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By D. S. Tannhauser, I. Bransky

Measurements of the electrical conductivity, the thermal electromotive force, and the deviation from stoichiometry by thermogravimetry were made on ferrous oxide (wüstite) single crystals as well as on poly-crystalline samples in the temperature range of -900" to 1330°C. In the region defined by T 2 1000°C and 1.05 5 O/Fe 5 1.10 the electrical conductivity was shown to be proportional to the sixth root of- the oxygen partial pressure and to be linearly dependent on the deviation from stoichiometry. The absolute Seebeck coefficient of single and polycrystalline wüstite was shown to be independent of temperature in the above region and a p to n transition of the Seebeck coefficient was observed at O/Fe = 1.09 in polycrystalline wüstite. Analysis of the results showed that the predominant defects in wüstite in the above region were doubly ionized cation vacancies. The analysis also ruled out the existence of complexes of the type postulated by Roth, except that below 1000°C there is some evidence of 'association of defects. Of the three oxides of iron (FeO, Fe3O4, Fe2O3) only FeO (wüstite) can exist within a wide range of the ratio O/Fe. This has been shown by several investigations of the phase diagram using for instance chemical analysis of quenched samples'-4 or thermogravimetric measurements. 5,8 Darken and Gurry's1 data for example in the temper- ature range 1100o to 1400°C show that the lowest O/Fe ratio obtainable for FeOl +. is about 1.045 and that the existence range extends to O/Fe = 1.20 at 1400oC. On the basis of detailed analysis of thermogravimetric measurements made by Vallet and Raccah6 the existence of three varieties of wüstite at elevated temperatures was suggested by these authors and by Kleman. It is well-established that wüstite has a NaCl structure with vacant cation sites.3, 8 From a neutron-diffraction study of wüstite samples quenched to room temperature Roth9 concluded that defects in wüstite are mostly complexes composed of two cation vacancies and one interstitial cation in a tetrahedral site. The atomic arrangement in the vicinity of such a defect is similar to that in magnetite, where each occupied tetrahedral site is surrounded by four vacant octahedral positions disposed at the corners of a tetrahedron, so arranged that each vacancy is shared by two tetrahedral cations. Thus there is an average of two vacancies per interstitial. Recent X-ray diffraction measurements made by Smuts10 on quenched wüstite samples confirmed the results of Roth's neutron-diffraction experiments. Roth's model of defects in FeO can be regarded as a solid solution of Fe3O4 in FeO; salmon1' used this defect model to calculate the activity of Fe3O1 in FeO at high temperature and claimed good agreement with the results obtained experimentally by Darken and Gurry.' Each missing cation in wüstite is accompanied by two trivalent cations, thus preserving charge neutrality. The "holes" which differentiate between the Fe 2+ and Fe3' states of the ions in octahedral positions can overcome the attractive field of the cation vacancies, and are then free to move through the crystal as charge carriers. A similar picture holds for COO, NiO, andMnO.l2, 13 Localization of the charge carriers in transition

Jan 1, 1968

By D. H. Forbes, I. B. Cadoff, H. M. Manasevit

Single-crystal silicon films have been obtained on several natural crystal faces of BeO using the thermal decomposition of silane and the hydrogen reduction of silicon tetrachloride. From an analysis of X-ray diffraction data it was determined that the following film-substrate orientation relationships exist: (111) Si 11(0001) BeO, (111) Si 11(1011) BeO, (100) Si 11f1010) BeO. and (110) Si 11(1010) BeO. An analysis of the crystallographic relationships between the film and substrate indicates that a match occurs between the silicon atoms in the film and the berylliuni ion sites in the substrate. This correspondence is in agreement with previous work on the deposition of silicon on sapphire.1-3 silicon on spinel: and tungsten on sapphire. The high resistivity, thermal conductivity, and radiation resistance of beryllium oxide make it an important substrate material for the deposition of thin films of silicon or other semiconductors. The importance of semiconductor-insulator composites to the field of integrated microelectronics has been well-documented in the case of silicon on sapphire.'-' The successful growth of large-area single-crystal silicon on an insulator, sapphire, was first reported in 1963.1,2 Since that time studies have been made of the crystallographic relationships between the deposited film and the sapphire substrate. On the basis of the observed relationships, a model has been proposed relative to the crystallographic requirements for epitaxy between the semiconductor film and the metal oxide substrate.3 It is proposed in this model that epitaxy is the result of a match between atoms of the deposited film and the metal ion sites of the substrate plane. This match is not limited to a 1 to 1 correspondence between sites in the two lattices. Sub- sequent studies of the deposition of silicon on spinel4 and tungsten on sapphire5 have yielded data which support this model. On the basis of this previous work it was felt that silicon on BeO should also fit this model. In the present study, the choice of substrate orientation was limited to the natural faces of synthetic BeO crystals. Of the faces available, the (0001) plane seemed the most favorable for epitaxial growth. EXPERIMENTAL PROCEDURE Silicon films were deposited from silane and silicon tetrachloride in the apparatus shown in Fig. 1. The hydrogen ambient gas was purified by passage either through a DEOXO unit, molecular sieves, and a liquid nitrogen cold trap, or through a heated Pd-Ag thimble. The gas was then mixed with the silicon source materiai and passed over the substrate which lies on a spacer above an inductively heated silicon pedestal. The following deposition conditions were used: a hydrogen flow rate of 3 liters per min with silane and silicon tetrachloride concentrations of 0.2 mole pct and a pedestal temperature of 1175" * 5°C as observed with an optical pyrometer assuming an emissivity of 1.0. Deposition was preceded by a 15- to 30-min hydrogen-etch period conducted at a temperature of 1275°C (obs). Adherent silicon films from 2 to 10 u were grown on the various BeO faces. The substrates were synthetically grown beryllium oxide single crystals ranging from 5 to 10 mm in

Jan 1, 1967

By A. J. Griest, P. D. Frost, J. R. Doig

During the past 5 years, research directed toward the development of titanium alloys having improved strength-ductility relationships and heat treatability has been carried out at Battelle for the U. S. Air Force.1"3 In the course of this work, a method of heat treating ß-stabilized titanium alloys was developed which produced a wide range of useful properties.4 The heat treatment consisted of two steps: a) solution treating at temperatures in the a-ß phase region, and b) overaging at a lower temperature in the range 800°to 1100°F. Corollary to the alloy development work, research was conducted on the mechanism of the heat-treatment reaction. The investigations of Frost and co-workers on isothermal transformation in Ti-Cr5 and Ti-Mn8 alloys disclosed the existence of the transition phase, w, during the course of the decomposition of metastable ß phase. Subsequent work at Battelle7,8 'and at Case Institute by Brotzen and co-workerss further clarified the nature of the decomposition process. Beta decomposition was found to proceed by the following series of reactions: 1 2 3 4 a + Ti, My (in eutectoid systems). ßo, ßr, and ßU refer to ß phase of original, enriched, and ultimate alloy contents, respectively. Omega is a transition phase having a complex structure. 10-13 Step 4, of course, occurs only in ß-eutectoid systems. This paper presents data correlating transformation behavior with mechanical properties for the following alloys: Ti-8Mn, Ti-8Mn-2A1, Ti-4Mn-4A1, Ti-6Al-4V, and Ti-4Fe. The isothermal decomposition of ß in titanium-manganese alloys of similar composition has been investigated by Frost and coworkers8 and the effect of various annealing treatments on alloys in this system has been studied by Holden, Ogden, and Jaffee.14 The compositions Ti-8Mn-2Al, Ti-4Mn-4A1, and Ti-6A1-4V, were studied in the present work in an effort to define more clearly the effect of aluminum on the response to solution and aging treatments. Ogden, Holden, and Jaffee15 have invesitgated the effect of aluminum on the response of a similar alloy (Ti-8.8Mn-2.46A1) to annealing treatments, and Luini and Lee16 have made an exploratory investigation of the heat-treatability of the Ti-4Mn-4Al alloy. The Ti-4Fe alloy was studied as an example of a moderate1y active eutectoid system. Holden, Ogden, and Jaffee 17 have studied Ti-Fe alloys and have presented some hardness data for aging at 400°C for alloys of Ti-2.56, 5.01, and 7.35 iron after quenching from the a-ß field (750°C). EXPERIMENTAL PROCEDURES The experimental procedures generally used in the precipitation-hardening study are outlined in the following sections. Departures from these techniques are noted in the discussions of the individual alloys. Table I presents the nominal and actual compositions of the alloys studied, together with the swaging and rolling temperatures. In all cases, these temperatures were in the a-ß field and the microstructures consisted of an equiaxed a-ß mixture. Melting and Fabrication—Except for the commer-

Jan 1, 1960

By C. E. Silverblatt, D. A. Dahlstrom

Previous bench-scale studies demonstrated that a substantial moisture reduction can be obtained by the application of steam to coal filter-cakes, particularly to those containing a limited amount of minus 200-mesh material. Consequently, U.S. Steel's Applied Research Laboratory conducted a study to determine the feasibility of steam filtration of 1/4 in. by 0 coal on a continuous pilot-scale installation in which an Eimco extractor is used. The test results showed that the moisture content of this coal could be reduced to 5.5% at a steam loading of about 175 lb of steam per ton of dry cake. In terms of steam consumption, this loading is calculated to be 1-1/2 lb of steam per lb of water removed. In some tests, only 1 lb of steam per lb of water removed was required. These levels of steam consumption are significantly less than the actual heat requirements of conventional thermal dryers. The satisfactory moisture reductions were obtained at filtration rates of 125 to 186 lb of dry solids per sq ft per hour. However, the proper design of commercial filters should improve the potential rates that can be attained. These results indicate that steam filtration has considerable economic potential for drying 1/4 in. by 0 coals and also has additional advantages over the conventional thermal drying of coal. The results of the previous bench-scale studies and those published by Burton' demonstrated that a substantial moisture-content reduction can be effected by the application of slightly superheated steam to coal filter-cakes, particularly to those containing a limited amount of minus 200-mesh material. Consequently, US Steel's Applied Research Laboratory conducted a study to determine the feasibility of steam filtration of 1/4 in. by 0 coal on a continuous basis. In the continuous process, the dewatering operation on the filter is conducted in stages. In the first, the bulk of the water in the feed slurry is removed by conventional mechanical dewatering on a portion of the filter before the steam is applied. In the second stage, steam is applied to the cake. The steam condenses and releases its latent heat, thereby reducing the viscosity of the remaining cake water; this reduced viscosity then facilitates further drainage and produces a cake of lower moisture content. Because of the availability of feed coal on a continuous basis and since steam was readily available from a low-pressure boiler, the Applied Research Laboratory selected for the test site a coal-preparation plant that cleans Pittsburgh Seam coal. A slurry of table and flotation coal in percentages as they occur normally was used as feed stock. Typical analyses of this slurry are shown in Table I. DESCRIPTION OF FILTER AND EXPERIMENTAL PROCEDURES An Eimco Extractor was selected for the evaluation of steam filtration in a continuous process. This unit was chosen because of its availability and its design features that permit relatively simple hood construction, instrumentation, and operation. A photograph of the Extractor is shown in Fig. 1. In the filter a cloth medium is used that travels horizontally and continuously with a grooved, rubber drainage belt. The total effective filter area was 12.5 sq ft. As the feed slurry flows by gravity from the feed box onto the medium,

Jan 1, 1964

By F. A. Veer, W. G. Burgers, B. H. Kolster

Starting-- from Cu-Si diffusion couples a study of diffusion in the intermetallic compound Cu3Si of the Cu-Si system has been made. Mmker experiments showed copper to be the diffusing element. From the rate of growth of the Cu3Si phase diffusion coefficients were derived. The activation energy for diffusion is 18.6 kcal per mole. The couples show some interesting microscopic features, for which a tentative explanation is given. THE synthesis of dimethyldichlorosilane, (CH3)2SiC12, an important compound in the manufacture of methyl-silicones, takes place at the surface of a thin Cu3Si layer deposited on a mass of silicon particles."' By passing CH3C1 vapor at about 350°C, silicon atoms are consumed from Cu3Si in forming the volatile silane molecules, thus leaving copper atoms at the surface. It is well-known that copper acts as a poison for the above-mentioned reaction by catalyzing the dissociation of methylchloride.' However, no poisonous effect is observed, at least not before most of the silicon from the particles is converted into silane.3 This would be understandable, if either the copper atoms diffuse through the Cu3Si deposit to the underlying silicon or silicon atoms diffuse in the reverse direction to the copper, both processes resulting in the formation of new Cu3Si and so ensuring the proceeding of the reaction. In this paper experiments are described, demonstrating copper to be the diffusing element. Also a very low activation energy for the diffusion is observed. EXPERIMENTAL The silicon used contained 1 ppm Mg and 1 ppm Cu; the copper was spectroscopically pure (Fe: 2 ppm; Ag, Mg, Si: 1 ppm). The copper and silicon samples were prepared in the form of blocks of approximately 10 by 10 by 5 mm with two parallel sides by spark-machining. The blocks were ground on emery paper (grit 600), etched (copper with nitric acid, silicon with a 4:l nitric acid:hydrofluoric acid mixture), and cleaned with alcohol. As the brittleness of the silicon did not allow a welding procedure to prepare the diffusion couples, the copper and silicon blocks were pressed together in a steel clamp. The pressure exerted by the clamp brought about contact between the parts of the couple and so ensured proceeding of the diffusion. The couples were heated in a vacuum furnace (about 10"5 Torr). The temperature was stabilized within 1 pct. After a heat treatment a section parallel to the direction of diffusion was examined in the microscope and in the X-ray scanning microanalyzer. To determine whether copper or silicon is the diffusing element marker experiments were carried out using tungsten wires with a 20-p diam. EXPERIMENTAL RESULTS Figs. 1, 2, 3, and 4 give micrographs of diffusion zones of Cu/Si couples. Analysis by the electron mi-croprobe of the Cu/Si samples after a definite heat treatment revealed the existence of only one intermetallic phase as can be seen from the line scan shown in Fig. 5. From the X-ray diffraction pattern it could be deduced that this phase was CU 3 Si.4 Even when diffusion zones of considerable width (up to 600 p) were obtained, no other phases occurring in the Cu-Si system could be detected, neither by the electron microprobe nor by X-ray diffraction analysis. The optical anisotropy of the Cu3Si phase made it possible to observe the columnar shape of the crystal-

Jan 1, 1969

By E. R. Morgan

A series of manganese-rich ferromagnetic alloys has been studied. The alloys are based upon an interstitial solution of carbon in manganese. In each of the systems investigated, the ferromagnetic phase was found to be face-centered-cubic in structure. This magnetic phase is based upon the composition (Mn, X)4C; where X is a metallic element which has both a positive size factor with respect to manganese and a high positive valence. Typical elements of this type are aluminum, indium, and tin. Preliminary magnetic measurements indicate that the effective magnetic moment of manganese in the alloys is at least 1.0 Bohr magneton per atom. It is emphasized that the critical atomic separation beyond which ferromagnetism can occur will be governed by the electronic configuration of the manganese atoms. Lattice parameter measurements show that the ferromagnetic condition in the present alloys is associated with an increased atomic separation of only 3 to 6 pct compared with a hypothetical face-centered-cubic lattice of pure manganese. MANGANESE which is paramagnetic and not ferromagnetic in the pure state can become ferromagnetic if suitably alloyed. Under favorable conditions manganese can have an effective ferromagnetic moment of the order of 3.41,2 or even 4.0 compared with a moment of 2.2 Bohr magnetons for iron. The incidence of ferromagnetism is believed to be controlled by the degree of atomic separation.4,5 This is consistent with the fact that the atomic separation, when considered in terms of the ratio of the atomic diameter R to the diameter r of the 3d-shell, is larger in the ferromagnetic metals. The values of R/r calculated by Slater,' for metals of the iron group are given in Table I, and Slater has suggested that the critical ratio of R/r is 1.5. Consideration of the criterion of atomic separation alone would suggest that there are three classes of possible ferromagnetic manganese alloys: 1— Ordered structures, of either solution or compound types, such that manganese atoms are not near neighbors; 2—Structures in which the separation of near-neighbor manganese atoms is sufficiently increased by the presence of suitable solute atoms; and 3—Dilute solutions of manganese. Typical ferro- magnetic alloys of types 1 and 2 are the Heusler alloys and Mn4N, respectively. There are no recognized ferromagnetic alloys of type 3. In view of the proximity of the ratio R/r for manganese to the critical ratio of 1.5, the present work was concentrated on manganese-rich alloys rather than on ferromagnetic alloys of low manganese content, several examples of which are already known. Calculation of the distance of closest approach of manganese atoms in each of its allotropic forms, Table 11, indicates that the high temperature ? phase provides the most suitable basis for ferromagnetic alloys of high manganese content. However the high temperature forms of pure manganese cannot be retained on quenching, although a face-centered-tetragonal form apparently can be produced by electrodeposition. Since the critical separation which must be exceeded in order to obtain ferromagnetism is dependent upon the number of electrons in the d-shell, no exact critical value of R/r can be assumed. Not only will this separation vary from one pure metal to another, but it will also vary with the valency of the given type of atom when it is in an alloy. Raynor8 has shown that metals of the iron group probably

Jan 1, 1955

By W. D. Robertson, R. E. Reed-Hill

DEFORMATION of magnesium crystals in a direction parallel to the basal plane has a special significance as a result of the preferred orientation characteristic of cold worked and recrystallized polycrystalline magnesium sheet and extruded rod in which the basal plane tends to lie in or near the plane of the sheet or the axis of a rod. The principal objective of the present study is a determination of the modes of plastic deformation in magnesium single crystals in this orientation. Evidence for nonbasal slip in magnesium has been presented by a number of authors. Schmid and Was-serman&apos; indicated that pyramidal slip on {1011} < 1120> or {1012} <1120> could occur above 225°C. Bakarian and Mathewson2 stablished that the slip system {1011} <1120> operates at high temperatures and that 225°C was a lower limit for pyramidal slip. The latter authors also showed that the critical resolved shear stress for {1011} slip was 400 g per sq mm at 330°C, while that for basal slip was 66 g per sq mm at the same temperature. Thus, at 330°C basal slip should be expected for all orientations except those in which the stress axis lies almost in the basal plane. More recently Burke and Hibbard3 oserved pyramidal slip at 25°C, when the stress axis was 6" to the basal plane and 14" to a <1120> slip direction. The critical resolved shear stress for pyramidal slip was 52 g per sq mm, which is only slightly greater than their value for basal slip (46 g per sq mm). Chadhuri, Chang, and Grant4 have observed non-basal slip in creep tests with polycrystalline specimens in the temperature range 250" to 350°C. The observed slip bands, which were extremely irregular in appearance, can be explained in terms of cooperative slip on {1011} and (1010) planes which have a common slip direction. Prismatic (1070) slip in polycrystalline magnesium was observed by Hauser, Landon, and Dorn.5 It was found to occur at low temperatures (78" and 195°K) and it was accompanied by cross slip in which the cooperating plane was the basal plane. Since prismatic slip occurred only at regions of high stress concentrations, the critical resolved shear stress could not be determined. Experimental Procedure The present work was performed on crystal specimens which were all cut from the same large single crystal. The original cylindrical crystal, 0.5 x 7 in., was grown in a Bridgman type furnace in which the temperature gradient was moved past the stationary crystal in the manner described by Jillson6 and Burke.&apos; High purity magnesium was furnished by the Dow Chemical Co. with the following spectro-graphic analysis in weight percent: 0.003 pct Al, <0.01 pct Ca, 0,002 pct Cu, <0.001 pct Fe, 0.008 pct Mn, <0.001 pct Ni, <0.002 pct Pb, <0.01 pct Si, <0.001 pct Sn, and <0.01 pct Zn. The large crystal was cut into four cylindrical pieces about 1.5 in. long. A flat surface parallel to the basal plane was made by hand grinding with lubricated metallographic paper on one side of each cylinder. In order to prevent bending in subsequent cutting operations, the crystals were supported by

Jan 1, 1958

By J. L. Huitt, IM. L. Slusser, E. E. Glenn, M. L. Slusser

This paper is concerned with: (1) an analysis and interpretation of the filtration characteristics of drilling muds on filter paper, and (2) an interpretation of early stage "filtration" on consolidated synthetic porous media, herein referred to as the "surge loss" period. It is shown that water-loss data can be plotted so as to disclose the existence of a surge period, a non-uni-form cake thickness period, and a constant pressure filtration period. The same periods occur during exposure of consolidated porous media to muds. The data on consolidated porous media indicate that: (1) mud particles bridge pores inside porous media during the surge period, and (2) "filter cake" build-up inside porous media occurs during subsequent filtration. The data also show that the surge loss increases with sample permeability and with pressure differential. INTRODUCTION The phenomenon of mud filtrate invasion into porous sands of a drilling well has been recognized for many years.1,2,3,4 Part of API Code 29 is concerned with the filtration testing of a drilling mud to yield data on this subject. In a number of investigations "plastering properties" of muds were studied,5,6,7,8 "plastering" apparently meaning cake forming properties. In such studies the characteristics (thickness, permeability, and toughness) of the cake and the rate at which the liquid phase of the mud was separated from the solids (filtration rate through the cake, commonly referred to as water loss) were measured or at least considered. From the standpoint of its effect on well productivity, filtrate invasion into "clean" water-wet pay sands (i.e., those containing no clay minerals) may not necessarily be a serious problem. An increase in water saturation in the zone immediately around the wellbore would cause loss of oil permeability. However, in such a system, much of this water may be removed by oil production. If filtration occurs into "dirty" sands (i.e., those containing appreciable clay minerals), clay swelling or other mechanisms may cause losses in oil permeability which cannot be overcome by oil production.&apos;.&apos; The phenomenon of mud particle invasion into the pay sand of a drilling well was considered to be a possible serious factor in the early days of rotary drilling. Opinions varied as to whether drilling fluids "mudded up" and "sealed" oil sands. In 1932 Rubel,9 Gill,10 and Parsons," in separate papers, presented differences of opinion together with some laboratory and field data concerning loss of oil production caused by drilling fluid invasion into pay zones. These papers, and the discussions, furnish a large background on this subject and indicate the very clear thinking of many men at a time when petroleum production technology was in its infancy. Jones and Babson,6 and Silent,&apos; experimentally found that the depth to which mud particles invaded water-saturated sand packs was small (no greater than 1/16 in). Arn-quist12 in 1937 observed loss of water permeability due to invasion of mud particles into water-saturated, consolidated, sandstone samples. Williams and Cannon5 studied the filtra-tion properties of drilling muds and mentioned "sludge" which penetrated a short distance into the water-saturated filtering medium (sand pack). Byck5 concluded that formation permeability had no effect on the plas-

Jan 1, 1958

By P. P. Gregory

The rate of drilling operations in the West Texas district during 1940 was approximately equal to that of 1939. The total number of wells dillled in the area during the year was 1834, of which 1716 were completed as oil producers, 12 were gas wells and 106 were dry holes. The number of wildcat wells drilled during the year was comparatively small. The drilling of inside locations in proven areas and the drilling of wells for the purpose of extending the productive limits in producing fields constituted the bulk of development during 1940. Gaines County led all other counties in the district in the total number of oil-well completions. The oil production totaled 83,345,381 bbl., the highest figure for any year since proration was begun. The 1940 oil production exceeded the 1939 production by approximately four million barrels. Discoveries While comparatively few new oil-producing areas were discovered during 1940, it appears that the oil production found in simpson lime in the Abell field, pecos County, was an outstanding discovery for the year. This was the second Ordovician discovery in Pecos County. Taubert, McKee & Siemoneit located its discovery well, V. W. Crockett No. 1, set. 4 1/2 H. & T. C. R.R, co, survey in the Imperial area of northwestern Pecos County. The top of pay was encountered at 5270 ft., and the well was bottomed at 5357 ft. in simpson lime, on act. 17, I940. The initial production was 928 bbl. of 43" gravity sweet oil in 11 hr. 23 min., flowing naturally through 2-in. tubing with gas-oil ratio of 783 cu. ft. per barrel. Following the completion of the discovery well, large blocks of land were leased in the area, and several locations were made toward the close of the year. There is every indication that the Abell field will become a major producing field in the West Texas district. There was no pipe-line outlet for the field at the end of the year. Shipley-Silurian field, discovered by the Gulf Oil Corporation, appears to be another major addition to the oil reserves in 1940. The discovery well, Wristen Brothers No. 5, is in sec. 18, block 5, H. & T. C. R.R. Co. survey in Ward County. The well was drilled to a total depth of 9187 ft. and was plugged back to 7075 ft. The Silurian lime section was acidized with 3000 gal., from 6993 to 7075 ft., and on Dec. 5, 1940, the well was completed for initial production of 3040 bbl- of 32.2" gravity oil in 24 hr., flowing through tubing. Todd Deep field, Crockett County, was discovered by the Continental Oil Co. et al. The discovery well, J. S. Todd No. 2, set. 29, block WX1 G.C. & S.F. R.R. Co. survey, was completed on April 3, 1940. The top of pay was encountered at 5623 ft., and the well was bottomed at 5691 ft. for initial production of 1613 bbl. of 40.6&apos; gravity oil flowing naturally through 2-in. tubing. The pay section was found in Strawn lime of Pennsylvanian age. There were six producing wells in the field at the end of the year. This appears to be another major discovery in 1940. There was no pipe-line outlet in the field at the end of the

Jan 1, 1941

By P. P. Gregory

The rate of drilling operations in the West Texas district during 1940 was approximately equal to that of 1939. The total number of wells dillled in the area during the year was 1834, of which 1716 were completed as oil producers, 12 were gas wells and 106 were dry holes. The number of wildcat wells drilled during the year was comparatively small. The drilling of inside locations in proven areas and the drilling of wells for the purpose of extending the productive limits in producing fields constituted the bulk of development during 1940. Gaines County led all other counties in the district in the total number of oil-well completions. The oil production totaled 83,345,381 bbl., the highest figure for any year since proration was begun. The 1940 oil production exceeded the 1939 production by approximately four million barrels. Discoveries While comparatively few new oil-producing areas were discovered during 1940, it appears that the oil production found in simpson lime in the Abell field, pecos County, was an outstanding discovery for the year. This was the second Ordovician discovery in Pecos County. Taubert, McKee & Siemoneit located its discovery well, V. W. Crockett No. 1, set. 4 1/2 H. & T. C. R.R, co, survey in the Imperial area of northwestern Pecos County. The top of pay was encountered at 5270 ft., and the well was bottomed at 5357 ft. in simpson lime, on act. 17, I940. The initial production was 928 bbl. of 43" gravity sweet oil in 11 hr. 23 min., flowing naturally through 2-in. tubing with gas-oil ratio of 783 cu. ft. per barrel. Following the completion of the discovery well, large blocks of land were leased in the area, and several locations were made toward the close of the year. There is every indication that the Abell field will become a major producing field in the West Texas district. There was no pipe-line outlet for the field at the end of the year. Shipley-Silurian field, discovered by the Gulf Oil Corporation, appears to be another major addition to the oil reserves in 1940. The discovery well, Wristen Brothers No. 5, is in sec. 18, block 5, H. & T. C. R.R. Co. survey in Ward County. The well was drilled to a total depth of 9187 ft. and was plugged back to 7075 ft. The Silurian lime section was acidized with 3000 gal., from 6993 to 7075 ft., and on Dec. 5, 1940, the well was completed for initial production of 3040 bbl- of 32.2" gravity oil in 24 hr., flowing through tubing. Todd Deep field, Crockett County, was discovered by the Continental Oil Co. et al. The discovery well, J. S. Todd No. 2, set. 29, block WX1 G.C. & S.F. R.R. Co. survey, was completed on April 3, 1940. The top of pay was encountered at 5623 ft., and the well was bottomed at 5691 ft. for initial production of 1613 bbl. of 40.6&apos; gravity oil flowing naturally through 2-in. tubing. The pay section was found in Strawn lime of Pennsylvanian age. There were six producing wells in the field at the end of the year. This appears to be another major discovery in 1940. There was no pipe-line outlet in the field at the end of the

Jan 1, 1941

By C. D. Cochran, F. H. Deily, M. M. White, Victor Horner

A laboratory study of the effects of physical and easily measured rheological properties upon dynamic filtration was carried out. The purpose was to determine the factors affecting dynamic filtration and thus learn how to control this important property. The recommended procedure for determining the amount of fluid loss prescribed by API Code RP 29 "Field Procedure for Testing Drilling Fluids,"&apos; is very useful for mud conditioning purposes, but inadequate for comparing filtration properties of different muds under dynamic conditions. Where dynamic filtration control becomes important for purposes such as logging and coring, other means of evaluating filtration properties are needed. A special device and testing technique were developed to provide reliable data on filtration characteristics of different fluids under dynamic conditions. Liquid saturated rock samples were drilled with a microbit, and the amount of connate liquid displaced by the fluid being investigated was measured. The empirical testing procedure was considered reliable. A large number of laboratory-prepared and field-mixed dritling fluids with a wide range of physical properties were studied. These properties included: (I) shape of consistency curves, (2) apparent viscosity, (3) plastic viscosity, (4) yield value, (5) density, and (6) API filter loss. Test results indicate that very little, if any, trend could be established between changes in these fluid properties and dynamic filtration. INTRODUCTION During the process of drilling, excessive loss of liquid from the mud to the formation is undesirable for many reasons. Filtration can reduce production-zone permeability, cause sloughing of formations, affect electric log curves, and render the fluid data obtained from cores unreliable. Thus, it is very important that we gain a knowledge of the factors that control filtration. It is generally agreed that in any type of filtration (static, dynamic, or combinations thereof), the mechanics of filtering depend in great part upon the composition of the fluid. Moreover, it is also true that the physical and rheological properties are influenced by the composition of the fluid. Indirectly, then, it was hypothesized that a relationship existed between dynamic filtration and physical-rheological properties, two effects of a common cause—fluid composition. This paper discusses an attempt to relate filtration-while-drilling to physical and easily measured rheological properties. It is believed that the results of this study may prove useful to others in the industry who are working on the problem of understanding filtration. The industry accepted practice for determining fluid loss from drilling mud is described in API Code RP 29. The practice is to measure the amount of filtrate that passes during a given interval of time from a quiescent drilling fluid under applied pressure through a piece of filter paper. This is primarily a test of static filtration properties. Other investigators have studied filtration under dynamic conditions. Williams5 and Pro-kop5 studied radial filtration and filter-cake buildup by circulating fluid through a porous cylinder under conditions similar to actual mud flow. Nowak,4 Krueger,3,4 and Vogel3 studied the effect of filtration upon permeability by flowing mud past the face of rock Samples. In their tests, the bit action was simulated by mechanical scrapers that kept the filter cake from building up. Ferguson and Klotz2 studied three types of filtration: static, dynamic, and beneath-the-bit. They investigated each type separately, using a model well in which bottom-hole hydraulics and mechanics were closely approximated.

Jan 1, 1958

By B. C. Craft, Murray F. Hawkins, John R. Rayne

A reservoir mechanism of sulfur recovery by the Frasch process is presented. Improving the economic, of recovery appears to be largely a well, rather than a reservoir problem. A most important factor is the limitation of the lateral extraction of .sulfur about the wells due to the almost vertical .flow of the injected hot water. Model studies are described which confirin the mechanism of sulfur recovery by presently used methods. Studies on a five-spot system indicate improved econo171ics regarding recovery, recovery rate, therinal efficiency, and well spacing. INTRODUCTION Sulfur mining by the Frasch process is one of the most important methods of sulfur production. Developed by Herman Frasch in 1894, it enjoyed a rapid growth and presently supplies 40 per cent of the world&apos;s sulfur and about 80 per cent of the U. S. sulfur." The Frasch process of mining the underground native sulfur deposits involves melting the sulfur in place by introducing super-heated water into the sulfur bearing formations, and producing the sulfur as a liquid. Many problems are encountered in mining these native sulfur deposits, and sulfur production depends chiefly upon the nature of the sulfur deposit and the underground thermal efficiency of the heat transfer system. THE RECOVERY MECHANISM Sulfur is typically found in salt dome cap rock as crystal aggregates occurring within the cavities, seams, and pores of limestone and gypsum formations.&apos; Sulfur-bearing limestone is typically cavernous, vugular, and fractured. Porosity averages about 20 per cent and sulfur saturation averages approximately 25 per cent by weight.1,15 Vhe sulfur bearing formations are very heterogeneous in nature and physical characteristics vary widely within small distances. Total cap rock thickness may vary from 50 to more than 1,000 ft, and net productive thicknesses from a few feet to a few hundred feet. In most cases the upper portion of the limestone formation is barren of sulfur, varying from 5 to 200 ft in thickness.1,15,33 The immediately overlying sediments and the underlying dense anhydrite formation provide permeability barriers to the flow of water from the cap rock section.&apos;" Sulfur wells are drilled with conventional oilfield drilling rigs. Fig. 1 illustrates the casing program of a completed sulfur well. The cap rock sections are drilled with core bits and continuous core logs are recorded. After coring, the cap rock section is underreamed to a diameter of 9 7/8 in. The bottom of the 8-in. casing is welded closed and rests on the bottom of the drill hole, which extends through the cap rock to a few feet above the bottom of the sulfur-bearing formation. The 8-in. pipe contains 5 ft of 3/4-in. perforations on 6-in. centers and 15 ft of 1-in. perforations on 1-ft centers. The 20-ft perforated section is set opposite the lower 20 ft of the sulfur-bearing formation. The 4-in. sulfur pipe is set inside the 8-in. water line on a seat ring at the top of the 5-ft section of 3/4-in. perforations. The mining water, heated to about 330°F under a pressure of 250 psi, is forced down the annulus between the 8-in. and 441-1. pipes and through the 1-in. perforations to the sulfur-bearing formation. Compressed air, at 400 psi pressure, is supplied through a 1-in. air line near the bottom of the well to provide air-lift of the liquid

Jan 1, 1957

By C. A. Hartnagel

During- the past 10 years the annual production of petroleum in New York has averaged close to 5,000,000 bbl., the total for the period being 49,881,000 bbl. In 6 of the 10 years, the production was slightly in excess of the 5,000,000 mark. The 1944 production of 4,697,000 bbl. represents a 7 per cent decline from the previous year. Of the total 1944 output, the Allegany County district, which includes two small areas of Steuben County, contributcd 3,614,065 bbl., a decline of 5 per cent from 1943, and the contribution of Cattaraugus County, which represents the northern extension of the Bradford pool of Pennsylvania into New York was 1,082,935 bbl., a decline of more than 14 per cent. Since March 1942, the posted price of New York crude oil has remained at $3.00 per bbl. On lug. I, 1944, a Federal subsidy of 75¢ per bbl. was granted to oil producers, thus making the price actually $3.75 per bbl. Since all of the oil produced in New York comes under the designation "stripper well operations," it is entitled to the Federal subsidy. During the last few years there has been little change in the number of wells drilled annually. In the Allegany field, which accounts for three fourths of the oil produced in the state, 1240 wells, including water-intake wells, were drilled during 1944 as compared with 1223 in 1943. There was no marked increase in the number of wells drilled after granting the subsidy of 75¢ per bbl. of oil on Aug. I, the increase being but 14 wells during the last half of the year over the preceding six months. In flooding operations it is not to be expected that even a substantial increase in the price of crude oil will be reflected quickly in an increase of the number of wells drilled or in a marked increase in production of crude oil. In flooded areas, oil is obtained through a program extending over a number of years. This program involves the drilling of the water or input pressure wells, drilling of the oil wells, building up the oil flood to maximum production, and finally the watering out of the well when the amount of oil produced in proportion to the water becomes so small that pumping is no longer profitable. The various operations may extend over a period of 10 years or more, during which time the price of crude may have fluctuated greatly. Although the rate of production can be controlled to a limited extent, it is evident that a flood when once begun must be continued regardless of the price of crude. During the past seven years New York crude has had a price range from $1.68 per bbl. in 1938 to the present price of $3.75 per barrel The field pattern now in general use for wells in a flood project is the "five-spot." Under this arrangement, the lease is divided into squares with a water well at each corner and an oil well in the center. In the all-over pattern of the lease each oil well is acted upon by four water wells and each water well supplies part of the pressure to four oil wells. Spacing between the input water wells and the oil wells usually varies from zoo to 225 ft. or, on an acre basis, there is one oil well and one water well for each 2 1/2 acres. In recent years there has been a tendency to increase

Jan 1, 1945

By A. M. Gaudin, D. W. Fuerstenau

IN concentration of certain ores by soap flotation, prevention of quartz flotation is desired; the contrary is true in treatment of some oxide iron ores. Experimental study of the flotation of quartz goes back at least a quarter of a century.&apos; Clean quartz does not float with fatty acids or soaps but does float when activated by one of many metallic salts. Control of pH is important. Broadly speaking the problem of quartz flotation has been approached from the empirical side, as was the related topic of flocculation or dispersion of quartz suspensions? Empirical studies indicated the existence of critical relationships between the additions of collector and activator. These additions were not stoichiometric for the formation of soaps of the activator cation. For example, Gaudin and Rizo-Patrona found optimum quartz flotation at pH 10.6 using barium activation and oleate collection when the molar ratio of oleate to barium was 1 to 1 instead of 2 to 1, as would be called for formation of Ba(OL),. Cooke and Digre" &apos; found that if calcium is the activator, a minimum quantity of that agent is required for effective flotation when the pH is 11.5. In other words, if the concentration of Na&apos; exceeds 10 -2.5 mols per liter or if the concentration of H exceeds 10-11 mols per liter, the concentration of Ca++ in solution required for quartz activation is increased. This suggests that H+ is much more effective than Na+ on 10-2.5 quartz, perhaps in the ratio ofp or 108. Schuh- mann and Prakash6 studied anew the activation of quartz by barium, calcium, aluminum, and ferric iron. Salts of these metals are activators provided they are in stoichiometric excess over the collector used with them. Alkaline-earth salts are effective only in alkaline circuits. Important as they are in giving data on the effect of various agents on quartz, all these studies fail to give information on the detailed structure of the quartz-solution interface. A beginning in this direction was made by Gaudin and Chang,? who measured the adsorption of radioactively marked barium and laurate ions at quartz surfaces, and by Gaudin. Spedden, and Laxen,8 ho measured the adsorption of radioactively marked sodium at quartz surfaces. Work has also been done by Bell0 n measurement of the adsorption of sodium ion and chloride ion at quartz-solution interfaces. In all these experimental measurements of adsorption, the solid was centrifuged or filtered from the bulk of the liquor with which it had been associated; and the composition of the solid surface was ascertained by analysis, after allowance was made for the ionic composition of the liquor included with the centrifuged solids on the assumption that it is identical to the bulk liquid. Adsorption measurements give only the total amount of collector adsorbed at the quartz-solution interface; they give no indication of the distribution of these adsorbed ions at the interfacial layer. It is the ionic structure of the solid-solution interface and its importance to flotation that is the subject of this paper. The structure of this interfacial layer can be investigated by means of electrokinetic methods so that by combining electrokinetic studies with adsorption measurements, a more complete picture of the quartz surface may be obtained. The following studies were made to ascertain how electrolytes used in the soap flotation

Jan 1, 1956

By P. Dayal, L. S. Darken

THE migration of carbon in austenite under the influence of an electric current has been observed qualitatively several times.14 Lebedev and Guterman5 recently have reported quantitative measurements; their method consisted of welding a low-carbon to a high-carbon wire, passing current, and later estimating the carbon distribution metal-lographically. We believe the method reported in this paper is superior in principle since electrolytic migration and ordinary diffusion are not necessarily coupled as in the weld method; also for the first time the extent of migration is determined by combustion analysis for carbon. A uniform tubular specimen (S.A.E. 1045 or 1095) was mounted as illustrated in the figures. the whole assembly being in an atmosphere of purified nitrogen. Direct current (129 to 226 amp at 0.65 to 1.0 v) served as source both of heat and of potential gradient for carbon migration. The duration of experiment was 7.5 to 12 hr, during which time the temperature was controlled (±10°C) manually. The experimental conditions are indicated in the first five columns of table I. With this experimental arrangement, the temperature initially has a maximum value at the central plane. Also, in this vicinity (by virtue of the symmetry), the carbon entering any volume element is equal in quantity to that leaving; the loss or accumulation of carbon occurs near the electrodes since the carbon moves uniformly near the center and is "frozen" at the cold ends. Hence, providing the time of experiment is not sufficiently long to seriously influence the conditions at the central plane, carbon crosses this plane only under the influence of the electrical potential gradient and not under the influence of temperature or concentration gradient. The amount of carbon which has crossed this plane was determined by combustion analysis of the two halves of the specimen. The results of these analyses are shown in the sixth and seventh columns of table I. It will be noted that substantial amounts of carbon migrated from the anode portion to the cathode portion (except at 920°C, which temperature was too low to exhibit the effect in the allotted time). In spite of precau-tions taken, considerable decarburization occurred as may be seen by comparing cols. 8 and 5. In three cases (indicated by asterisks in table I) the specimen was ground on one side, polished, and examined metallographically before analysis. One specimen was normalized and re-examined. Micrographs of selected areas in specimens 4 and 6 are shown in figs. 1 and 2, respectively. Evidence of carbon migration from the anode toward the cathode is quite apparent. Fig. 2 shows abundant graphite as well as cementite in a region near the cathode. The temperature of this zone is estimated at about 800°C. In fig. 1, particularly in the micrograph on the extreme right (the right side of which is of unaltered carbon content), there is evidence of slight depletion of carbon in the immediate vicinity of the cathode as contrasted to the general increase in carbon of the cathode half of the specimen. Although this may be attributed in part to decarbur-ization, it is believed that it is occasioned also by thermal diffusion—migration (of carbon) from a cool to a hot zone4—a phenomenon superimposed upon the electrical migration. Evidence of carbon migration was visible particu-larly during the course of the high-temperature,

Jan 1, 1951

By Leonard R. Weisberg

HE procedure of directional freezing by the Bridgman technique1 is frequently used in crystal preparation. On those occasions where the crystal is regrown, it can be advantageous to Crop part of the ingot before regrowth to achieve purification. This note describes some simple, yet interesting, observations concerning the effects of cropping an ingot between successive freezes. First, it is not effective to Crop the front end of an ingot, whether or not the distribution coefficient, k , of the impurities is greater or less than unity. This can be shown as follows. The concentration C, of an impurity in a directionally frozen ingot of length d with a uniform cross section is given by where x is the distance along the ingot, and C0 is the initial concentration per unit length. It is assumed in deriving this equation that diffusion is negligible in the solid, is complete in the melt, and that k is constant. Consider that a section of the ingot Ad is removed from the front end. Then the average impurity concentration in the remaining (d- Ad) section of the ingot can be shown by integration to be given by When the ingot is remelted and refrozen, the new impurity distribution is given by where xl is the distance along the refrozen ingot. Substituting the value of c into Eq. [3], one finds This is identical to Eq. [11 when x = (x, Ad), which represents the original impurity distribution in the (d - Ad) section of the ingot after the first directional freeze. Therefore, the cropping and re-freezing accomplished nothing. This can also be seen physically by realizing that the average impurity content in the melt after the first Ad section is frozen, is identical to that after the resulting ingot has been cropped and remelted. Hence, it is assumed in the following sections that only the tail end of the ingot is cropped. However, it must be realized that for impurities with k greater than one, the pieces cropped from the tail end are purer, and are therefore saved. After cropping an amount Ad from the tail end of an ingot, the average impurity concentration of impurities in the remaining portion of the ingot is given by wheref= d/d. For the case of k < 1, the purification is defined as c,/c. It is obvious from Eq. [5] that the purification increases asf increases, but the increase in purification is not large. For example, iff is doubled from 0.1 to 0.2, the purification increases by only 10 pct for k = 0.5, by only 24 pct for k = 0.1, and by 32 pct for k =0.01. Much smaller values off than 0.1 are not desirable since insufficient purification is achieved. These figures indicate that much larger values off do not lead to substantial improvement, especially considering that much of the original ingot is lost. Therefore, it is generally useful to Crop about 1/10 of the ingot to achieve purification. As compared to doubling the value off, it is much more helpful to remelt, refreeze, and crop the ingot twice. Using Eq. [51 reiteratively, and assuming f= 0.1, it is found that the purification after this process is found to be increased over the purification after a single freeze and cropping by 33 pct for k= 0.5, 450 pct for k = 0.1, and 4100 pct for k = 0.01. This indicates that considerable purification can be obtained by this procedure. However, if purification is the main goal, one should resort to zone refining,3

Jan 1, 1962

By Fred D. Gustafson

With the postwar emergency for new housing and for new industrial buildings, much research has been done on lightweight aggregates for use in concrete and plaster. The trend toward lighter weight aggregates to relieve the dead load on the higher, steel framework buildings started toward the end of the last century. Progressively the requirements became more stringent, crushed bank slag, weighing 80 lb per cu ft as compared to 100 lb for crushed rock, was supplemented in some sections by foamed slags and expanded shales weighing from 40 to 60 lb per cu ft. In other sections cinders were used weighing from 40 to 50 lb, including sand. Sections favored with more recent vulcanism turned to pumice weighing from 30 to 60 lb, whereas other localities made use of diatomite, from 28 to 40 lb. Exfoliated vermiculite weighing from only 6 to 10 lb per cu ft came into use. As the search for lighter weights in aggregates continued so did the search for other desirable properties such as nailability, ease of cutting or channeling, and good insulation to both sound and heat. This search eventually led to a widespread interest in the expansion of perlite, or similar volcanic glasses, with the result that in 1946, the Office of the Housing Expediter&apos; listed eleven firms reporting the operation of processing plants either on pilot or commercial scale producing aggregates weighing from 2 to 16 lb per cu ft. Geology Perlite is one of the large family of rocks originating from a granitic or acidic magma and generally has a "rhyolitic composition with a marked perlitic structure."² The name "perlite" is a derivation from "perlstein" originally given "to certain glassy rocks (hyaloliparites, hyalo-rhyolites) with numerous concentric cracks, from the fancied resemblance of broken out fragments to pearls."3 The cause of the perlitic texture is somewhat controversial. Johannsen attributes the texture to strain set up in the glass by cooling and describes the finding of peculiar, glassy balls, called marekanite, more or less rounded and showing concave indentations, which may be left when perlite is broken. Frank Rutley, on the other hand, in 1881, while working on vitreous rocks from Montana, observed that there was incipient or partially started crystallization with segregation of water toward the un-crystallized portion in all specimens of perlite examined. Further he observed evidence of strain around focii of crystallization to which he ascribed the development of the spherical cracking which gives the rock its perlitic texture.4 Widespread over the western and southwestern United States where Tertiary vulcanism is exposed, perlite commonly is associated with andesitic, basaltic, and rhyolitic lavas with inter-bedded tuffs and ash of Eocene age although some deposits are associated with rocks assigned to the Pliocene age.5, 6 n nearly all cases the perlite overlies water laid tuff beds or agglomerates or breccias of explosive nature, an outstanding exception being the occurrence of perlite as the chilled selvage of andesite intrusions.7&apos;8 Available chemical analyses of per-lites from the western and southwestern United States indicate that they are varieties of leucorhyolites rather than of normal rhyolites, leucorhyolites having less than 5 pct of dark minerals, normal rhyolites having more than 5 pct. This conforms with Johannsen&apos;s observation that leucorhyolites are the prevailing kind in North America.9 Tables 1 and 2 give

Jan 1, 1950

By G. F. Sager, B. J. Nelson

Magnesium alloy forgings offer higher and more uniform mechanical properties than heat treated magnesium alloy castings and are used principally for light weight parts that may be stressed in fatigue or subject to impact loads, or where space limitations do not permit the use of the necessarily bulkier magnesium alloy castings. Compositions and Properties of Magnesium Forging Alloys The nominal compositions and properties of the principal commercial magnesium forging alloys are given in Table 1. The two that are most commonly used are AMC58S and AM65S. The former has the highest strength and is, therefore, employed for heavy duty applications. However, the forging of this alloy and of AMC57S ordinarily requires the use of slow speed hydraulic presses. The forging alloy AM65S combines good, although somewhat lower, mechanical properties with excellent forging characteristics. This alloy can be forged on hammers, upsetters, rolls, and mechanical presses, as well as on hydraulic presses. These characteristics make it particularly useful for many applications. Manganese Segregation in AM65S The alloy AM65S contains 5 pct tin, 3 1/2 pct aluminum, and a small amount of manganese, the manganese being added to insure satisfactory resistance to corrosion. Some manganese segregation was occasionally encountered in this alloy. In many applications, such segregation is of no particular consequence, but when forgings are acid dipped prior to the application of various chemical coatings, the segregated particles of manganese constituent may stand in relief. The resultant surface roughening may impair appearance and is undesirable in forgings employed in the textile industry, where very smooth surfaces are essential to avoid the catching and breaking of fine threads. An effort was therefore made to determine the cause of manganese segregation in this alloy and find a method for its elimination. Radiographic examination of a series of cast ingot sections and extruded samples of the AM65S type having manganese contents ranging from zero to about 0.7 pct revealed no appreciable manganese segregation when the manganese was less than about 0.4 pct. A small amount was observed with a manganese content of 0.46 pct and considerable with manganese contents of 0.6 pct or higher. Attempts to eliminate the manganese segregation by variations in the melting and casting conditions were unsuccessful and it soon became apparent that the trouble was attributable to the fact that the manganese contents that caused segregation were in excess of the amounts that would remain in solution at temperatures encountered in the melting and/or casting operations prior to the complete solidification of the ingots. A knowledge of the amounts of manganese that would be soluble in molten alloys of the AM65S type at various temperatures was obviously desirable. The liquid solubilities of manganese in binary Mg-Mn alloys and in Mg-Al-Mn and Mg-Zn-Mn alloys have been determined by Tiner and others,* but no data on the solubility of manganese in molten magnesium alloys containing tin and aluminum are given in the literature. For this reason, an investigation to determine the solubility of manganese in a magnesium alloy containing 5 pct tin and 3.5 pct aluminum (AM65S type) was undertaken.

Jan 1, 1950

By J. E. Gruzleski, O. Knacke, M. J. Meixner

The evolution of CO from small specimens of solidifying steel was investigated using a thermobalance technique. Gas evolution begins in the temperature range between 1400" to .1450°C. This behavior is independent of the initial carbon content and the cooling rate. At a constant temperature above 1220°C, the rate of gas evolution is temperature independent. Out-gassing of the specimen is thought to proceed through small channels formed by the coalescence of bubbles between dendrites. LIQUID metals have a higher solubility for gas than the solid. During freezing, these gases form bubbles which may either escape or remain trapped in the solid. Recent work1 on the evolution of oxygen from solidifying silver showed that the gas is not liberated until a large fraction of the melt has solidified, and that the gas is evolved in an almost explosive manner. Because of the commercial importance of CO evolution in solidifying steel, a similar investigation was undertaken to study the mechanism of gas liberation in steel. EXPERIMENTAL The thermogravimetric method of Knacke and eixner1 to follow gas evolution by weight changes was employed. Weight differences of 0.1 mg could be reproducibly measured on specimens weighing 2.5 g. These specimens were taken from alloys with varying carbon contents from <0.01 to 0.11 wt pct and <0.01 wt pct of each of silicon, manganese, and aluminum. Specimens contained in 8 mm ID magnesium alumi-nate crucibles were heated to 1550°C under 1 atm of very pure (99.995 pct) CO with a tungsten resistance furnace. The specimen temperature was measured with a Pt-Pt/Rh thermocouple located directly beside the crucible. It is felt that the temperature thus measured was within 5" to 10°C of the specimen temperature since on fusion the weight of the specimen increased due to uptake of CO, and this weight increase was always observed to begin within the temperature range of 1530" to 1540°C. Even after 3 hr there was a small weight increase with time indicating that the molten specimen was not completely saturated with CO. Therefore, complete saturation was not attempted, and all specimens were simply held for 3 hr at 1550°C before cooling. Two types of cooling experiments were performed. One consisted of continuous cooling at linear rates from 5°C to 20°C per min down to 1020°C. The second type of experiment involved continuous cooling at 10°C per min to a predetermined temperature, and then holding the specimen at this temperature for a certain time. During all of these experiments, the sample weight was recorded as a function of time and temperature. OBSERVATIONS Continuous Cooling Experiments. No gas evolution was detected above 1450°C. The initial weight decrease always occurred between 1400" and 1450°C with the average at 1430°C. With further cooling, gas evolution continued to about 1150°C. Between this temperature and 1020°C no further outgassing was observed. This behavior did not seem to depend on the initial carbon content nor on the cooling rate in the range investigated. Typical patterns of gas evolution are shown in Figs. 1 and 2 for different initial carbon levels and cooling rates. The total amount of gas liberated during solidification varied with the rate of cooling. The total weight change on continuous cooling at a rate of 10°C per min

Jan 1, 1970

By E. C. W. Perryman

On electropolishing, high-purity Cu-Sn and Cu-Sn-P alloys with more than 5 to 9 pct Sn were found to contain many grain boundaries with a ridge-and-furrow profile. The effect was not eliminated by solution treatment and was present at the new boundaries in recrystallized material. It could be produced by diffusing tin into the 3 pct Sn alloy and it is concluded that the effect is due to enrichment of certain boundaries in tin, or possibly in an impurity present in the tin, in solid solution. IN the hot working of tin bronzes, especially those with moderately high tin contents, considerable difficulty is frequently encountered from intercrystal-line weakness, which results in cracking at the edges in sheet on strip rolling and in the unsupported regions of the rod in rod rolling.&apos; These difficulties are not at all pronounced with up to 3 pct Sn, but at 5 pct Sn impose serious limitations and at higher tin contents, especially if the phosphorus content is also high, they may become very severe. In some work carried out at the laboratories of The British Non-Ferrous Metals Research Association it was found that a notable lack of ductility in tension at elevated temperatures, associated with intercrystal-line failure, was characteristic of tin bronzes even of relatively high purity. That the intercrystalline fracture is not due to a brittle or molten impurity phase at the grain boundaries was shown by the fact that the temperature at which intercrystalline fracture first occurred decreased with decrease of rate of straining. Tensile tests on some commercial tin bronzes, reported by Goetzel,² show a similar fall in ductility with increasing temperature. As no visual evidence had been obtained showing that the grain boundaries of the tin bronzes were different from those in copper, a more detailed microscopical examination was carried out, and the results of this are given in the present report. Several workers"&apos; have observed that electrolytic polishing is a powerful tool for detecting small amounts of a second phase and in particular for detecting high solute concentrations, "equilibrium segregation," at grain boundaries. Since it had been found that the suggested solutions for electropolishing bronze and the standard solutions for brass and copper did not give satisfactory results it was first necessary to find a suitable electropolishing solution.&apos; Experimental Procedure Materials Used: The cast and wrought materials used for this work were the same as those used for the mechanical tests referred to above. They comprised 3, 6, and 9 pct Sn alloys without phosphorus and the same three basic alloys with 0.03 and 0.4 pct P. A 5 pct Sn alloy without phosphorus, of similar purity, was also examined. The basis materials were Chempur tin, high purity 15 pct phosphor-copper and cathode copper, and spectrographic analyses are given in Table I. Treatment: The cathode copper was first melted under charcoal, degassed by plunging marble chips beneath the surface, and cast through a coal gas flame into sand molds to produce a number of small ingots which after machining were of a suitable size for subsequent vacuum melting. Chill cast bars of the alloys, approximately 1¼ in. in diameter, were then made by melting and casting in vacuo, the tern-

Jan 1, 1954