Search Documents

Jan. 7, 1952, AIME, Boston Section, Massachusetts Institute of Technology, Campus Room, Graduate House, Cambridge, Mass. Jan. 8, Society for Applied Spectroscopy, 6 pm, supper, Tosca's; 8 pm, meeting, Socony-Vacuum Training Center, 63 Park Row, New York. Jan. 9, AIME, Chicago Section, Chicago Bar Assn., 29 S. La Salle St., Chicago. Jan. 13-15, Institute of Scrap Iron & Steel, Waldorf-Astoria, New York. Jan. 14-1.6, AIME, Minnesota Section, Hotel Duluth, Minn. Jan. 14-18, SAE, annual meeting, Hotel Book-Cadillac, Detroit. Jan. 1.6-18, Society of Plastic Engineers, Inc., annual national technical conference, Edgewater Beach Hotel, Chicago. Jan. 17, AIME, New York Section, Mining Club, 33 Broadway, New York. Jan. 1.7, AIME, Utah Section, Newhouse Hotel, Salt Lake City.

Jan 1, 1952

By D. J. DeLazaro, W. Rostoker, R. E. Riley, M. Hansen

At very low concentrations, carbon dissolves interstitially in molybdenum resulting in a linear expansion of lattice parameter with increase of carbon in solid solution. Geometrical consideration of the relative size of carbon atom to size of interstice approximately predicts the observed volume expansion. THE element carbon, occurring in molybdenum, either as an unavoidable impurity, or purposely added, markedly affects the mechanical properties of molybdenum. Several investigators1-" have noted the occurrence of molybdenum carbide at the grain boundaries of cast molybdenum, and Fischer and Rengstorff' have shown that this intergranular constituent can induce intergranular brittleness. The appreciable change, with temperature, of the solid solubility of carbon in molybdenum, found by Few and Manning," suggests other important effects upon mechanical properties. Finally the relative atom diameters of carbon and molybdenum (the ratio of atom diameters is 0.59) are indicative, by analogy with iron (ratio of carbon atom diameter to iron atom diameter is 0.65), of a possible interstitial solid solution. If carbon dissolves intersti-tially in molybdenum, anelastic effects and age-hardening effects, similar to those observed in other body-centered cubic metals, could be expected. However, from the work of Sykes, Van Horn, and Tucker," it might be inferred that carbon forms only a substitutional solid solution with molybdenum. These considerations made it desirable to study the effect of carbon on the lattice parameter of molybdenum in greater detail than heretofore. All heat treating was done in a high temperature furnace7 built specifically for heat treatment of molybdenum. The temperatures and times of heat treatment were determined from the a solubility limit for the Mo-C system." These heat treatments were carried out in argon which was purified with respect to N, and H.!0." Purification of the argon was accomplished by passing the argon over hot (750°C) titanium and then through a magnesium perchlorate drying tower. As many as six samples were run concurrently and quenched at different times without interrupting the furnace cycle. Both the purity of the furnace atmosphere and ability to quench samples from any temperature up to 4000 °F were of prime importance in the successful heat treatment of samples for the lattice parameter investigation. Carbon Analysis The Leco Combustion apparatus was used for carbon analysis. This apparatus is capable of an accuracy of & 0.003 pct for a 1 g sample in the range below 0.10 pct. However, it is felt the degree of accuracy is somewhat better than this limit in view of the consistency evident by cross checking a number of determinations. The Battelle Analytical Laboratory consistently reported check results to within k 0.001 pct C. X-ray Measurements The molybdenum wire specimens (20 mils) were carefully filed down to about 12 mils and then etched with nitric acid to 8 mils. Carbon analyses were made on specimens before reduction in size; however, since there was no evidence of surface carburization, it is probable that the carbon was uniformly distributed throughout the sample. The resultant specimens were strain free and small enough to minimize the error in the lattice parameter determinations due to X-ray absorption. Diffraction patterns were obtained with a Debye-Scherrer powder camera 114.59 mm in diam utilizing the Straumanis type asymmetrical film mounting. Nickel-filtered copper. Ka radiation and zirconium-filtered molybdenum Ka radiation were used. Line positions on the film were measured with a traveling microscope equipped with a vernier scale permitting measurement to 0.001 cm. The average of five readings was used to determine the position of each line. The lattice parameter for each specimen was determined from the data by the extrapolation method of Bradley and Jay, Y.e., the intercept at 90" of the straight line obtained by plotting the apparent lat-

Jan 1, 1953

By F. W. Smith

Within the Northern Pennine Orefield, England, intersections of fluorite veins are generally richest in ore, and their recognition enables investigation of the ore potential of the intersecting bodies. A method, based on routine analysis of fluorite for yttrium, has been used with success in mines of the district to predict the location of intersections in partially developed fluorite-bearing ore bodies. This short note is intended as a brief introduction; the details of United Kingdom applications are to be published at a later date. Geology The Northern Pennine Orefield is the second largest fluorspar-producing region in Britain. The associated minerals galena, sphalerite, chalcopyrite, barite, and witherite have all been extensively worked in the past but, with the exception of a single barytes mine, all of these operations are now abandoned. Galena alone is recovered as a byproduct of fluorspar beneficiation. At the present time two companies are producing about 38,000 tpy of fluorspar from high grade vein ore bodies, and a number of concerns are actively prospecting in old lead workings. The mineralization is localized in veins and replacement flats within favorable lithologies in an alternating limestone, sandstone, shale sequence. Since the thickness of individual beds is not great (generally less than 20 m), vein bodies tend to be ribbon-shaped, with length greatly exceeding width and height (Dunham). They thus present difficult exploration targets for conventional diamond drilling techniques. Ore grade varies greatly along the veins, which can change rapidly in character from mineral stained fault gouge to massive mineral bodies up to 10 m in width. It has been known for a very long time that the richer ore bodies tend to be associated with vein intersections in favorable beds. It is assumed that vein fissure intersections provided vertical channelways through which hot ore-bearing brines were able to ascend from deeper cavities in the sequence. Thus investigation of intersections at other horizons generally yields further ore bodies. Technique The relative concentration of yttrium in fluorite is a good indicator, in the North Pennines, of the direction of flow of mineralizing fluids. In all of the ore bodies so far studied in detail in this region, the concentration of yttrium increases markedly in the direction of vein intersections that are believed to have acted as feeder zones to the remainder of the bodies. The reason for this relationship is probably connected with the degradation of soluble rare earths-fluoride complexes by the changes in various physicochemical parameters of the hydrothermal fluids as they entered the ore body cavities from the feeder zones. The simultaneous release of free fluoride ions also contributed to the increased ore values in these intersection zones. Yttrium values in fluorite taken from a longitudinal traverse of the western ore body, Redburn mine, Rookhope, are plotted in [Fig. 1.] The position of a major vein branch and three cross veins are clearly indicated by yttrium maxima. The cross veins themselves contain up to 2.5 m of low grade fluorspar ore. The exact positions of B and C were unknown previous to the geochemical survey. Similar results have been obtained for several other veins and ore bodies in the area. Clean fluorspar was collected as bulk samples from within 300 mm of the vein wall and, since the vein infilling is simple, with mineral growth from the walls inward, analyses of the samples are considered comparable along the length of the ore body. A number of samples taken from the center of the vein show a

Jan 1, 1975

By Henry P. Chandler

Tripoli is the general name for a number of fine-grained, lightweight, friable, minutely porous, forms of decomposed siliceous rock, probably derived from siliceous limestones or calcareous cherts. Tripoli is often confused, both in the trade and technical literature, with tripolite, a diatomaceous earth (diatomite), found in Tripoli, North Africa. A material found near Seneca, Mo., resembling tripolite was incorrectly termed "tripoli." This name has persisted and now has a definite physical and trade meaning. However, tripoli contains no diatoms, is of an entirely different origin, and has chemical and physical properties different from those of tripolite. There are two distinct types of tripoli in the United States; that from the Missouri-Oklahoma field and that from the Southern Illinois field. Commercially the term "tripoli" is applied to the material from the Missouri-Oklahoma field, while the material from the Southern Illinois area is often referred to as "amorphous" or "soft" silica. Material similar to the Missouri-Oklahoma tripoli, but finer grained, occurs in northwestern Arkansas. In its Minerals Yearbook the Federal Bureau of Mines groups statistically under "natural silica abrasives," tripoli from these producing areas and rottenstone from Pennsylvania. The justification for this grouping is the similarity of use. Composition and Physical Properties Commercial tripoli contains 97 to 99 pet SiO2. The remainder is mostly alumina, iron, lime, soda, and potash, some of which may impart desirable physical properties to the material. Variations in the chemical composition of tripoli are not as important as its physical characteristics. The color of tripoli varies from white to cream, brown, rose, and red, the variations from white being the result of iron deposited from percolating surface waters. The commercial varieties of tripoli mined in the Missouri-Oklahoma area are designated as cream and rose. Other physical properties of the tripoli from this area are: Free quartz, less than 0.5 pct; oil absorption, 50.71 to 53.14 pct; water absorption of the crude tripoli, about 38 pct, and of prepared material, about 52 pct; fracture, uneven to conchoidal; specific gravity, 2.15 to 2.62; weight per cubic foot crude, 35 lb, ground, 55 lb; fusion point, 3,225° to 3,300°F; and refractive index, 1.54. Tripoli occupies about 1 cu yd to the short ton in place and about 1.5 cu yd when broken. Packed for shipment, the powdered material occupies about 33 cu ft to the ton. Its value and usefulness depend primarily on a low content of crystalline silica, size of the natural particles, absorption, and color. Some beds in the Missouri-Oklahoma area are of sufficiently compact material that large, fairly strong blocks may be removed. These find a market as filter blocks and have been used for building material. In the Southern Illinois field the color of the material is the important physical property; pure white is preferred. The rottenstone mined in Pennsylvania is of higher density and lower in silica content than the various types of tripoli. Its composition approximates 60 pct silica, 18 pct alumina, 9 pct iron oxide, 8 pct alkalies, with small amounts of lime and magnesia. The material apparently is a ferruginous and siliceous shale, having properties rendering it suitable as an abrasive or as a filter for paint, rubber, and plastics.

Jan 1, 1960

By W. W. Krysko

In order to calculate the critical particle size of lead oxide entrapped in lead, Stoke's Formula may be applied. All data were available except figures for the density of lead oxide at elevated temperatwes. The density of lead oxide was determined by means of dilatometmetrc and volumetric methods up to 1010°C. Graphs of the density of lead and lead oxide as well as the viscosity of lead are given and discussed, with the conclusion that the most unfavorable region for the separation of lead oxide from molten lead lies just above the melting point of lead. DURING previous investigations, particularly on the dedrossing of lead with aluminum1 and the oxygen solubility in lead,' the critical particle size of lead oxide which could be entrapped in solidifying lead was estimated by calculation, and it was shown that high values found for the oxygen content of lead may be due to the method of sampling and the entrapped particles of dross. Unfortunately, due to lack of data, an exact mathematical solution was not possible. The particle size which will separate under a given condition can be estimated from Stoke's Law, which states that where: d = diameter of the critical particle size ¦q = viscosity of lead in Poise V = constant velocity in cm sec-I g = 981 cm sec-2 61= specific gravity of lead 62= specific gravity of lead oxide The depth of the lead bath and the time before solidifying define the velocity. The viscosity of molten lead is known from earlier work by Krysko and is given in Table I. The specific gravity of lead is also known, see Table II. These values are according to Hofmann. A careful survey of literature revealed no values for the density of lead oxide at elevated temperatures. The present investigation was therefore conducted to provide this information. RESEARCH INVESTIGATIONS The density of lead oxide was determined from the following experiments: 1) Determination of the density of lead oxide at room temperature. 2) Dilatometric investigations on the same samples. 3) Determination of the shrinkage at the liquid-solid trans£ormation. 4) Density determinations on liquid lead oxide. 5) Time temperature curves during cooling. 1) The samples for the determination of the density of lead oxide in the solid state were prepared in the following manner. Molten lead oxide was cast into I hot mold which could be opened along the longitudinal (vertical) axis. The cast samples were cylinders of approximately 10 mm diam and approximately 80 mm length. The cylindrical hot mold was open at both ends and was placed on a large copper chill plate shortly before casting. The solidification of the lead oxides proceeded upwards without any formation of internal cavities. The sample was carefully checked with respect to density and crystalline appearance, and only the lower portions which were crystalline and free from porosity were used. The density was determined in a specially made pyknometer-like container, where the surplus liquid was squeezed out through an orifice approximately 1/10 mm in diameter. Mercury or water was used as the liquid. The densities of the samples were calculated from the weight, volume, and mean specific gravity of eight samples was 9.62 * 0.05 g cm"3 at 22"~. 2) The samples were machined to approximately 1 1/2 in. in length and fitted into a dilatometer. A

Jan 1, 1962

By Thomas L. Garwood, F. C. Menk

IT is generally, accepted that no method of coal cleaning except froth flotation is effective in cleaning dust. In the majority of coals mined in the United States the dust sizes contain a high percentage of impurities, hence the removal of the dust from the coarse sizes lowers the impurity content of these sizes. Dedusted coal is desired as a means of providing a better feed to cleaning plants because of increased efficiency in both dry and wet plants. In dry-cleaning plants, a dedusted feed makes for a pervious and uniform bed. With a dusty feed the fines tend to segr6gate in the feed stream and pass en masse over the air separators, causing a lack of uniform aeration and fluidity of the bed necessary to efficient cleaning. In wet-cleaning plants dedusting of the feed often decreases the sludge problem to the point of eliminating the necessity of wasting wash water. It may be advantageous to eliminate sludge-settling equipment in favor of dedusting equipment, to provide the advantages of a dedusted feed to the wet-washing process. Dedusting advantages may include: (1) the removal of fusain, especially advantageous in plants washing coal intended for metallurgical coke; (2) prevention of the gradual build-up of solids in the wash water, with a consequent variation in the washing ability of the system; (3) prevention of the loss of dust to the sludge ponds, providing instead a fuel for local consumption or special markets. DEDUSTING The practice of dedusting, sometimes called aspirating, has presented a problem in disposing of the dust and intermediate small sizes recovered in the process. It has been found that no difficulty is experienced in disposing of the intermediate sizes, since they are free of fine dust and burn freely on grates built for small coal. They handle well, flowing freely from bins and hoppers and into conveyors, and pulverize easily. They have a low angle of repose. In tests made on this size as a feed to coke ovens, the results have been excellent, in that the natural breakdown of .coal in handling and shooting in the mine gives this small-size coal good

Jan 1, 1943

By R. C. Buehl, J. P. Morris

F. D. Richardson—The authors are to be congratulated on this further contribution to our knowledge of the thermodynamics of the interaction between sulphur and carbon and silicon in liquid iron. As the authors state, the influence of carbon and silicon on the activity coefficient of sulphur in liquid iron is clearly of great importance in the blast furnace, since it must cause a three to fourfold improvement in the partition of sulphur between slag and metal. The influence of increasing temperature in further increasing the activity coefficient of the sulphur in the metal in the blast furnace by increasing the carbon content is also of interest. This effect, however, is probably only part of the reason for the general observation in blast furnace practice, that the sulphur content of the metal is lowered by increasing temperature. Other contributing factors are the lowering of the oxygen potential in the presence of carbon by increasing temperature and the probable increase in the activity coefficient of the lime in the slag for the same reason. The former of these effects, which works via the (CaO) + [S] = (CaS) + [O] equilibrium, might possibly account for a 70 pct improvement in the sulphur partition and the latter might give a further 50 pct improvement. C. Sherman—I would like to compliment the authors on their very careful research. If I may, I would like to show results of calculations on the carbon-sulphur-iron system similar to the ones that were shown in our paper for the silicon-sulphur-iron system. For Fe-S-C ternary system k=PHgs/PH2 x 1/(f1°) (f2°) (%S) where fs = sulphur activity coefficient fs' = fs for Fe-S system of equal pct S f3° = f2/f2 for Fe-S-C ternary system This same analysis has been used on other systems, but the results shown in fie.- 7 are for carbon and silicon. L. S. Darken—I would like to make two brief comments in addition to complimenting the authors on an apparently very precise and accurate investigation. The first is that the present work is in agreement with a calculation by Larsen and myself." Our calculation (much less precise than the present work) was based on: (1) Unpublished work on the sulphur content of molten iron (1.5 pct at 1500°C) in equilibrium with graphite and an iron sulphide slag; (2) the distribution coefficient of sulphur between slag and carbon-free liquid iron. We expressed the result in a form equivalent to log 7. = 0.18 [%C] which gives an activity coefficient (?s.) of sulphur only slightly higher than the authors find and certainly within the precision of the earlier work. My second comment concerns the correlation of the thermodynamic findings with atomistics. A rough pic- ture of the atomic arrangement in the liquid solution is rather easily conceived for this particular liquid solution containing iron, carbon, and sulphur. Carbon has a very much stronger affinity for iron than for sulphur. Hence we may conclude that a sulphur atom will but seldom be adjacent to a carbon atom—since this would be a position of high energy. From the metallic radii of iron and carbon we know that six iron atoms pack neatly around one carbon atom. Thus each carbon atom in retaining this shell of iron atoms (which latter may not be replaced by sulphur on account of the high energy requirement) decreases the available positions for each sulphur atom by six. Hence each atomic percent of carbon decreases the equilibrium sulphur content by 6 pct (of itself). Or, at low concentration each atomic percent of carbon increases the activity coefficient of sulphur by 6 pct. This is in good agreement with the observed increase (6 or 7 pct at low carbon content). It is indeed gratifying to find a case where, by such simple reasoning, quantitative agreement is found between precise data and the modern picture of the atomistics of the metallic state. J. P. Morris (authors' reply)—We would like to point out that there is an error in the equation on p. 322 of the paper. The third equation should read: ½S2 (gas) + H2 (gas) = H2S (gas) The authors wish to thank everyone for the interest they have shown in the paper. In regard to the general observation in blast furnace practice, that the sulphur content of the metal is lowered by increasing the temperature, Dr. Richardson is correct in stating that the cause can be attributed only in part to the increase in activity coefficient of sulphur resulting from the rise in carbon plus silicon content of the metal with rise in temperature. However, this factor is probably an important one. The results of one experiment, performed since this report was written, indicate that at a constant temperature the addition of silicon to a melt saturated with carbon causes an increase in the activity coefficient of sulphur even though the carbon solubility is lowered. In this test, 2.5 pct silicon was added to a melt saturated with carbon and maintained at 1400°C. Although the carbon content dropped from 4.85 to 4.1 pct, the activity coefficient of sulphur was increased by about 20 pct.

Jan 1, 1951

By H. C. Brown

SINCE 1934 the steel industry has been utilizing the spectrograph for supplementing wet chemical analysis in the production control of electric and open hearth furnaces. This means of control made great strides during the war years because of the general acceptance of the spectrograph and the increased emphasis that was placed on rapid control methods. However, in the post war era, with the demand still on increased production, it became apparent that a still more rapid and economical means of production control was needed. Since the spectrograph had been used mostly in the analysis of low alloying and residual elements, it also became apparent that equipment was needed to extend the spectrographic technique to the analysis of the high alloying elements in stainless steel. For these reasons, companies manufacturing spectrographic equipment were prompted to start development work on direct reading instruments. In June 1949, the Applied Research Laboratories of Glendale, Calif., announced that a direct method of spectrochemical analysis for stainless type steels had been developed. This paper will describe the use of the Applied Research Laboratories Production Control Quantometer in the quantitative control of stainless, silicon, and plain carbon steels being made at the Butler Pennsylvania Div. of the Armco Steel Corp. The Armco Butler Div. has one 70-ton electric furnace and six 150-ton open hearth furnaces. The electric furnace is employed in the making of all types of stainless steel and the open hearth furnaces are used for the production of silicon, wheel, and plain carbon steels. The ARL quantometer was purchased primarily for the purpose of controlling the steelmaking in the electric furnace, but its use has been extended for the analysis of final tests (ladle tests) on a number of different types of stainless, silicon, and plain carbon steels. Because of this additional work by the quantometer, substantial savings in manpower and time have been realized by the laboratory. In the analysis of a set of preliminary tests from the stainless steel furnace, approximately 40 min in laboratory time are saved due to quantometric analyses. Despite the fact that more specialty grades of stainless steel are being made in the electric furnace, the average tons per hour have been increased since the quantometer was put into operation. Specialty grades require more furnace time than regular commodity grades of stainless steel. The installation of the ARL production control quantometer was completed on March 13, 1952. By May 1, 1952, the instrument was calibrated for nickel, chromium, manganese, silicon, and molybdenum, which are the elements necessary for the production control of the stainless steel furnace. Within the following month, training of personnel on the quantometer was achieved and a study of the accuracy of the instrument showed that the results obtained were sufficiently accurate for control purposes. Therefore, on June 11, 1952, the quantometer was placed on production control for all types of stainless steels. Starting September 11, 1952, the instrument was gradually placed on ladle analysis (final tests) as the analytical curves were refined and additional curves were drawn. The quantometer has been relatively free of breakdowns since placing it on production control. The samples from only one stainless steel heat have had to be analyzed by wet chemistry because of instrument trouble. The previously existing heat-time record was also bettered by 15 min on a commodity grade of 18-8 stainless steel. Scope of Control In general, the quantometer determines all elements necessary for the production control of all types of stainless steel heats and for the ladle analysis of various types of stainless steel heats. It is also used in reporting final results for silicon, manganese, chromium, nickel, molybdenum, tin, copper, and aluminum on all silicon steel grades and manganese, chromium, nickel, molybdenum, tin, and copper on several plain carbon steel grades. Table I shows the elements and the concentration ranges of these elements in the various types of stainless, silicon, and plain carbon steel that are determined on the quantometer. A study of the results obtained on ladle test samples of stainless steel types 410, 430, 430 Ti, 446, 301, 302, 304, 304L, 305, and 17-7 PH will be discussed. Also included in the study are the results obtained on ladle test samples of a number of silicon steels. Apparatus In order to take full advantage of the potentials of the production control quantometer, the unit has been placed in an air-conditioned room with relative humidity control. The temperature is maintained at 73'22°F and the humidity at 45&5 pct. The air conditioning serves as a precaution to minimize the amount of adjustment and calibration needed during operation. It also reduces contaminating fumes and dust and thereby lessens the necessity for maintenance on the equipment. The quantometer is composed of three units: the high precision multisource unit, the 1.5 meter vertical spectrometer, and the console. The source unit supplies excitation conditions varying from spark-like discharges to arc-like discharges. The voltage to the source unit is supplied by a motor-generator

Jan 1, 1955

By R. L. Huntington, D. T. MacRoberts, Charles R. Hetherington

Since the equation of continuity governing transient flow of gases through porous media cannot be integrated mathematically into a simple usable expression free from series terms, empirical and approximate equations have been advanced relating cumulative production and future production rates from gas reservoirs with time. In order to check the accuracy of these empirical equations and to obtain an insight into the initial conditions pertinent to the solution of the fundamental equation of continuity, experimental work has been conducted on a vertical 2-in. tube, 91.6 ft. high, packed with unconsolidated Wilcox sand. The results presented in graphical form show the accuracy of the approximate relations. Data from unsteady-flow runs on the 2-in. experimental tube are presented graphically, and are applied to obtain an equation for this specific case, and are offered as an aid in future investigations of this basic equation. The close agreement between equations calculated for steady-state flow and the experiments indicates that the decline of actual gas reservoirs may be treated by an application of these equations without serious error. Introduction The steady-state flow of gas through a porous material—that is, flow wherein the boundary conditions do not vary with time—is subject to analytical solution. Muskat1 has shown that the general differential equation is simply the La Place equation in P2. Direct solutions may be at once obtained. The unsteady state, on the other hand, is not analytically reducible. Since nearly all phenomena of practical interest in gas production involve flow in the unsteady rather than in the steady state, it has been necessary to derive approximate Solutions to the general equation. The validity of such approximations has not hitherto been adequately tested. In the experiments to be described a simple, closed, linear system is substituted for the real complex gas field. The general results, however, are independent of the geometry Of the system' The problem studied is the rate of production, and the accompanying variations in pressure, when one end of a linear porous system is opened to the atmosphere and permitted to produce to exhaustion. An approximate solution to the general differential equation, based upon the assumption of an "infinite series of steady states," is then applied to the results to determine the validity of this method of dealing with actual reservoirs. Theoretical Considerations The fundamental differential equation governing the flow of a gas through a Porous medium can be derived easily from the equation of continuity, Darcy's law, Boyle's law and a statement of the thermo-dynamic nature of the flow. For isothermal flow it is: d2P2/dx2 + d2p2/dy2 + d2p2/dz2 = 2fµ/K dP-dT

Jan 1, 1942

By R. L. Huntington, D. T. MacRoberts, Charles R. Hetherington

Since the equation of continuity governing transient flow of gases through porous media cannot be integrated mathematically into a simple usable expression free from series terms, empirical and approximate equations have been advanced relating cumulative production and future production rates from gas reservoirs with time. In order to check the accuracy of these empirical equations and to obtain an insight into the initial conditions pertinent to the solution of the fundamental equation of continuity, experimental work has been conducted on a vertical 2-in. tube, 91.6 ft. high, packed with unconsolidated Wilcox sand. The results presented in graphical form show the accuracy of the approximate relations. Data from unsteady-flow runs on the 2-in. experimental tube are presented graphically, and are applied to obtain an equation for this specific case, and are offered as an aid in future investigations of this basic equation. The close agreement between equations calculated for steady-state flow and the experiments indicates that the decline of actual gas reservoirs may be treated by an application of these equations without serious error. Introduction The steady-state flow of gas through a porous material—that is, flow wherein the boundary conditions do not vary with time—is subject to analytical solution. Muskat1 has shown that the general differential equation is simply the La Place equation in P2. Direct solutions may be at once obtained. The unsteady state, on the other hand, is not analytically reducible. Since nearly all phenomena of practical interest in gas production involve flow in the unsteady rather than in the steady state, it has been necessary to derive approximate Solutions to the general equation. The validity of such approximations has not hitherto been adequately tested. In the experiments to be described a simple, closed, linear system is substituted for the real complex gas field. The general results, however, are independent of the geometry Of the system' The problem studied is the rate of production, and the accompanying variations in pressure, when one end of a linear porous system is opened to the atmosphere and permitted to produce to exhaustion. An approximate solution to the general differential equation, based upon the assumption of an "infinite series of steady states," is then applied to the results to determine the validity of this method of dealing with actual reservoirs. Theoretical Considerations The fundamental differential equation governing the flow of a gas through a Porous medium can be derived easily from the equation of continuity, Darcy's law, Boyle's law and a statement of the thermo-dynamic nature of the flow. For isothermal flow it is: d2P2/dx2 + d2p2/dy2 + d2p2/dz2 = 2fµ/K dP-dT

Jan 1, 1942

By M. J. Saarivirta, P. P. Taubenbla

This paper presents some high-temperature properties of copper-zirconium conductor alloy compared to copper-chromium alloy. Definite superiority of the copper -zirconium alloy over the copper-chromium alloy at high temperatures is shown. RECENT investigations have shown that cold-worked copper-zirconium alloy possesses good room-temperature strength, ductility, and conductivity and maintains most of its strength at temperatures up to 450°C (840°F). As a result, this alloy is now used for many applications, such as commutator segments, resistant welding wheels and tips, rectifier bases, electrical contacts, and so forth. Early investigations1-3 have shown that the maximum solid solubility of zirconium in copper is close to 0.15 pct and the alloy containing Cu-0.10-0.15 pct Zr exhibits the optimum mechanical and physical properties. Results2 have also shown that the alloy has better elevated temperature strength and ductility than copper-chromium and copper-silver alloys. The present investigation was undertaken to learn more about the elevated temperature properties of copper-zirconium alloy and to compare these properties with those of the copper-chromium alloy. WORK PROCEDURE The commercial copper-zirconium alloy, Amzirc was selected for this investigation. Because this alloy is composed of oxygen-free high-conductivity copper and 0.10-0.15 pct Zr, it was believed that possible disturbance from impurities would thus be negligible. Copper-chromium alloys used in this investigation contained 0.40 and 0.70 pct Cr and balance copper. The Cu-0.40 pct Cr alloy was a commercial brand, whereas the Cu-0.70 pct Cr alloy was made from OFHC copper and Cu-5 pct Cr master alloy. It was made in a graphite crucible under argon gas cover and cast. In the preparation of specimens, all three alloys were treated to give the optimum properties; thus the Cu-0.15 pct Zr alloy was solution annealed at different temperatures to determine the desirable solution annealing temperature. It was then cold worked and aged at 375" to 400°C (705" to 750" F). A solution annealing temperature of 1000°C (1830°F) was selected for the copper-chromium alloys because this temperature is widely used in commercial practice. The same alloy was aged at 450°C (840°F) after solution annealing and cold working. It was found that the maximum precipitation hardening of the copper-chromium alloy occurred at this temperature. When aged after solution annealing, the aging temperature was 500°C (930"F) for both alloys. The following properties were determined: 1) Tensile properties as a function of temperature. 2) Effect of solution annealing temperature on high-temperature tensile properties. 3) Stress to rupture strength at 350° and 400°C (660"to750°F). 4) Impact strength. 5) Electrical conductivity and resistivity as function of temperature. 6) Thermal expansion.

Jan 1, 1961

By Susan B. Leiter

That oxygen in copper has been a source of trouble is well known and that that trouble has been real in the commercial world has been shown by Fuller.' Moore and Beckinsale's paper2 at the annual meeting of the Institute of Metals in London, 1921, called forth considerable discussion. Prof. T. Turner expressed the opinion that it was not necessary to have cuprous oxide present in sufficiently large quantities to form either globules or seams in order to produce a bad effect if the copper were gassed. This brought up the question of the solubility of oxygen in copper and the authors desired to know whether there were any evidence of such solubility, because their experience was that whenever there was any oxygen in copper it was present in the form of free cuprous oxide, which was practically always in the form of globules. Later Hanson, Marryat, and Ford3 stated that 'for all practical purposes cuprous oxide may be regarded as insoluble in copper. However, they found particles of the eutectic to coalesce to form much larger particles. They suggested that cuprous oxide was actually slightly soluble in copper, for it was difficult otherwise to understand the mechanism by which such coalescence could take place. W. E. Ruder, in discussing that paper, said that his experiments had led him to conclude that a slight solubility must exist to allow for the ready coalescence of oxide particles, but conductivity tests convinced him that that solubility was very small. Nevertheless, there appeared to be a state of admixture of oxide with copper that closely resembled a colloidal mixture which at first was mistaken for a true solution and which usually existed at the grain boundaries. The purpose of this paper is to give the results of some investigations, begun in September, 1921, which would seem to show that although cuprous oxide may be only slightly soluble: (1) this solubility is sufficient

Jan 1, 1926

By R. W. Fountain, John Chipman

The solubility of nitrogen in Fe-B alloys (0.001 to 0.91 pet B) is determined by the Sieverts' technique for temperatures of 950° to 1150°C. The activity coefficient of nitrogen is decreased by boron. The three-phase equilibrium between ? iron, BN, and gas is established and also the four-phase equilibrium between iron, BN, Fe2B, and gas. The above equilibria are calculated for a iron. The relation of these data to hardenability and strain aging of boron-treated steels is discussed. BORON additions are known to enhanbe the hardenability of heat-treatable steels and to assist in the control of strain aging in sheet steel for deep drawing. The increase in hardenability is explained by the theory that adsorption of boron on austenite grain boundaries reduces their free energy and thus retards ferrite and upper bainite nucleation.l,2 Digges and Reinhart3 have shown that the full effectiveness of boron in commercial steels is achieved only when strong nitride formers such as titanium and zirconium are also present. The influence of nitrogen on eliminating the boron contribution to hardenability was also demonstrated by Shyne and Morgan.4 These workers prepared Ni-Mo steels containing either nitrogen or boron or nitrogen plus boron. The nitrogen-plus-boron steels showed the lowest hardenability which was attributed to the presence of stable nucleating particles, presumably nitride. Morgan and Shyne5-7 have shown that boron in the amount of 0.007 pet will completely eliminate strain aging due to nitrogen in low-carbon, open-hearth steels. In addition, by proper control of the boron additions, a rimming steel can be produced. Since the effectiveness of boron on hardenability and eliminating strain aging is influenced by the amount and distribution of the nitrogen in the steel, the present study was. undertaken to determine the influence of boron on the solubility of nitrogen in iron. EXPERIMENTAL PROCEDURE The solubility of nitrogen in Fe-B alloys was measured by the method of Sieverts, which consists of determining the amount of gas dissolved by the metal in a constant volume system. The apparatus employed in this investigation and the experimental details have beendescribed previously.B AMcLeodgage was added to the apparatus to allow measurements at very low pressures. The alloys were melted at reduced pressure in a basic-lined induction furnace using electrolytic iron and ferroboron. Ferroboron was added after the primary deoxidation of the iron with carbon. Since it was difficult to attain a constant low level of oxygen by this procedure, silicon was added after the carbon deoxidation and prior to the ferr obor on addition. The alloys were castas 2-in. sq ingots, heated in argon at 1050loC, and forged to 1/4-in. plate. After forging, 1116 in. was machined from each side of the plate to remove any possible contamination, and it was then cold-rolled to 0.010-in. sheet. The sheet was cut into approximately 1/4-in. squares and pickled in an inhibited H2SO4 solution to ensure a clean surface. In the case of the boron alloys, a hydrogen treatment could not be used for surface cleaning because boron losses resulted. The composition of the alloys is given in Table I. For a solubility determination, a 75-g sample was inserted in a quartz tube and sealed in place in the apparatus. The entire system was evacuated at room temperature and leak tested for 24 hr. If no leaks were observed, the system was heated to the temperature of measurement and again leak tested for 24 hr. If no leaks were detected, the hot volume and solubility determinations were begun. The hot volume was determined at a constant temperature for each run by admitting successive amounts of argon and recording pressure vs volume, which, in all cases, resulted in a straightline relationship. The argon was then removed and the procedure repeated with nitrogen. Successive additions were made until the desired nitrogen content of the metal and equilibrium pressure of the system were obtained. The

Jan 1, 1962

By W. W. Schmittroth, A. Y. Bethune

The commercial analysis of Special High-Grade zinc usually involves the determination of lead, iron, copper and cadmium as impurities in the base metal. Over the past 20 years, as the result of metallurgical improvements in the art of producing Special High-Grade zinc metal there has taken place a gradual exclusion of almost all extraneous elements, and the few that do remain in the final product have been virtually reduced to the vanishing point. Thousands of tons of zinc are now commercially produced annually and made available to the trade, in which impurities are present only in the order of 0.0010 per cent or less and the sum total of all impurities does not exceed 0.0025 per cent. To such zinc the term "super-purity" might well be applied without undue exaggeration. The techniques used for production control and final analysis of Special High-Grade zinc by means of emission spectra in the laboratories of the electrolytic zinc plant of the Sullivan Mining Co. are based on the premise that self-electrodes are to be preferred over all other forms for the examination of the zinc in question. Furthermore, after a survey of the literature and considerable experimental work,' it was decided that the spectrographic method of internal control, the principle of which was first announced by Gerlach,2 using a modification of the high-voltage alternating-current arc source introduced by Duffendack and Thompson,3 with the calibration of each photographic plate as recommended by Wolfe,4 would yield the most accurate and reproducible results. Self-electrodes were chosen in order to make use of one of the unique advantages inherent in spectrographic analysis; namely, the rapid and almost effortless detection of elements other than those being quantified by the analyst; or conversely, the proof that the zinc is free from such impurities if no spectral line of the suspected element appears. This fact was verified for certain elements, and will be discussed later. Carbon electrodes impregnated or packed with zinc salts chemically prepared from the zinc to be assayed were avoided for a number of reasons. First, the chemical manipulation was another time-consuming step, which increased the chances for contamination. Second, none of the common zinc salts, such as the chloride, nitrate or sulphate, yielded reproducible results under our conditions, nor did the spectral line of the impurity appear as readily in the low concentrations as when using zinc metal. Third, no commercial carbon, except the very expensive, was pure enough to use with this grade of zinc and the continued time, effort and expense incurred in the purification of carbon were not desirable. The use of special High-Grade zinc self-electrodes introduces certain complications with regard to obtaining satisfactory excitation conditions, because it seems necessary to raise the temperature

Jan 1, 1949

By Donald T. Hawkins, Ralph Hultgren

The lorsion effusion method has been used to measure the vapor pressure of lead over pure lead and eight Pb-Sn alloys ranging from 9.1 to 87.9 at. pct Pb in the temperature range 950° to 1125°K. The resulting ?H°y 298 = 46,630 ± 200 cal per g-atow for pure lead is in excellent agreement with previous work. Deriued ?Gph values for the alloys were smoothed and correlated with previous heat of formation data to obtain entropies for the liquid alloys. values for the tin component were calculated by Gibbs-Duhem integmtion. Surfhce depletion of these liquid alloys was found to be absent, as shown by the fact that the measured pressure remained substantially constant with time in contrast with previous measurements on iron-rich solid Fe-Mn alloys. The activities and Gibbs (free) energies of the liquid Pb-Sn system are not well known although the heats of formation have been accurately determined by K1eppa.l Vapor pressure determinations of the activity of lead by Voronin and Evseev2 disagree with those of Predel.3 Elliott and chipman4 measured activities by the electromotive -force technique in the ternary Pb-Sn-Cd system. From the resulting values of the activity of cadmium, they were able to calculate the activities of lead and tin for the binary Pb-Sn system at the compositions xsn = 0.33 and 0.67. Atarashiya, Uta, Shimoji, and Niwa5 determined the activity of tin from Hz-H2O equilibrium measurements, but their results are subject to question due to uncertainty in the final state of their samples. To resolve these differences, measurements of the activity of lead were made using a torsion-effusion apparatus. Among other advantages, this apparatus rapidly detects errors caused by surface depletion, which tends to reduce the apparent vapor pressure of the more volatile component. If the measured torques remain nearly constant with time, only bulk depletion is occurring. This contrasts with the rapid decrease in torque found in solid Fe-Mn alloys at high temperatures and low manganese contents.6 EXPERIMENTAL 99.999+ pct Pb was obtained from the American Smelting and Refining Co. and 99.999 pct Sn from Vulcan Detinning Co. Eight Pb-Sn alloys were prepared by melting together weighed amounts of the pure metals in evacuated Pyrex tubes and quenching the melts in water. Loss of weight in preparation was less than 0.02 pct in all cases. The effusion cells were made from high-purity, nonporous graphite. Graphite was chosen because of its resistance to reaction with lead and tin and because it can be accurately machined with precision orifices. Two cells were used with overall dimensions as shown in Fig. 1. The orifices of cells 1 and 2 were, respectively, 1 and 1.5 mm in diam.

Jan 1, 1968

By W. Rostoker, A. S. Yamamoto, K. Anderko

ALTHOUGH the corrosion resistance of magnesium and its alloys is closely related to iron content, there has been no direct measurement of the solid solubility of iron in magnesium. Bulian and Fahrenhors;1 and Mitchel]2 agree that pure iron or a limited terminal solid solution crystallizes from the Mg-rich liquid. For this reason a magnetic-moment method was selected to estimate that portion of the total iron content which is not in solid solution. Since iron in solid solution in magnesium cannot contribute to ferromagnetism, the difference between chemical and magnetic-iron analyses should yield the solid solubility. By experimentation it was found that the melting of pure sublimed magnesium (99.995 wt pet purity) in Armco-iron crucibles at about 800°C is a convenient way to introduce small amounts of iron. Melts retained 5, 10 and 20 min at 800°C analyzed 0.003,, 0.005,, and 0.018 & 0.001 weight pet Fe, respectively, after being stirred, heated to 850°C, and cast into graphite molds. The as-cast alloys were pickled in acid (dilute HC1 + HNO3), annealed at 600°C for 3 days, scalped on a lathe to remove the pitted surface, pickled again, extruded at about 100°C to 3-mm wire, reannealed 41/2 days at 500°C, and water-quenched. The specimens were again scalped, pickled, and used both for chemical and for magnetic analysis. Most of the precautions described were intended to prevent iron pickup by contact with tools or superficial iron enrichment by volatilization of magnesium during heat-treatment. It is believed that the specimens ultimately used for test were homogeneous and characteristic of phase equilibria at 500°C. Magnetic Analyses A susceptibility apparatus of the Curie type was used for magnetic analyses. Field strengths of up to 10,400 oersteds could be generated. By this method, an analytical balance measures the force of attraction which a calibrated magnetic field exerts on a suspended specimen. The force equation is as follows f/m = M dh/dy where f/m = force per unit mass of sample M = magnetic moment per unit mass dH/dy = magnetic field gradient The dH/dy characteristic of the instrument is determined by the use of a standard palladium sample, and the calibration is made independently for all values of H. Since a large finite field is required to saturate an assembly of ferromagnets, it is necessary to measure the apparent magnetic moment for increasing steps of H until a saturation value is obtained. The percentage of iron in the sample as free ferromagnetic iron may then be computed simply C= 100 (M1/M1) where C = percent content of undissolved iron in sample M1 = saturation magnetic moment of sample per unit mass M1 = saturation magnetic moment of iron per unit mass taken as 217 emu-cm per gm There is no serious difficulty in applying this method except for the unusual magnetic behavior of very fine particles of ferromagnetic substances. It has been found and is the basis for a widely accepted theory that with sufficient subdivision, the magnetic fields required to saturate and the coercive force after saturation rise to exceedingly high values. Recent work on precipitates of Fe and Co from copper solid solutions8 showed that about 5000 oersteds were necessary to approach saturation. The magnetic moments as a function of field strength measured in the present investigation are listed in Table I. Only the 0.018 wt pet Fe alloy yielded a magnetization curve with a fairly well-defined saturation plateau at 3.76x10 -2 emu-cm/ gm. This corresponds to 0.017 & 0.001 wt pet Fe in the alloy. This indicates that the solid solubility must be of the order of 0.001 wt pet Fe. The magnetic-moment data of the other two alloys are badly scattered, indicating that the amount of ferromagnetic iron in these samples is so low that the magnetic forces acting on them cannot be measured accurately by the analytical balance used. Nevertheless, the fact that even the 0.003, wt pet Fe alloy shows ferromagnetism indicates that the solid solubility must be below that value. Acknowledgment This work was sponsored by the Pitman-Dunn Laboratory of Frankford Arsenal, Philadelphia, Pa. The support and permission to publish are gratefully acknowledged. References W. Bulian and E. Fahrenhorst: Zeic. Metallkunde, 1942, vol. 34, pp. 116-170. 2 D. W. Mitchell: AIME Transactions, 1948, vol. 175, pp. 570-578. 3 G. Bate, D. Schofield, and W. Sucksmith: Philosophical Magnsine, 1955, vol. 46, pp. 621-631.

Jan 1, 1959

By Voyle R. McFarland, Robert A. Burmeister, David A. Stevenson

The distribution of lead between phases in the Ag-Sb-Te system was studied using microautoradio -graphy. Two compositions were investigated, both containing an intermediate phase Known as silver antimony telluride as the major phase, and one containing AgzTe and the other SbzTes as the minor phase. For both compositions, two thermal treatments were used: nonequilibrium solidification from the melt and long equilibration anneals of the as-solidified structure. For each composition, lead was segregated in the minor phase of the as-solidified structure, but was distributed in the matrix after anneal. The electrical resistivity and carrier type were insensitive to the distribution of lead in the two-phase structure. ThERE has been considerable interest in the Ag-Sb-Te system because of its thermoelectric properties. The major interest has been in compositions on the vertical section between AgzTe and SbzTes, particularly the 50 mole pct SbzTes composition AgSbTez (compositions are conveniently expressed as mole percent SbzTes along the AgzTe-SbzTes section). One of the major problems in the proper evaluation and utilization of this material is the inability to control the electrical properties through impurity additions: all alloys prepared to date have been p-type, even with the addition of large amounts of impurities. It has been shown Wit all the compositions previously studied contain an intermediate phase of the NaCl st'ructure as a major phase (denoted by b) and a second phase, either AgzTe or SbzTe3, as a minor phase.'-3 One explanation for the unusual electrical behavior of this material is that the impurity additions have a higher solubility in the second phase than in the matrix; the impurity would segregate to the second phase, leaving the bulk matrix essentially free of impurity.4 In order to investigate this mechanism with a specific impurity element, the distribution of lead between the two phases was determined using autoradiography. Lead 210 was chosen because of the suitability of its 0.029 mev 0 particle for autoradiography and also because of the interest in lead as an impurity in this system.5'6 EXPERIMENTAL PROCEDURE Two compositions were taken from the vertical section between AgzTe and SbzTes, 50 mole pet SbzTes (Viz. AgSbTez) and 75 mole pct SbzTes, in which AgzTe and SbzTes appear, respectively, as the minor phase. Lead containing radioactive lead (pb210) was added to the above compositions to provide a concentration of 0.1 wt pct Pb. The material was placed in a graphite crucible in a quartz tube which was then evacuated and sealed. The samples were melted and solidified by cooling at a rate of 8°C per min and then removed and prepared for microa~toradiography. After autoradiographic examination of these samples, they were again encapsulated and annealed in an isothermal bath at 300°C for a number of days and prepared for examination. An alternate method of preparation employed a zone-melting furnace; the molten zone traversed the sample at a rate of 1.2 cm per hr and the solid was maintained at a temperature of 500°C both before and after solidification. This treatment had the same effect as solidification at a slow rate followed by an anneal for several hours at 500°C. In order to obtain the best resolution, thin sections of the alloy were prepared by hand lapping to a thickness of approximately 20 p. Other samples were prepared for examination by lapping a flat surface on the bulk sample. The resolution, although somewhat better in the former procedure, was adequate in both instances and the majority of the samples were treated in the latter fashion. A piece of autoradiographic film (Kodak Experimental SP 764 Autoradiographic Permeable Base Safety Stripping Film) was stripped from its backing, care being taken to avoid fogging due to static-electrical discharge. A small amount of water was placed on the sample, the film applied emulsion side down on the surface of the sample, and the sample and the film dipped into water in order to assure smooth contact. After drying, the film was exposed for 2 to 5 days, the period of time selected to give the best resolution. The film was developed on the specimen and fixed and washed in place. Two major factors must be considered in establishing the reliability of an autoradiograph: the in-

Jan 1, 1964

By Roger W. Dewey

The opposition is all kinds. There are extremists. There are quiet, sensible sounding folk who can twist numbers and facts to make their point. But they are all out to shut you down! Some of them are genuinely concerned about miners' impact on the environment. Others are just anti- society, anti-big business - small is beautiful - live naturally. The opportunity for them to make those statements on television was provided by us, the Uranium Public Affairs Task Force, as part of a media tour of the State of Idaho in May. We fielded four representatives of the industry and got 25 hours of television coverage, 22 hours of radio coverage, and print coverage by every paper in Idaho. The tour included several debates, and these clips are from two of them. Our folks creamed them! This one was so upset that he ran off the set while his mike was still plugged in, trailing studio equipment behind him. But we don't always have the opportunity to rebut them. They are making these statements all the time, everywhere they can. They have learned their trade well. They use the hearing process like A1 Hirt uses the trumpet. If the process of intervention should shut us down or prevent us from getting a license, so much to the good. But even if it doesn't - they win - for it causes delay - delay costs money and so does complying with regulation. If they can make us uneconomic, and that's not too hard to do these days, they have won. Regulation restricts the decision process. Any time the decision process IS restricted, you face the possible loss of a more economic alternative. They are out to pile every regulation on you they can and every delay they can. Initiatives! They came after us - the uranium industry - in South Dakota and Montana last year. They won in Montana. We tried to reverse it in the legislature, but they were too frightened of public reaction to do it. They did put it on the ballot for reversal in November of '82. That puts it squarely up to us to influence the public so we can win a campaign. There will be more initiatives, and at local levels as well as at state. We must join together and win! The public generally supports the continued operation of nuclear power plants. They about split on whether to build more. But they strongly support regulating the industry more stringently. Every survey reflects concern about safety and the desire for the government to take responsibility and regulate. You and I know that regulation nearly always adds cost, and only sometimes increases safety. We need to influence the creation of regulation. We need to accept responsible regulation and fight that which is counter-productive. To win in hearings, to win initiatives, to win in getting responsible regulation, we need public support. We need an informed, understanding, and supportive public. To accomplish this, we need two kinds of efforts. The first is to reach the people at the local level with local representatives of our industry. Informal conversations at church, PTA, cocktail parties, whatever. Presentations to Kiwanis Clubs, League of Women Voters, church groups - wherever we can. Facts, information in printed form, to these same local audiences with the credibility of the local sources. The second is to reach mass audiences through the media. Positive media. This can be done by advertising, but it is very expensive. We have to look to influencing the reporters and editors to get more balanced and accurate reporting. We need to get free time - interviews, debates, letters to the editors, etc. The Uranium Public Affairs Task Force was created last year to provide tools for you to use to reach these audiences (it is affiliated with the Atomic Industrial Forum). Twenty-two companies provided money and man- power. A consultant, Denver Research Group, was retained to produce materials. In this Phase I effort, we first researched what issues were of greatest concern and what were felt to be the greatest needs in materials. We determined that we did not have the funds to go out and do the job for the industry, so we decided to develop tools for the Industry to go out and do the job for itself. From the research, we determined what tools we should develop for you to use. We first developed a set of the quest- ions most likely to be asked of you and the issues most likely to be thrown up to you. We have developed a loose-leaf notebook. Each page contains one of those questions or issues, a short verbatim response that you can use, a short discussion of the subject, and references you can cite or research for further information. It is organized by subject: tailings, water radiation, etc. This book is an extremely handy tool for anyone in the industry. Each uranium location should have at least one.

Jan 1, 1982

By A. L. Bollens, R. H. Johnson

The appraisal of oil wells, now that we have the age-size method of making composite decline curves, and the present worth of successive time units method of valuation, has its greatest remaining uncertainty in the difficulty of extending into the future the price curve and the composite production curve. The point of attack in this paper is the carrying on (or extrapolation) of the production curve. Led by the valuable discovery of Lewis and Beal that the decline curve is nearer the hyperbolic class, y = (x + a)-", than any other form, the current practice is the graphic method. The data are plotted on logarithmic paper and shifted with successive trials until the line becomes straight. This straight line can then be extended into the future. The method was a great help during the period when, for tax purposes, there was need for a quick method even though the errors were large. Now that we seek greater validity in our methods we find the following faults with the current method. 1. Where the shift is great (it exceeds 10 in some cases) the scale cannot be read with the necessary precision so that the resulting data would give a very irregular and inaccurate curve. 2. Where the curve cannot be straightened on logarithmic paper because of sigmoid shape the method has a serious systematic error. We believe the sigmoid curves to be more common than usually supposed, indeed when one considers the number of variable causative factors this is to be expected. We have therefore been seeking a method that is free from these difficulties and yet not so laborious as fitting a curve to the data and the calculation from the formula which, since it involves looking up logarithms, is unduly time-consuming. The method here described has been developed on the basis suggested by Earl Oliver, that the amount of oil produced per month or year for each reduction of production of a barrel of oil per day could be plotted to advantage. A step forward was made by Earl Carpenter in this laboratory, and some of the

Jan 1, 1928

THE increased demand for titanium alloys with improved high-temperature creep strengths has stimulated interest in silicon as an alloying addition to titanium. Silicon is a potent solid-solution strength-ener and, if added in sufficient concentration and properly heat-treated, can also dispersion-strengthen titanium by eutectoid decomposition.' However, better understanding of the nature and distribution of the resulting silicide dispersion in more highly alloyed titanium matrices is necessary for the development of useful titanium alloys which utilize the latter strengthening mechanism. This note describes the chemical and crystallographic characteristics of the silicide phase as it occurs in a typical high-temperature near-a titanium alloy matrix. Several Ti-6A1-3Sn-3Zr a11oys containing various amounts of silicon ranging from 0.1 to 1.0 pct were melted as 10- to 20-lb ingots and processed into 1/2-in.-diam bar stock. The microstructures of specimens annealed at various temperatures were conveniently summarized by the (Ti-6Al-3Sn-3Zr)-Si pseudobinary phase diagram illustrated in Fig. 1. Comparison with the Ti-Si equilibrium diagram indicates the substitutional solutes (Al-Sn-Zr) increase the eutectoid temperature and decrease the a terminal solubility. Annealing at temperatures sufficiently high to dissolve the silicon in a ß solid solution and cooling rapidly enough to preclude coarsening generally produced a uniform dispersion of fine silicide particles, whereas annealing at temperatures near but below the ß transus produced relatively coarse silicide particles. Annealing in the limited a, plus 3 region produced a duplex coarse and fine silicide array. Several a-annealed specimens were examined by X-ray diffraction to determine the crystallographic identity of the precipitate phase. Copper Ka X-ray diffraction patterns of bulk specimens which contained 0.5 and 0.8 pct Si were virtually identical to that of the silicon-free Ti-6Al-3Sn-3Zr base alloy except for a slight shift in some of the high-angle diffraction lines. Apparently the silicide volume fraction was too low to be detected in bulk specimens. X-

Jan 1, 1969