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By C. W. Hall

Owing to its isolation and comparatively small tonnage, the Yoquivo district is not widely known; though financially important and, geologically, quite interesting. San Francisco dc Yoquivo, the center of the mining district, is in the western part of the state of Chihuahua, Mexico; about 35 miles west of. San Juanito, on the Kansas City, Mexico & Orient R. R. The town can be reached from the railroad by a good trail over a rugged country. The elevation of Yoquivo is 6500 ft., and peaks surrounding the town are 2000 ft. higher. The mining towns of Concheno and Ocampo are 25 miles northwest, and Uruachic is 20 miles southwest. The climate, temperate and healthful, is almost ideal. The rainy season begins in July and ends the latter part of September. There is usually, though not always, some precipitation in all months except April, May, and June: The mountains are covered with pine and scrub oak. Water, wood and lumber are plentiful for all ordinary purposes, and hydroelectric power is available for. about six months of the year, when wood for steam, power is utilized as an expedient. The district has been worked: recurrently for over 60 years. The Yoquivo province lies on the steep western-slope of the Tara-humara division of the Sierra Madre range of mountains. The province is traversed by many deep canyons, most of which flow west. The town is situated on the San Francisco arroyo, which makes a confluence with the Huevachic stream 212 m. southwest; the Huevachic in turn joins the Candemeña river farther down and these two drain the western flank of the Tarahumara mountains and form the headwaters of the Mayo river. The claims of the Yoquivo Development Co., which, is the only organization in the district with a record of any considerable production,: lie within an area roughly 112 m. square. The area extends from the, San Francisco arroyo north, and from the Dolores arroyo west, and is confined to the andesitc formation.

Jan 2, 1926

By R. M. Treco

The effect of small additions of oxygen on the hardness, density, and lattice parameters of high purity zirconium has been investigated. Precision parameter values and density of oxygen-free zirconium are given as: a,, - 3.2258 kX units, C = 5.1373 kX units, O23 = 6.507 g per cc. THE effect of oxygen on the hexagonal-phase lattice constants of pure zirconium is of interest for several reasons. The extensive hardening effect of oxygen noted by previous investigators' must be due in part to the lattice distortion accompanying its introduction and possibly to the preferred position of the oxygen atoms. De Boer and Fast' have shown that oxygen is taken into solid solution in large amounts, appearing to occupy an interstitial position. These authors also found that expansion of the lattice was not uniform since the a axis attained a constant value after the addition of 10 atomic pct while the c axis continued to expand. It was thought in the present work that this expansion of the zirconium lattice with increasing amounts of oxygen

Jan 1, 1954

By Harold B. Goldman, Don Reining

The sand and gravel industry is the largest nonfuel mineral industry in the nation. In 1981, the production of sand and gravel totaled 755 million tons valued at $2.3 billion. California, which leads the nation with more than 110 million tons, together with Alaska, Texas, Michigan, and Ohio, account for 36% of the total production in the nation (Table 1). In commercial usage, sand applies to rock or mineral fragments ranging in size from particles retained on a No. 200 sieve (0.074 mm openings) to those passing a No. 4 sieve (4.76 mm openings). Gravel consists of rock or mineral fragments larger than 4.76 mm, ranging up to 88.9 mm (3 ½ -in.) maximum size. The construction industry consumes 97% of the sand and gravel produced; the remainder is sand used for specialized products such as glass (see the chapter on "Silica and Silicon"). Utilization The building industry uses sand and gravel chiefly as aggregate in portland cement concrete, mortar, and plaster; the paving industry uses sand and gravel in both asphaltic mixtures and portland cement concrete. Aggregate is commonly designated as the inert fragmental material which is bound into a conglomerate mass by a cementing material such as portland cement, asphalt, or gypsum plaster. Portland Cement Concrete Aggregates Portland cement concrete consists of sand and gravel surrounded and held together by hardened portland cement paste. Concrete mixes commonly contain 15-20% water, 7-14% cement, and 66-78% aggregate. Sand and gravel used as concrete aggregate have to meet many requirements (Goldman, 1956). Premature deterioration of concrete has been traced in many instances to the use of unsuitable aggregates. Asphaltic Aggregate Asphaltic mixtures used predominantly for paving consist of combinations of sand, gravel, and mineral filler (material finer than 0.003 in.), uniformly coated and mixed with asphalt produced in the refining of petroleum. Except for the addition of mineral filler, sand and gravel used as asphaltic aggregate must meet the same general physical requirements as materials used for portland cement concrete aggregate. General Requirements of Aggregates Construction aggregate has many requirements that are difficult to meet if only unprocessed material from natural deposits is used. Suitable material is composed of clean, uncoated, properly shaped particles which are sound and durable. Soundness and durability are terms used to denote the ability of aggre- [ ]

Jan 1, 1983

By K. Nassau

The Effect of tin and hydrogen on the C0 parameter of a titanium. specimens were capsule cooled in water to eliminate contamination by water. Deybe-Scherrer photograms were obtained in a 114.6 mm camera with CuKa radiation. The parameters shown in Table I and Fig. 1 were calculated from the 213 (8569°) and 302 (8173.5°) reflections? no attempt being made to correct for systematic errors. The principal difference in method of preparation of specimens between this investigation and that of Worner was the use of pickling by the latter to produce X-ray diffraction samples. The possibility that hydrogen introduced by pickling was responsible for the lower a and c-parameters was investigated with the same 80 pct HNO3- 20 pct HF solutions used by Worner. The 6 and 10 at. pct specimens, the parameters of which had already been determined, were pickled and the c-parameters obtained are also shown in Fig. 1. The a-parameters, not shown, are also diminished. The quality of the lines obtained from the unetched and etched samples was unchanged, being quite sharp in both cases. It is quite possible that if corrections for systematic error carried out that the parameters obtained for the unetched samples would approach the data of Worner. In any event, the parameters of the etched samples would be still lower. The data obtained here is evidence that hydrogen in solution has contracted the c and a -parameters. Crystallographic Angles of Calcium Tung-state (Tetragonal, c/a = 2.169) K. Nassau In connection with the preparation and orientation of single crystals of calcium tungstate (Scheelite -CaWO4), the need arose for a stereographic projection for this tetragonal material. There appear to be no tetragonal projections with a c/a ratio above that of indium1 (c/a = 1.522) in the literature. In addition to its use for calcium tungstate, such a projection might find other more general applications and is accordingly presented below. The most recent X-ray diffraction work on CaWO4 is that of Swanson, Gilfrich, and Cook,2 where a summary of previous work is also found. Lattice parameters given are: a = 5.242A, c = 11.372A, and c/a = 2.169. The material is tetragonal with space group Table I, giving angles between crystallographic planes (HKL) and (hkl), was calculated from the formula3

Jan 1, 1961

By Donald L. Katz

FIFTEEN years ago Dr. Manning published a paper in "Petroleum Development and Technology" on '.Fundamental Research Relating to Petroleum." He tabulated for several industries "the proportion of their present success which can be fairly attributed to the application of information and processes obtained by scientific research," giving petroleum a score of 7 compared to 100 for the electrical and coal-tar industries. Today the petroleum industry as a whole and the producing groups both have raised their score beyond the majority and are climbing toward the top. Present practices are being developed both by fundamental research and the application of the research method in field operation.

Jan 1, 1941

By Arthur Notman

DESPITE the tremendous drop in the volume of domestic production of metals, their prices, and profits, the world as a whole has managed to produce and consume nearly as much as in 1937. Measured by production, 1937 was the record year for copper, lead, and zinc. The Copper Institute figures for 1938 (estimating December as equal to November) show that although apparent domestic consumption declined 309,422 tons, foreign consumption increased 133.035 tons. The total for 1938 was 1,971,790 tons compared with 2,148,177 tons for 1937. The domestic decline was 38.5 per cent, the foreign increase 9.9 per cent, and the total decline 8.2 per cent.

Jan 1, 1939

Jan 1, 1883

By V. Annamalai, J. B. Hiskey, L. E. Murr

The kinetics of copper cementation on rotating disks of body and tear-top beverage can aluminum alloys were studied as a function of temperature and copper ion concentration. Both alloys followed the two-step kinetic regions, an initially slow rate followed by an enhanced rate. Experimental activation energy determinations (9.04 to 19.62 kJ/mol) indicated that ionic diffusion controlled the reaction mechanism between 20° and 60°C. At low temperatures (< 20°C), the system appeared to be controlled by the presence of an aluminum oxide surface film. The results of this study showed that cementation kinetics for the beverage can aluminum alloys are similar to those for pure aluminum. It was also found that the chemical removal of the oxide layer is less important for the alloys than /or the pure aluminum system. The characteristics of the resultant copper deposits were studied under a scanning electron microscope, and the reaction kinetics seemed to depend strongly on the nature and morphology of the deposits. In addition, maximum rates occurred when the deposit structures were fine feathery dendrites.

Jan 1, 1980

By W. M. McKewan

A large amount of work has been reported in the literature on reduction of cubes, spheres, or regularly shaped particles of iron ore. Previously, it has been difficult to evaluate these data because no equation has been developed that would yield one or more constants for comparison of overall reduction rates. Iron ore in the process of gaseous reduction is a complex system. The reduction takes place through the series Fe2O3-Fe304-Fe0-Fe. Edstrom and Bit-sianesl have reported that the gas-solid type of reaction was found only at the FeO-Fe interface and that the internal reduction proceeded by elementary diffusion of iron. Therefore, during reduction oxygen is essentially removed from the system only at the FeO-Fe interface. Kinetically, it is reasonable to consider iron ore in the process of reduction as a

Jan 1, 1959

By David L. Holt, Walter A. Backofen, Anwar-ul Karirn

ANNEALING the binary alloy, Mg-0.5 wt pct Zr in a hydrogen atmosphere results in extensive precipitation of zirconium hydride. The morphology of these precipitates has already been investigated.lm3 Squires, Weiner, and phillips4 found, following creep testing of the hydrided alloy at 450" and 500°C, that hydride denuded zones formed along grain boundaries that were aligned approximately normal to the tensile axis. Zone formation was attributed to diffusional creep by magnesium transport down the prevailing stress gradients.4&apos;5 Recently, electron microprobe analysis by Karim, Holt, and Backofen6 showed the zones indeed to be zirconium-free and furthermore it was shown that in compression, zones formed along boundaries approximately parallel to the stress axis. Thus it was confirmed that the zones are formed by diffusional creep. Typical zone-formation is shown in Fig. 1. Karim, Holt, and Backofen also measured the con- tribution to the total strain, from diffusional flow, slip creep, and grain boundary shear: results showed that diffusional strain tends to saturate with increasing imposed strain, while grain boundary shear eventually becomes the dominant deformation mode. It was suggested in explanation that the precipitate-denuded zones are soft and easily sheared, such deformation contributing to the grain boundary shear measurement. A point to be emphasized is that the Mg-0.5 Zr alloy was not superplastic for the index of strain rate sensitivity of flow stress, m = a log log 6 was only 0.25. It was recognized that diffusional creep in a poly crystalline aggregate must be accompanied by boundary shearing.&apos; The suggestion was that the non Newtonian-viscous character of diffusional creep in the Mg-0.5 wt pct Zr alloy is due to resistance to sliding of boundaries lying approximately parallel to the tensile axis.= The work described in the present note should be seen against the above background for it represents initial efforts to observe in a similar way diffusional creep in a superplastic alloy. Previous work with the ternary-alloy Mg-6 Zn-0.5 Zr, pellet extruded, showed it to be superplastic however it does not contain resolvable precipitates to act as internal markers for diffusional creep. Also the fine grain size of the alloy (0.5 p) made conventional metallography rather difficult. Solubility relationships in the Mg-Zn-Zr system are not well known, however making reasonable guesses about the probable phase diagram of the ternary, Mg-Zn-Zr, various heat treatments were attempted to produce hydride precipitation. Finally a 16-hr anneal at 495&apos; in hydrogen was found to pro-

Jan 1, 1970

By T. E. Watkins, M. D. Nelson

A method of determining the lime content of drilling muds proposed by Battle and Chaney* has been examined both in the Field Research Laboratories of Magnolia Petroleum Co. and in field drilling operations. This proposed analytical method is condensed as follows: Titrate one ml of mud and one ml of mud filtrate, each with 0.02 N H2SO4, to the end point with phenolphthalein. The volume of acid in ml required for the mud titration is recorded as Pm and that of the mud filtrate titration as Pf Calculation of the lb lime/bbl mud is accomplished by use of the formula, lb lime/bbl mud = 0.6 (Pm - 1.3Pf) - 0.6 The analytical procedure outlined by Battle and Chaney was found to be quite satisfactory when reasonable precautions are used in mud sampling technique. Calculation of lime concentration by the method proposed in the above publication, however, has given values that varied as much as 100 per cent from the known lime content, for muds of either high or low solids concentration. By use of a formula, lb lime/bbl mud = 0.26 (Pm-F1.Pf), based on chemical equivalents of acid required for titration, both laboratory and field data have been satisfactorily correlated with the known amounts of lime present in the muds. In this formula a correction, F1, or volume fraction of liquid in the mud, is made for the solid content of the mud. Pm and Pf * Paper on "Lime Base Muds," presented by J. L. Battle (Humble Oil and Refining Co., Houston, Tex., and P. E. Chaney (Sun Oil Co., Beaumont Tex.), at the 1949 Spring Meeting of the Southwestern District API Division of Production, Dallas, Tex. The analytical procedure has also had wide distribution in a trade journal, Kembreak, published by the Accuracy Rig and Tool Co., Houston, Tex, †Derivation of equation lb/bbl — grams/350 ml 1 ml 0,02 N acid = 0.000741 grams of lime 1 ml 0.02 N acid/ml lime suspension = 0.26 lb of lime bbl lb of lime/bbl = 0.26 (Pm -F1, Pf ) have the same significance as in the Battle and Chaney equation. Table I shows typical data employing both formulas in calculating the lime content of various lime muds. This suggested procedure ignores lime which is in solution in the mud. The solubility of lime in water, normally about 0.5 lb per bbl, is greatly decreased by the addition of caustic soda, and, in a lime mud, it is probable that the concentration of dissolved lime is of the order of 0.1 lb per bbl. Such an amount of lime can be ignored, since it is within the range of accuracy of the method.

Jan 1, 1950

By P. Wynblatt, J. E. Dorn

The effect of strain rate, temperature, and interstitial impurity concentration on the flow stress was investigated in a poly crystalline Fe-2 pct Mn alloy. The temperature dependence of the flow stress was found to be independent of the interstitial impurity concentration, removal of interstitials merely decreasing the atherma1 stress level. Below 160%, the large temperature dependence of the flow stress was interpreted in terms of the Dorn-Rajnak theory of the Peierls mechanism of plastic deformation. Above 160"K, some other thermally activated intrinsic meckanisln seems to be operating. The strong temperature dependence of the flow stress of bcc iron at low temperatures has been studied by numerous investigators and interpreted in terms of several different thermally activated dislocation mechanisms. The following mechanisms have been proposed: a) interaction of dislocations with interstitial impurity atoms1 or with solute atoms in general; b) interaction of dislocations with clusters of impurity atoms;3 c) resistance to the motion of dislocations due to jogs on screw dislocations;* d) resistance to the motion of dislocations due to the Snoeck effect;&apos; and e) interaction of dislocations with the intrinsic resistance of the bcc lattice or Peierls "hills". In previous work: it was found that the plastic behavior of polycrystalline iron containing 2 wt pct Mn (and 100 ppm C + N) is in good agreement with predictions based on the Peierls mechanismlo from 77" to 160°K whereas from 160" to about 370°K another as yet unidentified thermally activated mechanism is operative. The purpose of the present investigation was to determine the effect of interstitial impurities on the temperature dependence of the flow stress, by purifying the previously investigated alloy with respect to interstitial impurities. The investigation revealed that removal of the interstitial impurities to a level that eliminated Cottrell locking and the Portevin-LeChatelier effect (i.e., serrations in the stress-strain curve due to dynamic strain aging) affects neither the strong temperature dependence of the flow stress at low temperatures nor the general characteristics of the higher-temperature behavior. Such purification, however, lowered the athermal yield stress. I) EXPERIMENTAL PROCEDURE AND RESULTS The material used in this investigation consisted of an Fe-2 wt pct Mn alloy having the following additional elements present: 0.004 pct C, 0.006 pct N, 0.05 pct 0, 0.004 pct S, 0.003 pct P, and 0.001 pct Si. This was the same material as that studied in the previous investigation and will henceforth be referred to as the "impure material". The as received -jr by 2 in. hot-rolled bars were cold-rolled to 0.08-in. thickness, recrys-tallized under argon for 30 min at 80O0C, and further cold-rolled to 0.053-in. thickness. Flat tensile specimens 3 in. wide having a 1.625-in.-long gage section were machined from the sheet and then purified. The first stage of purification consisted of holding the specimens at 850°C for 24 hr in a stream of hydrogen saturated with water vapor at room temperature. Material prepared in this fashion will subsequently be referred to as "wet hydrogen purified material". It has been estimated that this type of treatment reduces the carbon content of iron to less than 5 ppm.&apos; The second stage of purification consisted of holding the specimens in a closed system through which hydrogen was circulated past the heated specimens as well as a zirconium hydride getter. The specimens were held at 850°C and the getter at 800°C. The process was continued for 212 hr. The starting material for this process was wet hydrogen purified material. Material prepared in this manner will be referred to as "ZrHz purified material". The technique used was substantially the same as that described by Stein et al.&apos; who have shown that the carbon level at the end of the process is reduced to about 5 parts per billion. The mean grain size of the three materials was found to be -60 C( for the impure material and -160p for the wet hydrogen and ZrHz purified materials. All tensile testing was carried out on an Instron Testing Machine either in controlled-temperature baths or at fixed-point baths such as boiling liquid nitrogen, and so forth. When fixed points were used the temperature was kept constant to better than *1°C whereas in all other tests the temperature variation was less than *2°C. Test of Purity. It was not possible to determine the purity achieved at each stage of the purification because the resulting level of interstitial impurities was near or below the limit of sensitivity of standard analytical techniques. It was possible, however, to obtain a qualitative measure of the extent of purification from the appearance of the stress-strain curves for the three materials. Fig. 1 shows the stress-strain curves for the three different materials tested at 300°K. It can be seen that the effect of wet hydrogen

Jan 1, 1967

By O. P. Arora, M. Metzger, G. R. Ramagopal

Single-phase aluminum containing 0.0001 to 0.06 pct Cu was studied in strong acid, mainly through observations of hydrogen evolution. The strong influence of copper was exerted almost entirely through the imposition after a certain delay time of an auto-catalytic localized-corrosiott reaction. Additions of cupric ion to the acid produced lower accelerations. The significance of the quantity and distribution of copper was discussed, and the implications for intergranular corrosion and neutral chloride pitting were indicated. AN investigation of intergranular corrosion in single-phase high purity aluminum exposed to hydrochloric acid indicated the copper content of the metal to have an influence on corrosion at lower levels than previously suspected.&apos; The work reported here was a closer examination of the action of copper but dealt with general corrosion to gain the advantage of having a continuous measure of corrosion through the volume of hydrogen evolved, the reduction of hydrogen ion to hydrogen gas being the principal or only cathode reaction in strong hydrochloric acid. Previous work on the hydrochloric acid corrosion of aluminum was sometimes insufficiently structure-conscious and the need for care in evaluating it arises from the low solubility of the iron impurity,&apos; and of some alloying elements, and the known or possible presence in many of the compositions studied of second phases leading to greatly increased corrosion rates.3 These increases are attributed to the presence of low hydrogen-overvoltage cathodes provided by the second phase.3&apos;4 For the present single-phase work, a few studies which used high-purity base material and small copper additions5-&apos; provide the essential information most unambiguously. The corrosion rate was shown to be increased markedly by the introduction into the acid of small quantities of the ions of copper (and of certain other metals) which cement on the aluminum and provide cathodes of low overvoltage.5 When there was sufficient copper in the aluminum, the same result was produced during the course of corrosion leading to a rate which increased with time as the reaction was stimulated by one of its products (autocatalytic reaction). In 2N (7pct) HC1, an accelerating rate was observed at 0.1 pct Cu but not at 0.01 pct.5,7 The present work dealt with corrosion rate and morphology and their correlation with the quantity and distribution of copper catalyst for copper contents from 0.0001 to 0.06 pct. PROCEDURE A lot of high-purity aluminum containing 0.0021 pct Cu, 0.001 pct Fe and 0.003 pct Si (Alloy A) was alloyed with copper to yield aluminum containing 0.014 pct Cu (B) and 0.06 pct Cu (C). Later it was found necessary to include the lower copper Alloy K which contained 0.0001 pct Cu, 0.0004 pct Fe and 0.0004 pct Si. The upper limit for any other element can be confidently estimated as 0.0005 pct. No element other than copper appears to be present in quantities sufficient to have an effect on general corrosion as great as the observed effect of the copper in A, B, and C. The only other heavy metal detected by spectrographic examination was silver (< 0.0001 pct). The acid was made up from a selected lot of 37 1/2 pct CP hydrochloric acid containing 0.1 ppm heavy metals (mainly Pb), 0.05 ppm Fe, and < 0.008 ppm As and from water distilled from 1 megohm-cm demineralized water and believed to have contained negligible quantities of heavy metals influencing corrosion. Acid strength was adjusted to within 0.05 pct HCl of the stated value by using precision specific gravity measurements. Test blanks 10 by 41 mm were sheared from 1.65-mm cold-rolled sheet. Edges were finished by filing. The blanks were annealed in air at 645°C for 24 hr in alundum boats and rapidly water quenched. The anneal is thought to have produced a substantially homogeneous solid solution—for iron, copper, or silicon, for example, the annealing temperature was 200°C or more above the solvus-and the quench is considered to have preserved the high-temperature structure except for the condensation of lattice vacancies into dislocation loops.&apos; The 0.06 pct Cu alloy did not appear unstable in respect to slow precipitation reactions at room temperature since two pairs of tests failed to show significant differences between specimens heat treated 3 1/2 years earlier and specimens heat treated 1 or 2 days before.

Jan 1, 1962

By J. C. Bradley

THE relation of annealing temperature to conductivity of copper wire has been determined.1 Conductivity hard was 98.26 per cent. After a 10-min. heating at 200° C. it was 98.69. By annealing 10 min. at 300° C. a large increase, to 100.93, occurred. Maximum conductivity, 101.15, was attained after a 500° C. anneal; thereafter it decreased to 100.53 after a 950° C. anneal. If copper is gassed the decrease is much more than this. MATERIAL AND METHOD The work was done on high grade electrolytic copper, 99.942 per cent. copper-plus silver, silver 0.0008 per cent. It was hot-rolled to 3 in., then cold drawn to 0.080 in. The wire was cut into 25 5-ft. lengths and numbered 1 to 25 as cut. Four samples were tested hard. The others were wound into 5-in. diameter coils. For the 100° C. heating a coil was put into water, the water brought to boiling, and the wire kept at this temperature for 10 min. For the higher temperatures the coils were placed in envelopes of sheet copper, a little water added, and the envelopes sealed by folding over the edges twice, and hammering them together. This kept the air out very well. The envelope and wire were brought to the desired temperature; this was maintained for 10 min., then the whole was water-quenched.

Jan 1, 1927

By Herbert H. Uhlig

ALTHOUGH the mechanical properties of high-carbon manganese-iron alloys, particularly the Hadfield manganese steels, have been established, the literature discloses discrepancies in the reported properties for the low-carbon alloys. Hadfieldlo summarized the existing data up to 1927, including the investigations of Guillet, Arnold, Strauss, Burgess and Aston, and reported his own values for alloys containing for the most part from 0.06 to 0.15 per cent carbon. He noted: From these comparisons it will be seen that while there is a broad and general agreement as to the character of the alloys at the different manganese percentages, there are disparities in individual cases, especially as regards the degree of toughness or brittleness displayed by an alloy with certain percentages and with particular types of treatment. These differences are not always readily explainable. Ib His data showed that alloys containing 4 to 10 per cent manganese water-quenched from 1000°C. were brittle and hard with maximum brittleness at about 7 per cent. Slight improvement in ductility was obtained with compositions from 10 to 17 per cent manganese. Alloys containing up to 17 per cent manganese slowly cooled rather than quenched from 870°C., he found, were slightly improved in ductility with significant improvement in alloys analyzing 4.1 and 4.8 per cent manganese. Recently Walters, Kramer and Loringa reported mechanical properties for alloys made up from electrolytic manganese and ingot iron and containing from 0.02 to 0.04 per cent carbon. They showed that a tempering treatment at 540°C. (1000°F.) for one hour significantly improved the ductility of compositions ranging from 6.7 to 20.7 per cent manganese. The differences of these compared with Hadfield&apos;s results they considered to originate in this tempering treatment plus the fact that Hadfield&apos;s alloys contained higher carbon and phosphorus (0.06 to 0.15 per cent C; 0.06 to 0.07 per cent P compared with 0.02 to 0.04 per cent C, <0.001 per cent P). In this paper it is shown that of the low- carbon alloys (0.02 to 0.03 per cent) containing from 3.3 to 21.5 per cent manganese moderately or rapidly quenched from 1000°C. some are brittle or ductile, depending on presence or absence of hydrogen. Hydrogen is readily absorbed at high temperatures, and much of it is retained when the alloys are cooled to room temperature. The presence of hydrogen in the range of composition from 10 to 18 per cent manganese is a major factor in determining relative ductility. At 22 per cent manganese, and also at compositions below 10 per cent manganese, factors other than or in addition to hydrogen play a role. These are discussed. Also data are presented to show that hydrogen absorbed by the high-carbon alloys of Hadfield composition is without effect on their mechanical properties.

Jan 1, 1944

By G. F. Olsen

ON superficial consideration a technical library might be considered a luxury to the business institution that possesses one. After all, public libraries and research institutions probably contain all the data that would be found in a private technical library, and able consultants are available both within and without a company. In all probability the technical men of a company have in their combined personal libraries sufficient information to answer most inquiries. Nevertheless, possession of such a department is of real economic benefit because of the time it saves its users, because it prevents expensive duplication of technical literature in a company, and lastly, but most important, be- cause it makes readily available a central storehouse of technical facts classified and indexed to meet the demands of the industry or industries concerned.

Jan 1, 1940

By F. O. Garrabrant

Power is furnished to the Climax Molybdenum Co. by the Public Service Co. of Colorado over two 100,000-volt lines to a bank of three 3333-kva. transformers 100/13.8 kv. These transformers are so designed that with the addition of forced cooling their capacity may be increased 33? per cent at 12,000-ft. altitude. Under present conditions, these transformers are operated at 140 Per cent of their rating with forced air cooling. On the secondary side of this bank there is a 15-kv., 1200-amp. Westinghouse oil circuit breaker provided with automatic reclosing relays allowing three successive short circuits before lockout. From this breaker 13.8-kv. power is transmitted to a central switching station (Fig. I) where all circuits radiate to the different operations of the property. Each circuit is protected by a 23-kv., 600-amp. oil circuit breaker with by-pass and isolating disconnecting switches. Mine Power at 13.8 kv. enters the mine through a ventilation raise over a three-conductor, size 1-0 varnished cambric insulated, leaded, steel-wire armored cable, insulated from 17 kv. This power is received and distributed through one switching station and four underground substations, shown in Fig. 2. No. 370 substation (Fig. 3) contains three a 13,800/440-volt, single- phase Pyranol transformers protected on the high-voltage side by a 600-amp. manually operated oil circuit breaker. This station serves 20 slusher-hoist motors, a 45-kw., three-phase, 220-volt electric furnace, a Massco hot miller for tempering and milling Timken detachable bits and a hoist with 175-hp motor on the No, 3 development shaft. Also at this shaft are three pumps. One two-stage pump, 1200 gal, per min., 500-ft. head, 3600 r.p.m., driven by a 150-hp. motor, is at the bottom of the shaft, Two deep-well pumps, 500 gal. per min., 500-ft. head, are at the collar of the shaft. under normal operation the one pumping 1200 gal. per min, is controlled by a float switch to take care of the water. If this pump fails, or if its capacity is insufficient, the first 500-gal. pump is automatically started1 and if still more capacity is needed the second 500-gal. pump automatically starts. Time delay relays are provided on the deep-well pumps, so that if power fails the column will have time to drain before the Pumps restart. On failure of any Of these, an alarm is sounded in the train dispatcher&apos;s office, so that mechanics can be sent to ascertain the cause of failure and make repairs. The cable from No. 37&apos; substation is run to the switching station, in which are four 15-kv., 600-amp. direct-current sole-noid-operated oil circuit breakers. The current for Operating and tripping is furnished by a 125-volt storage battery. All breakers are operated from the switchboard in the compressor room. One circuit from this switching station goes to the

Jan 1, 1946

By Zay Jeffries

IT is well known that many properties of a given metal vary with the size of grain or cell. For most industrial purposes, where high ultimate strength and high elastic limit are desired, the manufacturer tries to produce a. fine-grained structure. For some purposes, for example in transformer iron, a coarse-grained structure is desirable. The terms fine-grained and coarse-grained are used only in a relative sense. For example, a fine-grained cast copper might have grains 100 times larger than coarse-grained high-speed steel. Similarly, a fine-grained steel rail might have grains or cells 100 times larger than coarse-grained wire, which was made of steel from the same heat. In some metals, the change in grain size is more appreciable than the changes in any of the properties determined by the tensile test. Furthermore, in metals which have been annealed or subjected to high temperatures, grain size may prove to be a better indication of the life of the metal in use than the tensile test. One of the authors was able to supplant the tensile test with grain-size determinations in the control of. metal for a specific use, the latter determination being more indicative of. the life of the metal part than the tensile test. A grain-size determination with a tensile test is, of course, more valuable than either singly. At present there is a decided dearth of data on actual grain-size determinations in metals, and consequently a corresponding lack of ability to interpret the determinations after they are made. It would be desirable to have correlation made between grain size and properties of metals, comparing thousands of determinations. In this way, grain-size determinations might be interpreted in much the same manner that tensile tests are now.

Jan 12, 1915

By M. J. Pool, with Appendix by Larry Kaufman, R. W. Krenzer

Thermodynmic properties of the Cu-Mn system have been deterrrzined in the temperature range 973" to 1273°K by measuring the vapor pressure of manganese in equilibrium with alloys of compositions varying from 0.13 to 0.91 rnole fraction manganese using the Knudsen effusion technique. Activities of manganese calculated from the measured vapor pressures show large positive deviations. Calculated heats and entropies of mixing are positive with a maximum occurring at approximately 0. 7 mole fraction manganese. ThE investigation of thermodynamic properties of binary systems involving transition metals is of considerable interest at the present time. The incomplete subvalency electron levels of transition metals lead to unusual behavior in some alloys, and considerable information can be obtained by determining the thermodynamic characteristics of these systems and relating the thermodynamic behavior to observed physical properties. The Cu-Mn system, shown in Fig. 1,&apos; provides an example of an alloy system in which the determination of the equilibrium phase diagram and various physical properties has received considerable attention, but very little work has been done on measurement of the thermodynamic properties. Elemental copper and manganese have comparable electronegatives, atomic sizes, and cohesive energies, but differ in crystal structure. They form a continuous series of solid solutions only at high temperatures and the structure varies in a continuous manner from fcc at the copper-rich end to fct at the manganese-rich end.&apos; The purpose of this investigation was to measure the vapor pressure of manganese over a series of Cu-Mn alloys and from these values determine the thermodynamic properties of the binary system. Vapor pressure measurements were made in the temperature range 973" to 1273"K, remaining within the solid-solution region for each alloy studied. EXPERIMENTAL PROCEDURE The relative thermodynamic properties of solid Cu-Mn alloys were determined from vapor pressure measurements by means of the Knudsen effusion tech- nique. Several discussions of the theory can be found in the literature. In the case of copper and manganese, it is assumed that manganese is the only component subliming, so the vapor pressure of manganese over the various alloys can be determined directly by measuring the weight loss of the effusion cell. This is a valid assumption since the vapor pressure of manganese is about four orders of magnitude higher than the vapor pressure of copper in the temperature region of interest. The vapor pressure of manganese over the alloys at any given temperature is then related to the weight loss of the effusion cell per unit area per unit time. An upper limit of 1.5 x 10"s has been measured for the ratio of polyatomic to monoatomic molecules for manganese vapor in equilibrium with solid manganese at 1180°K, so it was assumed that manganese vapor is monoatomic. The effusion cells, fabricated from high-purity alumina, are 26 mm high, 18 mm OD, and have a wall thickness of 1 mm. Three different sized holes of 2.03, 2.54, and 3.18 mm diam were drilled in the lids from the inside face to minimize chipping, and the lids were then slip-cast onto the cells to provide a gas-tight seal. Alumina was selected for this particular application both because of its resistance to thermal shock and reaction with manganese vapor. In the ideal case, the orifice of the effusion cell should have a knife edge so that effusion through the orifice

Jan 1, 1970

By M. F. Burr, F. V. Lenel, G. S. Ansell

The mechanism of materials transport was studied in a model experiment in which a silver sphere was sintered to a silver plate under an applied external stress near 800° C. For this purpose the rate of growth of the neck between the sphere and the plate which is proportional to the strain rate of the creep process involved in a neck growth was determined by measuring the change in electrical resistance of the away. This rate of neck growth will depend upon the magnitude of the applied external stress. By measuring the rate just before and just after a change in the external load and therefore the applied stress, the relationship between strain rate and stress can be derived. For material transport by slip in a pure metal it is expected that the strain rate should be proportional to the 4.5th power of the stress, while for transport by diffusional flow the strain rate should be proportional to the first power of the stress. It was found that for stresses above 5 X 10&apos; dynes per sq cm (70 psi) the exponent in the stvain rate-stress relationship was near 4.5 while for a stress of 0.7 x 108 dynes per sq cm (10 psi) an exponent of 1.8 was determined indicating that under the conditions of the experiment the transport mechanism for creep in silver shifts from diffusional flow to slip in the region of 0.7 x 106 dynes per sq cm (10 psi). The importance of these findings for an understanding of the mechanism of material transport in conventional sintering (without an external load) is pointed out. In a paper by Early et al.,&apos; the mechanism of material transport during sintering was treated as a creep process. It was pointed out that two possible types of creep processes could operate during sintering. In one of these material transport takes place by vacancy diffusion due to a gradient in chemical potential. The vacancy sinks in this diffusion process may be either grain boundaries, as in Herring-Nabarro microcreep, or regions beneath a surface of small radius of curvature. The diffusive transport may be by volume, grain boundary, or surface diffusion. In the other mechanism, creep takes place by slip, i.e., dislocation motion with its rate generally controlled by dislocation climb. One method of distinguishing between these two modes of materials transport is to investigate the creep rate, i.e., the rate of material transport as a function of stress. For material transport by vacancy diffusion, the creep rate is proportional to the stress.&apos; For creep by slip, controlled by dislocation climb, the creep rate is proportional to a power of the stress. For pure metals this power is 4.5;374 for dispersion-strengthened material a fourth power relationship can be derived.5 This difference in the stress dependence of the strain rate is illustrated schematically in Fig. 1, in which the logarithm of strain rate is plotted vs the logarithm of the stress for material transport in a pure metal by vacancy flux and by dislocation climb. The stress range in which the two types of material transport overlap would be expected to be relatively small. In the experiments described by Early and coworkers compacts pressed from spherical copper powder were sintered isothermally under an applied axial external load in a dilatometer. During sintering the magnitude of the applied external load was changed and the rate of axial shrinkage of the compact before and after the load change determined. In order to find the stress dependence of the strain rate the magnitude of the stress acting on the neck area between the spherical particles before and after the load change had to be calculated. This stress is the resultant of the stresses due both to the externally applied load and to surface tension. The stress due to surface tension is a function of the geometry of the powder compacts. It can be determined, at least for simple geometrical arrays,&apos;76 but it is difficult to obtain exact values of the stresses for actual powder compacts when only average values of particle diameters and of neck diameters between particles are available. The calculation of stress and the strain rate-stress relationship is therefore only very approximate.

Jan 1, 1968