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By A. E. Nehrenberg

THE mechanism by which austenite forms in steels has received a great deal of attention in the literature in past years.'-'* Our present knowledge concerning this mechanism has been recently summarized quite concisely by Bain and Vilella,1 while a few years ago the literature was carefully reviewed by Roberts and Mehl.² The consensus is that any ferrite-carbide interface is a potential site for the nucleation of austenite during heating above the Acl temperature, and that the new austenite generally grows freely to produce approximately equiaxed grains, whether the carbides are initially present in the lamellar or the spheroidal form. In the case of eutectoid steels, growth of the new grains of austenite continues until contact is established with other grains. Then growth stops and an initial austenite grain size is established which does not change until the heating is continued to some high temperature at which grain coarsening begins. In the case of pearlitic steels which are not of eutectoid composition, the proeutectoid ferrite or carbide may interfere with the growth of the austenite if the temperature is not above that designated the A63 or the Acm, respectively. Although a large amount of work has been done to establish the mechanism of austenite formation in steels, it became clear to the present author while he was studying the transformation characteristics of a new 0.25 C Mn-Si-Ni-Mo hypoeutectoid steel" that the manner in which austenite grows in steels depends upon some factor, or factors, not previously considered. This was indicated by the fact that when this steel in the spheroidized condition was heated above the Ae1 temperature the new austenite which was formed did not envelop the carbides and grow in an equiaxed manner as described by Bain³ or spheroidized steels. Instead, in this steel, the austenite was observed to grow much more readily in certain directions than in others with the result that at temperatures within the Ac1-Ac³ ransformation range the austenite grains were acicular in shape. The excess ferrite was also found to be acicular with the distribution of these phases being such that a lamellar pattern was developed. This unusual directional growth of austenite in this new steel initially in the spheroidized condition is illustrated by fig. 1. A search of the literature revealed that this type of growth was not necessarily peculiar to this steel for similar microstructures had been observed by other investigators.4-8 However, the full significance of these microstructures does not appear to have been appreciated, and no work has been done to determine the conditions responsible for this directional growth of austenite or to arrive at an understanding of it. It was for this purpose that the work described in the present paper was carried out. Material: During the course of this investigation a total of 15 steels was studied. They consisted of hypoeutectoid, eutectoid and hypereutectoid carbon steels, and hypoeutectoid and hypereutectoid alloy steels, all of which were obtained in the annealed condition from commercial warehouse stock. As received, the carbon and alloy hypereutectoid steels had microstructures which consisted of spheroidal carbides in ferrite, whereas the eutectoid steel and the hypoeutectoid steels were pearlitic. The grades of steel represented were 1050, 1080, 10110, 3310, 4140, 4340, 4615, 6145, 8620, 9260, 9442,

Jan 1, 1951

By H. I. Aaronson, C. Laird

Cold rolling by 50 pct a A1-4 pct Cu alloy containing many 0' plates has been found to accelerate markedly the transformation of 8' to 0 upon further aging. Although the basic mechanism of this transformation remains unchanged by plastic deformation, the nuclea-tion kinetics of 8 become appreciably more rapid and also less dependent upon temperature. Particularly at lower aging temperatures, rounded idiomorphs replace several faceted rnorphologfes. The rates of growth of 9 idiomorphs in deformed specimens aged at 300°C are appreciably more rapid than simple volume diffusion control allows. This observation is shown to be explained by an excess vacancy, rather than by a dislocation Piping mechanism of growth. ThE rather complex phenomenology of the 8' —8 transformation in Al-Cu alloys has been recently elucidated in considerable detail by means of transmission electron microscopy.'-4 This technique was also employed in the present investigation in order to examine the effects of plastic deformation upon the transformation of 8' to 8. The mechanism of the transformation in undeformed Al-Cu alloys has been established as the following sequence of events.1"4 The first step is the nucleation of 9 at (Y:8' boundaries. Nucleation of a 0 crystal takes place, however, at only a very small proportion of the 8' plates present. Each 0 crystal simultaneously consumes the host 8' plate and the a! in the immediate vicinity, with growth into a being the rate-controlling process. The remaining 8' plates are then dissolved as they fall under the concentration shadow of the growing 8 crystals. The evidence on the effects of plastic deformation upon these processes is intriguing, but much less detailed. The careful X-ray studies of Graf and Guinier have shown that the aging times required to form detectable amounts of 8' and 8 are reduced by prior cold working. Thomas and Nutting confirmed these results by replication electron microscopy. Nile-shwar,* on the other hand, reported that creep deformation decreases the rate of formation of 0. While this difference may have been caused by the use of concurrent rather than successive deformation and ag- ing, the X-ray technique which he used was able to monitor only the 0 phase. It is thus possible that the times needed to form 8' were increased moreg than the kinetics of 8' — 8 transformation were accelerated. At 90 pct deformation by cold rolling, Graf and Guinier found that the usual 0' —0 8 sequence is reversed: 0 forms first. von Heimendahl 10 confirmed this result with transmission electron microscopy. Pollard and Nutting, 11 and more recently Driver and Barrand, 9 having used the same technique, report that 9 also forms first during creep deformation. In the present study, the maximum amount of deformation was limited to 50 pct reduction by cold rolling in order to insure that 8 formed principally by the decomposition of . I) EXPERIMENTAL PROCEDURES This investigation was conducted on an Al- 3.93 pct Cu alloy, prepared as previously described. 4 Morphological and crystallographic effects of plastic deformation were studied in specimens annealed 6 hr at 548°C, quenched, and then aged for either 3 or 8 hr at 250°C to form large numbers of 0' plates. After cold rolling to a 50 pct reduction in thickness, the

Jan 1, 1969

By C. A. Bruch, W. E. McHugh, R. W. Hockenbury

EXPERIMENTAL results of the last decade have shown that both accelerator particles and reactor radiations produce significant changes in the properties of metals. These changes, called radiation damage, are important from both academic and engineering viewpoints. An understanding of the radiation damage produced by reactor radiations is difficult, because many kinds of particles having varying energies are present. Therefore, many fundamental studies are being conducted using accelerators in order to obtain nearly mono-energetic beams of various charged particles. Furthermore, many of these experiments are conducted at low temperatures in order to freeze in the radiation-produced lattice defects, after which the specimens are annealed to study the movement of the defects. It is found that although much of the low temperature radiation damage disappears by annealing at room temperature, a significant amount remains. Because there is no assurance that irradiation followed by annealing at a higher temperature will produce the same effect as irradiation at the higher temperature, and because there is an immediate interest in reactor radiation effects during exposures at and above room temperature, a major program is in progress at this laboratory to investigate some of these effects. This paper, representing a part of the program, compares the radiation damage to a group of metals which were exposed under nearly identical irradiation conditions. The metals, representing the three major crystal systems, include copper, nickel, titanium, zirconium, iron, molybdenum, and type 347 stainless steel. The effects of reactor radiations have been treated from a theoretical viewpoint by Seitz' and Ozeroff.' The problem considered by them has been the atomic displacements produced in an infinite medium by mono-energetic beams of both neutrons and charged particles. For reactor experiments, this treatment is not wide enough in scope, because specimens and reactor components are finite, and there are continuous energy spectra of the various particles. Therefore, the theoretical considerations will be extended in this paper to cover reactor conditions and the findings will be compared with the observed radiation damage. Experimental Materials—The six basic metals for this investigation were of commercial or higher purity, and the type 347 stainless steel was of commercial quality. These materials were supplied in various forms ranging from ingots to finished rods, and were fabricated to rods approximately % in. in diam and annealed for specimen stock. A summary of data pertinent to these materials is shown in Table I. The values for chemical compositions include both actual analytical values and typical values supplied by the manufacturer. More information concerning typical

Jan 1, 1957

By H. E. Dunn, C. M. Cosman, J. H. Brennan

Up to the beginning of World War I, the American ferro-alloy industry was in its infancy and largely dependent on Europe. During that War, capacity was over expanded. Later recovery and commercial and scientific development have resulted in an industry which in 1957 produced 1.8 million tons of ferro-alloys. THE ferro-alloy industry is today an important element of the industrial structure of the United States. Its output is valued at almost half a billion dollars annually and its products are basic not only to National defense but also to the peacetime standard of living. This has not always been so. The ferro-alloy industry from late in the last century has grown from small beginnings, nurtured by the demand for stronger, tougher materials; by the search for steels capable of absorbing severe impact loads and resisting corrosive media and high temperatures; and also by the need for electrical and electronic specialties. Conversely, the ferro-alloy industry has grown because it developed improved steels and alloys by extensive research, and because it was able to show to steel makers the advantages accruing from the more extensive and the more economical use of alloying elements. The industry has grown in scope from producing a few grades of ferro-alloys of the more common metals-manganese, chromium, vanadium, silicon, titanium, tungsten, and molybdenum-until there are today some 150 compositions of ferro-alloys available to the steel maker, including such elements as columbium, zirconium, and boron. In 1912 the industry produced 360,000 tons of alloys valued at about $12,000,000, while 1957 production figures show an output of 1.8 million tons worth $440,000,000. In the United States, the history of an industry is largely the history of the companies making up this industry; hence, this paper will briefly trace the development of the most important ferro-alloy-producing companies. Quite varied have been the reasons that caused the different companies to move into the ferro-alloy field; the Willson Aluminum Co., seeking methods of producing aluminum, succeeded with the production of calcium carbide, and their developing electric furnace skills led them to the production of ferro-silicon and ferrochromium alloys. Willson was the predecessor of the Electro Metallurgical Co. of Union Carbide. Two Pittsburgh undertakers, interested in vanadium as an alloying agent for steel, set about to find a mine and, ranging as far as Peru, fathered American Vanadium Co., the predecessor of Vanadium Corp. of America Experiments of the

Jan 1, 1961

By C. M. Young

The following paper has been prepared with the object of placing on record in the Transactions some facts concerning the present condition and future prospects of the coal industry of Illinois. In presenting it, the writer wishes to say that a considerable amount of the material contained is taken from the publications and records of the Illinois Coal Mining Investigations, the annual Coal Report of the State Mining Board, and the work of the State Geological Survey. Coal Beds and Mining Methods According to the latest maps of the State Geological Survey, there are only 19 of the 102 counties of the State some portion of whose territory is not within the borders of the coal measures. If outlying areas in Calhoun and Whiteside Counties are considered, the number is reduced to 17. This does not mean that all of the 85 counties that are partly or wholly underlain by coal measures will become producers, as there are some portions of the State in which the coal does not occur in beds of such thickness as to warrant the hope that it can be mined. The mining of coal is widespread, however, for in 1916 there was production from 61 of the 102 counties of the State, There seem to be no cases in which operations will be limited by depth, as none of the coal measures lie at depths much greater than those at which it has been proved that coal may be profitably mined in this field. In fact, the deepest shaft reaching a bed of bituminous coal in the United States is located in this State at Assumption, where coal only 3 ½ ft. (1.07 m.) thick is worked at a depth of 1004 ft. (306 m.). The coal beds occur in the form of a basin which is deepest along a line extending through the central part of the State and bearing a little west of north. The northern, western and southern borders of this basin lie within the boundaries of the State, but on the eastern side the Illinois field is continuous with the Indiana field. The glacial drift covers all except the extreme southern end of the State and the visible outcropping

Jan 1, 1918

By I. Fatt

A recently developed system for measuring electrical resistivity of liquids without use of electrodes offers some interesting possibilities in electric logging technology. The equipment as supplied by the manufacturer is satisfactory for continuous mud logging on a drilling rig or for measuring mud or filtrate resistivity in the laboratory. A simple modification of the commercially available instrument makes it suitable for measuring resistivity of core samples in the laboratory. The continuous measurement of mud resistivity on a drilling rig is a convenient means for detecting mixing of formation water with the drilling mud. Such information is useful to the geologist, the mud engineer and the logging engineer. However, continuous mud resistivity logging by conventional electrode-type resistivity cells is beset with difficulties. The mud, sand and rock chips abrade the electrodes, thereby changing the cell constant and eventually destroying the cell. Also, additives and crude oil in the mud may poison the electrodes by coating them with a nonconductive material. An electrode-type resistivity cell. therefore, may give erroneous readings under certain conditions. Electric logging companies circumvent the electrode poisoning problem by using a four-electrode resistivity cell for measurement of mud resistivity. In this cell, change in electrode area does not change the cell constant. However, the four-electrode cell is difficult to adapt for continuous reading and does not solve completely the problem of electrode abrasion by the sand and cuttings in the mud. The measurement of electric logging parameters on core samples in the laboratory encounters some of the same problems discussed in connection with mud logging. Ideally, the electrical resistivity of a core sample should be measured by placing platinum black electrodes in direct contact with the plane ends of a cylindrical or rectangular sample. Platinum black electrodes however, are much too fragile and easily abraded to be brought in contact with a rock sample. Also, oil or other constituents in the fluid contained in the sample will poison platinum black. In practice, gold-plated brass electrodes, in an AC bridge circuit operating at about 1,000 cps, are used for routine core analysis. For more precise work in research studies, a four-electrode scheme is used.',' Preparation of the samples for the four-electrode method is much too involved for routine core analysis. An apparatus for measuring resistivity of liquids without use of electrodes was described by Guthrie and Boys3 in 1879. They suspended a beaker, containing the electrolyte, by a torsion wire and rotated a set of permanent bar magnets around the vessel. The eddy currents induced in the electrolyte reacted against the rotating magnetic field to develop a torque, which was measured as a deflection of the torsion wire. In 1879 this method could not be made precise or convenient because of the lack of strong permanent magnets. The writer described a very greatly improved apparatus similar to that of Guthrie and Boys, but it was not suitable for continuous measurements or core samples.' Many electrodeless resistivity devices using radio frequency current are described in the literature.5, 6 These generally are suitable only for noting the end-point in a chemical titration. They do not measure resistivity, instead measuring a complex quantity which includes the dielectric constant and the magnetic permeability. The first description of the apparatus to be discussed in this paper was given by Relis.7 Improvements and modifications are described by Fielden,s Gupta and Hills,> and Eichholz and Bettens.10 DESCRIPTION OF APPARATUS The apparatus used in this study is based on the principle that the solution under measurement can form a loop coupling two transformer coils, as shown in Fig. 1. For a fixed AC voltage applied across Coil A, the voltage appearing across Coil B is a function of the resistance of the liquid-filled loop. The details of the voltage generating and measuring circuits are given in Refs. 7, 8, 9 and 10. A block diagram of the equipment is given in Fig. 7. Special features worth mentioning are the operating frequency of 18,000 cps and the automatic temperature compensation which results in the given resistivity readings being automatically correlated to 25°C. The liquid loop supplied by the manufacturer, shown in Figs. 1 and 2, was modified for use in core analysis (Fig. 3). The core sample under test is substituted for a section of the original loop. As shown in Fig. 3, the unit accepts only plastic-mounted cylindrical core specimens. A Hassler-type sleeve easily can be designed for the unit if unmounted cores are to be measured. EXPERIMENTAL PROCEDURE MUD LOGGING A simulated mud line was set up in the laboratory.

By R. C. Beckstrom

Russia's first "Petaletka'' has ended. Technically it did not succeed but practically it has been a great achievement in the petroleum industry. Out of the chaos of revolution and civil war Russia has developed her oil industry to second place in the world's production. For 1932 production of crude oil is estimated at 150,000,000 bbl. and refined products at 145,000,000 barrels. Russia has been able to give the petroleum industry every advantage that a government can extend to a fast growing industry. She has obtained all of her property by confiscation. Under government ownership, operation and control, her petroleum industry is not handicapped in any way by state rulings or by unnecessary competition in production, refining and marketing. There are no damage suits resulting from offsetting, flooding, repressuring, laying of pipe lines, building of docks or other necessary work. Russian oil fields2 have been easy to develop and operate. They lie advantageously to transportation for foreign markets. The chief disadvantages have been a lack of credit and technical cooperation, but the former is being overcome by the sacrifice of the people. They go without the comforts of life that all salable articles may be exported for the imports of modern machinery. Modern machinery is fast replacing the obsolete and worn-out equipment. Technical cooperation has been difficult because it has been necessary to train thousands of adults to do technical and mechanical work. Great quantities of pipe, tools and electrical equipment were necessary for the rapidly developing fields and refineries. The supplies have been inadequate and the quality poor. This lack of equipment, along with the untrained technical supervision, has been the cause of the proposed quota falling short. Fig. 1 shows the production for 1931 and 1932. During 1932 a large percentage of the oil was produced in the proven fields of the Caucasus.

Jan 1, 1933

By Arthur J. Boynton

In the preparation of this paper the writer has been influenced by the fact that descriptions of various means of cleaning blast-furnace gas have been published and that further descriptive treatment of the subject will probably be less interesting than a statement of conclusions with regard to preferable methods which have been reached by him as a result of experience and observation in this country and also as a result of somewhat detailed investigation of the subject made toward the end of the year 1927 on the Continent of Europe and particularly in Germany. Owing to various circumstances, including a cost of fuel that is extremely high in relation to the wages of labor, the German iron and steel industry has accumulated experience in gas washing which is as yet in part lacking in the United States of America. The paper begins with a statement regarding the economics of the use of blast-furnace gas, then considers the principles and practices employed in its purification. Uses of Blast-furnace Gas For many reasons having to do with the utilization of coke-oven and blast-furnace gases in steel manufacture and with the use of hot metal, the blast furnace is now usually a part of a steel-producing unit, which also includes coke plant and rolling mill. Therefore both blast-furnace and coke-oven gas are usually applicable to any of the iron and steel-making processes, including the generation of power, and their allocation in any given works should be considered as a single problem. The uses to which blast-furnace gas, either alone or mixed with coke-oven gas may be put, include the following: Regenerative Heating of Ail. for the Blast Furnace.—This is the oldest and metallurgically the rnost important of all uses. It is universally performed with unmixed blast-furnace gas and under proper conditions should require not over 23.5 per cent. of the total gas generated for a blast temperature of 1350" F. For Steam-raising Purposes.—This is almost universally done with unmixed blast-furnace gas. From the standpoint of quantity used, it is at the present time the most important application in American steelworks practice.

By H. M. Chance

Jan 1, 1887

By Archer E., Wheeler

COPPER operations in the Congo mean the operations of the Union Miniere du Haut Katanga, because there are no other copper industries there. There is a mine at Bwana M'Kubwa, a little way to the South, in Rhodesia, which has been operated on a small scale, and-another farther south, the Falcon mine, but in quite a different section of the country. This Bwana M'Kubwa mine has recently been reorganized financially and the Minerals Separation interests have taken an extensive share in it, so that it may come into operation. The Union Miniere's operations are in Katanga, the most southeastern province of the Belgian Congo, and the company's concession is in the southeastern part of that province. The usual route for going into the country is by way of Cape Town, thence over the South African Railways through Kimberly and Mafe- king to Bulawayo, then by the Beira, Mashonland and Rhodesia Railways to the Rhodesia-Congo border, passing Victoria Falls on the way, and finally by the Belgian road, the Chemin de Fer du Katanga, to Elisa- bethville, the African headquarters of the company. From Cape Town to the border it is about 2150 mi. and from the border to Elisabethville about 158 mi., making a little over 2300 mi. from Cape Town, by rail.

Jan 1, 1924

By E. S. Machlin

An extension of the thermodynamic theory has been made for the case of irreversible growth processes occurring by the motion of an interface. The theory is applicable to such diverse phenomena as diffusion, growth in recrystallization, continuous grain growth, growth of carbides, etc., growth of eutectoid products, growth in solidification, recovery, "slipless" flow, etc. THE publication of a recent book1 has served to focus attention on a very powerful means of treating certain irreversible processes. This method which has been formally described as the thermodynamic theory of irreversible processes is applicable to processes which involve an approach to equilibrium and for which the deviations from equilibrium are small. The irreversible processes can be classified into three groups: chemical reactions, transport processes (diffusion, heat and electrical flows), and relaxation phenomena involving a degradation of internal energy to more stable states. The limits of applicability of the theory can be precisely defined1,2 for each type of irreversible process. For example, in a chemical reaction at constant temperature and pressure, the Gibbs free energy released per mol in the process should be less than the thermal energy, RT. Another type of irreversible process, which sometimes involves a combination of the first two of the above-mentioned groups, is treated in this paper. This process is one characterized by the motion of an interface separating two regions having different values of free energy and may be briefly described as a growth process. Prigogine2 and Herring3 have treated special cases of this type of process. Previous conscious applications of the theory in metallurgy have been limited to the field of diffusion, one of the transport processes. Darken,4 Bardeen,5 Prigogine2 and others have made significant contributions in this respect. Some other applications of the theory are described in this paper. The Theory The thermodynamic theory of irreversible processes is based on the work of Onsager,6 DeDonder,7 Prigogine2 and others. A resume of the theory has been given by Prigogine2 and DeGroot.1 A brief description of the theory follows, although for a complete understanding the reader is urged to read the references. It is first assumed that the change in entropy, even for a system removed from equilibrium, is given by dS = [dU + pdV - Si µi, dn, - Sk Pk dxk]T-1 Using this expression, the irreversible entropy production in the system is calculated by subtracting the contribution to the change in entropy of the system by transfer of heat, work, or matter from the surroundings. Thus, for example, the irreversible entropy production of a system at constant temperature and pressure is given by dtS = — — dG (DeDonder7) Now it has been shown by Prigogine,2 DeDonder,7 and DeGroot1 that the rate of irreversible entropy production diS/dt, when calculated in the manner suggested, can be written as a sum of products of conjugate forces XK and fluxes Jk, i.e., d,s/ = Sk Jk Xk [I-1] dt The assumption is next made that a linear relation exists between a given flux and the forces, obtained from Eq. I-1, i.e., Ji = Sk Lik Xk (i = 1, 2, . . . n) [I-2] Generally, there is a degree of freedom in choice of the fluxes and forces. However, for all the choices consistent with Eq. I-1 the Onsager8 relations, based on the principle of microscopic reversibility, namely, Lik = Lki, are valid. The coefficients Lik, depending upon the choice of the conjugate fluxes and forces, may be more or less dependent upon the parameters defining the state of the system. In general, the proper choice of fluxes and forces utilizing Eq. I-1, makes the coefficients Lik independent of time. Also, because many of the three classes of irreversible phenomena have already been treated,1,2 a proper choice can be made by analogy. In any case, the validity of Eq. 1-2, from whatever choice made using Eq. I-1, must be tested by experimentation. The theory, thus, comprises the following steps: 1—The irreversible entropy production is calculated to yield Eq. I-1. 2—The terms in Eq. I-1 are grouped

Jan 1, 1954

By T. L. Chu, G. A. Gruber

Silica films hare been rleposited 011 silicon substmtes at 400° to 600°C by a chemical-transport technique using hydrogen fluoride as the transport agent ill a closed system. This transport takes place from a source materia1 1071: temperature to substrates at higher temperatures, as indicated by the thermochemistry of the transport reaction. The experimental variables of- the transport process, such as the substrate temperature, the pressure pi the transport agent, and so forth, have been studied. The rate -determining step of the transport process appears to he the ),ale of chemical reaction in the source region. The transported films are similar to thermally grown silica films in physical proper-ties with the exception of 'some what higher dissolrrtion rates. SILICA films deposited on suitable substrates serve many purposes in electronic devices. They are used for the fabrication of tunneling devices, the surface passivation of devices, and the shielding of devices from nuclear radiation: and as selective masks against the diffusion of specific impurities into semiconductors. Doped silica films can also be used as sources for the diffusion of impurities into semiconductors. Several oxidation and deposition techniques for the preparation of silica films have been developed to meet the requirements of these applications. The therma1 oxidation of silicon by oxygen or steam at temperatures above 900 C is commonly used in silicon technology. The deposition techniques are perhaps more advantageous since they usually require lower temperatures and are not limited to silicon substrates. Silica films have been deposited on silicon and other substrates by reactive sputtering and chemical reactions. The sputtering of silicon in an oxygen atmosphere is capable of depositing good-quality silica films on silicon' and gallium arenide. Many chemical reactions are known to yield silica at room temperature or higher. These reactions may involve intermediate steps. However, the final step yielding silica should take place predominately on the substrate surface in order to produce adherent films. When silica is formed in the gas phase by volume reactions, no adherent deposit can be obtained. Generally, the experimental conditions of a reaction can be varied so that the surface reaction predominates over the volume reaction. The chemical reactions which have been used successfully for the deposition of silica films are briefly as follows. The pyrolysis of alkoxysilanes in an inert atmosphere or under reduced pressure has been employed to deposit silica films on germanium3 and silicon4 at 650" to 750°C in a flow system. The deposition of silica films from alkoxysilanes has also been achieved at nearly room temperature by a low-pressure plasma. Device quality silica films have been deposited on germanium and gallium arsenide by the deposition of an amorphous thin silicon film followed by oxidation at 600" to 700" . Silica films for high-temperature capacitors have been produced by the hydrolysis of silicon tetrabromide at 950°C in argon and hydrogen atmospheres.7 We have developed a chemical-transport technique for the deposition of silica films on semiconductor substrates at relatively low temperatures. The thermochemistry of the transport reaction, the experimental variables of the transport process, and the properties of the transported silica films are described in this paper. THERMOCHEMICAL CONSDERATIONS The transport of solid substances by chemical reactions in the presence of a temperature gradient has been used for the preparation of films and crystals of many electronic materials. In this technique, a gaseous reagent is chosen so that it reacts reversibly with the solid substance under consideration to form volatile products. Since the equilibrium constants of most reactions are temperature-dependent, the transport of these products to regions of suitable temperature in the reaction system would cause the reverse reaction to take place. depositing the original solid. When the equilibrium is shifted toward the formation of the solid as the temperature is decreased, the solid is transported from a high-temperature zone to a lower-temperature region, and vice versa. This chemical-transport technique can be carried out in a closed or gas-flow system. In a closed system, chemical equilibrium is presumably established in the different temperature regions of the system, and the transport agent regenerated in the deposition region repeats the transport process in a cyclic manner. The local chemical equilibrium may not be approached in a flow system: however, this system offers a greater degree of flexibility. Silica reacts reversibly with hydrogen fluoride and this reaction was chosen for the transport process. The over-all reaction between silica and hydrogen fluoride may be written as: SiO2(s) + 4HF(g-) = SiF4Ur) + 2H2O(^)

Jan 1, 1965

By J. B. Ackerman, J. D. Miller

Alunite [KA13(S04)2(OH)6] is a promising non-bauxitic aluminum resource, the domestic reserves of which are estimated to be 800 x 106 tons at 35 percent alunite. The major gangue mineral associated with alunite is quartz. The thermochemical process that has been developed for treatment of this ore does not provide for the initial removal of gangue prior to processing. In this regard, it may be desirable to concentrate the ore to gain significant technical and economic advantages. Experimental results indicate the effectiveness of an oleic acid flotation technique and exemplify the problems encountered in fine particles processing. These results show that the quality of separation studied as a function of temperature, collector addition, and depressant addition is dependent on the degree of liberation achieved during size reduction. At coarse grinds the quality of separation was limited by the presence of locked particles while for finer grinds where more extensive liberation is achieved, better separations were obtained. The degree of liberation for each size interval was determined by an SEM/energy dispersive x-ray technique and found to be independent of the extent of size reduction, suggesting that liberation occurs by indiscriminate fracture and not by detachment. Up to 89 percent liberation was realized for a minus 400 mesh grind. Under these circumstances, the quality of separation appears not only to be limited by the remaining locked particles, but, also, by contamination of the alunite concentrate with fine quartz gangue (< 2µm). The best separation for the minus 400 mesh grind was a rougher recovery of 88 percent with a grade of 65% alunite at 50°C.

Jan 1, 1980

By Oliver B. Hopkins

During the year 1936, a new high record was established for Peruvian production, the total amounting to 17,594,689 bbl., which brought the cumulative production of the country up to 205 million barrels. The 1936 figure represents an increase of 530,288 bbl. over that of 1935. The property of the International Petroleum Co. contributed 369,577 bbl. of this increase and the Lobitos property 158,233. Exploration work in the country was continued. The Selden Breck Co. examined a strip of the National Reserve in eastern Peru from Tambo del Sur to the Rio Pachitea. This company was granted a concession for a term of four years embracing approximately 50,000 acres near the confluence of the Rio Pachitea and the Rio Ucayali. During the year, the Peruvian Government commenced drilling a well on one of the reserved zones at Zorritos. At the end of the year, this well had reached a depth of 1300 feet. La Rrea-Parinas Estate.—Production on the La Brea-Parinas Estate of the International Petroleum Company, Ltd., reached an all-time high in 1936 of 15,126,491 bbl., an increase of 369,577 bbl. over the 1935 record. The total production from 1890 to 1936 was 163,668,014 barrels.

Jan 1, 1937

Jan 1, 1884

By John D. Sullivan, Chester R. Austin, Edwin J. Rogers

The problem of making a building unit combining the necessary physical and mechanical properties and good thermal insulation has been foremost in the minds of architects and ceramic and construction engineers for many years. This paper presents the results of studies on thermally expanding shales or clays to produce lightweight cellular products suitable for making building units. An expanded clay block suitable for building purposes should be large enough qo that substantial savings may be effected in labor costs in laying the wall. The permeability should be low and it should have sufficiently good "dry-wall" characteristics to permit exposing the exterior surface to the elements, and to permit plastering directly the inside wall surface. The thermal conductivity should be low and the mechanical properties should be adequate. Obviously, a unit possessing satisfactory qualities for constructing an - outside wall would be satisfactory for interior walls and for back-up purposes. The results of studies on bloating various shales or clays† and the properties of the expanded products are reported. In another paper1 basic factors involved in bloating of clays are discussed. Manufacturers of ceramic products, partitularly structural clay, may encounter bloating of the ware during burning, and precautions must be followed to avoid this phenomenon. About 1927 the C. F. Burgess Laboratories, Madison, Wis., while carrying on an investigation for the American Face Brick Research Corporation, conceived the idea of intentionally bloating clay while holding it in a restrained condition, with the hope of producing a unitary cellular mass. Work was carried on until about 1931, when studies were terminated because of business conditions. These studies were continued later by The Western Brick Co., Danville, Ill., which developed a process of "inwardly expansive bloating."² The major purpose of the latter investigation was to produce back-up tile to compete with concrete blocks made from Haydite or cinder aggregate. Haydite is a light-weight aggregate formed by heating certain clays or shales rapidly in a rotary kiln. While the investigations at the C. F. Burgess Laboratories or at Western Brick Co. were not carried far enough to lead to the commercial production of material for the construction of walls, particularly outside walls, they showed that certain clays could be thermally expanded and that it was possible to produce a material of low permeability with a large percentage of the total voids or cells closed. commencing in 1939, the Ozark Chemical Co. sponsored a research program at Battelle Memorial Institute for the Purpose Of determining whether it is technically feasible to make thermally expanded building units, and specifically to get answers to the following questions:

Jan 1, 1942

By John D. Sullivan, Edwin J. Rogers, Chester R. Austin

The problem of making a building unit combining the necessary physical and mechanical properties and good thermal insulation has been foremost in the minds of architects and ceramic and construction engineers for many years. This paper presents the results of studies on thermally expanding shales or clays to produce lightweight cellular products suitable for making building units. An expanded clay block suitable for building purposes should be large enough qo that substantial savings may be effected in labor costs in laying the wall. The permeability should be low and it should have sufficiently good "dry-wall" characteristics to permit exposing the exterior surface to the elements, and to permit plastering directly the inside wall surface. The thermal conductivity should be low and the mechanical properties should be adequate. Obviously, a unit possessing satisfactory qualities for constructing an - outside wall would be satisfactory for interior walls and for back-up purposes. The results of studies on bloating various shales or clays† and the properties of the expanded products are reported. In another paper1 basic factors involved in bloating of clays are discussed. Manufacturers of ceramic products, partitularly structural clay, may encounter bloating of the ware during burning, and precautions must be followed to avoid this phenomenon. About 1927 the C. F. Burgess Laboratories, Madison, Wis., while carrying on an investigation for the American Face Brick Research Corporation, conceived the idea of intentionally bloating clay while holding it in a restrained condition, with the hope of producing a unitary cellular mass. Work was carried on until about 1931, when studies were terminated because of business conditions. These studies were continued later by The Western Brick Co., Danville, Ill., which developed a process of "inwardly expansive bloating."² The major purpose of the latter investigation was to produce back-up tile to compete with concrete blocks made from Haydite or cinder aggregate. Haydite is a light-weight aggregate formed by heating certain clays or shales rapidly in a rotary kiln. While the investigations at the C. F. Burgess Laboratories or at Western Brick Co. were not carried far enough to lead to the commercial production of material for the construction of walls, particularly outside walls, they showed that certain clays could be thermally expanded and that it was possible to produce a material of low permeability with a large percentage of the total voids or cells closed. commencing in 1939, the Ozark Chemical Co. sponsored a research program at Battelle Memorial Institute for the Purpose Of determining whether it is technically feasible to make thermally expanded building units, and specifically to get answers to the following questions:

Jan 1, 1942

By L. D. Jaffe

IN previous metallographic work on titanium and its alloys, difficulty has been encountered in distinguishing spheroidal particles of titanium hydride, dispersed in a-titanium, from other phases that may be present, such as p-titanium. This problem is common in examination of commercial unalloyed titanium.&apos; In the course of an investigation of the Ti-H phase diagram, it was noted that titanium hydride, dispersed in a matrix of a-titanium, showed strong optical anisotropy when examined under polarized light. With sensitive tint illumination, particles of the hydride, when the stage is rotated, changed from bright yellow to bright blue in color. Since P-titanium is cubic, it showed no color change on rotation, remaining dark gray or blue-gray. Although a-titanium is hexagonal, it showed only a minor color change, going from pale pinkish-blue to pale purplish-blue. These colors could be modified somewhat by adjustment of the illumination. They were observed in specimens mechanically polished, both without etching and after etching with hydrofluoric acid-nitric acid mixtures in either water or glycerine. The strong color change of the hydride seems to offer a simple method for its metallographic identification. Optical anisotropy of titanium hydride is inconsistent with its accepted face-centered-cubic structure.&apos; Samples of iodide titanium containing 6 to 40 atomic pct deuterium were prepared for diffraction studies. After deuterating and slow cooling&apos; the samples were held 21 % hr at 400 °C, water quenched, held 61 hr at 100°C and quenched, then held 64% hr at 255 C and quenched. Debye ex-posures with MoKa X-rays and 1.111A neutrons were made at room temperature of samples as-deuterated and after the 100" and 255°C treatments. Table I shows the lines observed, in addition to those attributable to a-titanium. These data show that the hydride phase was not cubic, but probably tetragonal. The titanium atoms appeared to form a body-centered-tetragonal lattice complex, two titanium atoms per cell, with approximate dimensions: a = 3.12A, c = 4.18A, and c/a =1.34A. This is equivalent to a face-centered-tetragonal complex, four titanium atoms per cell, with approximate dimensions: a = 4.42A, c = 4.18A, and c/a - 0.946A. The presence of the 2.98 and 1.81A neutron lines indicates that the true Bravais lattice is not identical with this lattice complex, but may be primitive tetragonal with dimensions some multiple of those of the complex. The relative intensities of the hydride and a-titanium X-ray lines as functions of overall composition indicated that the hydride, presumably in equilibrium with the a at 100" to 255"C, contained more than 62 atomic pct H. Acknowledgments The experimental work covered in this report was done at Brookhaven National Laboratory, through the courtesy of D. Gurinsky. The cooperation of J. Sadofsky, 0. Kammerer, A. McReynolds, and A. Cendrowski is gratefully acknowledged.

Jan 1, 1957

By L. R. Smith

BUTANE OPERATED drilling rigs are a recent innovation in the petroleum industry, so extensive data on their operation are not available. However, experience indicates that, within limitations, as much can he accomplished with butane as with steam, at a decided reduction .in expense of installation and cost of operation. Commercial butane is a liquid motor fuel similar to gasoline, but much more volatile, so that it has to be stored under pressure. At 10° F. it is liquid at atmospheric pressure, but at 100° it has a pressure of 70 lb. or more. As soon as the pressure is reduced, it turns to vapor and in that state is far more easily mixed with the air necessary for combustion. Butane occurs as a by-product in the absorption process of natural gasoline extraction from casing-head gas. The product has been used to some extent 10 raise the octane value of gasoline. However, because of its volatile nature, such admixture is stable only to a limited degree. Attempts also have been made to introduce the product in a gaseous form into oil- hearing formations in repressuring work. It has, however, until recently, for the most part been wasted.

Jan 1, 1937

By Winthrop P. Haynes

The symposium on production for the year 1943 contains few papers on the foreign situation. It has always been the policy of officers in charge of the symposium to refrain from publishing information that might possibly injure national or private interests. At the close of the war we hope again to publish full and accurate records of production abroad. A noteworthy feature of the reports on Texas this year is the map on page 469, which shows the districts covered by the statistics. Excerpts from Circular to Authors In order to facilitate interpretation of the data in this chapter, we print the following excerpts from the Circular to Authors. The field is the unit in this tabulation. In cases of fields extending across State boundaries, such as Rodessa, it is suggested that each State author treat the section of the field in his State as a unit, and by a footnote indicate that the field extends into an adjacent State. Each place in the table may represent one of three possibilities; either the proper entry is determinable and can be supplied by the author, or an approximate figure can be supplied which is the author&apos;s best guess and should be entered followed by an x, or it does not apply to the particular field and the space is left blank. Contributions of great value may be made by the author in many cases where entries are not subject to precise determina-tion. In such cases the author should use his good judgment and make the best entry possible under the circumstances. The entry of a zero is a positive declaration, and it is an important declaration where it is in order. It is thought that the nearest whole numbers are suficiently accurate for our purposes except as to percentage of sulphur in oil. If an author desires to report any other figures to tenths, he may do so. The quantity of gas produced should include, where possible, gas sold or otherwise marketed, and gas blown into the air, burned as flares or otherwise wasted. Segregation of these figures would be interesting if the authors can make such segregation. In any event, the figures should represent as nearly as possible the total quantity of gas removed from the reservoir. Under the columns on &apos;&apos;Depth," the average depth to the top of the productive zones and to the bottom of the productive wells, when subtracted, should give the approximate thickness of the productive zone. For fields where this is not true because of unusually high dip or for some other reasons, it is suggested that the authors indicate in their text the approximate average thickness of the productive zone. The net thickness of the producing formation should be the thickness of the producing zone, less the estimated amount to cover the portions of the zone that do not yield oil, such as dense shales, etc. It is recognized that for some fields the authors can only make rough guesses; in such cases, they should enter their best estimate followed by an x. Average production per acre-foot need not be reported as it can be calculated by those interested from the figures given. In classifying wells as to producing methods, enter all wells that are not "flowing" in the column headed "Artificial Lift." If possible, add footnotes to indicate whether the lift is "pumping," "gas lift" or "air lift."

Jan 1, 1944