Search Documents

By Hugh H. Waesche

Of all the military services, the Signal Corps is the most concerned with piezoelectric minerals because of its function as a supply service to the strategic and tactical military forces. Consequently this paper is written from the point of view of one associated with that organization. The Signal Corps is responsible for the research, development, and supply of communications, radar, and components to the using services of the Department of the Army and to some extent the Other branches of the National Defense Department. Their work therefore includes the study of the sources* characteristics, and application of quartz and other piezoelectric materials. These materials have become a vital consideration in strategic planning and are essential for efficient tactical operation by all the Armed Forces. The Signal Corps at the beginning of world War 11 Was respon-sible for both Army Ground and Air Force electronic equipment. Since that time this Army service organization has probably done more in the development of frequency control devices using piezoelectric materials than any other group. The U.S. Department of the Interior, Bureau of Mines, Minerals yearbook of 1945, shows that during the four war years, 1942 through 1945, 9,598,-410 Ib of quartz crystal were imported for all uses and of this total, 5,168,000 lb were consumed to produce 78,320,-000 crystal units for electronic application. Other government records confirm these data which conclusively show that approximately 53 pct of the crystalline quartz imported was consumed in the production of electronically applied quartz crystal units. It may be assumed that some effort was made to maintain a stockpile over demands for all purposes. and this would mean that the actual percentage of quartz used electronically was considerably over the 53 pct figure. These data only emphasize that electronic application of crystalline quartz was the greatest requirement, and per- haps the actual value in this application to national defense is many times greater in importance than is apparent on first inspection. Current electronic research and development programs of the Armed Forces are planned around the fundamental use of piezoelectric minerals for frequency control and this at present, at least, means quartz. Definition and Early Development The word piezoelectricity is formed from combination of the Greek word "piezein". meaning "to press," and "electricity." It is that property shown by numerous crystalline substances whereby electrical charges of equal and opposite value are produced on certain surfaces when the crystal is subjected to mechanical stress. It appears to be intimately associated with the better known property, pyro-electricity and in fact, the two may be manifestations of the same phenomeuon. This property was discovered by Pierre and Jacques Curie in quartz, tourmaline, and other minerals in 1880 while studying the symmetry of crystals. The converse effect, that is, mechanical strain in the crystal when placed in an electrical field, was predicted by the French physicist, G. Lippman, in 1881, and verified by the Curies almost immediately. As has been the case with many discoveries of similar character in the basic sciences, not much attention was paid to this property for man)- years except as an entertaining curiosity. Between 1890 and 1892 a series of papers was published by W. voigt in which the theoretical physical properties were put into mathematical form. The first practical application of piezoelectricity occurred during World War I when professor P. Langevin of France used quartz mosaics to produce underwater sound waves. The same mosaics were used to pick up the sound reflections from submerged objects which were in turn, amplified by electronic means and used to determine the distances to such objects. This device was intended for use as a submarine detector but development was not completed in time for war service although it was used later for determining ocean depths. About the same time, A. M. Nicholson, of Bell Telephone Laboratories, developed microphones and phonograph pickups using Rochelle salt crystals. A major step in the application of piezoelectric quartz came in 1921, when professor W. G. Cady, of wesleyan university, showed that a radio oscillator could be controlled by a quartz crystal; from that date, this use of quartz has increased steadily, reaching its peak in world war 11 as is shown by the figures previously given. Essentially all American electronic equipment for communication, navigation, and radar, utilized quartz crystals for the exacting frequency control required. Crystalline Minerals with piezoelectric Properties QUARTZ Hundreds of piezoelectric crystalline materials are known, most of which are water soluble. Of these, quartz appears to be without a peer for electronic frequency control. Unfortunately, the quartz must be of superior quality. It must be free of mechanical flaws, essen-tially optically clear, free of both Brazil and Dauphiné twinning and must be, for average uses, over 100 g in weight. Because of these stringent requirements, raw quartz of the quality desired is of rare occurrence. In addition to quartz, several other naturally occurring crystalline materials are known to have the piezoelectric property and could perhaps be substituted for quartz in some applications. These

Jan 1, 1950

By William R. Webster

The unusual interest taken in the papers on steel at the New York (1922) meeting showed that the time is ripe for the renewal of the general discussion of the physics of steel, on the same lines that wete used formerly and produced such good and lasting results. The curves shown in Figs. 1 to 4 and the appendix were added to my paper1 after the February meeting, but, unfortunately, Figs. 1 and 3 were transposed; the curves on page 252 are for bessemer steel and belong on page 254; while those on page 254 are for open-hearth steel and belong on page 252. These errors are evident at once on referring to the data in Tables 1 and 2, pages 227 and 228. The curves for each 0.05 per cent. of carbon and manganese in basic open-hearth steel are given in Figs. 1 and 2; these lines for the lower carbons and manganese are comparatively uniform. Figs. 3 and 4 give similar lines for carbon and manganese in bessemer steel. The large break in the carbon lines from 0.55 per cent. to 0.60 per cent. is caused by much higher silicon in the steels of 0.60 per cent, carbon and over that are used for springs, etc. The estimated ultimate strength of pure iron, and the increase in strength by carbon, phosphorus, and manganese, with the different views regarding the same, were given and diseussed. All of this can be considered as an introduction to the practical use that is now being made of such data in selecting the heats of steel best suited to give the required physical tests called for in the finished rolled material. The chemical composition of the steel, of course, tells only a part of the story, as many other factors that have an influence on the physical properties of the steel must be considered, and controlled as far as is possible. Some of these have already been referred to, but there are other important ones to be considered and discussed.

Jan 1, 1923

Jan 1, 1930

By W. L. Fink, L. A. Willey

During the war there was introduced a new higher strength aircraft alloy designated 75S.1,2,3 The properties of this alloy assure extensive applications in both military and commercial aircraft. It is therefore important to understand its limitations as well as advantages. The properties of 75.5 alloy in the heat-treated tempers, like those of many other aluminum alloys, are affected by the rate of quenching. In general, low quenching rates tend to cause low strengths and to adversely affect the resistance to corrosion. Commercial quenching procedures are usually sufficiently rapid to permit the development of maximum properties. However, in the center of heavy sections, such as large rolled and extruded shapes, the quenching rates may not be rapid enough to develop maximum strength or resistance to corrosion. The investigations of 75s alloy described herein reveal the most critical range of temperature and the effects of quenching sheet and extrusions at different rates through that temperature range, on the tensile properties and resistance to corrosion. Procedure Preparation of Specimens Sheet specimens (3 in. by 9 in.) were prepared from a commercial lot of 75s "as rolled" sheet (0.064 in. thick). The composition4 was as follows: Weight Percentage Cu Mn Mg Zn Cr A1 with Normal Impurities 1.64 0.16 2.58 5.66 0.27 Remainder The specimens employed for the determination of the time-temperature relations during quenching of sheet were prepared by the following procedure: the hot junction of a 28-ga. iron-constantan thermoelement (asbestos insulated) was brazed to a thin strip of aluminum which was in turn brazed into the end of a 3/16-in. id by %-in. od by 30 in. long aluminum protection tube. Before brazing, the tube was flattened to 0.064-in. thickness over the junction and adjacent lead wires for a distance of I 1/2 in. The flattened end of the tube was fitted into a slot cut from one edge to the center of the 3-in. by 9-in. by 0.064-in. sheet and brazed into place. The brazed joint was dressed to the thickness of the sheet and the entire specimen buffed to approximately the brightness of "as rolled" material. Because of the brazing operations required, these specimens were prepared using 3S alloy. For the investigation of quenching rates in heavy sections, there were used 75s extrusions which had compositions similar to that of the sheet. The specimens consisted of 14 in. lengths of 3i-in., 2-in., 3-in, and 4-in. diam cylindrical rods and a roughly rectangular extruded section which was approximately 4 in. by 7 1/2 in. Thcrmocouple~ were peened into the bottoms Of .1/8-in. diam wells drilled into one end and parallel to the axis to a depth of

Jan 1, 1949

By J. B. Clark, F. N. Rhines

brittlement or notch sensitivity progressively increases. Further, in contrast to results obtained with the impact test, the notch strength for the large specimens does not reveal a 500°F embrittlement range. The notch sensitivity as determined with the 0.3-in. specimen of 4340 steel given the stepped austenitizing treatment has been discussed elsewhere. This quantity as measured for the 1.1-in.- diam notch tensile test and given in Fig. 3, is taken to signify that reduced notch sensitivity is encountered in the 600" to 800°F tempering range for specimens given the stepped austenitizing treatment. The stepped austenitizing treatment may, there- fore, be of use in promoting deeper hardenability for a 4340 steel while at the same time giving reduced notch sensitivity in the high-strength range in which this steel is now being used. Acknowledgments The work reported was supported by the U. S. Navy Bureau of Aeronautics. The authors are indebted to the Bureau of Aeronautics for granting permission to publish results of this research and to N. E. Promisel, H. Hessing, and J. Maltz for their interest.

Jan 1, 1958

By R. W. Heckel

A method is described whereby the relationship of both the "at-pressure" powder compact density and the "zero-pressure" compact density to the applied pressure may be obtained from continuous measurements of punch movement during a single compaction operation. The rate of density increase with applied pressure for the metal powders is found to be proportional to the volume fraction of pores for pressures exceeding a lower limit which varies from 15,000 to 30,000 psi, depending on the powder. 1 HE compaction of powdered materials is carried out primarily to increase the density of the material. If the ultimate goal of the over-all process is the attainment of minimum porosity, compaction is responsible for most of the densification. For example, loose powdered metals have porosities of about 65 to 75 pct. Axial loading in a die or hydrostatic pressure may effectively reduce the porosity of most powders to 20 pct or lower with pressures of 50,000 psi and greater. The relationship between the density of a powder compact and the pressure needed to achieve that density is most commonly obtained by pressing several compacts, each at a different pressure. Measurement of the densities of the individual compacts when they are removed from the die then provides the density-pressure relationship. However, this method suffers from several disadvantages. Because a large number of compacts and pressing operations are required, it is inherently slow. Furthermore, since density measurements are made after the specimens are removed from the die, data obtained refer only to pressures greater than those necessary to form a coherent compact. The third disadvantage is the inability of this method to provide information about the compact density at the applied pressure in the die. Because the determination of density-pressure relationships has been a slow, tedious process, investigators have sought to express the compaction behavior of powders by other means. The general terms "comparability" and L'compressibility" have been used to rank powders qualitatively according to their compaction characteristics. To restore a quantitative nature to the subject and to prevent confusion, Schwarzkopf1 has proposed that compac-tibility be defined as the minimum pressure needed to produce a given green strength, while compressibility should be used to indicate the extent to which the density of a powder is increased by a given pressure. Probably the most widely used of the compaction parameters is the "compression ratio,'' which is generally defined as the ratio of the compact density obtained by pressing at a given pressure to the apparent density of the loose powder.2 However, the description of the compaction behavior of a powder by these parameters provides only limited information about the process because of their applicability to just one specific condition such as a given green strength or a given pressure. The method of obtaining density-pressure relationships which will be described in the present paper was designed to eliminate the shortcomings of the previous techniques while maintaining equivalent accuracy and precision. EXPERIMENTAL TECHNIQUES The general principle employed makes use of the fact that the linear movement of the punch during a

Jan 1, 1962

By R. S. Sinha

A properly designed pre- and post-grouting program aided with coherent construction sequence and adoption of flexible design approach provide a practical combination to solve excavation problems in a hostile rock environment: intensely fractured and sheared. The Pacheco Pumping Plant demonstrates the utility of an engineered grouting program.

Jan 1, 1984

By Henry Hanson

A STUDY of the ore to be treated should be the first step in deciding on a machine for crushing or grinding. Coarse crushing is practically confined to the jaw and the gyratory crushers, the large-size jaw type being often employed in large installations as a primary crusher, followed by the gyratory type for secondary reduction. In small plants where mine-run ore is reduced in a single step, either of these machines will do the work. In intermediate and fine grinding, various machines are used. The relative merit of the different types will be governed in no small measure by the size of the installation, the character of the ore to be reduced and the final product desired for subsequent treatment. It should be possible, nevertheless, with the data available, if properly classified, to arrive at an approximation of the relative efficiency of these intermediate and fine grinders. It should be possible, also, to determine the economic grinding range of the different machines. With this in mind, it will be the object of this article to indicate, in rough outline, how the data available may be classified, rather than to attempt to discuss any particular practice and compare the results with other practices. Conclusions or generalizations can not be drawn without an exhaustive classification of data; in fact, many vital points will have to be determined by additional experiments which can be carried on most advantageously in the laboratory. The expense en-tailed in such experiments would be worth while if the data obtained should lead to definite conclusions that would aid in standardizing and simplifying grinding practice.

Jan 2, 1923

By A. S. Eve

This paper gives a brief summary of theory on radiation waves and describes experiments by the United States Bureau of Mines and by the Canadian Geological Survey at the Mammoth Cave, Kentucky. Dr. D. A. Keys, Dr. F. W. Lee and the writer did the experimental work, and Dr. L. V. King some of the theoretical work. In prospecting for orebodies underground it is a usual practice to employ a loop of wire carrying an alternating current that induces an electromotive force in good conductors beneath the earth. The conduc-tars are usually of such low resistance and impedance that currents of considerable magnitude may result in these orebodies or conductors, and these currents in turn induce an electromotive force in a detecting coil placed near the surface of the ground. By using amplifiers it is possible so to enhance the effect of this electromotive force in the detecting coil that the currents in the underground conductors are detected in spite of the powerful effects coming directly to the coil from the primary loop. In such cases distance or depth has primary importance, for the effects have to pass down to the orebody and the secondary effects induced therein have again to pass back through the ground to the observer's detection coil on the surface. However, there is another factor to consider—absorption of the electromagnetic disturbances by the intervening soils and rocks. This absorption will vary with their composition. Thus the main factors that determine the possibility of detecting ore underground are: 1. Its depth beneath the surface, 2. The magnitude of the conducting orebody, 3. The excellence of the conductivity of the orebody as compared with that of the surrounding strata, 4. The frequency of the alternating current,

Jan 1, 1932

In deposits in which the secondary zones are well defined a layer of rich oxidized ore is frequently found immediately to overlie the enriched sulphides, from which it is derived by direct oxidation in place. In deposits that contain oxidizing precipitants particles and masses of residual oxidized ore are likely to be scattered through the leached zone, having been precipitated during migration before reaching the zone of enrichment. This precipitation hinders secondary enrichment and in extreme cases prevents the formation of such concentrations. Residual ores are precipitated by various reagents. Carbonates are formed through the action of the carbonic acid contained in surface waters, and also directly through the replacement of calcite, especially where the containing rock is limestone. Native metals, such as copper, gold, and silver, are formed by the action of reducing agents, among which organic matter and ferrous sulphate are prominent. Kaolin, gouge, and certain shales occasionally act as powerful precipitants through adsorption. Silver is often found as residual chloride, formed through precipitation by the chlorine contained in surface waters. Residual ores are often the result of incomplete solution, the relatively insoluble minerals being left behind during the migration of associated metals; incomplete oxidation and solution often leave residual masses of unaltered, or partly altered, sulphides in the oxidized zone. Such residual particles or masses have commonly been enriched by additions from circulating, metal-bearing solutions. During oxidation under conditions that permit reprecipitation, such as the oxidation of sulphide deposits in limestone, a scat-

Jan 1, 1932

By Raymond E. Byler

THE challenge of unprecedented need for more metals to meet present-day re-armament and domestic requirements is being met with minerals beneficiation projects of great number and variety, and with new and improved methods, techniques, and. equipment. Iron Range Developments Much attention has been given during the year to the tremendous program for beneficiation of taconites and intermediate iron ores which is progressing through large pilot-plant tests preparatory to full-scale production operations. The greatest activity has been directed toward concentration of magnetic taconites on the Mesabi Range. The Reserve Mining Co. has let $75 million in construction contracts for the 2 ½ million-ton-per-yr project (concentrates) at Beaver Bay, Minn., and is building a 300,000-ton-per-yr pilot plant to prove up the magnetic separation and pelletizing operations. Oliver Iron Mining Co. has a pilot plant under construction near Mountain Iron for concentrating magnetic taconites, and is operating experimentally a sintering and nodulizing plant on fine ore screenings and concentrates at Virginia to fully develop agglomeration technique. The Erie Mining Co. plant at Aurora continues its production of concentrates from magnetic taconites which was begun three years ago. No plans have been announced to treat the Mesabi Range nonmagnetic taconites, but F. D. Devaney, Pickands Mather and Co., is studying a new process for magnetically roasting lean ores to make them amenable to low-intensity magnetic concentration. W. R. Van Slyke, Cleveland-Cliffs Iron Co., calls attention to several noteworthy developments in the field of intermediate ores, perhaps the most significant of which has been the first commercial operation of a Dutch State Mines (DSM) cyclone plant at the Buckeye mine of the M. A. Hanna Co. The plant concentrates the +1/4 in. fraction by means of conventional heavy-media treatment after suitable crushing, screening, and washing. The -1/4 in. +65 mesh material is treated in two 12-in. cyclones, the -65 mesh fraction being sent to tailing storage. The plant is operating successfully on feed rates up to 120 tons per hr, and indicates that successful treatment of the fine fractions of Mesabi intermediate ores is imminent. Another commercial-size DSM plant was placed in operation late in the year by Cleveland-Cliffs at the Holman mine, and two additional ones are expected to be in operation next year. Various other methods are also in use at different plants for treatment of the fine fractions, including classification, abrasion milling followed by classification, jigging, and Humphrey spirals. Where it can be economically justified, it seems at present that heavy-media treatment of the -1/4 in. fine fraction will also come into increasing use on the intermediate ores. During 1951 a one-unit, heavy-media plant to treat hematitic crude ore was erected at the Ohio mine on the Marquette Range by Cleveland-Cliffs and plans for another plant at Humboldt to produce 2000 tons of concentrates annually is contemplated, as is also the construction of a plant for agglomera-

Jan 1, 1952

Jan 1, 1970

By David Turnbull

In most reactions involving solids the transformation kinetics may be represented by the combination of two processes —those of nucleation and of growth. For example, Mehl and his coiq-orker in their studies on the transformation of austenite to pearlite in steels have been able to describe the kinetics in terms of the rates of nucleation and of growth. By micrographic examination of their specimens they determined the nucleation rate (rate of appearance of pearlite colonies) as a function of time, of percent transformation, and of temperature. They observed that after an incubation period in which no nuclei are observed, the number of nuclei appearing per unit time per unit of untransformed grain boundary area, increases at an increasng rate with time. When recrystallization rates have been interpreted in terms of rates of nucleation and growth and the rate of nucleation determined, an incubation period followed by an increasing rate of nucleation has also been reported. Among the studies in which this phenomenon has been observed are those of Kornfeld and coworkers3 on cold-drawn aluminum wire, of Anderson and Mehl4 n the recrystallization of aluminum sheet, and of Stanlcy and Meh15 on the recrystallization of silicon ferrite sheet. The existence of an incubation period during which no nuclei are observed does not appear to have been reconciled with the generally accepted Volmer-Becker theory of nucleation in condensed systems. This theory ostensibly requires the rate of appearance of nuclei to be independent of time. Volmer-Becker Theory In order to form a stable nuclcus of a new phase B in a mother phase A, the molecules or atoms of the mother phase must surmount a free energy barrier whose height is determined by the volume free energy change accompanying the transformation and the energy of the surface separating the two phases. The free energy difference between nuclei of various sizes and the molecules or atoms of the mother phase is plotted schematically in Fig I as a function of the radius of the nucleus r. This free energy difference is plotted for two values of the change of free energy per atom, (Jb — ja) accompanying the transformation when the volumes of the two phases are infinite. One of these values of (Jb—Ja) corresponds to a temperature above the temperature To at which the phascs A and B are in equilibrium, and the other to a temperature below To. In order for a nucleus of phase B to be stable at a temperature T² < TO, its radius must be equal to or greater than the critical value r* for which the free energy of formatioil of the nucleus is a maximum, the of phase B having radii equal to or less than r* will be called embryos hfehl and Jetter," in discussing the kinetics of nucleation in solid systems, suppose that embryos of critical size are formed

Jan 1, 1949

By Ben-Zion Weiss, Melvin R. Meyerson

Chromium diffusion coatings on commercial Armco iron lead to carbide precipitation at the grain boundaries in and below the coatings. High compressive stresses are introduced into the coating and, as a result, tensile stresses are introduced into the base material below the coating. In coated samples, fatigue cracks form at the grain boundaries below the coating after only a limited portion of the total lifetime (5 to 10 pct). Residual tensile stresses and a stress concentration caused by precipitated carbides seems to be responsible for early crack nucleation. Stage I of Propagation may be divided into two substages: I-a in which the crack Propagates along grain boundaries, and I-b in which the crack propagates along slip boundaries according to a shear mode. In uncoated samples, the cracks form at slip bands after 40 to 50 pct of the total lifetime. In coated samples the Propagation process takes longer than in uncoated samples because of the moderate rate of crack extension until the crack breaks through the coating. The chromium-diffusion coating causes little if any increase in fatigue life. CHROMIUM diffusion is one of the most popular processes used to apply coatings to iron alloys. This popularity stems from the fact that the diffusion treatment is comparatively easy to carry out, and it improves certain surface properties such as corrosion and wear resistance as well as some other properties. Very little effort has been devoted to the investigation of the effect of chromium-diffusion coatings on mechanical properties and particularly on fatigue properties. Since the chromium coating usually represents a small fraction of the total volume of the base material it is generally assumed that the macro properties are dependent principally on the base material rather than the coating. Insofar as fatigue is concerned, there are indications that the fatigue life of the chromium coating is not less than that of the basic material and the fatigue properties are generally not reduced by it.&apos; But chromium diffusion causes drastic structural and chemical changes in the region of the material surface2-4 which introduce additional residual stresses. Such changes must affect fatigue crack nucleation and may sometimes affect the initial stages of propagation. Furthermore, it is conceivable that the secondary stages of the crack propagation could be influenced by some irreversible structural changes in the core of the material, which stem from the long-time heat treatment at high temperatures required to apply the coating. This paper analyses the structural and compositional changes produced in commercial Armco iron by a chromium-diffusion coating and the effect of the coating on fatigue crack initiation and propagation. EXPERIMENTAL PROCEDURES The investigations were carried out with commercial Armco iron. The chemical composition of the iron, the number of specimens tested, the grain size produced during chromizing and heat treating, and the thickness and microhardness of the chromized layers are shown in Table I. Samples were chromized by a gas diffusion process. The temperature and time of the diffusion coating process were chosen according to a previous grain growth study. It had been found that at a temperature of 970°C and a holding time of between 3 and 9 hr there are practically no changes in grain size. To describe the grain size more accurately the ASTM method5 was supplemented by a statistical analysis of the mean volume diameter as outlined by Fullman6 and The The mean volume diameter was deter- mined from D = p/2m where D is the mean volume diameter, and m is the mean reciprocal value of grain diameters as seen on the micrograph. The shape and the size of the asymmetrical sample, see Fig. 1, were chosen so as to facilitate the study of fatigue crack initiation. Before coating, the samples were machined and the surface of the groove was polished. After chromizing, the two side surfaces were machined and polished so as to retain the coating only on the top surface of the groove. Residual stress in the chromized layer was measured on the top of the grooved section of the specimen after the diffusion process. The inclined incident X-ray beam procedure was used.9&apos;10 The computations were performed with the initial assumption of a zero surface normal stress component. An electron microprobe analyzer was used to obtain the relative amounts of chromium and iron con-

Jan 1, 1970

By J. C. Uy, A. A. Burr

IN the primary solid solutions of zirconium-base alloys, there is a striking regularity of the effect of solute valence on the stabilization of the allotropic phases.1 The valences derived by pauling2 are for elements as they are bonded in the solid metallic state. Effects of variations in isotopes, alloying elements, and allotropes on their valences are difficult to determine and such data are presently unavailable. Pauling&apos;s values are somewhat empirical and approximate, but if some definite correlations can be found between those values and experimental observations, this will lend support to the tacit assumption that the possible variations in valence mentioned above are small. Pauling has amassed a large amount of evidence of such correlations. It is the purpose of this technical note to show another application of the Pauling valences and to offer a possible explanation for this observation. The relationship between the Pauling metallic valence of the solute and the stabilization of allotropic phases in zirconium is shown in Table I, which has been compiled from available data in the literature3 plus the results of work done at Rens-selaer Polvtechnic Institute.&apos; The chemical valences are included for comparison. It can be seen that a solute whose metallic valence is lower than that of the solvent tends to stabilize the a phase while one whose metallic valence is higher than that of the solvent tends to stabilize the 0 phase. It should be noted that, inasmuch as the Pauling valences are periodic with atomic number, this is tantamount to saying that the elements in groups I-A, 11-A, III-A, III-B, IV-B, V-B, and VI-B are a stabilizers while those in groups IV-A, V-A, VI-A, VII-A, VIII-A, I-B, and 11-B are ß stabilizers. The chemical valences do not show such consistency. Although the zirconium-rich end of the Zr-Au diagram is not available, it call be expected that gold, having a metallic valence of 5.56, would stabilize the ß phase. At absolute zero, the Fermi energy level is the criterion of equilibrium, i.e., the structure having the lower Fermi level will be more stable. Conse- quently, allotropic transformation occurs in a metal when thermal excitation raises the Fermi level to a point at which the atoms can be better accomodated by a different structure which yields a lower Fermi level.4-6 Thus in allotropic transformation, a change in structure occurs as a result of the change in the energies of the bonding electrons. Since the Pauling valence is the number of bonding electrons per atom, and these are the only electrons whose energies are affected by thermal excitation,* it can be inferred that the introduction of a solute which has a higher Pauling valence than that of the solvent raises the initial Fermi level; consequently, the transformation temperature is lowered. The converse is also true. The fact that at the transformation temperatures this statement is still fairly valid implies that the contribution due to the difference in specific heat terms of the two allotropes is comparatively small.

Jan 1, 1962

By John A. Church

In the year 1874, when the price of pig-iron was still high, that staple product became the subject of discussion in the newspapers and among those philosophers who are determined to know the "reason why" for all things. The object of the inquiry was to find out Why iron did not fall in price as much as some other things had fallen. Indeed, there seemed to be an impression that iron and gold ought to move on nearly parallel lines, for the fact was constantly brought forward that iron then cost twice as much as it did before the war, though gold had returned to within twelve or fifteen per cent. of its former value. After some time the papers, by what seemed to be nearly unanimous consent, reached the conclusion that the maintenance of high prices was the work of the furnace proprietors, who, as the result of their shrewdness, were pocketing enormous profits. No proof was given to support this opinion, and the figures of cost and sale that were produced were of the most general kind, and used in the most vague manner. Visiting the president of the Thomas Iron Company, whose great works at Hokendaqua and Catasauqua, in Pennsylvania, are so well known as the largest and among the best conducted in America, I found him quite willing to meet the vague suspicions of the newspaper wiseacres, by a publication of the figures contained in the furnace-books of his company. These were accordingly given to the world through the Engineering and Mining Journal, and attracted the general attention they so well deserve. Though my own name became connected with these statistics, from the fact that I used them as the basis for the first attempt ever made to calcalate the furnace economy of an American works, I can, without the suspicion of egotism, say that the statistics referred to are the most valuable contribution the literature of American blast-furnace work has yet received, for their interest is independent of personal considerations, and due entirely to the fact that they represent faithfully the details of practice in one of the most prominent American works. They are an exact transcript of the furnace-books, and form a body of accurate information of the greatest value to the metullurgical student. Their importance is shown by the fact that though the theoretical conclusions which I based upon them have been several times attacked, not one of my critics has made the slightest contribution to

By H. L. Talbot, R. S. Young, A. Golledge

THE differentiation of, oxidized forms of lead from lead sulphide in complex products by chemical analysis is of considerable importance to certain mining and metallurgical companies. A method for the separation of "oxide" lead, (non-sulphide), from sulphide lead, based on the solubility of the former and virtual insolubility of the latter in concentrated ammonium acetate solution, has been employed for many years in the industry.1,2 Unfortunately this solvent, while satisfactory for lead sulphate and carbonate, is without action on lead phosphates or vanadates, with the result that at Rhodesia Broken Hill Development Co. where these latter minerals are present, they have counted as sulphides when using this procedure. For the control of operations in the new concentrator it became necessary to have a closer check on sulphide lead than could be obtained by the only current method of differentiating this constituent from oxidized lead. For some time this problem has engaged our attention, and after a large number of solvents had been tried, the following procedure was evolved. Like all methods depending on selective solution in a complex material, it will not give 100 pct separation into oxide and sulphide portions. Because of the ease of oxidation of galena this is almost an impossibility. Our procedure will, however, give a recovery of 99-100 pct of the oxidized lead, contaminated with very small quantities of lead sulphide, and a corresponding recovery of 97-98 pct of the sulphide lead. The procedure is simple and reproducible, and gives results quite satisfactory for routine control purposes. EXPERIMENTAL For this work standard samples of the following pure lead minerals were obtained from Broken Hill, Northern Rhodesia. These were hand-picked specimens, and were carefully ground to - 200 mesh. Since it was realized that a fair-sized sample would be necessary for this work to thoroughly test the large number of procedures we had in mind, a compromise had to be effected between a few grams of very pure minerals and a large sample of lower grade material. For this work the presence of gangue was not deleterious, so long as the oxide lead minerals did not contain lead sulphide, and vice versa. Table I shows the lead minerals used, and their total lead content, both theoretical and actual. Apart from the pyromorphite the minerals are seen by analysis to be quite pure. Many solutions were tried in an effort to dissolve the oxidized lead minerals and

Jan 1, 1947

The Institute assembled in the library of the Sheffield Scientific School at 8 o&apos;clock, Tuesday evening, February 23d. Prof. G. J. Brush greeted the members present on behalf of the Government of the Sheffield School in a few words of cordial welcome, to which President Raymond responded. Dr. Raymond then delivered an address on the History of the Relative Values of Gold and Silver. The Council presented, through the President, a list of names of persons duly proposed for members and associates, with recommendation for election. The following gentlemen were unanimously elected: *Prof. George J. Brush,. .. New Haven, Conn. *Prof. Oscar D. Allen,. .. New Haven, Conn. *C. Constable,.....New York City. *Leven S Goodrich,.... Oxmoor, Jefferson Co., Ala. *Charles J. Nourse,.... Columbia, Lancaster Co., Pa. *J. W. Mickley,.....Hockendauqua, Pa. *Hugh Alex. Crawford,. ..St. Louis, No. *General Ario Pardee,. .. Hazleton, Luzerne Co., Pa. N. W. Lord,.....New Pork City. J. Holme Maghee,.... New York City. *George E. B. Jackson,. .. Portland, Me. *Charles W. Watkis,.... Salt Lake City, Utah. *Charles E. Hall,....Philadelphia. *Charles J. Duval,.... San Francisco, Cal. Joseph Gorlinski,.... Salt Lake City, Utah. * Alfred Wartenweiler,. .. Salt Lake City, Utah. Wilmot J. Bowen,.... Salt Lake City, Utah. *Joseph Stokes,..... Trenton, N. J. Jason P. Brown,.... Boston, Mass. *William Davis Hartshorne,. . Bethlehem, Hunterdon Co., N. J. *Henry Williams,.... Spanish Bar, Clear Creek Co., Cot. *Robert Forsyth ,....Chicago, Ill. *S. T. Wellman,.....Cleveland, Ohio. *H. C. Walton,.....Chicago, 111. *Andrew Roy,.....Columbus, Ohio. *James H. Rittenhonse,. .. Providence, Pa.

By A. J. Teplitz, R. J. Goodwin

A new type water shut-off for use in air drilling has been developed. The method has been 99 to 100 per rent effective in several different formations of inter-ranular-type porosity. Since costs for materials, time and equipment used are relatively small, the process should extend economies of air drilling to many new areas. The treatment involves a new technique for forming a water-inroluble precipitate within the pores of a rock. Advantage it taken of the difference in mobility of a liquid and a gas in porous media to achieve the greatest volume of precipitate in a given pore. Reactants selected for the laboratory (2nd field tests were aluminum sulfate solution and gaseous ammonia. This process has been tested in both intergranular and fractured-type porosities. It has consistently shut-of between 99 and 100 per cent of the water flowing from formations having intergranular-type porosity and perrlreuhilities ranging from a few millidarcise to over a darcy The treatment is not particularly suitable for shutting-off water from fractured formations although plugging of the order of 50 per cent or greater has been achieved in all such applications. Among advantages of the treatment are: (I) no reaction waiting rime after a relatively short placement time, (2) a low mate-rials cost of about $3/f1 of hole treated, (3) use of common service-type equipment for treatment, and (4) no unusual requirements for mixing and placement. INTRODUCTION In rotary drilling with air or gas it has been possible to increase bit life by tenfold and more than double rate of penetration over corresponding performance when drilling with mud. These factors have amounted to as much as 22 per cent savings on total cost of drilling a well. However, these advantages are rapidly lost when water is encountered in an air- or gas-drilled well because water interferes with the removal of cuttings from the hole and also gives rise to other difficulties. In attempting to combat water troubles, operators have commonly resorted to such measures as mist drilling, treatment with cement or chemicals, converting to conventional mud drilling, or setting casing. In many cases these measures have either been costly or ineffective. In an effort to overcome this problem, studies were undertaken to develop an effective and economical water shut-off technique for use in formations possessing inter-granular-type porosity. Extensive laboratory experimentation finally led to a unique method for producing a water-insoluble precipitate within the pores of a sandstone. The unique part of the treatment is use of a liquid and a gas to form the precipitate, and in this case the reactants used were aluminum sulfate solution and gaseous ammonia. The reaction between these two materials is shown in the following equation. Al2 (SO1)3 - 18 H20 6NH2? saturated Water- Solution Cat 2A1(OH)3 . n H20 3(NH4)2SO • n H20 Solid Solid That is, a solid precipitate consisting of aluminum hydroxide and ammonium sulfate is formed when ammonia reacts with aqueous aluminum sulfate. The aluminum hydroxide is insoluble in water and the ammonium sulfate, though soluble, can only be removed from the formation pores by diffusion—an extremely slow process. Although the precipitate formed by the reaction is not particularly firm, great strength is not needed for a precipitate to bridge and plug intergran-ular-type porosity. A flow path in such a system is extremely tortuous and involves a great variety of pore

By R. R. Spencer, C. A. Campbell, R. J. Marcotte, A. S. Kromer, P. H. Ostlender

Calumet Div. of Calumet & Hecla Inc. is engaged primarily in mining, milling, and smelting the native copper ores of northern Michigan. The copper occurs in fragmental tops of lava flows and in certain interbedded felsitic conglomerates of Pre- Cambrian age. The most famous native copper ore- body in world history is the Calumet conglomerate, which outcrops between the villages of Calumet and Laurium for a distance of about 2 miles. The Osceola lode parallels the conglomerate lode and is mineralized for about 3 miles. Horizontal distance between the two is 750 ft. In 1932 the price of copper dropped to 54 per lb. Coupled with the high cost of obtaining copper from extreme depths, this low price made the venture un- profitable, and the mining unit was abandoned. After the shaft pillar copper was removed from several of the conglomerate shafts in a retreating operation, the mine was allowed to fill with water. In post-depression years, when the price of copper stabilized at about 12¢, Calumet Div. found it profitable to operate its remaining mines on other lodes, as well as its tailings reclamation plants.

Apr 1, 1956