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Discussion of the paper of W. H. Gunniss, presented at the Butte meeting, August, 1913, and printed in Bulletin No. 81, September, 1913, pp. 2309 to 2310. PROF. J. W. RICHARDS, South Bethlehem, Pa. :-In regard to the physical nature of quartz for making silica brick, is the coarse-grained preferable ? E. P. MATHEWSON, Anaconda, Mont. :-A dense quartz is preferable. The quartzite is the actual material used by the Anaconda Company. The sandstone referred to, the foreign quartz, was a very pure sandstone and bad hardly any impurities in it, and the brick made from that particular material, while apparently beautiful while coming out of the kiln, and true, immediately on heating in the furnace buffed up half an inch and were cracked open.

Jan 11, 1913

By Strathmore R. B. Cooke, Iwao Iwasaki, C. S. Chang

The effects of aeration on an aqueous suspension of pyrrhotite were studied and their results correlated with flotation tests using xanthates as collectors. The effects of copper activation and of pH variation were determined and possible mechanisms postulated. PYRRHOTITE has long been considered a gangue mineral to be eliminated as tailing in the treatment of various sulphide ores. However, in recent years the world-wide lack of sulphur resources has called attention to this mineral as a potential source of both sulphur and iron. Its importance as an economic mineral, however, has not been particularly emphasized. For this reason very little is known about its response to flotation, except that it can be depressed easily in alkaline circuit, by long aeration,1,2 addition of oxidizing agents,3 or by starch.' The object of this work was to study the floatabil-ity of pyrrhotite. This includes the effect of oxidation by aeration, of copper activation, and of change in pH. Preparation of the Pyrrhotite Sample: It was desirable that the highest grade of pyrrhotite obtainable be used for this experiment, since the presence of other minerals could affect the surface properties.5 However, no pyrrhotite was available as crystals, and massive deposits of hydrothermal origin commonly contain considerable amounts of chalcopyrite. Pyrrhotite concentrate was, therefore, prepared from a sulphide deposit occurring near Aitkin, Minn. The deposit is of pyrometamorphic nature consistirlg mainly of pyrrhotite and pyrite with graphite, silicates, and carbonates as gangue. The ore, already crushed through 3 mesh when received, was screened at 65 mesh and the undersize discarded. The oversize was crushed through rolls, and then stage-ground dry in an Abbe porcelain mill, the —65 mesh portion being screened out after every 15 min of grinding until all the material passed through this size. The ground product was then concentrated with a drum-type dry magnetic separator. The rougher concentrate was cleaned twice and then demagnetized. The final product was split in a Jones splitter and stored in air-tight bottles. Microscopic examination of the concentrate showed that it was relatively clean and free of pyrite, locked particles, and gangue. By means of the krypton gas adsorption method," the specific surface was determined to be 3000 cm2 per g. The chemical and screen analyses of the final concentrate are given in Tables I and II respectively. It is a well-recognized fact that the oxidation of some sulphide ores during stockpiling, grinding, and conditioning affects their flotation behavior. The problem of oxidation may become serious in the case of pyrrhotite, since this is known to be more easily oxidized than many other sulphides. To ascertain the extent of oxidation, an experiment was carried out by aerating an aqueous suspension of pyrrhotite with air, oxygen, and nitrogen as follows. A 300-g sample of pyrrhotite in 2700 ml of water was agitated and simultaneously aerated in a Fager-gren-type laboratory flotation machine. A Precision wet test meter was connected to the air inlet valve, the flow rate of the gas being kept constant at 0.3 cu ft per min throughout the experiment. Samples of approximately 30 ml each were taken from the cell at 0, 4, 10, 20, 35, 60, and 90 min. After the pH was taken, each sample was filtered and the filtrate was analyzed for total iron and sulphur. The iron was determined colorimetrically by the thioglycolate method using a green filter.' The filtrate was oxidized with bromine to convert all of the soluble sulphur compounds into sulphate and this was determined with a Parr turbidimeter." When aeration tests were made in alkaline circuit, calcium hydroxide or sodium hydroxide was added at regular intervals to maintain a constant pH. A similar procedure was followed in an experiment to determine the abstraction of copper. ion by pyrrhotite. In this case various quantities of cupric chloride were added. The filtrate from each sample taken was analyzed for copper, total iron, and sulphur. The carbamate method with a green filter was used for the copper analysis,' since this method could tolerate a considerable amount of iron in the solution. A pneumatic cell, made from a 350-ml fritted glass Buechner funnel, was used for this experiment. The detail of the assemblage has been described elsewhere." In the present work a stainless steel baffle was inserted in the cell. This baffle overcame the tendency for the coarse pyrrhotite particles to be swirled around the wall of the cell and thus fail to collect in the froth. A 50-g sample of pyrrhotite was added to the cell which contained 260 ml of water. When pretreat-ment of the sample was desired, reagents, such as activator and pH regulator, were then added and the pulp was conditioned for a specified conditioning time. Prior to the addition of the collector approximately 15 ml of the solution were removed for pH measurement and for iron and sulphur analyses. Copper when used as activator was also determined. Collector and frother were then added and the pulp was conditioned for an additional 2 min. Air was admitted to the cell and the froth removed. The separation required from 4 to 6 min, depending on the characteristics of the froth. The float and non-float products were filtered, dried, weighed, and assayed for iron.

Jan 1, 1955

By H. H. Rachford, D. S. Howard

In the withdrawal of fluids from tilted aquifers it is of value to be able to predict pressure patterns during the course of the pressure decline. As an example of this, in the displacement of fluids from oil reservoirs being produced by water-drive, prediction of the reservoir pressure is an important factor in fixing production rate. The prediction of pressure patterns in the depletion of an inclined aquifer has conventionally been made by solving the well known flow equations for the pressure Patterns in a horizontal aquifer, and correcting these patterm for the pressure difference due to the hydrostatic head associated with the vertical distance between a point in the horizontal aquifer and the corresponding point in the tilted aquifer. Inasmuch as the equation describing flow in tilted strata is different from that for horizontal flow. there was question as to the validity of the simple corrective procedure current1y in use. To examine the magnitude of error made using this procedure, an inclined aquifer was chosen for which the error was expected to he large, and the equation for flow in this tilted stratum was solved numerically. The results of the conventional procedure of correcting the solution of the equation for horizontal flow was compared with the solution of the correct equation by studying the difference between predicted pressures by the two methods. Three forms of the hydrostatic head correction were studied. The results for all three forms of the head correction are similar. The error in the approximate solution is quite dependent on the position of the horizontal aquifer with respect to the inclined one. The error is greatest at the producing end ad increases with amount of fluid withdrawn. The magnitude of the errors is not large if a good choice is made for the position of the horizontal datum. The most satisfactory position for the datum in all cases is near or slightly about the mid-point of the inclined stratum. Use of the best approximate method studied with the best datum tested yielded predicted pressures in error no greater than 7 psi. INTRODUCTION The movement of water by expansion from an aquifer to displace fluids from a contiguous oil reservoir was first recognized over 20 years ago.9 Since that time much work has been done to relate this mechanism to reservoir behavior mathematically. The result of this effort on the part of many workers has led to an understanding of underground fluid movement which has enabled us to follow and predict the behavior of the water-drive reservoir. One reason that good progress has been made in the application of mathematics to the study of pressure patterns and water movements in aquifers has been that the differential equation which describes this process is of a relatively simple form. The equation for the isothermal, horizontal, viscous flow of water through homogeneous sandstone is identical with that for the diffusion of heat through homogeneous solids, and this equation and means of obtaining solutions for it with many types of boundary conditions have been studied extensively. That this work has been highly successful is clearly emphasized by the large number of solutions developed for problems of interest both by methods of formal mathemat-

Jan 1, 1957

By AIME AIME

THE time of the Section delegates was economized this year by providing the section reports in mimeo- graphed form, together with the reports of the officers and committees of the Institute, for their consideration on arrival. The meeting was called for Thursday forenoon and despite a certain amount of oratory managed to get through before all the luncheon was gone. In all, nine section delegates and one from the Iron and Steel Division attended and took part. One delegate, who had come many miles, got lost in the complication of the program and failed to attend. Six appointed dele- gates failed to attend and two sections neglected to make appointments.

Jan 1, 1929

By M. M. Singh, H. L. Hartman

This paper reports on the results of a fundamental investigation of the behavior of rock under impact of a chisel-shaped bit. Drop-tester studies were conducted with strain gauges attached to the rock and striking bit-edge. It was established that rock behaves viscoelastically. Little correlation was found to exist between the strain waveforms detected on the rock surface and in the bit; thus, strain-time curves obtained with transducers mounted on the bit cannot be used to explain the sequence of events in rock breakage. It is estimated that nearly 1 per cent of the total energy of the blow is expended in permanent deformation of the rock. The strain- energy distribution on a rock surface as a result of chisel impact, which follows a simple law, is presented graphically. Experiments also were conducted with gauges embedded in the rock vertically below the line of impact and at an angle of approximately 45' to the vertical. No essential difference was observed in the type of wave obtained with embedded gauges and with gauges on the surface, as may have been anticipated from theory. INTRODUCTION Through the ages great strides have been taken towards improvement of the various techniques applied in the breakage of rock. Indeed, numerous applications of the rock-failure process are an integral part of present-day industry, including oil well drilling. Yet, astonishingly, little is known regarding the behavior of rock under dynamic loading or the mechanism of rock failure. The value of impact loading studies from the point of view of drilling is evident, however, and requires little elaboration because impact of a chisel edge on rock forms the basic action constituting most common methods of drilling. RELATED STUDIES Impact studies of communition and fragmentation conducted by Fahrenwald, et a1,8 Poncelet,l7 Axelson, et a1,2 Piret,16 Hartman and pfleider,ll Charles and deBruyn,5 and others have been of considerable help in understanding rock-breakage phenomena. Further insight into the basic action of drilling and penetration has been obtained by the work of Irving,13 Cherkasov and Shlyapin,6 BOrcherdt,3 Shepherd,19 Shreiner and Pavlova,20 Drilling Research Inc.7 Hartman,10 Appl and Gatley1 and several other investigators. However, knowledge concerning the stresses and strains induced in the rock and bit during impact remains scant. Recent photoelastic studies by Tandanand and Hartman (1961. 1962)22, 23 have shed light on stress distributions and Fracturing produced in plastics by chisel-shaped bits. In the field of transient strain Pulses and their role in rock drilling, the only extensive work has been performed by Drilling Research Inc. (DRI). They attached strain gauges to the shank of a bit and conducted drop-tester studies, using a die-shaped bit to obtain force-time diagrams. Their work led to the conclusion that, for a given rock type, the first peak of force occurs at a fixed level regardless of the total energy in the system, provided it exceeds a certain minimum threshold level. Further, on this basis an explanation was offered for the sequence of events in crater formation as the result of a single blow on rock. PURPOSE OF PRESENT STUDY The investigations reported in this paper were conducted in a manner similar to the DRI approach, but with the objective of determining the strain distribution in the rock around the area of bit impact and, to a limited extent, the strain in the chisel-shaped bit itself. It was expected that a knowledge of the disposition of these strains, along with the rate of attenuation of strain energy in the rock

By J. S. Owens, R. W. Marsden, J. W. Emanuelson, R. F. Werner, N. E. Walker

The iron ores of the Mesabi Range occur in a 340 to 750-foot thick, Precambrian cherty iron formation termed "taconite." For about 65 years, extensive natural iron ore bodies were mined, and the ores either shipped as a direct ore or processed by gravity methods to a shipping grade iron ore. Since 1956, magnetite taconite ores, occurring in magnetite-rich horizons in the Biwabik iron formation, have been commercially concentrated and agglomerated. The transition from natural ores to concentrating-grade ores is progressing rapidly so that, in the near future, a major percentage of the iron ore shipped from the Mesabi Range will be as iron ore pellets produced from taconite. Natural iron ores of the Mesabi Range occur in the Biwabik formation as trough ore bodies in elongated channels and as irregular and tabular deposits in fractured areas associated with faults and folds. Ore bodies range in size from a few thousand tons to hundreds of millions of tons and may occur in any part of the iron formation. In some areas of strong ore development, ore was formed from the hanging-wall argillite to the footwall quartzite. The natural ores and beneficiating-grade natural crude ores were formed by the oxidation of the iron minerals, magnetite, greenalite, stilpnomelane, minnesotaite, and siderite, to hematite and goethite and by the removal of much of the silica in the cherty quartz and in the associated silicates by leaching. The ores are believed to have formed by the oxidizing and leaching action of surface waters. Magnetite taconite ores occur as stratigraphic zones in the Biwabik formation where it contains sufficient magnetite to be concentrated profitably, by magnetic methods, to give a magnetite concentrate that is agglomerated into a high quality product. Unoxidized taconite has an extensive distribution away from and between channels of oxidation and leaching but only a part of the unoxidized taconite is of ore grade. Two general types of magnetite taconite ore occur: ( 1) magnetite taconite of the Main Mesabi Range, generally west of Mesaba, which is composed of magnetite associated with cherty quartz, greenalite, stilpnomelane, minnesotaite, and carbonates and (2) magnetite taconite of the Eastern Mesabi, generally east of Mesaba, composed of magnetite associated with quartz, cummingtonite, actinolite, ferrohypersthene, hedenbergite, fayalite, hornblende, pyroxene, garnet, and biotite. The Mesabi taconite is a metasediment derived from an iron- and silica-rich chemical sediment that has been regionally metamorphosed and, on the eastern end, additionally metamorphosed by the Duluth Gabbro Complex.

Jan 1, 1968

By Elmars Ence, Harold Margolin

The titanium-aluminum system has been investigated in the composition region 0 to 34 pct Al in the temperature range 800" to 1450°C. The phases encountered in this region were: a,ß, TiAl3, The reactions observed are as follows: 13 ; L - 6T. A1, 0 (15 pct Al) + 6 (18 pct Al) - yTi Al (16.5 pct Al) at -1170°C andP (7 pctpct Al) + y (9.2 pet Al) - ah(9 pct Al) at - 1060°C. A eutectoid reaction: y — a +d belm 700°C is postulated. THE Ti-A1 system has been the sub.ect of a number of investigations. Several of these1-3 have indicated extensive solubility of A1 in both a and ß titanium. Ence and Margolin, as a result of work on the Ti-A1-0 system:'5 have shown that the a solubility ofalumi-num is considerably restricted, and found that a compound, Ti2A1 existed in the region formerly designated as Q a This structure was identified as hexagonal with c/a = 0.803. Pietrokowsky confirmed the existence of this phase7 and pointed out that the structure was isomorphous with Ti3Sn.8 Although the existence of Ti,A1 has been confirmed by others,9-12 there has been considerable disagreement regarding the composition and mode of formation. A detailed reinvestigation of the Ti-A1 system has been published by Sagel et al.13 The tentative diagram indicated two phases, a, and e, occurring in the former all a region. The a, phase has the same structure as Ti2A1 and was indicated as having a broad region of solubility. Epsilon, a tetragonal phase, was shown to form within the a, solubility region. AS a result of unpublished work,14 Ence and Mugy3 olin disagreed with the interpretation of Sage1 et al., although some common features existed. The present study was conducted in an attempt to clarify prevailing uncertainties. EXPERIMENTAL PROCEDURE Alloy Preparation—Alloys were prepared from iodide titanium (99.9 pct Ti with less than 0.01 pct Zr) or Bureau of Mines electrolytic titanium (BHN-73) and high purity aluminum (99.99 pct). Alloys were arc-melted in argon or helium atmosphere as 15-g buttons in the composition range up to 34 pct Al. Depending on need, alloys were made in increments varying from 0.25 to 2 pct Al. Up to five 15-g buttons of some compositions were made. Weight losses during melting did not exceed about 1 pct of the charge and chemical analysis revealed that both titanium and aluminum were evaporated. In general, nominal and analyzed compositions agreed within 0.5 pct and therefore nominal compositions were used in plotting the data. Unavoidably, some overlap of composition occurred, particularly where small increments of A1 were used. The small increments were primarily used to obtain alloys which would fall into the narrow a -, r region and this purpose was achieved. In general, the data obtained from Bureau of Mines base titanium and iodide titanium alloys were in agreement. Forging—Both as-cast and forged samples were employed. Samples were heated for hand forging by an oxygen-hydrogen torch to the region 1200" to 1300°C. A titanium anvil and cover plate were used to prevent any iron pick-up and consequent formation of a low melting point compound. Frequent reheating kept the temperature in the desired range. Under these conditions, alloys containing up to 15.5 pct could be successfully forged. To check on the depth of contamination, forged alloys were heated slightlybelow the ß transformation temperature. Metal was removed to a depth below the contaminated surface so revealed, and the subsequent results obtained from these samples agreed closely with those secured from as-cast material. Heat Treatment—Prior to heat treatment, all alloys were vacuum annealed to remove hydrogen. Samples

Jan 1, 1962

By Robert Burrows

IN preparing this paper the object has been to set forth facts relating to illumination problems, which, judging from the results realized in the iron and steel and other industries somewhat similar to mining, will tend toward furthering safety, production, and contentment of employees, as well as economy of operation in mines. By applying the principles of illumination with the assistance of modern appliances, the full benefits in efficiency may be derived from improvements already made in other details of mine operation. The lighting of a typical coal mine may be divided into four distinct parts: 1, The lighting of the buildings about the top; 2, the lighting of the working faces; 3, general illumination at the bottom; and 4, special applications of lighting. The lighting of buildings about the top may be treated in the same manner as that of any other industrial plant, for we have a boiler room, an engine and generator room, a forge, a machine shop, and a hoist room. These can be well and efficiently lighted by the use of 100-watt tungsten-filament multiple lamps with proper reflectors so spaced and suspended that a power consumption of from ¼ watt per square foot in the boiler room to 1 watt per square foot in the machine shop is obtained. The methods that apply to this kind of lighting have been ably treated by a number of authors,1 and for this reason a detailed discussion is unnecessary.

Jan 11, 1915

By R. W. Jordan, J. Winter, A. J. Goldman

Kirkendall diffusion of copper and nickel atoms across the bond interfaces, as well as oxygen diffusion in the core to the interfaces, are the mechanisms which control the variation in bond strength with annealing time at 1600°to 1800°F in the cupro-nickel clad copper Mint composite. The unequal mass transfer resulting from the high diffusion rate of copper in cupro-nickel compared with that of nickel in copper caused void formation in the core. Small voids also formed in the cladding after short annealing times. These may have been nucleated by nickel oxide particles which are formed by the dissociation of the cuprous oxide in the core and the movement of oxygen to the cupro-nickel interfaces. The bond strength drops to very low values for annealing time up to 3 hr when the void density is greatest. The increase in bond strength after 16 to 72 hr at 1600°F is a result of the decrease in the void density in the cupro-nickel cladding and the growth of grains across the interface. The void density decrease is attributable to grain boundary diffusion of vacancies to the surface. The abnormally large grains in the copper preclude a similar process from taking place in the core. THE solution to many engineering materials problems that cannot be satisfied by using a single metal or alloy is often attained by combining two or more metals in such a way that each component performs a different function, while the composite meets the overall requirements. The Coinage Act of 1965 authorized a changeover from the traditional 90 Ag-10 Cu dimes and quarters to a bimetallic laminate of 75 Cu-25 Ni clad on a copper core. Economic considerations as well as physical, chemical, and mechanical properties provided a basis for the selection of this composite as a substitute for the silver-bearing alloy. An extensive survey of alloys suitable for use as coinage was prepared by Battelle Memorial Institute for the U.S. Mint.1 It was found that the cupro-nickel/cop-per/cupro-nickel composite satisfied the required color, density, mechanical properties, corrosion resistance, electrical properties, and magnetic properties to make it completely acceptable to the general public and the vending machine industry. This investigation is part of a program to determine the feasibility of reclaiming composite scrap by thermally degrading the bond strength of the cupro-nickel clad copper laminate. The composite exhibits bond degradation and subsequent bond improvement during annealing in the temperature range 1600" to 1800°F. A study of the operative diffusion processes and the resultant structural changes was made in order to explain the observed variations in bond strength with annealing time. EXPERIMENTAL PROCEDURES AND RESULTS Bond Degradation. A measurement of the forces required to peel the cupro-nickel cladding from the

Jan 1, 1969

By J. J. Kanter

There has been much research and commercial development in recent years in the use of chromium and nickel in steels of various types, including those intended for high-temperature service. By "high-temperature steels" are meant those specifically designed for service at elevated temperatures in steam plants, oil refineries and other industries where high-temperature operations are conducted. This paper is devoted to some preliminary data on the effect of silicon on certain of the most popular chromium-molybdenum steels now being used in quantity by the refining industry and includes a short statement on the influence of copper in steels intended for high-temperature service. Uses of Silicon Next to oxygen, silicon is the most widely distributed and abundant of the earth's substances. Although classed as a nonmetal, it is highly important in the metallurgy of all steels, having been used for years as an efficient and economical degasifier and deoxidizer. Silicon is added to various steels in the form of ferrosilicon, generally at the end of the heat so as to avoid oxidation losses. With acid steels it is added in the furnace (also in the ladle) and generally with basic steels is added in the ladle, so as to avoid reaction with the basic lining through high-temperature acidic reaction with silica, which may be formed by oxidation of the silicon alloy. Several grades of ferrosilicon are available, containing, respectively, 15, 50, 75 and 90 per cent Si. By far the largest tonnage produced is the 50 per cent grade although the 75 and 90 per cent ferro-silicons are used as ladle and furnace additions in the manufacture of steels of high silicon content. The introduction of silicon into steel as an alloying element is well known in connection with high-yield-strength constructional steel for bridges, ships, car construction, etc., and it is also well known as an alloy-

Jan 1, 1938

By J. J. Kanter

There has been much research and commercial development in recent years in the use of chromium and nickel in steels of various types, including those intended for high-temperature service. By "high-temperature steels" are meant those specifically designed for service at elevated temperatures in steam plants, oil refineries and other industries where high-temperature operations are conducted. This paper is devoted to some preliminary data on the effect of silicon on certain of the most popular chromium-molybdenum steels now being used in quantity by the refining industry and includes a short statement on the influence of copper in steels intended for high-temperature service. Uses of Silicon Next to oxygen, silicon is the most widely distributed and abundant of the earth's substances. Although classed as a nonmetal, it is highly important in the metallurgy of all steels, having been used for years as an efficient and economical degasifier and deoxidizer. Silicon is added to various steels in the form of ferrosilicon, generally at the end of the heat so as to avoid oxidation losses. With acid steels it is added in the furnace (also in the ladle) and generally with basic steels is added in the ladle, so as to avoid reaction with the basic lining through high-temperature acidic reaction with silica, which may be formed by oxidation of the silicon alloy. Several grades of ferrosilicon are available, containing, respectively, 15, 50, 75 and 90 per cent Si. By far the largest tonnage produced is the 50 per cent grade although the 75 and 90 per cent ferro-silicons are used as ladle and furnace additions in the manufacture of steels of high silicon content. The introduction of silicon into steel as an alloying element is well known in connection with high-yield-strength constructional steel for bridges, ships, car construction, etc., and it is also well known as an alloy-

Jan 1, 1938

By Ingersoll Olmsted

Mr. D. H. BRowne's paper upon " The Distribution of Phosphorus in the Ludington Mine" (Trans., xvii., 616) has interested me very much, and perhaps I cannot give a better proof of that, interest than an account of my work and observations in the same direction while chemist of the Hudson River Ore and Iron Company. The ores of this company lie in a chain of low hills running northwest and southeast, about three miles back from the eastern bank of the Hudson river, below Hudson, N. Y. They occur in thick veins, with the characteristic Hudson river slate formation as hangingrock and foot-wall, and dip about 45' east, outcropping in many places near the top of the western slopes.

Jan 1, 1890

By H. M. Chance

One hundred and twenty miles of hard travel over steep ridges almost due east from Fayetteville, on the St. Louis and San Francisco Railroad, about 100 miles from Eureka Hot Springs, or 75 miles northwest from Batesville, will bring the traveller to the waters of the Buffalo Fork of the White river, in a wild, thinlysettled, heavily-timbered country, now being prospected quite actively for zinc, and known as the Buffalo or Rush Creek district. Excepting here and there a piece of bottom land, patented before the discovery of zinc, the land is unoccupied Government land, and subject to entry under the United States mineral laws. Claims are now being taken, 600 by 1500 feet, but a movement made this summer, if successful, will largely modify the position of claim-holders. A few claims are now being filed under the Placer Act on the ground that as the zinc occurs as a horizontal, sedimentary deposit, etc., it can only be properly so classified. The zinc occurs in limestone, which is at times so siliceous that

Jan 1, 1890

By M. M. Rao, P. G. Winchell

The growth rates of bainitic plates were measured at 400°C in Fe-Ni-C alloys containing 0.10 atom-fract~on nickel and 0.0012 to 0.0075 atonz-fraction carbon. The growth rates are adequately represented by where xc is nearly the atom fraction carbon of the bulk austenite and PXCy is nearly the carbon atom fractlon in the ferrlte of radiids p In equilibrium with austetzite. The form of the equation is that predicted by a model in which carbon diffusion in austernite controls the gvowth, but the numerical constatnt is two orders of magnitude below that suggested by the model. THE growth of bainitic plates in steel is often assumed to be controlled by the diffusion of carbon away from the advancing plate tip. This hypothesis predicts that the growth rate will increase as the carbon content of the austenite, xCz, is reduced toward the carbon content of the saturated ferrite comprising the plate tip, PxCY The growth rate should vary approximately as (xCg- pxCy)-1. Experimental observation of the growth behavior at low carbon levels should provide a significant test of this model. An alloying element in addition to carbon is required so that low-carbon austenite can be experimentally observed while undergoing bainitic transformation. Nickel was selected. The presence of nickel complicates the interpretation of the data in two ways: First, diffusion of nickel during the transformation would make analysis very difficult. Nickel is assumed immobile during the transformation. Second, nickel affects the solubility of carbon in ferrite and austenite in equilibrium. This effect has been evaluated.' At the completion of our experimental work Goode-now et al.2 published data in essential agreement with the observations to be reported here. Since their discussion is abbreviated and their data are scanty in the region of interest, we believe the present work is of significance. I) THE MODEL OF BAINITIC PLATE GROWTH The rate of lengthening of a plate is assumed to be controlled by the diffusion of carbon from the advancing ferrite-austenite interface into the surrounding austenite. The precipitation of carbides is assumed to be a secondary process. For ease of analysis the carbon-atom ratio,* pxCy, of austenite in equilibrium with ferrite which is convex with minimum curvature radius p, and the carbon-atom ratio, PxCY, of that ferrite in equilibrium with austenite are assumed independent of location on the ferrite-austenite interface. Since these carbon contents vary with the radius of curvature of the ferrite, p, their assumed positional independence must be held as an approximation. The consequences of these assumptions have been developed approximately by zener3 and Hillert,4 and the resulting equation for a platelet has been applied to bainite by Speich and cohen5 and Kaufman, Radcliffe, and Cohen.8 The Zener-Hillert equation* for plates is: The analysis of Hillert is supported by that of Hor-vay and cahn7 which involves no mathematical approximations but does include the assumption that the a/y interface coincides with an isoconcentration line. The solutions of Horvay and Cahn for elliptic paraboloids are replotted in Fig. 1. The shape of the paraboloid is expressed in terms of the ratio of the principal radii of curvature at its tip, A =p1/p2, which is also the ratio of the minor to the major axis of the elliptic cross section. The Zener-Hillert equation for plates is also plotted. The agreement is within a factor of two for (pxyaCr - xyC )/(xyC - PxCaY) between 0.5 and 100. This is the range of interest here and in most other work on bainite. The original form of the Zener-Hillert equation was the form given above with the right-hand side replaced by (pxCya -xCy)/(PxCya). This replacement is not appropriate here. 11) THE EXPERIMENTAL PROCEDURE Alloys were prepared and three kinds of experiments carried out. Continuous-cooling-transformation experiments were carried out on wires by measuring temperature and resistance during continuous cooling. Isothermal-transformation experiments were carried out on wires by measuring electrical resistance as a

Jan 1, 1968

By Matti J. Saarivirta

The relative machinabilities of the precipitation-hardenable Cu-0.9 pct Cr, Cu-0.25 pct Zr, and Cu-0.9 pct Cr-0.25 pct Zr alloys are improved from 18 to 80 pct by 0.75 to 1.25 pct Pb. The Lead also improves the tensile strength, hardness, ad resistance to softening of the Cu-Cr and Cu-Cr-Zr alloys. When the alloy containing 0.7 to 2.2 pct Cr, 0.10 to 0.25 pct Zr, 0.75 to 1.25 pct Pb, and balance copper is solution-annealed at 1000°C (1830°F) and then aged at 525°C (Y75°F), tensile strength of 65,000 psi, 16 pct elongation, 62Rb hardness, and 84 to 87pct IACS electrical conductivity are obtained. The copper base Cu-Cr, Cu-Zr, and Cu-Cr-Zr alloys have high electrical and thermal conductivities, high strength and resistance to softening at elevated temperatures, but their machinability is poor, i.e., close to that of the pure copper. In the manufacture of various components such as welding electrodes or electrical and thermal conductors it is ofter desirable that the alloy have good machinability for high production rates and long tool life. Thus, alloys that combine these properties may be used not only for existing applications, but for new ones where good machinability is a requirement. This investigation was undertaken to improve machinability without impairing other desirable characteristics of the Cu-Cr, Cu-Zr, and Cu-Cr-Zr alloys. These commercial alloys contain about 0.4 to 1.2 pct Cr, 0.10 to 0.25 pct Zr, and balance copper. Lead was selected as an element that should improve the machinability and possibly other characteristics of the alloy. WORK PROCEDURE This investigation began with a study of the effect of lead on the hardness, tensile strength, electrical conductivity, and machinability of the binary alloy containing 0.10 to 1.30 pct Cr and balance copper. This was followed by an investigation of the effect of lead on the Cu-0.1 to 0.4 pct Zr and Cu-Cr-Zr alloys. The alloys were made from initially oxygen-free copper and for comparison some castings were made from phosphorus-deoxidized Lake Copper. Commercially pure chromium, zirconium, and lead were used for alloying. In melting the chromium was added to molten copper at 1400°C (2550°F), the heat held for 15 min at temperature, and the temperature then lowered to 1350°C (2460°F) when the other elements were added. The alloys were held for 15 min at this temperature and cast into a cast-iron mold. One-kilogram, 3-in.-diam castings were made. An argon cover was maintained during melting and casting to prevent oxidation. The chemical compositions of the alloys are shown in Table I. The micro structure and properties of the alloys were studied in the cast and wrought conditions prior to and after various solution-annealing and heat-treating cycles. The relative machinability was determined as a function of the lead content and compared with the free-machining Cu-lpct Pb alloy. To determine the machinability, 13/16-in.-diam cast specimens were cut by a machine hack saw using a constant cutting speed of 50 fpm, a fixed feed force, and a new blade for each alloy specimen. Molybdenum highspeed steel saw blades, 0.032 in. thick with 14 teeth per in., were used in all tests. No cutting fluid was used. Five tests were made on each specimen and the average elapsed time per test was taken as a measure of the relative machinability for that alloy. The variation of cutting time for each alloy was less than 110 pct.

Jan 1, 1969

By M. C. Fuerstenau, D. W. Fuerstenau

Studies of the collection of alkali and ammonium halides utilizing vacuum flotation techniques and contact angle measurements show that ionic size controls the flotation of techniquesthese halides with amine salts measurementsas collector. Contact angles of air bubbles on sylvite in saturated brines were withaminemeasured salts asascollector.a function of such variables as collector addition, length of collector chain, and pH of the brine. No contact occurs between halite and an air bubble in brines containing dodecylammonium acetate as collector. LONG-CHAINED aliphatic amine salts have been used for the separation of sylvite (KCl) from halite (NaCl) by flotation.1,2 It is puzzling how these two minerals, which are so similar chemically and crystallographically, can be separated by this method. Gaudin" has postulated that the difference in floatability of halite and sylvite with salts of primary amines depends on ionic size: In the case of amine flotation, the cation would attach itself to the chloride. I have a speculation there, which I cannot prove, that the ammonium group, that is the —NH3 group in the amine, floats potassium chloride because the dimensions of this grour, as it has been measured in other compounds is almost identically the dimensions of the potassium ion, quite different from the sodium ion, and so it fits where potassium had been, in place of it and not attached to it. Apparently, because an aminium ion (RNH3+) is much larger than a sodium ion, it cannot fit into the lattice of halite. Taggart also has speculated that ionic size may control the floatability of sylvite.4 The object of this experimental investigation has been to test this hypothesis and to study what controls the adsorption of cationic collectors at the surface of sylvite. Since collection is to be approached from the viewpoint of ionic size, the ionic radii that are of interest in this work are presented in Table I. The values of the ionic radii of the ions listed in Table I, except NH4+, are those given by Pauling." Several different values for the radius of the ammonium ion have been given, but that of Goldschmidt6 seems to be preferred. The radius of the charged head of a dodecylammonium ion is assumed to be the same as that for the ammonium ion. Little experimental work has been reported in the technical literature concerning the separation of sylvite from halite by flotation. Guyer and Perren studied the separation by flotation of 50 pct binary mixtures of NaCl, KC1, NH,Cl, NaNO3, KNO3, K2SO4, and Na,SO, using either oleic acid or a sodium sul-fonate as collector.' It is possible to measure floatability under actual flotation conditions where all three phases, air- water-mineral, are present by vacuum flotation tests and contact angle measurements.9 Both of these techniques were used in the experimental approach in this paper. Experimental Method and Materials The vacuum flotation tests were run with glass-stoppered pyrex graduated cylinders. Twenty-five ml graduates were used to test the floatability of all salts studied except rubidium and cesium salts. For each test distilled water containing the desired collector concentration was saturated with the salt to be floated. Sufficient salt (—48 mesh) was added to leave about 2 ml of solids in the bottom of the graduate. After the graduate had been agitated several minutes to saturate the solution with air, a vacuum was applied. If the salt were floatable in the collector solution, the gas bubbles attached themselves to the particles, and the particles floated to the surface. In determining the floatability of the expensive Rb and Cs halides, the experiments were run in 10 ml graduates with about 11/2 ml of collector solution initially. Contact angles were measured in the usual manner except that the solutions had to be previously saturated with the mineral to avoid dissolution of the crystal. Solutions for studying contact angles were made by adding the desired amount of collector to a saturated brine, giving the collector concentration in molarity. The mixture was agitated until dissolution of the collector was complete, with the exception of those concentrations greater than about millimolar. At these high concentrations complete dissolution of the collector was impossible. The face of the mineral to be tested was a freshly cleaved crystal of halite or sylvite. The mineral was placed in the brine and conditioned with collector for at least 15 min, which was found to be long enough to obtain a maximum value for the contact angle. The temperature remained constant during each experiment. The experiments were run at 24°C ±2°C. For contact angle measurements, a crystal of halite from Carlsbad, N. M., was used. Several samples of sylvite were used in this work: a crystal of sylvite from Stassfurt, Germany; a crystal from Carlsbad, N. M.; and a crystal of chemically pure potassium chloride. Saturated brines were made from reagent grade chemicals and distilled water.

Jan 1, 1957

By M. Marciano, K. Kreider

Silicon carbide coated boron fiber (Borsic) reinforced aluminum composites were made which exhibit strength and modulus values predicted by the rule of mixtures. A successful technique for fabricating these composites consists of plasma spraying of monolayer filament reinforced tapes and subsequent diffusion bonding of these tapes into composites. The elastic properties of the composites were given by the rule of mixtures in reinforced directions. (The modulus parallel to the fibers was 32 x 106 psi for a composite with 50 pct by volume fibers. The other elastic properties for a composite with 50 pct fiber were transverse modulus = 14 to 16 X 10 psi, G = 9.5 x 106psi, and v,, = 0.23. Tensile strengths of over 190,000 psi were measured for the composites with 50 pct fiber and the average strength for these composites was 162,000 psi. These same composites had interlaminar shear strengths of 12 to 15,000 psi. Multidirectionally reinforced composites demonstrated the same reinforcement efficiency in strength and modulus as the uni-directimlly reinforced composites. Comrpessive strengths of composites with 50 pct by volume fiber were found to be greater than 250,000 psi. STRUCTURAL filamentary composite materials are being considered for use where high strength, high modulus, and lightweight materials are required. Metal matrix composites have been considered for use at temperatures ranging from cryogenic (aluminum stainless steel) to 6000°F (plasma sprayed tungsten plus tungsten fiber) and other requirements have been similarly diverse. Metal matrix composites offer high modulus and high strength in unreinforced directions, the ability to be joined by brazing or welding, and greater fracture toughness compared with the more easily fabricated resin matrix composites. This paper deals with the mechanical properties of aluminum boron composites, a system which is being considered for applications where lightweight, high modulus, and high strength are required at temperatures including those above the normal operating temperatures of resin composites. The boron fiber used in this investigation had an average room temperature strength of greater than 400,000 psi, a modulus of 58 x 106 psi, and a density of 0.09 lb per cu in. (2.6 g per cu cm).' The fiber used in the composites had a coating of silicon carbide to retard degrading reactions with the matrix at elevated temperatures. The coated fiber, which is sold commercially as Borsic: has been reported to have excellent resistance to degradation at temperatures up to 600°C in air and in aluminum2 and the same mechanical properties as the standard bare boron fiber. Fabrication of Composites. The composites were diffusion bonded from plasma sprayed monolayer tapes. These tapes were fabricated on a substrate of aluminum alloy foil which is incorporated in the composite matrix. The technique consists of winding a layer of fiber on the foil, and plasma spraying the balance of the matrix alloy over the windings which bonds all of the components together. Advantages of this process include the ability to achieve good fiber spacing, Fig. 1, the formation of a good bond between fiber and matrix (achieved during the plasma spraying), and the adaptability of the process for forming large and complex parts. This is particularly true when used with brazing foil backing which alloys low pressure bonding of the structural shape. PROPERTY EVALUATION TECHNIQUES Tensile test specimens, 5 to 7 in. long with a reduced gage section and ,030 to ,040 in. thick, were cut from composite sheets with a diamond saw. The gage section was .200 in. wide, while the gripped section was .240 in. wide and over 2 in. long in each grip. The standard gage length used was 1 in., however, transverse specimens (i.e., specimens with the fibers oriented 90 deg to the loading axis) were tested without a reduced section. Twelve specimens were also made with a 3-in. gage length but no significant effect of gage length was measured. The tensile test specimens were mounted in a fixture and aligned in friction grips using a 10X microscope. Unbonded foil doublers (0.010-in.-thick aluminum) were used to insure firm gripping with a minimum of damage to the fibers. The test specimens were transferred to the testing machine in a rigid fixture and mounted in the self aligning loading train. Testing was performed using a Tinius Olsen four screw testing machine with a torsion bar LVDT load

Jan 1, 1970

By T. T. Read

FOR the second time the Mineral Industry Education Division opened the sessions at the Annual Meeting by gathering at the Engineering Woman's Club, Sunday at 3 p. in., and, in spite of the informality of the hour, with a good attendance of representative men in the educational field. The chairman of the Division, Thomas T. Read, after briefly reviewing some of the more significant events of the past year, introduced H. P. Hammond, professor of civil engineering, Brooklyn Polytechnic Institute, a leading figure in the project of the Engineers' Council for Professional Development for accrediting engineering schools. Prof. Hammond made it clear that the project is not to rate engineering schools but to accredit them; not to arrange them in order of excellence, but to segregate them into two groups, those that are entitled to recognition as genuine engineering schools, and those that are not. About thirty schools in the whole country will presumably fall into the latter class; they are typified by an unnamed institution where the teacher of mathematics bears the title of Professor of Civil Engineering and the man who teaches chemistry that of Professor of Chemical Engineering, and having no engineering instruction except some elementary surveying, but still claiming in its catalogue to be an engineering college. While everyone would like to avoid the necessity of accrediting engineering colleges, it cannot be avoided, since the University of the State of New York, and several other agencies, are already doing it. If it cannot be avoided it is best that it should be done by a qualified agency set up by the national engineering societies, so that the results may command respect and general acceptance. It is for this reason, and this alone, that the accrediting committee of the E. C. P. D. has been set up. It is now ready to begin its task, and during-the coming year it will accredit the schools in two of the seven geographical districts into which the country has been divided, beginning with New England and the Mid-Atlantic States.

Jan 1, 1935

By Lucien F. Trueb

The microstructure of explosion-bonded pairs of similar and dissimilar metals has been investigated by electron microscopy. A review of the specific problems encountered and the methods used for obtaining surface replicas and thin-film transmission specimens of the bond interface is given. The bond area is mainly characterized by continuous and practically diffusionless metallurgical bonding. The very large shear stresses induced along the collision front of the plates being joined causes extreme grain elongation and a symmetrical pattern of subgrains in the bonding direction. The bond zone is also characterized by a very high density of dislocations and pressure-induced twins. Localized heating occurring during the cladding process can result in partial re-crystallization or the formation of thin layers of molten material. The force of precisely controlled explosions causing a high-velocity impact between metal plates has been used for several years to achieve metallurgical bonding between an extremely wide variety of metals. This method essentially consists of accelerating a plate to high velocity toward a stationary plate by a detonating explosive. Since the restrictions to bonding are not those encountered with conventional nethods, it becomes possible to bond pairs of metals having widely different mechanical properties that are immiscible or form brittle intermetallic compounds. Many applications of such composite metals are found in the field of corrosion protection as well as numerous other fields; for example, explosion bonding is being applied for fabricating the materials used by the United States Mint in the new sandwich-type coins. The primary condition for establishing a metallurgical bond is that absolutely clean metal surfaces be brought together. Any metal exposed to the atmosphere is covered with oxides, adsorbed gases, and other contaminants; even a very forceful impact of two such surfaces is not sufficient for bonding. Cowan and Holtz-man,"' who reviewed the dynamics of colliding plates in detail, showed that in order to achieve a good bond the explosion conditions must be chosen in such a way that the plate collision velocity is less than the sonic velocity, in which case no oblique shock waves are attached to the collision front. A pressure wave is then generated ahead of the collision line, and the material forming the colliding surface of each of the plates flows forward and is ejected in the form of a spray, the so-called jet. The dynamic elastic limit of the metals must be exceeded so that there is sufficient plastic deformation. At the point where the jet formed by the junction of the inner surface layers of both plates separates from the combined plates, the material experi- ences a very high shearing strain and the pressure can reach several hundred kilobars. This process strongly influences the microstructure of the bond zone as will be seen later. Behind the collision front, uncontami-nated layers of internal material are brought together under high pressure and are thus metallurgically bonded. I) STRUCTURE OF EXPLOSION BONDS The different types of explosion bonds that can be obtained depend on the explosion conditions, and have been investigated by Cowan and Holtzman,1'2 Holtzman,3 Klein; Bahrani and crossland,' and Buck and Horn-bogen. The preferred kind for practical applications is the so-called wavy bond, typical examples of which are given in Fig. 1 showing light micrographs of various metal-to-metal interfaces. In forming this type-- of bond the collision energy is mainly expended in jetting, the formation of waves, and localized melting. Beyond the crest of the waves, eddy-shaped areas are observed in which the two metals are mixed in a complex pattern of streaks. Cowan and Holtzmanl first proposed that this wavy pattern is analogous to periodic eddy shedding in the flow of a viscous fluid around an obstacle (Von Karman's eddy street). The mass of metal ahead of the stagnation point, which is associated with the jet and has forward momentum, plays the role of an obstacle and the eddies created in the flow of solid metal around the stagnation point are preserved in the final clad specimen. This idea has been reviewed more recently by Klein4 and the variables involved in the wave formation have been discussed in some detail by Bahrani and crosslands and Buck and Hornbogen.6 Several studies of the structure of explosion bonds by light metallography have already been published.1-6 Aside from the waviness and the eddies which were mentioned above, the most striking characteristic of the area in the vicinity of the bond interface is a very considerable longitudinal grain deformation which appears to be strongest at the metal-to-metal boundary and dies out as one moves away from it. Large twins are often observed within the deformed grains, and molten areas are found in the center of the eddy-shaped structures situated beyond the crest of the waves. The large hydrostatic pressures and shear stresses occurring at the interface modify the mechanical and chemical properties of the bond zone. Increases in hardness in this area have been reported by various authors.396 The defects along the interface can also cause a local increase of the chemical reactivity and thus might be expected to boost the etching rate. However, the effects of this preferential etching cannot be observed by light microscopy due to its inherently limited resolution power. The same limitation precludes the observation of morphological features directly along the bond interface as well as the interface itself. Furthermore, no information can be gained by light-

Jan 1, 1969

By E. B. Mayo

David LeCount Evans (Consulting Petroleum and Mining Geologist, Wichita, Kans.)-—Not only E. B. Mayo but also W. C. Lacy, who apparently urged the preparation of this analysis, is to be commended. Regional thinking of this type is needed to assure future success in the never-ending search for new mineralized and petroliferous districts. As is usually the case, here is a regional study that will be read by the mining geologist alone. It is ironic that several of the trends established in this study have suggested themselves in northern mid-continent, detailed, and regional studies. These, where established, have offered new keys to petroleum exploration and have provided a possible basis for unraveling a number of broad generalities. The oil geologists, active in Colorado, Kansas, and Oklahoma, would find much food for thought in Mr. Mayo's projections. To be more specific: 1) The parallelism between E. B. Mayo's Texas Lineament and the Amarillo Uplift, the Wichita Complex and the Arbuckle Complex of the Texas Panhandle and Southern Oklahoma is viewed with interest and appears especially significant when compared with the similar northwest trend of the Central Kansas Uplift, a major trend of production. 2) Considering the various northeast zones of Fig. 2, and with particular reference to Mayo's C-C, the Jemez Zone is on direct line with one of several northeast-southwest controls which the present writer has been using with some success in Kansas subsurface correlations. Considering zones of shearing, with no apparent vertical displacement, but suggesting strike-slip movement, because of the staggered effect on other features which cross such trends, Mayo's philosophy presents regional possibilities for lines of weakness, considered to this time of only local significance. 3) And, finally, in an area as distant from the Southwest as central Kansas, the north-south trends of the Fiarport-Ruggles anticline, the Voshel-Hol-low Nikkel-Burrton structures, the Dayton to Stut-gart trend, the north, slightly east trend of the Ne-maha structural complex, and others all seem to approach the north-south alignments, a through f, of Mayo's Fig. 3. Mayo's employment of structural intersections to pinpoint crustal weakness, to localize igneous activity and its accompanying mineralization is not, perhaps, a new concept, but it is a 1958 model, produced by tools improved from the ever-increasing accumulation of geological observations. The use of intersecting trends in petroleum geology is not a new idea, since much production in earlier days was encountered via the straight line projections of established trends to centers of intersection. A tragedy in this age of specialization is that iron curtains have been raised between groups, all seeking raw materials, all acolytes at the altar of structural geology, but all smugly content in and protected by the ivory towers of petroleum geology, engineering geology, mining geology, and geophysics. Mayo presents basic ideas which can stimulate mid-continent structural thinking and, in the case of cen- tral Kansas. he provides a key to replace the broad and overworked simple monoclinal, sinkhole-dotted, Karst topography credo, which is not finding its share of new oil in a state where the declining discovery ratio is disconcerting. The American Association of Petroleum Geologists would do well to add E. B. Mayo to its list of Distinguished Lecturers. Evans B. Mayo (author's reply)—In reply to David LeCount Evans' comments, it is pleasing to learn that some of the elements discussed in my paper may interest petroleum geologists as well as mining geologists. This should not be surprising, however, because the lineaments make up the framework of the continent, and the oil-bearing sediments must reflect to varying degrees adjustments of basement blocks along their boundaries. A further possibility that petroleum geologists must have considered is that the slow escape of heat from buried lineaments and their intersections has aided the separation of oil from the sediments and started the migration into traps. Regarding the specific points listed by Evans, the following are suggested: 1) The branch of Texas Lineament marked 1' (Fig. 3) is thought to extend eastward through the Capitan Mts., New Mexico, through the long Tertiary dikes east of Roswell, and beyond via the Matador and Electra ranges of the Red River Uplift, Texas. Its further continuation might be the eastern flank of the Ouachita Fold Belt. The Amarillo-Wichita-Arbuckle zone of uplifts appears to continue east-southeastward the Spanish Peaks belt (3-5, Fig. 3). The northwest-trending Central Kansas Uplift would not belong to the above set, except insofar as the Central Kansas Uplift is traversed by west-northwest folds, possible continuations of the Uinta belt (5-5, Fig. 3). 2) The possible continuations into Kansas of the Jemez zone are new to me and are most welcome suggestions. 3) Most of the nearly north-south Kansan structures mentioned by Evans are unfamiliar to me, but the Nemaha Uplift itself appears to be part of a very pronounced structure traceable from the Cerralvo Fault Zone, south of the Rio Grande, through the Bend Arch, Texas, and the Nemaha Uplift, into the Pre-Cambrian of Minnesota (?). This nearly meridional zone is crossed and broken by the Rio Grande Embayment and by the Red River-Wichita Syntaxis. Petroleum geologists realize the economic importance of these features. Perhaps it is inevitable that some papers of general interest be buried in the journals of specialized groups. Moreover, papers dealing with regional, or lineament, tectonics and its applications to exploration for economic mineral deposits are as yet few in the American literature. The opportunity to advance this field is open to all those who are not ultra-conservative and who have a lively curiosity, plenty of patience, and not too many business restrictions. In conclusion, much appreciation is extended to D. L. Evans for his comments.

Jan 1, 1960