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By Norman D. Fitz Gerald

The lack of a continuous operating balance in petroleum refining, which is analyzed in this paper, is by no means a feature solely of this division of the oil industry. Serious disequilibria of a capital as well as an operating nature exist both in the producing and marketing departments, while problems in the former and to some degree the latter are complicated by political involvements. Attention has previously been directed to the unstabilizing influence of present proration formulas in stimulating unnecessary drilling.' While equilibrium in petroleum refining operations has been fairly well maintained in the past decade, examination of departures may prove fruitful. Economic analysis is the application of time and motion study to the functioning of management, rather than labor. Properly applied it may reveal changes in policies that would increase the utility of the properties and facilities of the industry for stockholders, employees and the public, while contributing a stabilizing influence to the general economy. The study of economic equilibrium is essentially one of measurement and interpretation, requiring adequate data and the development of a technique of analysis that employs statistical and mathematical methods as a supplement to the broad descriptive phase of economics. Economic equilibrium in petroleum refining is a dual concept. It embraces both the over-all balance between total storage and total demand for major products and the internal balance between the demands and inventories of the various products. The latter is the more complex of the two for it is concerned with proportionating the supplies of the several products stemming from the joint source to the demands for the individual products which are subject to wide variations. All the products are essentially nondurable goods, and they are used both by producers and consumers but in varying proportions. Motor fuel is very largely a consumer's good, while residual fuel oil is almost entirely a producer's good, the other products falling between these extremes. The peculiar-

Jan 1, 1939

By Ove Sandberg, Olav Bowitz

The operational characteristics of the Soderberg vertical spike anode are briefly discussed stressing the importance of the flow properties of paste in the fluid zone, the thermal shrinkage in the carbonizing zone, and the surface disintegration in the consumption zone. The requirements for paste recipe and binder quality are combined with design and operation of cell. A low temperature susceptibility of viscosity and low thermal shrinkage of paste together with a low microporosity of the binder coke are important properties. PRACTICAL application of Soderberg's idea of a selfbaking carbon electrode proved successful just before 1920. Shortly after, experimental work was started with the aim of developing a continuous electrode that could be adopted as anode in aluminium reduction cells. The intermittent operation of a large number of small prebaked anodes made the idea of developing a continuous anode for electrolytic production of aluminium especially tempting. Moreover, the electrode consumption in this process, even on a theoretical basis, is very high. Many installations were carried out in the 1930's and during the Second World War. During the tremendous post-war expansion of the aluminium industry, the Soderberg electrode has been steadily more widely adopted. Thus, today more than 60 pct of the Western World's output of aluminium is produced in cells with selfbaking anodes, see Big. 1. The quality of the anode paste of Sfiderberg elec- trodes is considered a major factor influencing the specific carbon consumption. The purpose of this paper is to survey the fundamental requirements which must be met in order to obtain good anode operation. We have limited this paper to a discussion of Elektrokemisk's research on the vertical spike type anode. I) FUNDAMEKI'TALS OF ANODE CARBON PERFORMANCE A) Brief Introduction. The only practical method for producing a conductive carbon anode of the size required is to form and carbonize a mixture of a carbonaceous binder and a precalcined dry aggregate coke. In the Soderberg electrode, the forming and carbonization take place in the electrolytic cell

Jan 1, 1962

By C. Stansfield Hitchen

THE introduction of the logarithmic sector method of quantitative spectrography by Scheibe and Neuhäusser in 1928, and the subsequent .modification and improvement of the method by Twyman and Simeon, would seem to have marked yet a further advance in quantitative spec-trum analysis and its industrial application, inasmuch as it offers a simple means of eliminating some of the uncertainties inherent in the older methods based upon mere visual comparison of line intensities. In their recent admirable review of the position and capabilities of industrial spectroscopy, Brownsdon and van Someren1 say: Ways and means of facilitating the comparison of line-intensities so as to give them numerical values are helpful, and of these a logarithmic sector rotating in front of the slit appears to he one of the most promising; . . . the success recently experienced by the author in using this method for the examination of steels and solutions of metallic salts prompted him ,to investigate its possible use in estimating the impurities commonly present in crude and refined tin. The results of this investigation are submitted in the present paper. Details of a number of spectrographic analyses of tin for various impurities have already been published. Thus, Schweitzer2 describes the spectrographic examination of tin for lead, bismuth and cadmium, and was able to distinguish between such atomic percentages as 0.01, 0.05, 0.10, 0.30, 0.60, 1.20, 3.00 and 10.00. Negresco3 investigated the bismuth content of tin over a range of from 0.0005 to 35 per cent. Meggers, Kiess and Stimson4 compare spectrographic and chemical analyses of tin metal for copper, lead, iron, zinc, silver, nickel and bismuth. They stress also the value of spectrum analysis in the examination of tin used for boiler plugs, where the requirements that only minute quantities of impurities shall be present render the chemical analysis both tedious and difficult.

Jan 1, 1933

By Paul Weir

Bleaching clays have been used extensively in the oil-refining industries for a number of years. Their use in water purification is relatively recent and less extensive. They are frequently classified as (1) those naturally active and (2) those active after artificial activation with acid. Fuller's earths fall within the general group of bleaching clays and gradually the commercial term "fuller's earth" has been applied to natural clays originating, for the most part, in the southeastern section of the United States. Bentonitic clays are usually classed as activable and are prevalent in the southwestern section of the United States.l Bleaching clays vary considerably in chemical and physical properties throughout the country, or even in different parts of one deposit (Table 1). The fuller's earth type of clay is characterized by a lack of plasticity, relatively adsorbent, foliated structure, and does not swell to form a

Jan 1, 1942

By Paul Weir

Bleaching clays have been used extensively in the oil-refining industries for a number of years. Their use in water purification is relatively recent and less extensive. They are frequently classified as (1) those naturally active and (2) those active after artificial activation with acid. Fuller's earths fall within the general group of bleaching clays and gradually the commercial term "fuller's earth" has been applied to natural clays originating, for the most part, in the southeastern section of the United States. Bentonitic clays are usually classed as activable and are prevalent in the southwestern section of the United States.l Bleaching clays vary considerably in chemical and physical properties throughout the country, or even in different parts of one deposit (Table 1). The fuller's earth type of clay is characterized by a lack of plasticity, relatively adsorbent, foliated structure, and does not swell to form a

Jan 1, 1942

By E. S. Machlin

The wzodel of Blandin and Diplunt;, generalized to include a phase factor, is applied to the carbon-carbon interaction in iron. Darken&apos;s "energetic" model is generalized to include not only first neighbor interactions but further neighbor interactions as well. On the bases of these generalized models relations are derived for the activity of carbon in both austenite and ferrite in terms of the carbon-carbon Pair interaction energies. A single function then yields the pair interaction energies consistent with the experimental activities of carbon in both ferrite and austenite. Thus, a simple explanation is given for the observation that the nearest-neighbor interaction between carbon is repulsive in austenite and attractive in ferrite. Certain consequences of this approach are explored. OnE object of the present paper is to attempt to take into account the consequences of electrostatic contributions to the carbon-carbon pair interaction energy for carbon as a solute in iron. Friedel&apos; has shown that oscillations in electrostatic potential are to be expected about a solute atom in a metallic solution. Blandin and 6lant6&apos; have shown that such oscillations yield an interaction energy between pairs of solute atoms that obeys the relation: W{ = A cos(2ftFri + 4>)/(kFri)3 [l] where kF = Fermi wave vector, ri = distance between solute atoms comprising the pair7 <p = phase factor dependent only on electronic nature of solute and solvent, A = coefficient dependent only on electronic nature of solute and solvent. Machlin3 found that Eq. [I] accurately described the pair interaction energy derived from short-range order measurements based on field ion microscope observations of dilute alloys of platinum. He also found that the value of the phase factor $ derived from residual resistivity measurements agreed well with that obtained from the analysis of the short-range order data. Harrison and paskin4 were able to predict the long-range ordering energy of 0 brass using Relation [I] and residual resistivity values to predict the value of the phase factor $. Machlin5 has repeated their analysis and applied it to the prediction of the long-range ordering energy in AgZn and AgCd with excellent agreement between prediction and experiment. Both A and $ are independent of the crystal structure. The Fermi wave vector depends uniquely upon the conduction electron concentration per unit volume in the spherical approximation of the Fermi surface. Thus, Eq. [I] is expected to apply to both fer- rite and austenite with only one set of values of A and $. Mossbauer studies6 yield the result that iron has one 4s electron. We shall make an assumption found to hold previously for platinum3&apos;7 and nikel, which is that only the s electrons are involved in shielding the perturbing potential of carbon. With this assumption, kF = 1.35 A-l. Although A and $ may be obtained from certain mdels&apos;&apos;&apos; we shall take A and $ to be empirical constants in the spirit of Kohn and osko.&apos; Thus, Eq. [I] involves two adjustible parameters. Consequently, two independent relations in A and $I are required in order to evaluate them for carbon as a solute in iron. We may use a recent analysis of Aaronson, Domain, and poundg who showed that Darken&apos;s energetic model,1° as well as others, can be used to describe the activity-temperature data for carbon in iron in both the aus-tenitic and ferritic phases. Darken&apos;s model takes into account only first neighbor pair interactions. For our needs, all neighbor pairs need to be taken into account. It is convenient to generalize Darken&apos;s model. The result for the partition function for austenite is: over the temperature range 800" to 1200°C and where the uncertainty corresponds to one standard deviation. Eq. [4] effectively yields only one relation. Another relation is required to obtain unique values for A and $. One property of Eq. [4] is that it is independent of crystal structure. Hence, data for a iron can be used to obtain another relation. To arrive at this relation we must generalize Eqs. [2] and [3] so that they may be applied to the bcc a iron. The result is that:

Jan 1, 1969

By T. Seldenrath

In the development of a fluid -operated hammer drill&apos; for accelerated penetration of hard rock formations in oil wells, a research investigation was conducted to evaluate the percussion effects obtained with different design characteristics and to determine the possibilities of percussion in the low frequency range. Tests were conducted on granite blocks and comparable impact forces were measured with a load cell under selected test conditions. These full-scale laboratory tests provided an evaluation of the effectiveness of percussion which was further supported by actual downhole field performance. While much pertinent data have been presented by other investigators the method of evaluation described in this article resulted in good correlation between laboratory and field performance and may be applicable in other low frequency percussion developments. EXPERIMENTAL METHOD For these tests the bit was held stationary and the test block was rotated and forced upward against the bit by a hydraulically-lifted rotary table. "Weight on bit" was calculated from pressure readings on the fluid system of the lifting cylinders—corrected for tare and friction. Percussion was obtained with several tubular hammers of different weights up to 320 lb. These were lifted mechanically and allowed to drop by gravity from various heights onto a slidably-mounted bit sub or "floating anvil" for calibration of the load cell response with known kinetic energy of the hammers. During evaluation of percussion effects, the hammers were hydraulically operated to provide a range of percussion frequencies up to 1,020 blows per minute delivered to the anvil. To obtain comparable test readings, the load cell of the strain gauge type, was attached to the bottom of the anvil or bit sub in place of the bit. The load cell rested on a typical granite test block mounted on the drilling table. The latter was hydraulically supported as in the actual drilling operation. The effect of support resistance was the same for all tools when calibrating. Impact forces so determined werethusdirectly comparable with one another for the purposes of this investigation. When a roller bit was substituted for the load cell for actual drilling, the impact force would probably be reduced due to the resiliency of the bit body, legs. cones and teeth and the penetration of the teeth into the rock. However, since the bits and rock specimens were uniform in these tests, an evaluation of actual tool performance, in terms of parameters previously determined with the load cell at the selected standard conditions of calibration, proved satisfactory. Throughout these tests, 8¾-in. standard tricone, hard rock toothed roller bits and carbide-insert roller bits were used. Rotary speeds were 50 and 100 rpm; static weight on bit was applied up to 40,000 Ib, and percussion frequencies up to 1,020 blows per minute were available. During this investigation it was found that toothed bits on which the teeth had developed flat ends about 3/16 in. wide did not change appreciably for the duration of a test. Hence, all toothed bits used in this study were in this condition. Conventional reference curves obtained in these tests show that increasing weight on hit by 2:1 yielded an increased penetration rate of approximately 2.7:1, while an increase in rotary speed of 2:1 netted an increased penetration rate of roughly 1.7:l. Results are thus of the same order as those reported for hard rock drilling by other investigators." CALIBRATION Under the selected standard test conditions previously described, with the lifting table hydraulically supported, and the anvil interposed between hammer and load cell, the hammers were dropped from known heights. Thus, with the kinetic energy of the hammer known, the corresponding maximum impact force shown by the cell was determined. (It may be of passing interest to note here that special drop tests with the hammers showed that no appreciable reduction in impact force resulted from introduction of the anvil or hit sub.) From these calibrations, it was possible to determine the theoretical kinetic energy available in the hammer from the maximum impact force shown by the load cell while operat-

By I. A. Goddard

INTRODUCTION This paper deals with the development of the sublevel open stoping (SLOS) method in lead orebodies at the Isa Mine of Mount Isa Mines Limited, during the last ten years. Open stoping in different forms has been used at the Isa Mine for many years. Prior to the period under review, stopes were small, pillars were not always recovered, and scrapers extracted the ore. By the end of the sixties, the use of load-haul-dump units was becoming more widespread. Wagner ST5&apos;s were the mucking units for the lead cut and fill stopes. Some of the open stopes in 5 orebody above 13 level had 100 kW slushers, but the more southerly stopes were the sites for the introduction of diesel front-end loaders for extraction. In the early seventies, new methods were used in the block of six stopes in 2 and 5 orebodies between 8 level and 13 level and a trial stoping project was undertaken in 7 orebody between 11 level and 13 level to determine possible stope dimensions for the extraction of the Racecourse orebodies below 13 level. By the mid-19701s, stoping was well underway in 5, 7 and 8 orebodies between 13 level and 15 level, using the &apos;triplet&apos; system, incorporating cemented hydraulic fill to allow greater pillar recovery. As the eighties were entered, development of the Racecourse orebodies below 15 level commenced, as did preparations for 1 orebody in the upper levels of the north end of the mine. In both cases, the pillar recovery method has been changed to reduce the amount of cemented fill required for pillar recovery. GEOLOGY Most of the lead orebodies at Isa Mine lie chiefly to the north of the central shaft complex. They are bedded sulphide deposits in a host rock called Urquhart Shale, which dips at roughly 650 to the west. The main minerals are galena and sphalerite, with the silver mineral, freibergite, being contained in the galena. To the hangingwall of the sequence are the Black Star orebodies (1, 2 and 5) which are relatively wide, pyritic and with low to above average grade lead. The Racecourse orebodies (6 to 16) lie to the footwall, and have a large variation in width, low to high grade lead, and gradation in the lead to zinc ratio from north to south. Stope outlines are often determined by economic or engineering considerations rather than geological. The published extraction reserves are 56 million tonnes of primary ore, containing 150 grams of silver per tonne, 6.4% lead and 6.5% zinc. Traditionally, it has been regarded as lead ore, although the dominant revenue earner varies from time to time. In the Black Star orebodies, the ore and hangingwalls are more competent and open stoping has long been used. The major Racecourse orebodies which have been open stoped are 7 and 8 orebodies. This has been where the orebodies are wider (to the south) and where hangingwall conditions allow. This latter aspect has been greatly influenced by the presence of &apos;silica dolomite1. This tough, relatively homogeneous, non-bedded rock is, in fact, the host rock for the copper mineralisation at Mount Isa, and provides a competent hangingwall for some of the lead stopes. While the shale&apos;s bedding and jointing has a major influence on the ground conditions, there is a major fault system which causes local problems. The principal virgin stress direction is perpendicular to the bedding, but the local stress situation is complicated because of shielding by filled stopes in the hangingwall copper orebodies and because of the interaction between orebodies being extracted to the footwall. Most development on strike is mined with a &apos;shanty-back’, with the back being as close to normal to the bedding as possible. This is near parallel to most jointing and the principal stress direction. Figure 1 is a plan view of 14 level north, which provides a representative horizontal section through the orebodies. A typical cross section is shown in Figure 2. The narrow, parallel footwall orebodies can be seen to differ from the wider hangingwall orebodies.

Jan 1, 1981

By C. E. Coleman, D. Hardie, A. E. Wraith

A photoguaplric method of measuring crack velocities has been applied to an examilzation of- the effect of hydrogen on the impact properties of zirconium. Results indicate that the crack in hydrided zirconit travels at about 26 m per sec whereas that in the uacuum -annealed is dependent on the speed of the hammer. RECENT work on the effect of hydrogen on zirconium reveals that when hydrided zirconium is tested in slow bending the crack producing failure can be unstable. The mode of fracture seems to involve the crack linking up broken hydrides by a ductile mechanism in the zirconium matrix.2" In order to compare the fracture of zirconium with that of other metals which show unstable crack propagation, notably steel, the rate of the crack spread must be known. As the methods previously used for measuring crack growth are either unsuitable for the present work5-&apos;&apos; or very costly," a simple technique has been devised in which the maximum crack velocity is derived from a series of crack position-time measurements. EXPERIMENTAL PROCEDURE The experimental arrangement is shown schematically in Fig. 1. The flash unit12 was triggered when the Charpy hammer touched the specimen and the 6-psec flash of the lamp delayed by a preselected time interval in the range 100psec to 10 msec. The camera was left on open shutter during the test. From direct measurement on a calibrated photographic print, Fig. 2, the position of the crack and the specimen was found at a known time after impact and, from a series of such tests using an appropriate range of flash-delay times, the crack velocity was estimated. Preliminary experiments were carried out on mild steel above and below its transition temperature. Vacuum-annealed zirconium, and zirconium hydrided to 100 ppm H were then tested at 20" and 150°C. For comparison, Zr-2.6 pct Nb alloy (in the 0 + transformed /3 condition), vacuum-annealed or hydrided to 100 ppm H, was tested at 20 C. The chemical analyses of these materials are given in Table I. For the high-temperature tests a fine chromel-alumel thermocouple was spot-welded onto each specimen close to the notch. The test piece was heated up to 200°C to allow enough time for preparing the apparatus while the specimen cooled to the testing tem- perature. It was assumed that the specimen cooled uniformly. The accuracy of the flash-delay time was better than i2 pct i 5 psec. The crack length was taken as its maximum distance traveled normal to the length axis of the specimen. Errors in these measurements arise as a result of the uncertainty in the location of the crack tip and the difficulty in defining the exact position of the crack starting point. The latter was due to the bonding and large amounts of deformation at the hammer contact point, especially in the vacuum-annealed specimens tested at 150°C. The maximum error in the measurements was however estimated to be about 5 pct. DISCUSSION OF RESULTS From the trial experiments using mild steel above its transition temperature it can be seen from the plot of crack length against time after impact, Fig. 3. that a reasonable estimate of the maximum crack velocity at the surface of the specimen may be made. Other features of note are the initiation time before the crack is first seen and the slowing down period

Jan 1, 1967

By Che, C. W. Spencer, C. A. Steidel, Yu Li

Grain boundary grooving as it occurs in a 5.5-deg simple-tilt nickel bicrystal immersed in a saturated Ni-S liquid has been studied. A 1/3 (t= time) dependence for the depth of the groove indicates that the rate -controlling meckanism for groove developvnent is volume diffusion in the liquid. The activation energy for the diffusive process is estimated at 15 kcal per mole. Using an extended form of W. W. Mullins&apos; analysis for grooving reactions, a computer is employed to fit the appropriate diffusion equation by a numerical method. From the analysis a possible method of measuring L.S. the solid-liquid interfacial tension is demonstrated. WHEN a polycrystalline solid is heated in equilibrium with a saturated fluid phase, grooves will form at the intersections of the grain boundaries and surface. The equilibrium root angle of these grooves is determined by the balance between the grain boundary and solid-fluid interfacial tensions. The grooves deepen and widen with time due to a difference in chemical potential between the flat interface and the curved interface of the groove. In this investigation solid-liquid interaction at a grain boundary is studied, with the object to determine the mechanism of grain boundary grooving in the presence of a saturated liquid. Extension of Mullin analysis then permits the estimation of the solid-liquid interfacial tension. Herring has demonstrated by dimensional analysis that the quasi-steady state change of the dimensions of a small particle during sintering is proportional flow, evaporation-condensation, volume-diffusion, and surface-diffusion mechanisms, respectively, if geometric similarity of consecutive configurations of the particles holds. Mullins has extended this analysis to grain boundary grooving. In the case of shallow grooves he solves the diffusion equations for evaporation-condensation, volume-diffusion, and surface-diffusion mechanisms, and obtains the same time dependence for any linear dimension of a groove as Herring found for the change in dimension of small particles. In Mullins&apos; analysis2&apos;3 grain boundary grooving of a bicrystal by volume diffusion in the presence of a saturated fluid phase was considered. Several assumptions were made prior to the analysis: 1) the solid-fluid interfacial tension is independent of crystallographic orientation; 2) the Gibbs-Thompson equation relating curvature and chemical potential is applicable at the solid-fluid interface; 3) the relaxation time of the diffusion field is small compared with the time for appreciable changes in the curvature of the groove, so that the diffusion is divergence-less; and 4) the groove has a small slope relative to the initial flat interface. Usually this last condition is fulfilled only for solid-gas systems. The solution of the diffusion equation under the above conditions produces a t1/3 dependence for any linear dimension of the groove in the case where volume diffusion is rate-controlling. The t1/3 dependence is valid because geometric similarity of the grooves exists for all time. EXPERIMENT In the experiment a 5.5-deg nickel bicrystal of <100> simple-tilt orientation was used.4 Grooving was studied in the presence of a saturated Ni-S liquid alloy as a function of time at 750°, 800°, 850°, and 900°C. A low-angle bicrystal was chosen for study to insure that 2L.S. > .b., where l.s.

Jan 1, 1964

By C. H. Ault, D. D. Carr

Four counties in Indiana- LaPorte, Vigo, Vanderburgh, and Switzerland-have potential for deep underground limestone mining because they are in or near high population areas and have no surface-mineable limestone deposits. The principal markets are Gary-South Bend, Terre Haute, Evansville, and Cincinnati. Mineable seams suitable for aggregate are 120-150 m (400-500 ft) below the surface in LaPorte and Vigo Counties, about 90 m (300 ft) below the surface in Switzerland County, and about 600 m (2,000 ft) below the surface in Vanderburgh County. Some deposits are also suitable for high-purity uses or for cement raw materials, which enhances their potential for exploitation.

Jan 1, 1983

By Y. Zimmels, I. J. Lin, I. Yaniv

The potential application of magnetic and electric separation techniques in beneficiation of fine-particle feeds are reviewed. Special features of these techniques are considered and compared with a view to increased amenability of such feeds to separation in electro- magnetic fields. The following techniques are discussed, with reference to those already developed and in use to-date: - Differential-susceptibility separation (DSF). - High-gradient differential-dielectric separation (HGDDS). - High-gradient magneto-gravimetric separation (HGMGS). In this context the new approach - whereby selectivity of solid- solid separation processes, in wet high-gradient magnetic and electric separation, can be improved - is described, including experimental results from DSF and HGDDS tests.

Jan 1, 1980

By John Wulff, H. H. Uhlig

Since its first mention in the literature in the eighteenth century12 the phenomenon of passivity in metals has stimulated much speculation and attendant controversy as to its nature and cause. No one of the numerous theories so far proposed has been generally accepted. ‡ Faraday,&apos; in 1836, associated the passivity of iron with a protective film over the surface of the metal, which materially prevents or slows down reaction with corrosive environments. His theory was that oxidizing acids like nitric acid form an unstable oxygen or oxide layer over the iron surface, which protects the underlying metal from further attack. This concept was simple yet plausible, and without alteration has frequently been assigned in present-day discussions as explanation of the passivity of many metals. With the advent in recent times of stainless steels, it is not surprising that this oxide film theory of passivity proposed by Faraday has been used to explain the phenomenal corrosion resistance of stainless steels and other passive alloys. The passive alloys, such as the chrome-iron alloys, are supposedly covered with a protective oxide film, which forms on exposure of the alloy to air, is extremely stable and self-healing, and accounts for the remarkable resistance of these alloys to corrosion. Within the past few years, several investigators, following the theory of film protection, have attempted to gauge the resistance of the supposed film on steels. Brennert8 and Donker and Dengg9 determined the potential at which a negative ion (e.g., C1-) moving in an electric field reacted with the metal anode, as detected by increased current flow or change in potential of the steel electrode in an electrolytic cell. The potential corresponding to reaction Brennert called the film break-through potential.

Jan 1, 1939

By John Wulff, H. H. Uhlig

Since its first mention in the literature in the eighteenth century12 the phenomenon of passivity in metals has stimulated much speculation and attendant controversy as to its nature and cause. No one of the numerous theories so far proposed has been generally accepted. ‡ Faraday,&apos; in 1836, associated the passivity of iron with a protective film over the surface of the metal, which materially prevents or slows down reaction with corrosive environments. His theory was that oxidizing acids like nitric acid form an unstable oxygen or oxide layer over the iron surface, which protects the underlying metal from further attack. This concept was simple yet plausible, and without alteration has frequently been assigned in present-day discussions as explanation of the passivity of many metals. With the advent in recent times of stainless steels, it is not surprising that this oxide film theory of passivity proposed by Faraday has been used to explain the phenomenal corrosion resistance of stainless steels and other passive alloys. The passive alloys, such as the chrome-iron alloys, are supposedly covered with a protective oxide film, which forms on exposure of the alloy to air, is extremely stable and self-healing, and accounts for the remarkable resistance of these alloys to corrosion. Within the past few years, several investigators, following the theory of film protection, have attempted to gauge the resistance of the supposed film on steels. Brennert8 and Donker and Dengg9 determined the potential at which a negative ion (e.g., C1-) moving in an electric field reacted with the metal anode, as detected by increased current flow or change in potential of the steel electrode in an electrolytic cell. The potential corresponding to reaction Brennert called the film break-through potential.

Jan 1, 1939

By William J. Priestley

In the manufacture of gun forgings and other steel parts that, in service, are subject to sudden high stresses and shocks, it is most desirable to use steel possessing the greatest toughness and ductility possible without sacrifice of strength. In order to obtain this condition, it is necessary to procure steel that shows the highest possible elongation and reduction of area without lowering the tensile strength and clastic limit. Proper heat treatment of the steel can control this condition within certain limits. When heat treatment has failed to produce the desired results, metallurgists have used steels containing molybdenum, zirconium, vanadium, chromium, tungston, etc. The purpose of this paper is to describe a method by which these desired physical properties may be procured—by the elimination of certain impurities that inherently exist in steel made by the open-hearth process, and without the use of expensive alloys. Design of Gun Forgings In the manufacture of gun forgings, a certain elastic limit is fixed by the designer, and the walls of the gun arc made of the proper thickness, allowing a suitable factor of safety for the high stresses and sudden shocks that occur during gun firing. The clastic strength of the gun is about 1.4 times the stress set up at any point along the bore of the gun during firing with the maximum powder charge. As the stresses set up in the walls of the gun during firing are mostly "tangential," all physical tests are taken in this direction. Due to the length of the forgings, these tangential test bars are always taken at right angles and transverse to the direction of flow of the metal in forging. Furthermore, test bars taken across the grain of the metal will more frequently expose defects and foreign inclusions in the steel than will bars

Jan 1, 1922

By William J. Priestley

In the manufacture of gun forgings and other steel parts that, in service, are subject to sudden high stresses and shocks, it is most desirable to use steel possessing the greatest toughness and ductility possible without sacrifice of strength. In order to obtain this condition, it is necessary to procure steel that shows the highest possible elongation and reduction of area without lowering the tensile strength and clastic limit. Proper heat treatment of the steel can control this condition within certain limits. When heat treatment has failed to produce the desired results, metallurgists have used steels containing molybdenum, zirconium, vanadium, chromium, tungston, etc. The purpose of this paper is to describe a method by which these desired physical properties may be procured—by the elimination of certain impurities that inherently exist in steel made by the open-hearth process, and without the use of expensive alloys. Design of Gun Forgings In the manufacture of gun forgings, a certain elastic limit is fixed by the designer, and the walls of the gun arc made of the proper thickness, allowing a suitable factor of safety for the high stresses and sudden shocks that occur during gun firing. The clastic strength of the gun is about 1.4 times the stress set up at any point along the bore of the gun during firing with the maximum powder charge. As the stresses set up in the walls of the gun during firing are mostly "tangential," all physical tests are taken in this direction. Due to the length of the forgings, these tangential test bars are always taken at right angles and transverse to the direction of flow of the metal in forging. Furthermore, test bars taken across the grain of the metal will more frequently expose defects and foreign inclusions in the steel than will bars

Jan 1, 1922

By T. J. Koppenaal, M. E. Fine

The critical resolved shear stress of aCu-A1 single crystals has been investigated as a function of composition, testing temperature, and strain rate. The strength, and its temperature and strain rate dependency increase markedly with aluminum content. The solid solution strengthening at 4.2°K is much larger than at room temperature. The activation energy for the low temperature dislocation cutting process increases from about 0.17 ev for a 0.5 at. pct A1 alloy to about 0.50 ev for a 14 at. pct A1 alloy. This result is attributed to an increase in the width of extended dislocations due to the known decrease in the stacking fault energy. In addition, the activation volumes at 4.2 and 77°K decrease with aluminum additions. Concerning the solid solution strengthening in the 296° to 373°K range, no definite conclusions are reached, but it is suggested that subgrains and cutting of subgrains are important. In a previous paper,&apos; the authors reported that adding aluminum to copper produces two types of strengthening: a yield point effect and an increase in the lower yield stress. This behavior is illustrated in Fig. 1 by shear stress-shear strain curves of furnace-cooled single crystals of pure copper and Cu-14 at. pct A1. The yield point effect, At, was thoroughly studied previously1 and shown to be associated with short-range order. The present paper reports an investigation of the lower-yield stress in aCu-A1 single crystals as a function of composition, testing temperature, and strain rate. EXPERIMENTAL PROCEDURE Single cryski1 tensile specimens were prepared in the same manner as previously described.l Briefly,

Jan 1, 1962

By Carl H. Beal, E. D. Nolan

In February, 1918, the conclusion was published by Lewis and Beal "that wells of equal output on the average will produce equal amounts of oil in the future, regardless of the ages of the wells." This conclusion was based upon the study of data collected principally in Oklahoma and was not known at that time to be true for other oil fields. An abundance of statistical proof was later collected by the senior author of the present paper, which showed that the conclusion was undoubtedly well founded and that it applied to other fields as well. Accordingly, it was later restated2 as the "law of equal expectations" as follows: "If two wells under similar conditions produce equal amounts during any given year, the amounts they will produce thereafter, on the average, will be approximately equal, regardless of their relative ages." Although only scanty data from the California oil fields were available at the time this publication was prepared, sufficient information was analyzed upon which to base the insert on Fig. 80, which showed beyond a doubt that the law held at least for a part of the Midway oil field in California. Recently the authors have collected more complete data in California, and it is the purpose of this paper to explain the method used in demonstrating the truth of the law and, in addition, to give several methods by which curves constructed in accordance with this law can be used in a practical way with ease and accuracy. The Family Curve The law of equal expectations means that each individual of a group of wells producing under similar conditions will decline along approximately the same type of curve, the rapidity of decline varying with the output

Jan 1, 1921

By D. V. Carter, Dan C. Williams, Franklin M. Hackbusch

During 1939 little of consequence happened in East and East Central Texas in the way of oil discoveries. At the end of the year, there were 47 oil and gas fields in the district. Twelve other fields, 11 oil and one gas, have been abandoned. The ranking fields in order of the number of completions for the year were East Texas, Talco, and Rodessa (Texas portion). There were 511 oil wells (distillate wells included), 32 gas wells, and 257 dry holes completed in the district. Exploration, Discoveries and Extensions During the year, 113 exploratory wells were drilled, the same number as in 1938; four oil fields and one gas-distillate field were discovered. Perhaps the most important discovery, which has been named Barron field, was that of M. Samuel et al., No. 1 Barron in Limestone County. The wells in this field are of the gas-distillate type. Other than the Talco and Sulphur Bluff fields, which produce oil from the Paluxy sand (Upper Trinity), this is the first field on the Corsicana-Mexia fault zone to obtain commercial production from deeper Trinity strata. This "pay" is the Petit lime of the Lower Glen Rose of the Trinity group. The four oil discoveries were: Redland, Angelina County; Bazette, Henderson County; Rowe and Baker, Henderson County; and Marion County Shallow in Marion County. It is believed that the Bazette field, Navarro County, represents an extension of the Flag Lake field. For details concerning discoveries, extensions and important wildcat wells drilled during 1939 see Table 2. Production and Proration The district produced 175,053,729 bbl. of oil (distillate production included) which is a decrease of 4.0 per cent from the 182,369,484 bbl. (distillate production included) produced during 1938. The district&apos;s production for the year 1937 was 208,594,453 bbl. The East Texas

Jan 1, 1940

By S. Weissmann, P. R. Swann, D. F. Wriedt

The sizes and density of precipitates in an intemally oxidized 0.19 wt pct Al-Ag single crystal have been determined by low-angle X-ray scattering and by transmission electron microscopy . The correlation in particle sizes measured by the two techniques is reasonably good. For an oxidizing temperature of 800°C the particles were found to INTERNAL oxidation of dilute alloys of aluminum in silver produces an oxide which has an excess of oxygen compared to Al2O3.&apos; It is believed that the excess oxygen is an indication of the small sizes of the oxide particles. Depending upon the particular model chosen for the oxide structure, the size of the o-A1 particles can be calculated as a function of the oxygen-to-aluminum ratio. These calculations pre- have diameters in the range 30 to 140A, with a mean size of about 50.4 as observed by electron microscopy. At lower oxidizing temperatures, less than 600°C, no clearly resolved particles are formed, and it is suspected that if A1-0 clusters exist they must be exceedingly small, i.e., 10A or less in diameter. dicto that the particles would vary in size from 15 to 100A. This range of sizes is amenable to detection by both small-angle X-ray scattering and transmission electron microscopy. This paper compares the cluster sizes in such internally oxidized A1-Ag alloys determined by transmission electron microscopy and small-angle X-ray scattering. SPECIMEN PREPARATION Single crystals were prepared from 99.9999 pct Ag, obtained from Cominco Products, and 99.99 pct Al, obtained from Aluminum Co. of America. All melting operations were carried out in graphite molds under flowing purified hydrogen in a horizontal zone refiner. The silver was first degassed,

Jan 1, 1964