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By F. Ernest Brackett

Much new data on the flow of gases have been discovered by recent experiments by the United States Bureau of Mines and others. Although additional investigation is still desirable, the information now collected seems sufficient to attempt a tentative coördination of the friction factors. This study is confined entirely to fluid friction when the density throughout the duct is so nearly constant that it may be so considered. In the subsequent discussion the following notation is used: v = mean velocity of fluid in duct, feet per second. v' = mean velocity of fluid in duct, meters per second. R = hydraulic radius of duct, feet. R' = hydraulic radius of duct, meters. S = the hydraulic slope. P = pressure absorbed by friction, pounds per square foot. p = pressure absorbed by friction, pounds per square inch. p' = pressure absorbed by friction, kilograms per square centimeter. A = sectional area of duct, square feet. O = perimeter of duct, feet. L = total length of duct, feet. L' = total length of duct, meters. d = diameter of a cylindrical duct, inches. w = density of the fluid, pounda per cubic foot. g = specific gravity of the fluid compared with water = w % 62.4. C, k and B, coefficients for formulas using English measures. C' = metric coefficient, v' = C'R'S. n = coefficient of roughness for English or metric units. The basic formula for the flow of all fluids at constant density appears in the three following forms, which may be denominated: (a) The slope formula, v = CRS (b) The ventilation formula, " n = (c) The pipe formula, C is Kutter's coefficient, which is extensively applied to the flow of water in ducts and channels of all kinds; E is Atkinson's coefficient, used principally with air in ventilation problems; B is a coefficient conveniently adapted to studying the flow of water, gases and vapors in pipes. 312

Jan 1, 1927

By G. S. Phipps, E. E. Schumacher, G. M. Bouton

THE seriousness of the present tin scarcity has stimulated large consumers of this vital metal to develop drastic conservation measures in order to extend the available supplies to cover the emergency period. By devising new soldering methods and alloys the Bell System has contributed a substantial share in the tin conservation effort, Fortunately, the changes, as far as can be determined now, have not introduced weakness into the soldered joints. Some of the new procedures were already in the process of development at the onset of the emergency, while others were devised under its stress. In some instances, the newly developed solders were found to be more difficult to use than the alloys previously available, and would not have been introduced under normal conditions. One major change made that previously had been under consideration will result in large savings of tin. Unless service difficulties are encountered, this modification gives promise of remaining after the emergency has passed. The change involves a reduction in the amount of solder placed on a wiped joint between the cable sheath and the sleeve. Instead of the customary full sized wiped joint, a wipe of fillet proportions is formed. Through this change, a solder saving of more than 60 per cent per joint can be realized. Plumbers and cable splicers for many years have joined lead pipes and cable sheath by a soldering process called "wiping." The name is an apt description of the operation. For a wiped joint, the sections to be united' are heated by molten solder poured over their surfaces, and the resulting semiliquid mass is manipulated by wiping with cloth pads to a well rounded symmetrical form like the one shown in Fig. I, The operation requires considerable skill on the part of the splicer and close control of the composition of the solder. At first consideration, the problem of tightness in such joints seems simple but experience shows that even under the best conditions the fissures frequently found in the solder occasionally link and form a path that allows leakage to occur. In telephone cables not maintained under gas pressure, such leaks permit the entrance of water, which wets the paper-covered conductors and thereby impairs the insulation value and causes service interruptions. By going to an extreme and wiping off all the solder in excess. of a fillet, it has been found that many causes of porosity are eliminated. Figs. 2 and 3 show cross sections of joints wiped in the old and the new ways. The saving in solder, and consequently in strategic tin, is evident. The field splicing forces find that joints are easier to make by the new method and are less likely to be porous. The metallurgical considerations that are responsible for the success of the fillet wipe are of interest. Much has been written about the wiping process of soldering cable joints and the many requirements of a good wiping solder have frequently been listed. The success of the procedure described

Jan 1, 1943

By G. W. P. Rengstorff, L. E. Olds

High purity molybdenum ingots containing controlled amounts of a single impurity element (oxygen, nitrogen, or carbon) were prepared. These ingots were tested for ductility by bending test specimens at various temperatures. The relationship between the plastic behavior of the ingots and their chemical composition has been determined. MANY proposed applications for molybdenum require ductility at or near room temperature. At the present time, it is possible to obtain wrought molybdenum with considerable ductility only if special fabrication techniques are used to control the grain structure. Starting with are-cast or powder metallurgy ingots, the usual methods for obtaining ductility rely on fabrication procedures that result in fibered microstructures in the finished product. Recently, it has been found that the ductility of either powder metallurgy or are-cast molybdenum can be improved by uniform recrystallization of the metal to a very fine equiaxed grain structure.' The need for a fibered or a fine grained structure may limit the practical usefulness of molybdenum. For example, welding. which may be used in fabricating the metal, generally produces coarse grained structures that lead to brittleness. This applies, certainly, to currently available commercial molybdenum. Although commercial molybdenum is brittle when the grains are coarse, it has been shown experimentally that fine grained structures are not always essential for ductility. For instance, as-cast molybdenum with a coarse columnar grain structure is ductile if it is sufficiently pure.' Because high purity cast molybdenum has good ductility even when coarse grained, it is probable that the brittleness in coarse grained commercial molybdenum is caused by the impurity content of the metal. Although the general effects of impurities on the cold ductility of molybdenum have been known in a qualitative manner for some time, no quantitative evaluation of these effects has been available. The present investigation was made in order to determine more accurately the effects of oxygen, nitrogen, and carbon on the cold ductility of cast molybdenum. Oxygen has long been known to be detrimental to ductility, although the minimum amount which will embrittle molybdenum has been open to speculation. Parke and Ham" showed that ingots with oxygen contents above 0.003 pct could not be forged. Maringer and Schwope have described the embrittle-ment of molybdenum wire by oxygen. A discussion on the effects of heat treatment on the distribution of oxygen in molybdenum has been given by Perry, Spacil, and Wulff." Although nitrogen would also be expected to have harmful effects on ductility, no extensive work has been done previously to determine whether this is so. However, Tury and Krausz" found that wires presumably with less than 0.007 pct N were brittle. Carbon is added to commercial cast molybdenum for deoxidation. Parke and Ham" have shown that molybdenum containing as much as 0.06 pct C could be forged if the oxygen was kept below 0.003 pct. Also, Bruckart and others' found that the room temperature ductility of sintered molybdenum improved with carbon contents up to 0.84 pct. However, Rengstorff and Fischer' found that residual carbide particles in cast molybdenum apparently had an unfavorable effect on room temperature ductility.

Jan 1, 1957

By W. A. Doble

Opinions differ as to whether the water-wheel almost universally known as the Pelton type belongs to the impulse, the tangential, the reactive, the jet or the percussion class, or to a cross between two or more of these classes. The fact is, that for an almost infinitesimal part of a second the axis of the jet of water strikes the bucket of this wheel at a true tangent to its base-line. The percussion of the water, striking the bucket, imparts an impulse to the wheel, causing rotation; and generally the bucket is so shaped that the direction of the jet is

Jan 1, 1900

By S. Vela, R. M. McKinley, L. A. Carlton

Johnson et al. have described a new well-testing technique that measures formation flow properties between wells.' The technique, called pulse-testing, requires a sequence of rate changes in the flow at one well and measzcrement of the re.rulting pressure changes at an adjacent well with a very sensitive differential pressure gauge. This paper describes an extensive application of the technique in a producing oil field. Pulse-tests on 28 of 45 possible well pairs in the field provided a picture of the areal distribution of reservoir hydraulic diffusivity, trans-missibility and storage. The primary objective in presenting these data is to demonstrate the potential of the methcid for reservoir description. A second objective is to show in three ways the qualitative and quantitative accuracy of reservoir parameters determined from pulse-tests: (I) pulse-test data show a nonuniformity in the field, closely correlating with the oil-water distribution as given by production data: (2) pulse-test values for permeability are comparable with core va1ue.s; and (3) perhaps most important, the field responds to a conventional interference test in the manner in which pulse-test data predict it should. The pulse-testing technique by Johnson et al.' is an ideal source of data for purposes of reservoir description, for it provides a measurement of formation storage S = +ch, hydraulic diffusivity 91 = k/+cp and transmissibility T — This paper describes an application of this method in a producing oil field. Results were analyzed to give numerical values for the parameters 7, T and S. These values were compared with oil-water production data (for the effect of fluid saturation), with core data and with data from an interference test. The reservoir in which the pulse-test survey was run is the result of a structural trap formed by a fault along the east side of a north-south trending anticline. A down-structure aquifer providcs a natural flank water drive for the pool. The producing formation is a dolomitic lime- stone having mainly vugular permeability; the formation oil has a gravity of 29" API with negligible dissolved gas. The field contains 19 wells, all on pump, arranged on 40-acre spacing along the top of the anticline. Fig. 1 shows the location of all these wells except two at the south end of the field. The dashed line on the right-hand side of the figure represents the approximate location of the fault with respect to well positions. Pulse-Test Survey and Analysis of Data A pulse-test requires a pulsing well and a responding well. In the field, changes were made in the rate of flow at the pulsing well by stopping and starting the pump periodically and measuring the corresponding pressure

Jan 1, 1969

By Paul F. Gnirk

INTRODUCTION The notion of permanent disposal of high-level radioactive waste in natural salt formations was formally proposed in 1957 by the Committee on Waste Disposal of the National Academy of Sciences- National Research Council. This proposal was the result of the Committee's deliberations in response to a request from the U.S. Atomic Energy Commission (AEC) in 1955 to assess the viability of geologic formations for such disposal. The research investigations for waste disposal in salt were initiated at the Oak Ridge National Laboratory (ORNL) in the late 1950's and continued through the 1960's and early 1970's at a relatively modest level of funding. During the period of transfer of Federal Administrative authority from the AEC to the Energy Research and Development Administration (ERDA) to the Department of Energy (DOE) during the latter part of the 197O’s, financial support for the research program was enhanced substantially. The program at OWL was regrouped under the Office of Waste Isolation (OWI) and later transferred to the Office of Nuclear Waste Isolation (ONWI) at Battelle Memorial Institute. With this enhancement in the research program, consideration of basalt, granite, shale, and tuff as repository host media was initiated. In February, 1980 the President of the United States established officially a comprehensive waste management program which called for the selection of the first repository site in 1985 from a suite of four or five potentially suitable sites, and initiation of a repository operation at that site in the mid-1990's. The current disposal system concept involves the emplacement of radioactive waste packages in mined disposal rooms at depth in suitable geologic formations, with closure of the facility effected

Jan 1, 1983

By Michael Perch, Charles C. Russell

Nearly 75 per cent of the total coke production in the United States in 1940 was consumed in blast furnaces. In 1939 the percentage was 69.9, and in 1938 it was 61.3. To produce a net ton of pig iron 1757 lb. of coke was required in 1940 and 1760 lb. in 1939. These figures indicate how dependent the production of pig iron is upon the production of coke. The rate of iron production is in some measure influenced by the physical and chemical characteristics of the coke. Blast-furnace operators believe that the physical properties of coke profoundly influence the operation of the furnace. Although it is true that coke of a wide variety of physical properties is used in American blast furnaces, the periodic fluctuation of these properties is one of the causes of irregularity of blast-furnace operation. The purpose of this paper is to present a broad picture of the physical properties of by-product coke that are generally considered to be important by coke-oven and blast-furnace operators. Effects of the kind of coal used, the preparation of the coal, the rate of coking, and other factors will be considered. Of all these variables, the kind of coal used is by far the most important. In this discussion use will be made of the method of coal classification by rank' standardized by the American Society for Testing Materials. Although this method of classification has been an American stand¬ard for several years, it has not been given the attention it deserves, especially in connection with the selection of coal for production of coke. Despite the fact that many producers of blast-furnace coke are limited to some particular source or sources of coal, a good understanding of the principles involved in setting up the standard method of classification may lead to a better appreciation of the causes of changes in coke characteristics. Furthermore, where it is necessary to select new coals as a substitute for the original supply, this method of classification can be of great assistance. The data presented have been gathered from many sources, but no attempt has been made to cover the vast literature. Instead, some of the more important data have been selected to show how coals and their carbonization affect some of the physical properties of coke. It must be emphasized that generalizations concerning the behavior of coking coals are presented and that individual coals may vary widely from the specific behavior depicted. Nevertheless, it is believed that the data illustrate certain typical behaviors. Neither was it possible to cover completely all the factors involved; for example, the macroscopic constituents of coal are believed to have important effects on the physical properties of coke, but since there is little information available for such study, and since vitrain, clarain, and durain are neither

Jan 1, 1944

By F. R. Hensel

PURE silver and silver-lead alloys have been studied as to their suitability for bearings.1-8 A review of the properties of thallium and the silver-thallium constitutional diagram was made by the author to analyze the possibilities of silver-thallium compositions for antifriction materials.† The silver-rich end of the diagram as reported in the literature9-11 was found to be sketchy and it was necessary to carry out considerable experimental work to arrive at definite conclusions. Some of the results of this work are reported in this paper. TEST MATERIALS In the beginning of the work, only fused alloys were investigated. Later, research [TABLE I. Composition of Fused Silver thallium Alloys Tested for Antifriction Properties PERCENTAGE ALLOY No.OF THALLIUM 15330.48 153406 231 HT2.04 2312.10 232 HT3.83Balance 2324.07Silver 233 HT5.86 2336.38 2349.84 234 HT10.07] was carried out on electroplating methods and diffusion processes. In preparing the fused alloys, care was taken to exhaust the toxic fumes caused by the thallium content. The compositions of the series of fused alloys are listed in Table I. The silver-thallium alloys were melted in clay-graphite crucibles and cast into preheated steel molds of 3/4-in. diameter. In the cast condition, they showed a cored structure, as indicated by the micrographs of Figs. I to 3. The etching reagent used was a mixture of 2 grams K2Cr2O7, 8 c.c. H2SO4, and 100 c.c. H2O. The cored structure is unsatisfactory for the type of corrosion resistance required for bearing applications, and homogenizing experiments were carried out at various temperatures, the results of which are shown in Figs. 4 through 8. The alloys with a lower thallium concentration, which were heated for 2 hr. at 525°C. show an almost completely homogenized solid solution type of structure. With higher thallium concentration, the homogenizing temperature was dropped to 475°C. to eliminate the formation of a liquid phase. It is evident that heating for 2 hr. at this temperature did not result in complete elimination of the cored structure. As would be expected, cold-working of the cast structure is an expedient in establishing equilibrium conditions. The fine homogeneous grain structure shown in Fig. 7 corresponds to the cold-worked area under the Rockwell ball penetration when the hardness was taken before heat-treatment. A detailed structural study was made on a cast silver-thallium alloy containing 3.67 per cent thallium. Three micrographs (Figs. 9, 10 and 11) show the transition

Jan 1, 1945

By James A. Soles

Concrete is a complex, multicomponent mass whose stability is dependent on three principal variables: quality of the mix, its composition, and environment of the site. The aggregate is only one component, but its constituent minerals may react in unfavorable regimes and, given sufficient time, destroy the concrete. Therefore, besides ensuring that a concrete will meet the strength requirements of a structure, the concrete engineer must be confident that the mortar and aggregates will resist destructive processes. This paper reviews the principal causes and effects of aggregate instability, notes reactions of certain phases, and suggests precautionary measures that can be taken to extend the useful life of concrete structures.

Jan 1, 1984

By Fred Bond

THE process of comminution by grinding is properly classified as an art, rather than as a science. Like most other operations concerned in ore dressing, or in the treat-ment of nonmetallic minerals, the mathe-matical relationships of rock breaking are still obscure, and much disputed. If some basic formula exists, comparable for in-stance to E = RI in electricity, it has not yet been placed in common use. The absence of such a comprehensive mathe-matical background undoubtedly is the cause of many inefficient designs and installations, as well as of much poorly oriented experimental work. On the other hand, the mathematical immaturity of the process constitutes an opportunity for a real contribution on the part of those who enjoy mental pioneering. Some of the statements made in any such exploratory work may be little more than opinions, and it is to be expected that some will later be proved untrue; but such an evolutionary development is necessary if we are ever to arrive at the fundamental laws, the discovery of which can change the empirical art into a mathematically exact science. The most significant principle of com-minution that we possess is probably Rittinger's law, which states that the work done in crushing or grinding is proportional to the area of the new surface produced. There is an alternative theory, known as Kick's law, which formerly was preferred to Rittinger's but which now is rather dis-credited. According to Kick, the work done in comminution is proportional to the volume, or weight, of the pieces broken, or to the cube of their diameters, while accord-ing to Rittinger it is proportional to the square of the diameters.

Jan 1, 1940

By T. V. Philip, Paul A. Beck

IN a previous note1 it was pointed out that the available information suggests a distinct correlation between the occurrence of the CsCl-type ordered structures formed in equi-atomic binary alloys of transition elements and the location of the components in the periodic table. A definite increase in the bond strength between unlike atoms, as compared with that between like atoms, is indicated when, in binary alloys of iron group elements, the other component is changed from chromium to vanadium or tantalum, to titanium. Laves and Wallbaum,2 eported a CsCl-type ordered structure for the stable intermediate phase at the equi-atomic composition in the Ti-Fe system (and also in the Ti-Ru and Ti-Os systems). On the other hand, Tagaya, Nenno, and Nishiyama8 found no ordering of this kind in the body-centered-cubic solid solutions in the Cr-Fe system. It was concluded' that the occurrence of a CsC1-type ordered phase of intermediate stability may be expected in the V-Fe system. Preliminary results were described: suggesting that at least some degree of order does exist in the equi-atomic alloy VFe, annealed at 1200° C and quenched in cold water. Using CrK radiation, at least one weak superlattice line was found in the X-ray diffraction pattern which could be indexed as (100). and which disappeared, as expected, when FeK radiation was used. It was found more recently that the impurity phase (presumably VN), previously giving rise to additional X-ray diffraction lines and thus preventing definite indentification of the (111) superlattice line,' can be eliminated by preparing the alloy by arc melting in a helium atmosphere. The alloy specimen melted in this manner had clean surfaces and showed very littte, if any, nitride phase in the microstructure after annealing in vacuum at 1250°C and quenching. The relative intensity of the (100). superlattice line with CrK radiation was greatly increased and, in addition, a fairly strong (Ill) , superlattice line and even a detectable (210) , super- lattice line was obtained, when the powder produced by filing from the 1250°C annealed and quenched specimen was reannealed in vacuum at 625°C for 1 hr. By using a cellulose acetate film as a filter in front of the photographic film in order to absorb the soft radiation resulting from air fluorescence, the background intensity could be reduced considerably in relation to the intensity of the diffraction lines. All three superlattice lines, (100),, (111)., and (210)a, disappeared, as expected, when a radiation other than CrK, was used.1 For the powder reannealed at 625ºC, the strongest lines of the s pattern also appeared weakly, indicating that during an: nealing at 625°C a small amount of transformation took place from the body-centered-cubic to the u phase. However, since all superlattice lines to be expected in the 0 angle range used were actually very clearly present, it was evident that the high temperature body-centered-cubic phase had transformed into a CsCl-type ordered structure before much s phase could form. Reannealing filings for 1 hr at 700°C resulted in complete transformation into the u phase. After 1 hr at 650°C the transformation into IT was not quite complete, the strongest body-centered-cubic diffraction lines were still present, although fairly weak, and only the (100), super-lattice line was detectable (extremely weak). These findings not only confirm the previous conclusionsL as to the existence of a CsCl-type ordered structure in the Fe-V system, but they also indicate that this metastable ordered structure forms at about 600°C preceding the formation of the stable s phase, while at 1250°C the disordered body-centered-cubic phase is stable. The faint (loo) , super-lattice line previously observed in specimens quenched from 1200°C was probably due to the fact that the quenching of the powder in an evacuated fuse:! quartz capsule was not fast enough to prevent completely the ordering reaction on cooling. The present results conform with the suggestion that the A-B bond, in relation to the A-A and B-B bonds, increases in strength from CrFe to VFe to TiFc. It is, therefore, of interest to compare the measured values of the average atomic diameter for these three alloys with the corresponding average atomic diameters calculated from the atomic radii of the elements concerned. ASSUming A-B contacts

Jan 1, 1958

By J. B. Wagner, p. Hembree

The iron tracer diffusion coefficient of umstite has been measured at 110(fC across the phase field and at a single composition at 800°C. Assuming a simple cation vacancy model the tracer diffusion coefficient was found to be a linear function of the cation vacancy concentration at 1100°C. The equation is D = 3 x 20 29 where denotes the concentration of vacancies in numbers per cc. The tracer work at 800°C was carried out to investigate the reported "pinning" of tracer to the wustite surface at low temperatures. No evidence for the "pinning" of the tracer was found at 800°C in COz-CO gas mixtures. HIMMEL, Mehl, and Birchenall,&apos; Carter and Richardson,2 and Desmarescaux and La combe3 have measured the diffusion of iron tracer in wustite at several temperatures and compositions. The present work was undertaken to extend the measurements over a large composition range at 1100°C and to resolve certain apparent discrepancies in the data, expecially at lower temperatures. EXPERIMENTAL Wustite was prepared by oxidizing rectangular iron plates* in C02-CO mixtures. The samples were •The iron was supplied by the Battelle Memorial Institute courtesy of the American Iron and Steel Institute. The analysis is presented in Table I. quenched. Due to the inward flow of cation vacancies during oxidation, the center of the sample contained a thin void. The edges of the wustite slab were sanded until the sample could be split into two parts. Each part was then sanded on the front and back flat area until a smooth surface was obtained. The specimens were then replaced in the furnace and equilibrated at llOO°C in a predetermined COa-CO mixture by methods described elsewhere.4"6 The specimens were again quenched and the surfaces were lightly sanded to remove any roughness following the first equilibration. The specimens were then reequi lib rated in the same C02-CO mixture for thirty minutes in order to relieve any mechanical damage on the surface due to the polishing. The specimens were then quenched and the tracer was applied by an electroplating technique. The work of Carter and ~ichardson&apos; demonstrated that there was no systematic difference in the iron tracer diffusion coefficient in wustite if the tracer was plated, dried, or evaporated on the specimen. In the present study a piece of filter paper was saturated with an iron chloride solution of pH <* 3 that contained the tracer FeS5. The wustite was placed on the filter paper and made the cathode. A current density of 0.4 to 0.6 ma per sq cm was passed for about five to ten minutes. The thickness of the tracer layer was estimated to be about 7 x lom6 cm. This estimate was made by considering the area plated, the current flow, and time for plating and the activity of the iron in the plating solution. Different areas of the specimen were counted using a collimator to determine the uniformity of the tracer. Any specimen which exhibited a variation from the initial count rate (about 1500 cpm) by more than 15 pct was rejected. An estimate of the time necessary to convert the thin layer of iron tracer to wustite was made using the data of Pettit and wagner." he estimated time was 1 sec at 1100°C assuming linear oxidation kinetics. The shortest diffusion anneals were 1800 sec. The samples were suspended in the hot zone of a furnace by two platinum wires. Two separate specimens were run at the same time. Only the edges of each sample were in contact with the wires. The C02-CO gas of the same composition as that used in the pre-diffusion anneals flowed freely around the samples at a linear velocity of 0.9 cm per sec. To initiate a run, the specimens were lowered from the cold zone of a furnace to the hot zone by a magnetic lowering device." bout 60 sec were required for lowering. To terminate a run, the sample was withdrawn from the hot zone to the cold zone. Time zero for the beginning of the experiment was taken when the sample blended into the red glow of the furnace and conversely for the end of the experiment. The surface decrease method of measuring the tracer diffusion coefficient was used to collect the data. This method requires that counting geometry be reproducible because the specimen is counted before the diffusion anneal and after the anneal. A special jig was constructed for each specimen so the specimen could be removed from the jig and returned to the jig such that the well geometry was reproducible.

Jan 1, 1970

By H. K. Work, H. B. Emerick

IN the past year the steel industry underwent an abrupt conversion from a war tempo to a highly competitive peacetime schedule. It is still too early to gain a comprehensive picture as to which of the measures in production metallurgy, that made the war effort so successful, will remain in the postwar production of steel, but many of them undoubtedly will fill an important place after the war. Considerable speculation has developed regarding the disposition of the war-born production facilities of the steel industry. These include new open-hearth and electric furnaces, as well as vast numbers of auxiliary, supplementary, and balancing units that increased and speeded up production beyond the normal capacities of existing melting furnaces and finishing mills. Although these facilities were installed primarily to help meet war requirements, consideration was also given, in planning, to their possible peacetime use. The new equipment is generally modern and efficient, and it seems reasonable to suppose that strategically located units will gradually be absorbed by various steel companies to supplement their own facilities, or to replace in kind, obsolete and inefficient equipment now ready to be scrapped. Some, however,

Jan 1, 1946

By AIME AIME

LAST month we published (p. 440) the first half of the L discussion by O. E. Kiessling of the paper on copper by Mr. Vogelstein that appeared in the same-issue, but lack of space made it necessary to hold the remainder for this number. Mr. Kiessling now asks to have the last " sentence of the part already published revised to the form given in the first sentence which follows, and also asks that the two parts, though necessarily published separately, be read together, as a mistaken impression may be derived from the first Dart unless it is read in connection with the statement of the Bureau of Mines policy respecting secondary metals which is here published. .

Jan 1, 1931

By J. L. Perry

FOR many years, you and your fellow members of the American Institute of Mining and Metallurgical Engineers have devotedly and ably applied yourselves to the art of making iron and steel. having foremost in your minds the conservation of raw materials, suitable and efficient facilities, economical processes, and improved quality of product. For the past three strenuous years you have contributed wholeheartedly to meeting the problems of increased production. You have conducted scientific and technical investigations and research, recommended experiments. and gathered all the available and valuable information possible to gain the desired objectives. You have had many obstacles and difficulties to overcome. In the early days of your organization, there was some lack of co-operation from the industry itself-perhaps, for example, some failure to recognize the mutual advantages of free exchange of experiences and information. But regardless of any hindrances, you have made many and valuable contribution which have tended to make iron and steel manufacture leas of an art and more of a science.

Jan 1, 1944

By W. M. Tuddenham, R. J. P. Lyon

In many areas surrounding the orebodies in mining districts rocks have been bleached and altered by the ore-forming solutions and have been oxidized during later weathering processes. A number of the rock-forming silic-ates have been broken down to clay, sericitic micas and chlorites have been developed, and pyrite may be found hundreds of feet outside the economic limits of the orebody. These halos of altered ground are prime targets used by geologists in many districts to delineate promising sites for drilling. Both in the field and in the laboratory it is often difficult to map these mineralogical changes in the halos in detail without numerous petrologic examinations. The secondary minerals are generally fine-grained, and since conversion of one mineral to another is often progressive, many alteration processes have not proceeded to completion (feldspars to clay to sericite mica). Qualitative detection of these minerals is difficult; quantitative determination is frequently impossible.

Jan 1, 1960

By M. H. Merriss

IN THE last few years, there have been developed at the plant of the Nichols Copper Co., Laurel Hill, Borough of Queens, New York City, improvements in electrolytic copper refining by the series system that have materially increased the flexibility and economy of that system. The purpose of this paper is to discuss, as of interest to refiners and to those who have copper to refine, as well as to the engineering profession in general, the changes that have taken place resulting in wider application and increased efficiency of the series system. Copper is electrolytically refined in two ways, which are spoken of as the "multiple system" and the "series system." In both systems, the electrolytic tanks are in series electrically. In the multiple system the electrodes in a single tank are in multiple or in parallel, thus: In the series system, the electrodes in a single tank are in series, thus: There are two important adaptations of the series process, one represented by the series electrolytic tank room at the Baltimore Copper, Smelting & Rolling Co., Baltimore, Md., and the other by that of the Nichols Copper Co.&apos;s plant. At Baltimore, the anode is rolled to perfect

Jan 6, 1925

By Eugene S. Meieran

The effects of methods of crystal growing, wafer sawing, polishing, routine handling, diffusion, and epitaxial growth on the defects in GaAs are reviewed and studied using reflection and transmission X-ray topographic techniques. In general, it was found that boat-grown crystals exhibited fewer defects than Czochralski crystals, although all crystals showed large numbers of precipitates visible when examined in the electron microscope. Mechanical surface treatments such as sawing and mechanical polishing introduce damage to a depth of about 5 µ, most of which can be removed by suitable chemical or chem-mechanical polishing. In addition, defects can be introduced through routine handling of wafers, for example with metallic tweezers. These defects can be quite severe, and have been observed 20 µ below the wafer surface. Defects can also be introduced through diffusion and epitaxial growth. These defects, which include precipitates, growth pyramids, stacking faults, dislocations, and so forth, can be detrimental to device fabrication. It is shown that wafers or films which appear defect-free optically can contain defects visible in the X-ray topographs. WHILE the use of GaAs in the semiconductor industry has increased very rapidly in the last few years, due mainly to the recent development of many important GaAs devices,1,2 the major limit to the production of commercial quantities of many GaAs devices remains a severe lack of suitable materials technology. This lack is apparent in two critical areas. First, production quantities of high-quality GaAs crystals, reproducibly doped and precipitate-free, simply are not available commercially, although some reasonable quality material is available on a limited first-come, first-serve basis. Second, in comparison to silicon technology, little is known about the effects of processing variables on the defects either present in as-grown GaAs or introduced through processing and handling of wafers. These areas are now receiving some attention from semiconductor device manufacturers, who are studying defects in GaAs in order to better understand how either to prevent their occurrence or to cope with their existence. Most investigations of the defects in GaAs have been made by optical microscopy3-5 or transmission electron microscopy techniques.&apos;-&apos; Recently, however, the imaging techniques of X-ray topography, electron mi-croprobe analysis, and scanning electron microscopy are being applied to the study of GaAs.9-14 In the case of X-ray topography, a one-to-one image is obtained that must be photographically enlarged. In compensa- tion, the defects within entire wafers may be imaged by simple scanning (Lang technique15) if the wafer is reasonably perfect, or by using the scan oscillation technique developed by Schwuttke16 if the wafer is warped or distorted. The purpose of this paper is to both review and extend the general application of X-ray topographic techniques to GaAs. Emphasis will be placed on the effects of growth and process variables on the quality and perfection of both bulk and epitaxial GaAs. Reference to optical or electron microscopy results will be made when useful. Since the effects on defects of a wide variety of processing variables such as crystal growing, sawing, polishing, diffusion, and epitaxial growth will be somewhat superficially reviewed, a fairly extensive bibliography of the most important recent results in these areas is included. However, for completeness, important defects will be illustrated here, although such defects have been previously shown by others. While this paper is concerned with defects rather than with the physics of X-ray scattering, the mechanisms of contrast formation in the topographs will of necessity be briefly mentioned. EXPERIMENTAL GaAs crystals, both boat-grown18 and Czochralski-grown,&apos;8 containing a variety of dopants of various concentrations, were purchased from outside vendors. Wafers were sliced from the crystals using a Hamco ID saw and were mechanically polished using 1 µ diamond paste. Chem-mechanical polishing was done in bromine-methanol as described by Sullivan and Kolb.18 Chemical polishing was done using a modified sulfuric-peroxide solution, 11 parts H2SO4, 1 part 30 pct H2O2, 1 part DI water.5 Zinc diffusion was carried out in a closed tube, using a 10 pct Zn-In source at 825°C for 1 hr. Oxide masking techniques were used to select the area to be diffused. Epitaxial wafers were either purchased or prepared here. All epitaxial runs prepared here were carried out using a Ga-GaAs-AsC13 source in a closed tube at a substrate temperature of 750°C. Wafers were chem-mechanically polished and gas-etched prior to deposition. The X-ray topographs were taken on a Krystallos Lang camera, operating in the transmission scanning geometry (Lang technique15) or in the reflection scanning geometry (modified Berg-Barrett technique20,21). MoKa, radiation was used for all transmission topographs using a Jarrell-Ash 100-µ spot focus. CuKal radiation was used for all reflection topographs using a General Electric CA-7 1-mm spot focus X- ray tube. Topographs were printed from an intermediate contrast inversion film, so the contrast shown in all figures here is the same as that of the original 50-µ-thick emulsion L4 Iiford nuclear plate used to record the topograph.

Jan 1, 1969

By W. E. Anderson, T. M. Brady

As part of a larger study to identify factors influencing the practical operating life of wire rope used on large draglines in surface coal mining, field trips to operating surface coal mines were made during late 1975. Wire rope performance information was obtained from personnel at 13 mine sites west of the Appalachians. Seventeen pieces of equipment, utilizing bucket sizes ranging from 30 to 220 cu yd (23 to 168 m), were documented. Draglines at large US surface coal mines can be represented as 120 machines having 60-cu yd (46-m3) buckets, moving 1.8 x 10[9] cu yd (1.4 X 10[9] m3) of overburden during 6650 hours of productive availability per year. Based on the limited field study, the calculated downtime resulting from rope-related causes averages 105.6 hours per year for each typical 60-cu yd (43-m3) dragline. The total loss in production from this source alone is thereby estimated at about 25 X 10[6] cu yd (19 X 10[6] m3) annually.

Jan 11, 1979

By Harry K. Ihrig

The hot-working of iron and steel is an art dating back to antiquity, but until about 25 years ago, relatively few alloying elements were used, and these were present only in small percentages. With the exception of sulphur, the amounts of other elements in steels did not markedly affect their hot-workability. The references in the literature on the effect of other elements on the hot-workability of steel are usually reports of failure of these steels in forging or rolling.1-8 With the increased use of alloying elements, and their use in larger amounts, it was observed that many of the new steels were red short in certain critical ranges or at all hot-working temperatures. The stainless steels are particularly difficult to hot-work. The determining of the correct conditions for piercing, rolling and forging of these alloys by experimentation in the mill often results in large losses of these expensive metals. It also is found that the hot-workability limits of many types vary from heat to heat, and hence poor results are obtained on changing to a new heat after a previous one has rolled satisfactorily. To determine the effect on hot-workability of iron to which various elements have been added, it was necessary to devise a method that could be used on small quantities of metal. In such a method, the minimum number of variables should be present, and the procedure should be simple, quick and correlatable with large-scale hot-working operations. Sauveur,9 in the first Henry Marion Howe lecture in 1924, described the effect of carbon on the ductility of steels in torsion near their critical points. He found that carbon increases the plasticity of gamma iron. In the 1930 Campbell Memorial lecture,10 he gives the effect of carbon, chromium, and chromium and nickel on the ductility of steels under 2000°F. in torsion. Ellis11 has studied the malleability of steels at various elevated temperatures by means of a single-blow drop-hammer test. In this test the percentage decrease in height of standard cylinders is taken as a measure of their malleability. He has shown that in the low-alloy steels studied, carbon has a greater effect than nickel, chromium and vanadium. In 1938 the first tests were run on a new quantitative hot-workability test in the laboratories of the Globe Steel Tubes CO. Thum12 mentioned it in 1940. An illustration of the apparatus was published in January 1942.&apos;&apos; The effect of a few alloying elements on the hot-workability of metals was shown in a description of the test in 1944.14 Description of Test Method The method adopted after a trial of several others is a rapid twisting of bars to failure in a furnace. The standard-size bar was chosen as 9/16 in. It is prepared from larger pieces by forging and cold-

Jan 1, 1947