By W. J. Joslin

The frontal-advance equation can determine how the fluid withdrawal rate and subsurface operating pressure influence oil recovery from pressure-maintained reservoirs having characteristics favorable for efficient vertical segregation. For effective vertical segregation in formations having low dip angles, the requirements are: thick, massive sands, low viscosity oil and high vertical permeability with few discontinuous shale members. This approach has been successfully applied to the LL-370, which is a massive Eocene sandstone reservoir containing crude with an average gravity of 26" APT, a dip of only 3" and vertical permeability of ½ darcy. The average gas cap saturation was calculated for various rates of vertical gas-oil contact movement corresponding to a wide range of reservoir producing rates. This method also evaluated the effect of different pressure maintenance levels on oil recovery. Applicability of this procedure for calculating the present oil saturation in the LL-370 gas cap has been substantiated from field performance, where the oil saturation was computed by comparing oil recovery with the gas cap volume vacated. INTRODUCTION During the natural depletion history of the LL-370 reservoir, located in Lake Maracaibo, Venezuela, excellent vertical segregation resulted in the formation of a thin gas zone over a substantial portion of the oil-productive area. Subsequently, gas injection forced this thin gas-saturated zone slowly downward, reducing the oil saturation in the gas cap to a low value. The oil recovery has been raised considerably above earlier predictions where vertical segregation effects were under-estimated. In order to determine the maximum efficient producing rate and optimum operating pressure for this reservoir, a vertical gas frontal-advance analysis has been made through application of the fractional flow equation. LL-370 RESERVOIR CHARACTERISTICS The reservoir consists of a truncated monocline of massive. highly-permeable Eocene sandstone, called the B-b formation, covering an area of more than 13,500 acres. The original oil in place was 2.17 billion STB. Internal non-sealing faults subdivide the structure into four blocks called the B-6-x.6, 10, 11 and 13, which are effectively bounded by major faulting on the flanks, an unconformity updip to the west, and an immobile aquifer to the southeast. The producing formation occurs at an average depth of 5,250 ft subsea and has a closure of more than 1,500 ft. A typical producing section has a net oil sand thickness of 170 ft. Scattered throughout the section are a few randomly-positioned shale lenses which increase in thickness and areal extent downdip. The reservoir rock and fluid properties vary with depth. The permeability and produced oil gravity are 1600 md and 28" API at the top, compared to 300 md and 18° API at the water-oil contact. The productivity of updip wells is, therefore, much higher than the reservoir average. The reservoir oil was originally saturated at the crest, grading to a slight degree of undersaturation at the water-oil contact. There was no original gas cap; and material balance and the field performance indicate no water influx. Except for the northern B-6-x.6 block, the fluid and rock properties have already been published.' Average LL-370 reservoir properties are shown in Table 1. RESERVOIR PERFORMANCE UNDER NATURAL DEPLETION Fig. 1 shows production performance from 1939 to date. Early development was gradual, with 30 wells pro-

Jan 1, 1965

By I. R. Kramer

The delay time for single crystals of iron, zinc, and pre-strained aluminum was measured under conditions of high-speed deformation. The delay time of aluminum was found to be affected by the orientation of the crystal. Under the dynamic conditions employed, tile calculated "activated volume" term appears to be very small for the three metals studied. IN a previous paper,1 it was shown that under dynamic testing conditions at 78° K, there was a delayed yield in single crystals of aluminum and copper which had been cold-worked prior to testing. The experimental results also indicated that the delay-time effect was not due to the interaction of dislocations with impurity atoms or vacancies, but rather to a dislocation-dislocation interaction since aluminum which has not been prestrained shows no delay-time phenomenon. In this paper, some data are reported on the effects of orientation on the delay time of aluminum single crystals; the delay time of zinc single crystals saturated with nitrogen and the delay time of iron single crystals also were measured. EXPERIMENTAL PROCEDURE Aluminum (99.997 pct) and zinc (99.999 pct) crystals, 1/2 in. in diam and 8 in. long were grown by the Bridgman technique. The iron single crystal was supplied by Dr. R. Maddin. The zinc crystals containing nitrogen were prepared by melting high-purity zinc in a graphite crucible and the nitrogen was introduced by additions of ammonium chloride. The liquid zinc was then drawn up into glass tubes of 1/2 in. diam and allowed to solidify. The rods were cooled to room temperature before the transfer to the mold for conversion into single crystals. The orientation of all specimens was determined by the Laue' back-reflection technique, Fig. 2 and Table I. To prepare for the delay-time measurements, the crystals were cut with a fine jewelers saw and the ends carefully machined. The specimens then were electrolytic ally polished to remove the cold-worked metal, mounted in a special fixture and hand-lapped. As a final step, the crystals were annealed in evacuated tubes. Specimens of aluminum crystals, Nos. 24 and 26, were compressed 0.5 and 2 pct, respectively, in the direction of the later impact. The zinc specimens were aged at 50°C for 15 min, In the case of iron, only two specimens could be obtained. To obtain sufficient data, it was necessary to resort to a reaging treatment. After each delay-time test, the specimens were aged at 65° C for 100 min. This treatment, according to Clark,2 is sufficient to restore the original delay time. It is believed that although the specimens were plastically deformed approximately 10-4 pct, after each test the delay-time values are reliable. The delay-time measurements were made in an apparatus similar to that described previously.' Single crystals approximately 1 in. long and having a diameter of 1/2 in. were placed in a pendulum which consisted of a bar 1/2 in. in diam and 8 ft long, designed with a crystal holder to accommodate the specimen at low temperatures. The crystal was held at a position 2 ft from the front part of the pendulum. This portion of the apparatus was supported on a fine molybdenum wire. A projectile bar of the same diameter and length comprised the other portion of the apparatus. This bar was supported on

Jan 1, 1962

By R. M. Asimow, J. J. Svitak

Tile crilical resoll,r,d shear stress, CRSS, for slip of slow1y cooled Ag-All single crystals was measured at 201K. Tlze importance of short-range order and Suzuki sogregalion was inrestigated by deter~rlining llze ciic.cl of quenching on the CRSS. Thr obserz.ed rfrtenching effects were generally small and indicate that short-range ordcr and Slczuki srgregation do no1 account for n significant portion of the solid-solution strengthening in this system. However, all alloys slzozcwi yield drops ulhich rilere heat- lreat nrenl-sensiline THERE have been a number of mechanisms proposed to explain alloy strengthening in the Ag-Au system. The effectiveness of some of the proposed mechanisms, especially those that depend on Suzuki segregation1" or on short-range order,2-6 SRO? should be strongly dependent on heat treatment. Since internal friction investigations in this system indicate that there is stress-induced order,' we must also consider the possibility of local atomic rearrangement or short-range ordering in the stress field of a dislocation. There is not complete agreement whether these mechanisms should be most effective in raising the flow stress, in causing yield drops. or some combination of these two effects. This work was undertaken to determine the effects in the Ag-Au system of mechanisms that depend on segregation or order by using known but drastically different cooling rates following a high-temperature treatment. By comparing the critical resolved shear stress, CRSS, for slip measured after a very slow cool and again after a fast cool (quench) of the same crystal, it is possible to determine the effect of cooling rate on CRSS* and on yield drops. The single-crystal CRSS was determined at several compositions because there has been no data published across the phase field since the publication of room-temperature flow stress by Sachs and Weerts.' EXPERIMENTAL PROCEDURE Starting with materials of 99.999 pct purity, single-crystal specimens of random orientation 1.25 mm square by 4 cm long were prepared with 0, 10, 14, 25, 30. 50, 70. 75. 80, 90. and 100 at. pct Au. Crystals were grown in an inert atmosphere using a modified Bridgman technique with a growth rate of 1.5 cm per hr in a gradient of 3°C per cm. To obtain a maximum practical degree of SRO, the crystals were cooled at a rate of 275'C per hr to about 310°C and then cooled at 6°C per hr to approximately 200°C. Specimens were tested in tension immersed in an alcohol bath at -72°C (201°K) at a strain rate > = 0.003 mm"1 to determine the CRSS (7). The activation volume of several crystals was determined from the flow stress increment (72 - T1) for a tenfold increase in strain rate. The total shear strain varied from 0.05 to 2.3 pct but was generally less than 0.4 pct. After testing, each crystal was then held at 500°C for 10 min, quenched into brine at -35°C and. after storage at -71°C for 1 day, retested in tension using a procedure identical to that of the first test. The quenching apparatus, see Fig. 1, was designed to enable accurate temperature control and rapid quenching while preventing specimen contamination and accidental deformation. Test data from a specimen with a fine thermocouple spot-welded to it indicated a cooling rate of 104C per sec. The relatively low heat-treatment temperature was chosen to minimize quenching defects caused by a large vacancy

Jan 1, 1970

By Dean S. Rogers

The conventional role of exploration, development and grade control is examined in this paper within the context of the many and varied types of gold occurrences which are found at the Dome Mine. The account endeavours to trace the development of the total ore evaluation process, from diamond drilling through the exploration and drifting stage, to the stope development and planning phase of the operation, with an emphasis on sampling techniques and assaying procedure. The concept of ore reserve calculations is developed and the practice of grade control is described. In summary, the role of the geological, the engineering and the mining department is presented in relation to the contribution each has to make in the evaluation and exploitation of ore from one of the world's classic Archean gold deposits.

Jan 1, 1985

By J. C. Sarace, S. M. Sze, C. R. Crowell

Thin films of tungsten 077 n-type germanium, silicon, and gallium arsenide were obtained by reacting tungsten hexafluoride with the semiconductor surface in an argom atmosplrere at temperatures between 325° and 400° C. Capacity-voltage, current-iloltage, and photoelectric measurements were used to investigate the characteristics of the tungsten -semiconductor diodes thus Produced. The junctions are shown to he very close to ideal Schottky barlp/ers with barrier heights measured with respect to the Fermi energy of 0.18, 0.65, and 0.78 1.1 jar W-Ge, W-Si, and W-GaAs, respectively. The electrical properties of the W-Si interface show no deterioration when heated to 1000°C in dry forming gas for 5 min. A theoretical value of the Richardson constant, A, appropriate to the semiconductor-hand structure has been used in evaluating the current-voltage characteristics. ThE W-Si surface-barrier diode was initially proposed for investigation because the eutectic temperature with silicon (1400°C) is much higher than that in the Si-Au system 1370°C).1 This would permit more flexibility in heat treatment and possibly provide greater reliability at elevated temperatures. The lower work function of tungsten (4.54 ev)2 compared with that of gold (4.78 ev)3 also suggested that a lower barrier height would be obtained with tungsten and hence a lower forward bias and lower minority carrier injection ratio for a given current density. The investigation was extended to include the characterization of W-Ge md W-GaAs surface-barrier diodes. The tungsten films have been produced by reacting WF6 with germanium, silicon, and GaAs surfaces in an argon atmosphere at temperatures from 300° to 500°C.4 This process is a very satisfactory alternative to the relatively difficult process of evaporating tungsten films in vacuo. To ensure an adequate electrical characterization of the tungsten-semiconductor interface, three types of barrier-height measurements have been performed. The mutually consistent results obtained lead to the conclusion that the tungsten-semiconductor junctions are indeed of the Schottky type. EXPERIMENTAL PROCEDURE The apparatus used for producing tungsten films is shown schematically in Fig. 1. It consists of an argon carrier gas line to which metered amounts of tungsten hexafluoride can be rapidly added. The mixture passes through a heated reaction tube containing the semiconductor slices and is exhausted to a hood. The argon is purified by passage through a 6-in. column of titanium turnings maintained at 800°C. The tungsten hexafluoride dispensing arrangement was designed by V. C. Garbarini and W. R. Bracht.4 A measured amount of liquid tungsten hexafluoride is injected into the argon stream and vaporizes. The mixture passes through a sodium fluoride absorption cell to remove traces of hydrogen fluoride, then into the nickel reaction tube. The tube is 12 in. long with an inside diameter of 1/2 in. The center section is heated by a furnace of the self-supporting wire-filament type. It was chosen for its rapid heatup and cooling. The wall thickness is 10 mils except for a 3-in. hot zone which is 30 mils thick to reduce thermal gradients along the length. The samples to be coated are placed on a sapphire plate and centered in this section. The tungsten is deposited with the following sequential steps: the loaded reaction tube is flushed with argon at a rate of 500 cu cm per min and heated to 370°C. Then 0.45 g of liquid tungsten hexafluoride is injected into the argon stream. The samples are held at this temperature for 2 min. The tube and samples are then cooled to room temperature and the samples removed. Tungsten films were grown on (111) faces of silicon and germanium polished with Linde A abrasive and lightly etched with HF-HNO3. The GaAs surfaces were (100) faces chemically polished with a H2SO4-H2O2 solution. The films have typical sheet resistances of 0.2, 8, and 15 52/0 when grown on germanium, silicon, and GaAs, respectively. After the tungsten deposition, ohmic contacts were alloyed on the back surfaces of the wafers. Ohmic contacts to the germanium and silicon were obtained by alloying Au-Sb at 370°C, ohmic con-

Jan 1, 1965

By Frank L. Gaddy

Falls of roof account for over 50% of the fatalities that occur in coal mines in the US. Thus, roof control is one of the more important phases of underground mining. In reality, the control of roof influences the system of mining and is a major determinant of the width and spacing of working places, operations at the mining face, ventilation control, and surface subsidence. Frequently, the control of roof is the largest single cost item. Roof control is a never-ending task, not only at the working face and throughout sections where men are working, but along haulways and air- ways that must be maintained for the life of the mine. This is because roof, even the best of roof, slowly deteriorates, so it must be frequently examined, with corrective support applied when needed. As coal is excavated, stresses are set up in the roof because the previous equilibrium is upset, resulting in pressures that cause fractures and slight movements that are frequently hard to detect. Unless the immediate roof, in the excavated area, is given support by artificial means, it might fall or there might be a succession of falls, varying from a thin scale to several feet, depending on the nature of the top. Exceptions to this are those rare mines, or sections of mines, with hard, strong, nonweathering roof that requires no support. GENERAL CLASSIFICATION OF ROOF There are two broad types of roof as far as support is concerned: the immediate roof above the coal and the main roof. Artificial support for mining purposes is only concerned with the immediate roof as nothing except large blocks of solid coal, or massive concrete, will support the main roof. The immediate roof is generally a few feet thick but can vary from inches to 6.1 m (20 ft) or more. There are examples of where there is no immediate roof as the massive main roof lies directly on the coal

Jan 1, 1981

By H. W. Camp

ALTHOUGH the situation in the oil industry during the past year has. not been conducive to large expenditures for development and research, there is little indication that such expenditures have been curtailed. While few outstanding achievements have been reported, considerable progress has been made in the development of new products and the adaptation of petroleum derivatives to new uses. The most important question facing the refiner today is the anti-knock quality of his gasoline. This year has seen the widespread adoption of the term "octane number" as a measure for anti-knock values, and in the latter months of the year the public has been made acutely aware of this condition through competitive advertising. Gaso-line is no longer priced on volatility and gravity alone, but on octane number as well; and premiums are being paid for material of relatively high octane rating. The situation has grown more and more competitive and has forced refiners continually to raise the octane rating of their regular and com-petitive grades, and at this writing the same situation exists for premium grades which have possessed relatively high anti-knock properties for some time. Straight-run gasoline produced from paraffin-base or semiparaffin-base crudes has an inherently low anti-knock value, and in order to convert this material to a higher quality it has been found necessary to crack an increasing percentage of the crude oil charge. By completely cracking the heavier portions of the crude, and blending back with the straight-run gasoline, it has been possible to produce an average of 63 to 65 octane number gasoline' on average Mid-Continent crude. This operation carried to the fullest extent does not suffice, however, and the recent and rapid development of the so-called "re-forming unit," has resulted. The straight-run gasoline fraction is cut into two parts: a light, low boiling point gasoline; and a heavy gasoline or naphtha. The latter containing the low anti-knock portions of the gasoline, is sent through a re-forming unit and subjected either to high temperature ,or pressure, or both, which materially increases its octane number. On average Mid-Continent the blend of low boiling point straight-run,

Jan 1, 1932

By P. G. Shewmon, W. M. Robertson

The derivative of the surface tension with orientation, ??/??, for copper has been measured over the entire unit triangle. This derivative or torque term was determined from the variation of the dihedral angles at the intersection of twin boundaries and free surfaces. High-temperature anneals in graphite with a hydrogen atmosphere gave torque terms of 0.097 at (111), 0.066 at (100), and 0.0257 at (110). A variation from -36oto +23oC in the dew Point of the H2 had no effect on these values, nor did a change from 99.98 to 99.999 pct Pure copper. The removal of graphite from the system decreased ??/?? slightly. Considering the surface near a low-index plane to be smooth except for occasional steps, the free-energy increment per cm of step is calculated, and it is shown that the observed variation of ??/?? is consistent with a random distribution of steps and an interaction energy between steps. Integration of ??/?? gave the relative values of y at (100), (110), and (111) as comPared to ymax: (Y111/Ymax) =0.974, (Y110/Ymax) =0.996, (y100/Ymax) = 0.983. The ratio of the surface tension of coherent twin boundaries to the surface tension of the free surface was found to be (yT/ys) = 0.027 * 0.011. In a crystalline solid the surface tension y (surface free energy per unit area) depends on the orientation of the surface relative to the crystallographic axes of the crystal. Measurements of this variation of y with surface orientation have been reported for metals only within the last few years. Consider the grain boundary groove shown in Fig. 1. Here the three surfaces are all normal to the plane of the paper, and each has a different surface tension, y1, y2, and y3. If the system is at equilibrium, the total surface free energy must remain unchanged for a slight vertical displacement of the intersection (points A, B, and C are kept fixed). As shown by Herring,' the following equation is obtained:

Jan 1, 1962

By H. T. Morris

ONE of the chief concerns of the Bethlehem Steel Co. naturally is the proper functioning of its organization. This involves the training of a continuous supply of younger men to fill the vacancies caused not only by the inevitable departure of older men, but also by the growth of existing establishment, and by expansion in new directions. It does not oper-ate a student training course with a fixed time schedule or with definite periods of rotation through the differ-ent divisions. To state the case positively, the gradu-ate's training course must operate continuously from the beginning of his employment through a long term of years. No period of weeks or months nor pair of years suffice to bring him into contact with all the com-binations needed to qualify him for the larger destiny toward which we hope he is headed. Our first step in selecting a college man is to require that he have a degree. We thus approximate the assur-ance that at least four annual siftings have reduced the chance that a non-worker may find himself in a job where work is necessary. The next step is to try to ascertain facts, from the graduate and from others who have known him at his home and in 'his college, to indi-cate whether our opportunities offer him a career that will challenge his continuing interest, and hold him to tenacious effort against all happenings. We aim to avoid knowingly bringing into our organization a man who will not develop in it enough enthusiasm to keep him happily striving. Having made our selections, we assemble the gradu-ates into a probationary observation circuit. We-put ourselves under their observation by taking them in small groups, usually of two to four men, on a circuit of every part of the Bethlehem plant, in which every manufacturing principle of our steel business is ex-emplified. The probationers work at something from day to day, with their hands if it can be arranged; otherwise in questioning, examining, and note-taking. Their observations include talks with superintendents, foremen, and workmen, the conditions under which workmen labor, apparatus, machinery, methods, design and operation of plant.

Jan 7, 1928

By Harry Klemic

Zirconium and hafnium minerals are used industrially both as minerals valuable for their chemical and physical characteristics and as ores of zirconium and hafnium. The principal zirconium-hafnium-bearing minerals, their composition, and their ranges in content of zirconium and hafnium dioxides are listed in Table 1. The supply of zirconium and hafnium is based almost entirely upon the supply of the minerals zircon and baddeleyite. Eudialyte may eventually also be of importance as a source of these elements. Zircon, which generally contains nearly 49% zirconium and between 0.4 and 1.5% hafnium, is the principal industrial mineral of this group. Baddeleyite, a commercially important but less abundant mineral, contains as much as 73% zirconium and 0.4 to 1.7% hafnium. Eudialyte has a wide range in content of these elements, but analyses of material from several localities indicate values of 6 to 11 % zirconium and 0.07 to 0.4% hafnium. Zircon is a mineral consisting principally of zirconium, silicon, and oxygen that crystallizes from magmas during the formation of igneous rocks. Zircon also occurs in veins and in metamorphic rocks. It is in the tetragonal crystal system. It commonly forms as small well-developed prisms having pyramidal terminations but also occurs as irregular-shaped grains. Zircon has a hardness of 7.5 on the Mohs' scale. Its specific gravity is commonly between 4.68 and 4.70 (Dana, 1932), but the specific gravity varies somewhat depending upon com- position and state of alteration. Zircon has no good cleavage directions and is brittle, breaking with a conchoidal fracture. Zircon of the composition ZrSiO, would contain 67.2% Zr02 and 32.8% SiO2. However, in addition to about 1 % of hafnium, minor amounts of thorium, uranium, rare earth elements, yttrium, calcium, magnesium, iron, aluminum, phosphorus, and hydrogen, and trace amounts of other elements are commonly present in the mineral (Frondel, 1957). Radiogenic lead and other daughter products from the radioactive decay of uranium and thorium also accrue in the mineral. Radiation damage to the structure of zircons that contain appreciable amounts of uranium and thorium may alter the internal structure of the crystals to

Jan 1, 1975

By S. M. Marshall, B. M. Bird

For a number of years European investigators have used laboratory methods of predicting the probable strength of coke made from coal, and recently several investigators in the United States have reported the use of various tests for this purpose. There is at present no method accepted as standard, however, nor is there even agreement as to the general type of test that should be used. Furthermore, because the details of most of the tests have not been worked out carefully, one investigator can not hope to duplicate the work of another. The extension of coke manufacture to new localities in the United States, and the increasing need for cokes of exceptional qualities made from the most economical mixtures, made it desirable to have some simple laboratory test which will determine whether given coals, alone or blended with other coals, are more satisfactory from the standpoint of coke strenpth- than others of different cost. The work described herein has resulted in the development of a simple laboratory test which, it is believed, can be generally adopted in coal laborat,ories, and which will give concordant results even though performed by different investigators in different laboratories. The general method of predicting whether a coal or a mixture of coals will produce a strong coke, resistant to crushing and shattering, has been to correlate the known strengths of the cokes produced in commercial ovens with some measurable constituent or with some property of the coals, and then to use the relationship so found for forming an estimate of the coking strengths of coals unknown. Several such correlations have utilized the percentages of the various ultimate constituents of coal, such as the oxygen content and the hydrogen-oxygen ratio;(39)§ other correlations have involved the proportion of a, B and r com-pounds, (17,21,30c) or of "oil and solid bitumens."(16,30) Also a relationship has been traced between the coking properties of coal and the rate of change of the resistance offered to the flow of an inert gas by fine particles of the coal while being slowly heated. (11,176) But the most general corre-

Jan 1, 1930

By Charles R. Fettke

The Bradford and Richburg oil fields are the only pools where artificially conducted water drives on an extensive scale have been economically successful. Field practice has progressed from the original accidental or intentional circle flood, through the line flood development plan, to the intensive complete development plan, which is the most-recent and generally considered to be the most successful. Of the intensive development plan the five-spot arrangement of wells is the one that has been used most extensively. A further development associated with the latter method is the application of additional hydraulic pressure to that of the hydrostatic head of the column of water in the intake well. In conjunction with this method is the practice of delayed drilling of the oil wells until the water from the intake wells has entered even the less permeable portions of the sand and developed a "bank" of oil at which time all oil wells are drilled as nearly simultaneously as possible. The five-spot pressurc flood with delayed drilling gives more rapid return on investment than any other method. The seven-spot and nine-spot patterns are rarely used. No chemicals, such as sodium carbonate and other so-called flooding agents, are being added to the water at present since the field tests carried on in 1926 gave no positive results. All air and gas drives have been discontinued.

Jan 1, 1930

Jan 1, 1968

By Nath S. Parate

Emphasis on publications related to coal mining subsidence and damages is appropriate at present in view of the energy crisis and increased coal production and public alertness. I have worked in Harrisburg with the state government Public Utilities Commission on energy-fuel matters and issues (Parate, 1978-80). I have participated in the communication on subsidence/ damage reviews and status with the Bureau of Mines Liasion Office (Kebblish, 1978-79). I have done research (Parate, 1965) and published papers (Parate, 1972; Parate, 1967) in Britain on coal mining subsidence and damages around Sheffield-Nottinghamshire coal fields. I have a few comments on the recent paper titled, "Pennsylvania Subsidence Control Guidelines," by C.J. Bise. 1) What is the basis of the empirical formula or guideline, LD _ (0.27 x D) ± 4.6, defining the support area? 2) The particular structure may not be damaged due to vertical uniform displacement caused by mining beneath unless the displacement is differential (King, 1964). 3) The author mentions the limited subsidence research in the US, and quite rightly so. But he fails to quote any work reference by continental investigators except the British or review work by the US. What are the reasons? 4) The author has not mentioned the importance and role of angle of draw for Pennsylvania, Kentucky, or Illinois coal fields. Is there any current research investigation on the relationship between subsidence research investigation, damage, and transference of strains to structures? There have been a number of newspaper reports on subsidence damage in Wilkesbarre and other areas in Pennsylvania. Is the author aware of such instances and traditional attitudes to such issues? Many times government agencies--due to lack of funds, technical expertise, and public policies--are unable or do not find it interesting to keep updates on these issues, as per the author's knowledge and experience with state governments. 5) What is the net effect and role of the D.E.R. Insurance Office on the monitoring, reducing, or controlling subsidence damage, particularly in Pennsylvania?

Jan 1, 1983