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By P. A. Tucker, C. R. Hudgens, D. E. Etter, D. L. Roesch, D. B. Martin

The equilibrium phase diagram of the Pu-Cd system is presented based on data obtained by differential thermal analysis, metallography, and electron-microprobe X-ray analysis. Liquidus temperatures range from 320° to 934°C. The system contains one congruently melting compound, PuCd, (945°C), and three incongruently melting compounds, PuCd, (800°C), PuCd, (730°C), and PuCd11 (410°C). A liquid-miscibility gap extends from 2 to 60 at. pet Cd with the monotectic reaction isotherm at 910°C. INTEREST in the potential use of plutonium alloys as reactor-fuel materials has prompted investigation of the phase equilibria in plutonium binary systems. A cursory investigation of the phase equilibria in the Pu-Cd binary system was conducted by differential thermal analysis (DTA), metallography, and electron-microprobe X-ray analysis (EMX). Extensive solid solubility of cadmium in both e and 6 plutonium was predicted1 based on atomic radii and electronegativities. Liquid immiscibility between these two elements was also predicted based on Mott's extension of Hildebrand's method. In the only previous investigation of the Pu-Cd system,2 two intermetallic compounds, PuCd11 (incon-gruent melting point 406°C) and PuCd8, were identified. EXPERIMENTAL The plutonium metal used in this work had a total impurity content of 500 ppm; the major impurities were: carbon (215 pprn), silicon (75 ppm), iron (60 ppm), nickel (40 ppm), and aluminum (25 ppm). The cadmium was reagent grade with a purity of 99.99 pet. The DTA technique for the study of plutonium alloys was previously described in detail.3 The alloys to be studied were prepared in tantalum DTA specimen capsules which were sealed by inert-gas welding. The alloys were homogenized in the liquid state in these sealed capsules which prevented the loss of cadmium by vaporization. Only the thermal arrests in the DTA heating curves were used to define the transformation temperatures of the system since supercooling affected many of the results during cooling. After the alloys were analyzed by DTA, the same alloys were used for the metallographic studies. Metallographic examinations were conducted in the manner described for plutonium alloys., No reaction was detected between the alloys and the tantalum capsules. Alloys for EMX analysis were placed in metallographic mounts together with specimens of unalloyed plutonium and cadmium which served as standards. The samples were highly polished but unetched. No protective coatings were applied to the surfaces of these radioactive specimens. Such coatings are detrimental to the excitation conditions and have been found to be unnecessary for the control of radioactive contamination. RESULTS The results of the DTA studies are presented in Table I. The phase diagram, constructed from these data plus the metallographic and EMX results, is presented in Fig. 1. The congruently melting compound, PuCd2, was identified by the occurrence of a maximum melting point (945°C) at 33.3 at. pet Pu-66.7 at. pet Cd and by the presence of a single phase in this composition.

Jan 1, 1965

By Fred C. Bond

Many grindability tests have been made in the Allis-Chalmers laboratory since the tabulated results were last published.' The lists of standard ball-mill and standard rod-mill grindability tests are brought up to date in this paper, and considerable new material is added. This includes a tabulation of open-circuit grinding tests, with impact and compression-crushing tests. The standard ball-mill grindability tests (Table I) were made in a standard laboratory ball mill, 12 by 12 in. inside, running at 70 rpm, with a charge of 285 iron balls ranging from 1½ to 3/4 in. in diameter and weighing 20,125 grams. Seven hundred cubic centimeters of minus 6-mesh stage-crushed dry feed was used, and the circulating load was maintained constant at 250 pct by adjusting the number of mill revolutions for each grinding period. Tests were made at all mesh sizes from 28 to 200, and the grindability is the number of net grams of screen undersize produced per revolution. The table includes 479 tests. It has been calculated that the ball mill does 52.3 joules of useful work on the ore per revolution2 with 93 joules input to the mill. The standard rod-mill grindability tests (Table 2) were made in a laboratory tilting rod mill, 12 in. in diameter by 24 in. long inside, with a wave-type lining, running at 46 rpm. The grinding charge consisted of six I1/4-in. diameter and two 13/4-in. diameter steel rods, all 21 in. long and weighing 33,380 grams. The mill was rotated level for eight revolutions, then tilted up 5' for one revolution, down 5° for one revolution, and returned to level for eight revolutions. It was discharged by tilting downward at 45° for 30 revolutions. Feed consisted of 1250 cc of minus in. stone and the circulating load was maintained constant at 100 pct by adjusting the number of mill revolutions for each grinding period. Tests were made at all mesh sizes from 3 to 65, and the rod-mill grindability is the number of net grams of screen undersize produced per revolution. The table includes 105 tests. The impact and compression-crushing tests (Table 3) are given in a table that is an extension of a previous publication8 in which the method of testing was described in detail. Two equal hammers weighing about 30 lb each were arranged to strike simultaneous blows on opposite sides of the test specimen. Broken pieces of rock passing a 3-in. square and retained on a 2-in. square were set up with the smallest dimension between the hammers, and this distance was measured. The height of the hammers was increased slightly before each blow until the specimen broke, and the foot-pounds per inch of thickness was calculated. Ten pieces

Jan 1, 1949

By Fred W. Stiefel

THIS paper covers the operation and maintenance of Diesel locomotives underground on a portion of the Delaware River Aqueduct.[t] This part of the tunnel is 15 miles long, with shafts 14 ft. in diameter spaced about 5 miles apart. These shafts (2, 2a and 3) are 825 ft., 1551 and 840 ft. deep, respectively. The grade of the tunnel is almost level, except for the 12,100 ft. north of shaft 2, which has a grade of 2.31 per cent. The tunnel is circular, 17 to 19 ft. in diameter. It lies at a depth of 400 ft. below sea level, with a maximum over-burden of 2400 feet. The tunnel driving was carried on in six headings, using 15 storage-battery locomotives, each of 13 gross tons and having a maximum speed of 8 miles per hour. The longest haul was 3 miles, which proved to be the maximum distance for which storage-battery locomotives could be employed economically for the amount of material to be moved. One locomotive was used for switching cars at each heading, one for switching cars at the bottom of each shaft and one on the main-line haul from the heading to the shaft. The maximum amount of material hoisted in one shaft from two headings when 104 ft. of tunnel was driven in 24 hr. was 1000 cu. yd., or about 2000 tons of rock in place. The total quantity excavated was 750,000 cu. yd. (1,500,000 tons of rock). The tunnel-lining operations using concrete presented a problem of hauling a maximum distance of 5 miles in the tunnel. The concrete-placing equipment had a capacity of about 2000 cu. yd., or 4000 tons in 24 hours. Experience had shown that storage-battery equipment could not handle this quantity of material within the time required at the distance of 5 miles. Trolley-locomotive haulage was considered dangerous and expensive, and would cause interference because transmission equipment would be required. Therefore the performance of Diesel locomotives of 160 hp., with a speed of 18 miles per hour, in comparison with that of other types of locomotives, was studied. CHOICE OF LOCOMOTIVES In deciding upon the type of locomotive to be used for the 5-mile haul, four alternatives were considered, as follows: I. To purchase additional storage-battery locomotives with the necessary batteries over the 6 locomotives and 12 batteries available. 2. To convert the existing battery locomotives to the trolley type. 3. To purchase new trolley locomotives. 4. To purchase Diesel locomotives. PROPOSITION No. I The 90-hp. storage-battery locomotives available (each weighing about 12 tons), when hauling a load of 64 tons, with a drawbar pull of about 1900 lb. on a level track, developed a speed of 8 miles per hour and could make five round trips in 8 hr. with a

Jan 1, 1942

By A. N. Holden, J. H. Hollomon

Inhomogeneous yielding during the early stages of plastic flow has been observed in many metals and has long been a subject of controversy. Low carbon steel, when strained at room temperature, exhibits a distinct yield point at which the metal ceases to behave elastically and begins to flow plastically without further increase in stress,† often with an actual decrease in stress from that existing at the yield point. One manifestation of this behavior is the familiar Lüders lines. The extent of the yield point elongation (the plastic strain which results without raising the stress above that at the initial yield point) may be several percent. Several explanations of this type of yielding in steels have appeared in the literature:1-3}; 1. The segregation of carbides or other constituents at the grain boundaries of ferrite forms cell-like blocks which break down at a higher stress than that at which the ferrite alone will flow. 2. The precipitation of various constituents within the ferrite itself in some way blocks initial flow until a higher stress is reached, after which a great deal of flow occurs without further increase in stress. 3. The restraining influence of neighboring, less favorably oriented grains in a polycrystal results in a storing up of energy, which on yielding is sufficient to cause the continued propagation of slip bands on the multiplicity of slip systems available in adjacent iron crystals without increase in stress. 4. Local segregation of carbon atoms increases the stress required for the initial propagation of dislocations. The stress required for further deformation is lower.3 Such an explanation would require the presence of upper and lower yield points in single crystals. Low and Gensamer2 have shown that heterogeneous yielding can be eliminated by removal of carbon and nitrogen from polycrystalline steels by wet-hydrogen treatment. They also demonstrated that the re-introduction of minute amounts of carbon or nitrogen caused a return of the yield point. Observations of the initial flow of single crystals containing small amounts of carbon and nitrogen- should provide a clue to the explanation of inhomogeneous yielding. Previous tests of iron crystals4-6 can not be considered conclusive because it is uncertain whether the carbon and nitrogen were satisfactorily removed by the decarburization technique employed. The purpose of the experiments described herein was to determine whether single iron crystals containing either carbon or nitrogen would exhibit in-homogeneous yielding. Experimental Procedures THE PREPARATION OF SINGLE CRYSTALS All crvstals were formed in the following way. Aluminum killed sheet material 80 mils thick was machined into specimens of the outer contour shown in Fig 1. These mildly tapered specimens were decarburized at 730°C for 16 hr in hydrogen that had been bubbled rapidly through water maintained at 70°. The resultant grain size after decarburizing was approximately ASTM 5. Several stress-strain curves were made of the decarburized niate-

Jan 1, 1950

By Ben Gumpertz

The important factors in any study of the screening of sand with a gravel envelope, as applied to use in oil wells, are: (I) sand size and shape, (z) gravel size and shape, (3) ratio of gravel size to sand size, (4) flow velocity, (5) viscosity of the fluid. Perhaps the first extensive investigation of the function of gravel in screening sand was performed by Coberly and Wagner,' from which the following conclusion was drawn: "The diameter of the largest grains in a single classified sand suitable for gravel packing is approximately 13 times the grain size at the ten-percentile analysis of the formation sample." ?;his applies to sands classified by Tyler screens and is for gravel grains of the maximum size that could be used to form a stable bridge. Field practice has shown that the screening effect of a given gravel for a given sand apparently varies with the flow velocity." Also, it has been assumed by some operators that the thickness of the walls of the gravel envelope surrounding the well has little effect upon the screening process. It is thought by others that a narrow envelope of gravel might form an ineffective screen. Thus the purposes of this work are: 1. To investigate the effect of gravel-sand size ratio upon screening action under the condition of varying flow velocities. 2. To investigate the effect upon screening action of varying the thickness of the gravel screen. 3. To investigate sand migration in the gravel screen and the effect of flow velocity and gravel size upon sand migration. Description of Apparatus In an attempt to reproduce field conditions for the purposes of this investigation, a flow tube was constructed, according to the manner of Urenj3 to represent a radial drainage segment of an oil sand. To arrive at the dimensions of the flow tube, a radial drainage segment of rectangular cross section was assumed to define an area of z sq. in. on the face of a well 6 in. in diameter. From this the dimensions of the segment were calculated out to a distance of 5 ft. from the face of the well. By computing cross-sectional areas at a number of sections along the rectangular segment and transforming these areas into the circular form, a drainage cone was obtained having everywhere the same cross-sectional area as the drainage element of rectangular cross section. To construct the apparatus, two sections of pipe of 7%-in. inside diameter, one 13 in. and the other 4 ft. long, were joined by a bolted flange. A mandrel having the dimensions of the drainage cone was centered in the pipe and a neat cement mixture was cast around it. A protective gasket was placed between the two sections of pipe so that the cement body could be separated at that point. When the mandrel was withdrawn a drainage cone was obtained (Fig. I).

Jan 1, 1941

By William R. Patterson

ACCORDING to the phase diagram for the Mn-Ni system,' the high-temperature, fcc y-manganese solid solution is stabilized to below room temperature, in the range approximately 22 to 28 wt pct Ni. However, pearson2 cites evidence in the literature showing that for manganese contents greater than about 75 wt pct the quenched phase in Mn-Ni alloys is fct. This is in keeping with zener's3 suggestion that in manganese-rich alloys the fcc high-temperature phase undergoes a diffusionless or martensitic transformation to a fct structure upon quenching. Work by Basinski and christian4 on manganese-rich compositions in the similar alloy system Mn-Cu established that in alloys of greater than about 82 wt pct Mn the y-manganese phase underwent a fee fct martensitic transformation upon quenching to room temperature. Striking evidence for this martensitic transformation was the highly twinned or banded microstructure, an example of which is shown in Fig. 1. Similar microstructures have also been found in quenched Mn-Cr5 and Mn-Au6 alloys. In the present investigation, we attempted to obtain similar evidence of a fcc — fct martensitic transformation in manganese-rich Mn-Ni alloys. Manganese alloys in the range 10 to 30 wt pct Ni were prepared by arc-melting, under argon, at atmospheric pressure. The alloys all were 50 g in size, and negligible weight loss occurred during melting. The starting materials were electrolytic manganese and nickel, both of 99.9+ pct purity. The alloys were subsequently homogenized 48 hr at 1750°F, hot-rolled 50 pct at 1700°F, annealed 2 hr at 1700°F, and water-quenched to room temperature. All heat treatment was done in purified argon. Both X-ray and metallographic techniques were used to examine the structures of the quenched alloys. X-ray diffractometer studies were conducted on powder specimens obtained from filings rean-nealed 2 hr at 1700°F in argon and water-quenched. Identification of the intensity peaks from the diffractometer counter traces showed that below about 10 to 12 pct Ni the y phase decomposed partially upon quenching to give an a- + ?-manganese structure. In the range approximately 12 to 25 pct Ni, the structure was found to be fct ? manganese with a c/a ratio approaching 1.0 at 25 pct Ni. Beyond approximately 25 pct Ni, the structure remained fcc. These results, including lattice-parameter determinations, are given in Table I. Metallographic examination. was carried out on specimens polished and etched after quenching, and also on polished specimens reannealed and quenched. In the first case, the distinctive twinning or banding so prevalent in Mn-Cu alloys was sought, while in the second, the surface relief effect generally regarded as being truly characteristic of a martensitic transformation was sought. The microstructure of representative alloys in the range 12 to 25 pct Ni is shown in Fig. 2. The structure of the Mn-15 pct Ni

Jan 1, 1965

By Ben Gumpertz

The important factors in any study of the screening of sand with a gravel envelope, as applied to use in oil wells, are: (I) sand size and shape, (z) gravel size and shape, (3) ratio of gravel size to sand size, (4) flow velocity, (5) viscosity of the fluid. Perhaps the first extensive investigation of the function of gravel in screening sand was performed by Coberly and Wagner,' from which the following conclusion was drawn: "The diameter of the largest grains in a single classified sand suitable for gravel packing is approximately 13 times the grain size at the ten-percentile analysis of the formation sample." ?;his applies to sands classified by Tyler screens and is for gravel grains of the maximum size that could be used to form a stable bridge. Field practice has shown that the screening effect of a given gravel for a given sand apparently varies with the flow velocity." Also, it has been assumed by some operators that the thickness of the walls of the gravel envelope surrounding the well has little effect upon the screening process. It is thought by others that a narrow envelope of gravel might form an ineffective screen. Thus the purposes of this work are: 1. To investigate the effect of gravel-sand size ratio upon screening action under the condition of varying flow velocities. 2. To investigate the effect upon screening action of varying the thickness of the gravel screen. 3. To investigate sand migration in the gravel screen and the effect of flow velocity and gravel size upon sand migration. Description of Apparatus In an attempt to reproduce field conditions for the purposes of this investigation, a flow tube was constructed, according to the manner of Urenj3 to represent a radial drainage segment of an oil sand. To arrive at the dimensions of the flow tube, a radial drainage segment of rectangular cross section was assumed to define an area of z sq. in. on the face of a well 6 in. in diameter. From this the dimensions of the segment were calculated out to a distance of 5 ft. from the face of the well. By computing cross-sectional areas at a number of sections along the rectangular segment and transforming these areas into the circular form, a drainage cone was obtained having everywhere the same cross-sectional area as the drainage element of rectangular cross section. To construct the apparatus, two sections of pipe of 7%-in. inside diameter, one 13 in. and the other 4 ft. long, were joined by a bolted flange. A mandrel having the dimensions of the drainage cone was centered in the pipe and a neat cement mixture was cast around it. A protective gasket was placed between the two sections of pipe so that the cement body could be separated at that point. When the mandrel was withdrawn a drainage cone was obtained (Fig. I).

Jan 1, 1941

By A. K. Mukherjee, J. E. Dorn

A modified Peierls model is Presented for the rationalization of the asymmetric plastic behavior of single crystals of bcc metals. The model assumes that the asymmetry of slip arises from a tendency toward asymnetric splitting of the a/2[111] screw dislocation. The approach differs from former theories however insofar as it assumes that the splitting is so minor ttut only the core energy is modified and that no real partial dislocations exist. As a consequence, the concepts of a line energy of a partial dislocation, interaction between partial dislocations, constriction energies, and stacking fault energies are not invoked. Instead the present analysis is based on a specialization of the Peierls mechanism which assumes an asymmetric dislocation core which is modified by the effective stress and permits cross slip. The theoretical predictions on the stress-temperature -strain rate and orientation relationship agree qualitatively with the limited experimental data that are currently available. Additional experimental work over wider ranges of conditions is suggested to provide more complete evaluation of the possible validity of this theory. RECENT experimental investigations on the low-temperature thermally activated deformation of bcc metals have confirmed the existence of several unique orientation effects. These will be described with the aid of the standard stereographic projection shown in Fig. 1. If slip were determined exclusively by crystal symmetry, the deformation characteristics would be symmetrical about X; = 0 and independent of whether the specimen were subjected to a tension or a compression stress, regardless of what combinations of slip planes might be operative. Experiments, however, reveal that neither of these symmetry based predictions are valid. A schematic representation of the commonly observed asymmetry of both the yield stress and the plane of slip is shown in Fig. 2. A reversal of the direction of stressing results in an inversion of the asvmmetric behavior. 1) Asymmetry bf Yielding. A detailed investigation on the asymmetric yielding in an Fe-2.7 pct Si alloy was repoEted by Tabka, Tikeuchi, and Furubayashi,1 Similar trends have been observed by Keh and Nakada on iron,' Stein on molybdenum,3 Bowen, Christian, and Taylor4 on columbium, Sherwood, Guiu, Kim, and pratt5 on Ta, Cb, and Mo. The degree of asymmetry not only depends on the atomic number and alloying but, in all cases that have been examined, it also increases with a decrease in the test temperature. 2) Asymmetry of the Slip Plane. Asymmetric $I-~: curves of the type shown in Fig. 2 have been found for several Fe-Si alloys6-8,1 and columbium.4 There is general agre_ement that near X: = 30 deg slip occurs by the [111](211) mode so that ?1 = 30 deg. As X; decreases it appears that [111](211) to [111](101) cross slip takes place leading to slip band traces on intermediate planes. And as xi approaches 0 deg, sharp

Jan 1, 1970

By J. E. Lawrence

Copper-decorated lattice disorders in silicon have been analyzed by electron transmission microscopy, chemical etching, and P-N junction reverse current measurements before and following different gettering treatments. Lattice disorders acted as the nucleating sites for copper precipitation. Copper precipitates in silicon resist chemical etching, absorb electron beams more than silicon, and cause excess reverse currents. Totally gettered disorders will chemically etch rapidly, be transparent to electron beams at extinction contrast, and not contribute to excess reverse currents. Three different gettering procedures were performed to determine the effectiveness of different EXTRANEOUS metal contamination can alter the minority carrier lifetime and resistivity of bulk silicon as well as cause excessive reverse currents in semiconductor devices. Previous workers have reported such activity for gold,1,2 copper,'-* iron,' and rnanganese.2,5 Gettering is a method employed to render these impurities electrically inactive. However, some property of the junction-degrading metals prevents gettering procedures from being wholly reliable. The comparative effectiveness of gettering with different agents has been the topic of earlier publications.2,3,6-11 Two mechanisms for gettering metallic impurities have been proposed: the distribution coefficient mechanism by Thurmond and Logan7 and the compound formation mechanism by Goetzberger and Shockley.2 Both of these models evolved from data gettering mechanisms. First, phosphorus was allowed to enter a protective SiO2 film but remain away from the Si-SiO2 interface to test the effectiveness of the compound formation gettering mechanism. Second, phosphorus was allowed to enter the backside of silicon wafers to test the effectiveness of the lattice strain gettering mechanism. Finally, nickel was diffused into the backside of silicon wafers to test the effectiveness of the distribution coefficient gettering mechanism. In each case, copper precipitates dissolved as a result of the gettering treatment. Tightly packed precipitates will resist gettering more than loosely packed copper precipitates. acquired by the electrical analyses of gettered semiconductor materials. An electrical analysis, however, cannot identify the fate of the gettered metals. The radiotracer technique has recently been applied to determine the redistribution of metals following different gettering treatments.3,9,10 The spatial resolu tion of the radiotracer technique prevented the analysis of metal precipitates which contribute to the excessive reverse currents of P-N junctions. The gettering processes employed by the earlier workers, almost without exception, allowed the gettering agent to enter the silicon lattice. This procedure makes it quite difficult to differentiate between the distribution coefficient and the compound formation mechanisms. The metallographic analysis of gettered copper precipitates discussed in this work supplements the earlier work by obtaining direct evidence of silicon lattice defects decorated with copper before and following different gettering treatments. The effectiveness of a process which restricts the gettering agent, phosphorus, to a dielectric film and thus away from the silicon lattice is discussed in addition to the ef-

Jan 1, 1969

By E. C. Wright

THE bessemer process is nearly one hundred years old. William Kelly, the American inventor, was able to demonstrate that he had accomplished the pneumatic purification of molten pig iron as early as 1847; Henry Bessemer's English patent was granted in 1855. The application of this steelmaking process since then and the present position of bessemer steel are concisely discussed on pages 355 and 356 of the fifth. edition of "The . Making, Shaping and Treating of Steel." The great expansion of the automotive, machine-tool, chemical and oil industries after 1910 opened up a large market for special steels, whereas the output of steel before that time was mainly for structural purposes. The need for building more blast-furnace capacity complementary to bessemer operations, combined with the availability of the necessary amounts of steel scrap, both contributed to the extension of open-hearth plants at the expense of bessemer capacity. The ability of the open-hearth furnaces to consume virtually all types of raw materials as far as phosphorus content is concerned, and the need for selecting low-phosphorus ores of rapidly decreasing sources for the bessemer, also played a part in the reduction of bessemer steelmaking operations and the increase in basic open-hearth plants. As a consequence, the proportion of bessemer steel made in this country decreased from 65.7 per cent of the total in 1900 to 37.1 per cent in 1910, and only 6.8 per cent of the total in 1937. The metallurgical concepts existent between 1910 and 1920 caused the writing of many specifications of very low phosphorus and sulphur content, which definitely barred bessemer steel from many commodities. Now sulphur is being added to many open-hearth and bessemer steels in amounts far exceeding the maximum sulphur content of good bessemer steel. Rephosphorizing is also widely practiced for several specific applications. Even today, the chemical-analysis limits of many important steel specifications have an arbitrary and archaic tinge. The old standard "0.30 .to 0.60 per cent manganese" might be mentioned in this connection as similar to the rigid requirements for maximum sulphur and phosphorus that were established at least 25 years ago. The literature is full of vague and complex discussions of the effects of nitrogen and oxygen where these elements existed in steel in amounts less than 0.02 per cent. Many failures have been attributed to these elements without reasonable proof on which to base the conclusion. Methods of determining oxygen in steel require such complicated equipment that only a few research laboratories have the required apparatus. Even so, the accuracy of oxygen determinations in steel has been only recently reproducible. Up to the present time, no one has succeeded in obtaining a sample of molten steel that accurately indicates the full. oxygen content of the metal in the furnace or ladle because the molten sample

Jan 1, 1944

By David W. Mitchell

WHILE pure magnesium does not corrode rapidly the presence of even very small quantities of certain other metals accelerates corrosion remarkably. Because magnesium is such an electropositive metal (E° = +2.34 volts)' the presence of substances that permit galvanic activity is extremely undesirable. It is stated that as little as 0.017 pct of iron in magnesium causes a marked increase in the corrosion rate.2 Magnesium and its alloys are commonly melted in iron or steel pots; consequently the commercial metal has the opportunity to pick up iron if it has that tendency. Quantitative data on the solubility of iron in magnesium are of practical as well as of academic interest. Some magnesium alloy castings tend to have large grain size unless suitable treatment is given to the liquid metal just prior to casting. One method of grain refinement consists of "superheating" the metal just prior to casting. "Superheating" is heating to a temperature 100 to 200°C above the casting temperature and holding for a short period of time. Superheated metal has a much finer grain than unsuperheated metal. A satisfactory explanation of this phenomenon has not been forthcoming. One hypothesis attributes the grain refinement in the superheated metal to precipitation of some phase that is miscible at the temperature of superheat but not miscible just below the casting temperature and which is thought to provide nucleating centers for crystallization. This phase, if the foregoing hypothesis is correct, would probably be a metal or an intermetallic compound. Of the metals likely to be found in magnesium alloys, iron is one of the most likely candidates for the role of grain refiner for iron occurs in small quantities in all commercial magnesium and magnesium alloys. A. Beck' states that magnesium, in either the liquid or the solid state, cannot dissolve iron and that iron exists as a finely divided suspension which does not settle out because of its extreme fineness. Beck also presents a micrograph showing a large iron dendrite in magnesium but does not comment on the crystallization of iron from a solution supposed to contain none. It is doubtful that dendrite formation from suspended iron would be possible. This suspension theory is the basis of patents4 covering the removal of iron from magnesium by allowing the iron particles to act as nuclei for the formation of primary magnesium crystals which can be separated by segregation. Also covered by patents is the removal of iron by the addition of another metal to form an intermetallic compound with the iron which, because of its increased particle size, is able to settle out of the molten metal. Here, too, quantitative information on the extent of iron solubility in liquid magnesium is of more than theoretical interest. M. Hansen,5 in his critical collection of the data on binary alloys, states that iron is not soluble in liquid magnesium. W. R. D. Jones6 who studied the physical properties of low iron magnesium alloys observed a

Jan 1, 1948

By T. W. Smoot

Bentonites are composed chiefly of montmorillonites which are clay minerals generally distinguished from other clay minerals by their surface activity and extremely fine particle sizes. The uses of bentonite are many and varied, depending principally on one or more of the following characteristics: 1) Thixotropy, 2) Dispersion, 3) Plasticity, 4) Swelling, 5) Surface area, activity, ab- and adsorbtive properties. Some of the major uses of bentonite are briefly reviewed as are the mineralogical and physical properties. The uses of X-ray diffraction, differential thermal analysis and other tests for physical properties are reviewed as to their uses in evaluation. In the past 40 years, the industrial uses of bentonite have grown to include many applications. The physical and chemical properties of bentonites are such that they can be used as catalysts, adsorbants, plasticizers, binders, drilling muds, and pelletizers. Not all bentonites, however, can be used for all of these purposes and some are probably of little or no value for any use. The purpose of this paper is to briefly review the mineralogical, physical, and chemical characteristics and variations of bentonites. The determination of these characteristics and their uses in industry are also reviewed so that these determinations can be used as guides for evaluation. DEFINITION OF BENTONITE The word bentonite, as used in this paper, refers to a clay material, usually (but not necessarily) the result of the in-place-weathering of volcanic ash. Its mineralogical composition is dominated by the clay mineral montmorillonite and generally carries other clay minerals and silica minerals as the major 'impurities'. For this discussion, such a definition is justified since most of the economic uses of bentonite~ depend upon the physical and chemical characteristics of the montmorillonite minerals involved. The terms montmorillonite and bentonite have been used almost interchangeably in industry although the latter is much more commonly used. Therefore, where montmorillonite is discussed, it should be understood that the major feature of a bentonite is the subject. STRUCTIJRE OF MONTMORILLONlTE The economic importance of bentonites is generally based on one or more of the following characteristics of montmorillonite: 1) high-thixotropy and easy dispersion in water, 2) high-plasticity, 3) swelling properties, 4) large surface area/unit mass, 5) high surface activity, and 6) adsorptive properties. To understand these properties, an appreciation of the structural scheme of montmorillonite is helpful. Montmorillonite IS one of the three-layer clay minerals composed essentially of hydrous aluminum silicates. The essential building blocks of these layered silicate:; are: 1) silica tetrahedron composed of a silicon atom surrounded by four oxygen atoms, and 2) aluminun (iron, magnesium, etc.) octahedral unit that, ideally, has one of these atoms surrounded by six hydroxal units. Fig. 1 is a diagrammatic sketch of the montmorillonite structure. In the montmorillonite structure, the tetrahedron are pointed inward and attached to the octahedral units so that the O= atoms replace the hydroxal units where they are bonded; hence two-thirds of the hydroxal units

Jan 1, 1962

By Frank Marotta, Louis B. Lesem, Frank Greytok, John J. McKetta

Although one of the primary variables in the calculation of the flowing bottom-hole pressure in gas wells from surface measurements is the temperature at any point and its distribution in the flow-string, only few experimental data are available in the literature and little attention has been given to analysis of the problem. Virtually all of the recently published methods of calculating flowing bottom-hole pressures depend on the assumption that either the temperature is constant at some average value or that the variation is linear with depth. The purposes of this work are to analyze the problem theoretically and to verify the analysis by comparison with experimental data so that practical problems in the analysis of the behavior of gas wells can be solved with greater accuracy, reliability, and ease. MATHEMATICAL OUTLINE OF PROBLEM Assuming that: 1. The mass velocity and chemical composition of the gas stream are constant and in normal gas well operations, the change in linear velocity in the entire flow-string is trivial, 2. The product of the density and heat capacity of the gas is constant, 3. No horizontal temperature gradient exists in the gas stream, 4. Net flow of heat by conduction within the formation and in the gas stream in the vertical direction is trivial in magnitude and can be neglected, 5. The regional vertical geothermal gradient is constant, and 6. The temperature of the gas entering the borehole is constant, and equal to that of the reservoir, a set of two simultaneous, linear partial differential equations with appropriate boundary conditions was derived to describe the temperature distribution in the gas stream and the surrounding formation. These equations were solved by operational techniques for the distribution of temperature in the gas stream. The resulting integrals were evaluated numerically on an IBM 604 at the Machine Accounting Div. of the Railroad Commission of Texas. DERIVATION OF FUNCTIONS FOR THE DISTRIBUTION OF TEMPERATURE The physical system is a circular hole of radius a in an infinite medium with thermal conductivity K, density p8, and heat capacity c,. Under shut-in conditions the well is in thermal equilibrium with the surroundings and the increment in temperature is given by - ?T3/L x. Gas of density pg and heat capacity c.. flows upwardly through this hole in the direction of increasing x with a linear velocity W. Writing a heat balance on an element of gas ?x in thickness, convective heat transfer + conductive heat transfer + energy required to lift a unit mass of fluid = change in energy content. pa2W po Co To - pa2Wpo Co To x+xx - 2apK?x ?T8/?r r=a - Wpa2 po?x/778 = CoPopa2?x?To/?t... Dividing by (copopa2?x) and taking the limit as ?x tends to zero, -W (?To/?x + 1/778Co) + 2 K/a Po Co ?T3/?r r=u = ?To/?t

Jan 1, 1958

At all business meetings of the Institute the President, or, in his absence, the First Vice-President, or, in the absence of both of them, any other Vice-President or Director, chosen by the meeting, shall preside. At all other meetings of the Institute the President, or, in his absence, one of the Vice-presidents shall preside. If none of these be present the meeting shall elect a Chairman. The President shall do and perform such other duties as may from time to time be assigned to him by resolution of the Board of Directors of the Institute. II. ORDER OF BUSINESS. At each business meeting of the Institute the order of business shall be as follows: 1. Reading of minutes of preceding meeting. 2. Report of the President. 3. Report of the Treasurer. 4. Report of the Secretary. 5. Election of Directors. 6. Reports of Standing Committees. 7. Reports of Special Committees. 8. Special Orders. 9. Miscellaneous business. This order of business may be changed at any meeting, by a vote of a majority of the Members and Associates present. At all sessions of the Institute, other than business meetings, the order of proceedings and the time of adjournment shall rest in the discretion of the presiding officer. III. SECRETARY OF THE INSTITUTE. The Secretary shall keep a record of the proceedings of all the meetings of the Institute, He shall be custodian of the corporate seal, of the minute books and of all the legal documents belonging to the Institute. He shall have charge on behalf of the Institute of all correspondence. He shall notify all Officers and Directors and all members of committees of their election and appointment; shall issue notices of all meetings of the Board, and of the annual and other business meetings of the Institute; and shall, in calling special meetings of the Directors, specify the objects of such meetings. He shall act as clerk at all the meetings of the Board of Directors and at all meetings of the Institute. The Secretary shall be custodian of all technical or scientific papers submitted to the Institute for its consideration and shall have general charge and supervision of the editing and proof-reading of all material published by the Institute, and of the distribution thereof. The Secretary shall be the custodian of all back numbers of the Transactions and other publications of the Institute. There shall be kept under his direction an account in ledger form of all such back numbers. He shall on the first day of January of each year submit to the Library Committee a statement of the number of copies of Transactions, magazines and other publications printed during the preceding year, giving the number distributed and remaining undistributed; also a statement covering additions to and withdrawals from the total stock of Institute publications, with the number remaining on hand at date of statement.

Jan 1, 1928

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

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

Jan 1, 1942

By James W. Halley

' FINE-GRAINED " steels have been standard products for many years. This paper describes an investigation of the effects of some of the more common grain-growth; inhibitors used to produce these steels. The properties, response to heat-treatment, and the deoxidation practice necessary to produce "fine-grained" steels have been the subjects of numerous papers. It has been shown that a substantial quantity of' aluminum is necessary to produce this type of steel, and it has been indicated that titanium and zirconium produce a similar result. For some time there was a lively argument between those who felt that aluminum refined the grain and those who felt that aluminum oxide was the effective agent. This argument subsided with an apparent victory for those promoting aluminum oxide. Most of the work on grain size has divided steels into two broad classifications based upon McQuaid and Ehn's original carburizing test at 1700°F. or some similar test at this temperature. If the steel coarsened at this temperature, it was coarse grained, while if it did not it was fine grained. Quantitative data concerning how much a certain amount of aluminum raised the coarsening temperature and affected the properties, all other factors being constant, are very meager. Similar information regarding titanium and zirconium is practically nonexistent. The published information on aluminum yields some quantitative information. Epstein, Nead and Washburn' gave the first quantitative information on the amount of aluminum necessary to prevent grain growth at 1700°F. They showed that the addition of a pound to a pound and a half of aluminum per ton (0.05 to 0.075 per cent) would assure steel that would not .coarsen during a McQuaid-Ehn test at 1700°F. Herty, McBride and Hough2 reported that a steel containing 0.020 per cent acid-soluble aluminum coarsened between 1742° and 1832°F., while steels containing 0.016 per cent and 0.017 per cent acid-soluble aluminum coarsened between 1652~ and 1742°F. compared with similar aluminum-free steels that started to coarsen at 1580°F. Herty3 also showed a marked improvement in low-temperature notched impact resistance with increasing acid-soluble aluminum up to 0.030 per cent. McQuaid4 compared the coarsening of steels containing 0.011 to 0.204 per cent total aluminum and found a maximum coarsening temperature at 0.098 per cent aluminum. He had no samples between 0.015 and 0.098 per cent aluminum. Houdrement5 found a marked decrease in coarsening temperature with aluminum contents above 0.50 per cent. Kinzel, Crafts and Egan6 found that aluminum and zirconium improved thy low-temperature impact resistance of a low-alloy steel, while titanium was detrimental. Sims7 shows that sulphur increases the coarsening temperature and that the maximum coarsening temperature is between 0.04and 0.06 Per cent added aluminum. The

Jan 1, 1946

By Fred W. Stiefel

This paper covers the operation and maintenance of Diesel locomotives underground on a portion of the Delaware River Aqueduct. † This part of the tunnel is 15 miles long, with shafts 14 ft. in diameter spaced about 5 miles apart. These shafts (2, 2a and 3) are 825 ft., 1551 and 840 ft. deep, respectively. The grade of the tunnel is almost level, except for the 12,100 ft. north of shaft 2, which has a grade of 2.31 per cent. The tunnel is circular, 17 to 19 ft. in diameter. It lies at a depth of 400 ft. below sea level, with a maximum overburden of 2400 feet. The tunnel driving was carried on in six headings, using 15 storage-battery locomotives, each of 13 gross tons and having a maximum speed of 8 miles per hour. The longest haul was 3 miles, which proved to be the maximum distance for which storage-battery locomotives could be employed economically for the amount of material to be moved. One locomotive was used for switching cars at each heading, one for switching cars at the bottom of each shaft and one on the main-line haul from the heading to the shaft. The maximum amount of material hoisted in one shaft from two headings when 104 ft. of tunnel was driven in 24 hr. was 1000 cu. yd., or about 2000 tons of rock in place. The total quantity excavated was 750,000 cu. yd. (1,500,000 tons of rock). The tunnel-lining operations using concrete presented a problem of hading a maximum distance of 5 miles in the tunnel. The concrete-placing equipment had a capacity of about 2000 CU. yd., or 4000 tons in 24 hours. Experience had shown that storage-battery equipment could not handle this quantity of material within the time required at the distance of 5 miles. Trolley-locomotive haulage was considered dangerous and expensive, and would cause interference because transmission equipment would be required. Therefore the performance of Diesel locomotives of 160 hp., with a speed of 18 miles per hour, in comparison with that of other types of locomotives, was studied. Choice of Locomotives In deciding upon the type of locomotive to be used for the 5-mile haul, four alternatives were considered, as follows: I. To purchase additional storage-battery locomotives with the necessary batteries over the 6 locomotives and 12 batteries available. 2. To convert the existing battery locomotives to the trolley type. 3. To purchase new trolley locomotives. 4. To purchase Diesel locomotives. Proposition No. i The 90-hp. storage-battery locomotives the (each weighing about 12 tons), when hauling a load of 64 tons, with a drawbar pull of about 1900 lb. on a level track, developed a speed of 8 miles per hour and could make five round trips in 8 hr. with a

Jan 1, 1943

By Dorsey Hager

North Central Texas has recently become a center of interest for the oil men of America. The bringing in of the McClosky well at Ranger, Eastland County, and the shallow pool at Brownwood, Brown County, in 1917, has stimulated interest in this area to fever pitch. Oil men from all over the United States are now investing there. The area of present interest is shown by the accompanying map (Fig. 1). The money spent in leases runs into millions of dollars. It is no exaggeration to say that a strip of country 200 miles (321 km.) long and 125 miles (201 km.) wide, comprising some 15,000,000 acres (6,070,310 ha.), has been leased practically solid at a cost for rentals and bonuses of at least $1 per acre. The test holes contracted for will certainly number 400, at a cost of at least $5,000,000. From what has been done in the past six months, $20,000,000 at least will be spent. To pay returns on this amount of money, new production to the extent of at least 12,000,000 bbl. must be obtained. At present, the production from new fields will not average over 5000 bbl. per day; three wells at Ranger are producing 3000 bbl.; 250 wells at Brownwood produce 1000 bbl.; and the Gray well, Coleman County, is as yet an unknown factor. However, at Ranger there is every indication of developing a good pool covering from 1500 to 2000 acres (607 to 809 ha.), more or less, but the wells are deep, 3400 to 3800 ft. (1036 to 1158 m.), and cost $35,000 to $40,000 to drill. Large wells are necessary to pay for such expensive holes. As new wells are drilled, the gas pressure will be lowered rapidly, and large production need not be expected. For those oil men who expect a second Cushing or an Eldorado, Ranger holds little of promise. At Brownwood, Brown County, there are some 250 shallow wells (depths from 200 to 350 ft.) averaging 4 to 7 bbl. per day. There is a chance of an extensive producing area for these shallow sands to the southwest, and the opening of several thousand acres of shallow oil territory, and also some promise of deeper oil horizons in the Ranger horizon, but probably all under 2500 ft. At present, the lease brokers and speculators, and only a handful of oil men, have made any money. More fields must be developed, and it is more particularly with these possibilities that this paper deals. Lack of water for drilling purposes has undoubtedly held back development so far this year; this part of Texas has had a drouth for two years and there is an actual scarcity of water. Geological investigations so far undertaken cover nearly all the area outlined, and while pakt of the

Jan 1, 1920

By Fred W. Stiefel

This paper covers the operation and maintenance of Diesel locomotives underground on a portion of the Delaware River Aqueduct. † This part of the tunnel is 15 miles long, with shafts 14 ft. in diameter spaced about 5 miles apart. These shafts (2, 2a and 3) are 825 ft., 1551 and 840 ft. deep, respectively. The grade of the tunnel is almost level, except for the 12,100 ft. north of shaft 2, which has a grade of 2.31 per cent. The tunnel is circular, 17 to 19 ft. in diameter. It lies at a depth of 400 ft. below sea level, with a maximum overburden of 2400 feet. The tunnel driving was carried on in six headings, using 15 storage-battery locomotives, each of 13 gross tons and having a maximum speed of 8 miles per hour. The longest haul was 3 miles, which proved to be the maximum distance for which storage-battery locomotives could be employed economically for the amount of material to be moved. One locomotive was used for switching cars at each heading, one for switching cars at the bottom of each shaft and one on the main-line haul from the heading to the shaft. The maximum amount of material hoisted in one shaft from two headings when 104 ft. of tunnel was driven in 24 hr. was 1000 cu. yd., or about 2000 tons of rock in place. The total quantity excavated was 750,000 cu. yd. (1,500,000 tons of rock). The tunnel-lining operations using concrete presented a problem of hading a maximum distance of 5 miles in the tunnel. The concrete-placing equipment had a capacity of about 2000 CU. yd., or 4000 tons in 24 hours. Experience had shown that storage-battery equipment could not handle this quantity of material within the time required at the distance of 5 miles. Trolley-locomotive haulage was considered dangerous and expensive, and would cause interference because transmission equipment would be required. Therefore the performance of Diesel locomotives of 160 hp., with a speed of 18 miles per hour, in comparison with that of other types of locomotives, was studied. Choice of Locomotives In deciding upon the type of locomotive to be used for the 5-mile haul, four alternatives were considered, as follows: I. To purchase additional storage-battery locomotives with the necessary batteries over the 6 locomotives and 12 batteries available. 2. To convert the existing battery locomotives to the trolley type. 3. To purchase new trolley locomotives. 4. To purchase Diesel locomotives. Proposition No. i The 90-hp. storage-battery locomotives the (each weighing about 12 tons), when hauling a load of 64 tons, with a drawbar pull of about 1900 lb. on a level track, developed a speed of 8 miles per hour and could make five round trips in 8 hr. with a

Jan 1, 1943

By Karl J. Benecke

Though the first patent on a bucket wheel excavator (BWE) was granted in 1881 in the US, this technology was developed in Germany to the high standards of today. However, this development was only possible in parallel with development of shiftable belt conveyors and boom stackers. The combination of these three types of equipment in the open pits of the Federal Republic of Germany has made lignite the cheapest energy source for power generation, despite the low heating value of German lignite on the order of 8500 kJ/kg (3600 Btu/lb) only. Comparing the costs for fuels used in power generating on the basis of their heating value, the relation between lignite, high quality black coal, and imported crude oil is on the order of 1 to 1.5 to 2.5, hence highly in favour of lignite. These cost advantages for lignite in Germany are due mainly to the concentration of lignite mining in a few high-output mines. The largest one, Fortuna mine in the Cologne district, produced a total of 45 million tons of lignite in 1976. That equals the annual fuel need of a 5750 MW power plant running 7000 hours per year at full capacity. Altogether 95.2 million bank m3 equal to 200 million tons of overburden had to be removed to accomplish this lignite output. The largest BWE ever built is working in the Fortuna mine [(Fig. 1)]. At a digging height of 51 m above crawler level, the total vertical reach in relation to the face conveyor level is 98 m by means of its conveying bridge and loading unit. The hourly output is 10 400 bank m3. Its weight in operation is 13 000 tons and its wheel diameter 21.6 m, as high as a seven-story building. Major reasons for the development of BWE technology in Germany were: ? Lignite deposits with moderately consolidated, alluvial-type overburden (gravel, sand, loam, marl, clay, etc.) ? Great overall depth of the deposits, ranging far beyond 100 m, requiring a wide opening of the mine, hence not permitting direct overcasting of overburden. ? Multiple-seam deposits of poor-quality coal divided by reject partings, which demand a perfectly selective digging tool for clean separation. In general, these conditions are almost identical to those prevailing in the lignite deposits of Texas and neighbouring states: The type of overburden suitable for BWE digging, the overall deposit depth ranges down to around 100 m, and finally, the multi-seam occurrence with partings between seams, the latter ranging from just 1 m to a few meters in thickness. Technique As the Texas-type lignite deposits come into focus more and more as a possible fuel source in power plants to replace natural gas and crude oil, the following will deal with the BWE technology for mining a typical Texas lignite deposit under the aspect of producing enough fuel for a 500-MW power plant located at the mine mouth.

Jan 1, 1980