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By N. M. Langdon

INTRODUCTION. IN considering the magnificent success of Mr. Gayley's Bold experiment of applying dry blast to the blast-furnace, whereby , saving of 20 per cent. of fuel per ton of iron is effected, the question arises whether, still further economy in fuel is possible, and, if so, how it is to be attained? The manner in which the heat generated in the furnace is utilized in the production of pig-iron may be determined, by the method of Bell and Gruner, for any furnace for which the necessary data are obtainable ; and the study of the operation,. tinder various conditions, of a number of furnaces, for which such information has been worked out., should enable us to form some conclusion on the subject. The tables and calculations given below cover the operations of several furnaces reported in our Transactions; also the two furnaces using natural and dry blast in ,Mr. Gayley's experiment, for which the heat-equation has been worked out by Prof. Joseph W. Richards in his admirable discussion' of Mr. Gayley's paper, The Application of Dry Air Blast to the Manufacture of Iron, and, finally, various hypothetical furnaces.. The full list is as follows : A. Isabella furnace, with natural blast. B. Isabella furnace, with dry blast. The data stated. for A and B in Table III. are those given by Professor Richards; except that the heat-units are given for one unit of iron instead of 100 units, and some items of heat supplied, as stated by Richards, have been subdivided, the total being the same as given by Richards. (Columns A and B are introduced in Table III. for comparison with C and D.)

Oct 1, 1909

By John D. Sullivan

MAJOR technical advances seldom occur in a single year, and this is especially true with aluminum and magnesium where marked improvements in metallurgical processes and products took place during the war years. Nevertheless, the light metals and alloys, particularly aluminum, are advancing in commercial importance and are finding their niche in industry. New applications during the year have resulted from a better over-all knowledge of properties, handling, etc., rather than from revolutionary new developments.

Jan 1, 1948

By Albert E. Wiggin, Frederick Laist

Page I. Introduction............................470 II. The Sources and Amount of Slime................470 II. The Composition of the Slime..................471 IV. The Experimental Development of the .Anaconda Slime Plant.. 471 1. The Great Falls Slime Plant and Experimental Work......471 2. The Experimental Work Done at Anaconda..........473 (a) SlimeThickening Devices.............. 474 (b) SlimeConcentrators................. 475 (c) Dewatering the Slime Plant Concentrate......... (d) The Use of Chemicals to Accelerate the Settlement of Slime........................ 478 (e) The Effect of Temperature upon the Settlement of Slime 478 V. A Description of the Anaconda Slime Plant........... 479 1. A Diagrammatic Flow Sheet of Plant............. 480 2. The Slime-Thickening Division................ 480 3. The Concentrating Division.................. 481 4. The Concentrate-Dewatering Division............. 483 5. General Data........................ 484 I. IntRoduction The new slime-concentrating plant at the Washoe Reduction Works, Anaconda, was put into operation during March, 1914. This plant, which has a capacity of 26,000,000 gal. of slime pulp carrying 2,500 tons of solid matter per day, consists of Dorr thickeners and Anaconda multiple-deck slime concentrators. This plant is the culmination of a great deal of experimental work extending over a considerable period of time, which , work will be described briefly in the following pages. II. The Sources and Amount of Slime Up to the beginning of this year, the ore from the Anaconda company's mines in Butte, Mont., has been concentrated both at the Great Falls

Jan 1, 1915

By R. H. Lynn, T. C. Craig

During the year 1933, in the Texas Panhandle, 113 oil wells were completed, adding 33,337 bbl. to the daily potential of the field. The field potential on Jan. 1, 1933, as determined by the Texas Railroad Commission, was 149,260 bbl., with a daily allowable production of 41,000 bbl. The potential was raised gradually, until on July 16, 1933, it reached 155,344 bbl. with a daily allowable of 55,000 bbl. This potential and allowable was maintained over a period from July 16, 1933, to Sept. 8, 1933, when the potential was reduced to 136,893, with a daily allowable of 43,727 bbl. Since Sept. 8, 1933, there has been a gradual increase, until on Jan. 1, 1934, the field potential reached 159,740 bbl. with a daily allowable of 42,000 bbl. Of this amount 26,429 bbl. arc "marginal oil" and 2682 bbl. are exempt on account of water. Deepening of Wells During the year 64 wells were deepened, increasing their total oil production 9631 bbl. per day. Of this amount the Gray County granite wash contributed 9256 bbl. from 57 wells. It has been found in many places that the granite wash carries an additional oil pay from 50 to 75 ft. below sea level. The majority of the wells that were .drilled during the early development in Gray County encountered their oil above sea level. When the wells producing from the upper horizon have become unprofit-

Jan 1, 1934

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 B. C. Allen, R. I. Jaffee, D. J. Maykuth

Wrought unalloyed iodide chromium, containing 39 to 95 ppm total interstitials, has a tensile transition temperature of —15°C. Re crystallizing at 1100°C causes the transition to rise to 90° to 390°C, depending on the purity, grain size, and cooling rate after annealing. At about the 100 ppm level, individual additions of carbon or nitrogen raise the transition of both wrought and recrystallized chromium by as much as 210°C, while oxygen has a lesser effect, and sulfur essentially no effect. High transitzon temperatures are exhibited by recrystallized and quenched chromium, and appear to be associated with the amount and distribution of inter-stitials. The latter cm be either in solid solution or in the form of precipitates within the grains or at the grain boundaries. Quench hardening in chromium is primarily caused by nitrogen. The hardness, re crystallization, and grain growth behavior of chromium with and without impurity additions were also investigated. BECAUSE of low density and good oxidation resistance, chromium-base alloys are potentially useful for elevated-temperature applications. The main deterrent to the use of chromium in structural applications is its lack of low-temperature ductility, especially in the recrystallized condition. Accumulated evidence has shown that the ductility of chromium is sensitive to purity. The objective of the current study was to determine the effect of common nonmetallic impurities on the tensile properties of high purity chromium. The separate effects of carbon, oxygen, nitrogen, and sulfur additions on the ductile-to-brittle transition were evaluated for wrought and recrystallized material after various cooling rates. EXPERIMENTAL WORK Unalloyed iodide chromium and seven impurity alloys containing individual carbon, oxygen, nitrogen, or sulfur additions were prepared in rod form. Nominal additions were 100 ppm C, N, and S, and 100 to 500 ppm O. The additions were about a factor of ten greater than the residual amounts in the unalloyed material. The seven alloys and two unalloyed compositions were consolidated into four-pound ingots by conventional consumable arc melting of pressed and welded electrodes under 0.5 atm of helium. Impurity additions were made to the electrode in the form of crushed master alloys. The impurity alloys were double melted to improve homogeneity. The ingots were broken down by extrusion at 1200°C in evacuated steel cans at a reduction ratio of 18 :1, using a molten borosilicate glass lubricant and a ram speed of 80 in. per min. The cans were removed by acid pickling, and the chromium core ground free of surface undulations. Cut lengths were sheathed in mild steel and swaged at 900°C until the core was about 1/4 in. in diam. Two additional 15-lb ingots of unalloyed chromium (ICr-3, ICr-4) were prepared by arc melting and broken down by 26:1 extrusion at 1250°C without a steel can. The billet was lubricated and protected from contamination by a coating of molten glass. The resulting extrusion was then sheath swaged as described previously. Representative chemical analyses of each of the materials, after removal of a 10-mil surface layer

Jan 1, 1963

Idaho Bureau of Mines and Geology, University of Idaho, Moscow, Ida. John W. Finch, Director. A list of publications will be sent upon application. A series of Bulletins and Pamphlets have been issued by the Bureau to date since 1920 Of the Bulletins, six are out of print, and a charge is made for eight. Each of the Bulletins, in the main, treats of the geology and resources of a particular district in Idaho, as follows (only available Bulletins listed): Bulletin 1, South central Idaho (1920), 15 cents, 7, North central Idaho (1924), 50 cents, 8, Bonneville, Bingham and Caribou counties (1924), 50 cents, 9, Boise Basin (1924), 50 cents; 10, Boundary County (1926), 50 cents; 11, Region about Silver City (1926), 50 cents; 12, Clark Fork district (1930), 50 cents, 14, Eastern Cassia County (1931), 50 cents, Press Bulletin 15, Teton County (1927), Bulletin 16, Melon Valley near Buhl (1927); 17, Concerning land slips near Whitebird, Idaho (1928) The 37 Pamphlets are issued free of cost, and each treats, also, in the main of the geology and resources of a particular district in Idaho Nos 1, 2, 3, 4, 5, 7, 8, 10, 17, 18, 20, 22, 25, 26, 30 and 35 are out of print Of those available, attention may be called to Pamphlet 6, Reported platinum occurrences near Coeur d' Alene (1925), 11, Bruneau River Basin, 12, Power and Oneida

Jan 1, 1933

By C. H. Li, R. D. Carnahan, R. J. Stokes, T. L. Johnston

When silver chloride deforms by pencil glide at temperatures of 26ºand 72°C, grain size has no effect upon the proportional limit and the material necks down to a knife edge under tension. At -196ºC, deformation takes place on fewer slip systems to produce straight slip traces, the flow stress becomes sensitive to grain size and fracture occurs by cleavage from an intergranular source without any reduction in area. THERE are significant differences between the appearance of the slip bands formed in silver chloride and in the alkali halides at room temperature. The bands in sodium chloride, e.g., are fine and geometrically straight, whereas in silver chloride they are coarse and wavy.' Such differences in the slip behavior prompted us to inquire what the effects of grain boundaries might be on the mechanical properties of these solids. As an introduction to a general study of ionic poly-crystal behavior, we have investigated the effect of grain size on the stress-strain relationships in silver chloride at different temperatures. We have chosen silver chloride chiefly because polycrystals can be easily prepared free from cracks and macroscopic voids by conventional techniques. Moreover, as we shall see, the slip behavior can be readily modified by changing the temperature. It will be shown that the effect of grain size on the yield stress of silver chloride is strikingly dependent upon the temperature of deformation and that this temperature effect comes about through a change in the number of slip systems which operate at the onset of plastic flow. EXPERIMENTAL PROCEDURES Polycrystalline tensile specimens were made by recrystallizing cold-rolled AgCl sheet. Thirty-gram quantities of AR grade silver chloride powder were melted in a low heat capacity furnace, cast into cylindrical forms 3/4 in. in dim and approximately 1 in. in length and then extruded with a 16:l reduction ratio into rods 3/16 in. in dim. Extrusion temperatures were varied from room temperature to 350°C. In order to impart various degrees of cold'work to the extruded rod. All extrusions were then cross rolled to sheet 0.040 in. in thickness at room temperature and machined to form tensile specimens having a gage length of 0.750 in. with a width of either 0.250 or 0.145 in.* Annealing was carried out in an air oven at 200°C for periods up to 20 hr. specimens having average grain diameters ranging from 0.024 to 0.40 mm were prepared by varying the extrusion temperature and annealing time in the conventional manner. To obtain specimens with grain sizes larger than 0.40mm, lightly deformed thin prisims of silver chloride single crystals (supplied by Harshaw Chemical Co.) were recrystallized. Grain size determinations were made by an intercept method and revealed that the grains were equi-axed. Laue back-reflection X-ray patterns showed little tendency to form a preferred orientation texture. Specimens which were to be used for the slip band studies were polished by immersion in fresh boiling concentrated NH,OH for 60 sec. They were then etch polished for 10 sec on each side by hand lapping on a stationary velveteen lap wetted with a dilute Hypo solution (5 g of Kodak Acid Fixer in 100 cc H20). Finally the specimens were rinsed in warm water and alcohol, blown dry and carefully mounted in the tensile machine for testing. Tensile tests were performed at three temperatures, namely, 26º, -72º, and -196°C. A screw-driven hard tensile machine was used at a constant strain rate of 0.006 in. per in. per min. Loads were determined with a light- proof ring fitted with A-18 strain gages and extensions were measured with a 0.0001 in. dial gage. Constant level baths of alcohol with dry ice and liquid nitrogen were used to maintain the two lower test temperatures. EXPERIMENTAL RESULTS Reproducibility—In view of the light sensitivity and reactive nature of silver chloride, it was necessary to determine whether reproducibility depended upon either exposure to light or to the condition of the surface. However, during the course of the work it became clear that variation of laboratory lighting

Jan 1, 1962

By Walter W. Bradley

FOR a number of years up to the economic setback of the 1929-1931 period, the greatest proportional advances in the mineral industries in California were made among the substances in the nonmetallic groupings, particularly among the so-called industrial minerals and the salines. During the past year or two, although these have not regained the stride that marked their progress in the preceding decade, we can still record, -some new developments. California produces annually between 55 and' 60 different minerals on a commercial scale. Of these, some 40 to 45 comprise the "structural," "industrial," and "salines" materials as grouped in the reports of the State's Division of Mines. Barite-The barite deposits of California were described in Report

Jan 1, 1935

By R. Laird Auchmuty

A NUMBER of factors, of varying importance, should be considered in assessing mineral land-here specifically coal land -for tax purposes. (1) Is the coal developed or un- developed'! (2) If undeveloped, is it surrounded by active development in adjoining properties? (3) Accessibility of railroad facilities to the property. Sometimes the railroad itself is of importance. (4) Cost of development of the seam under consideration, whether it can be developed by a drift from the outcrop or whether it will require deep and costly shafts or slopes. (5) Is it definitely known that the coal seam being assessed is of minable thickness and quality on the property? (6) Thickness of recoverable coal from the seam. (7) Quality of the coal. (8) Is the seam being assessed likely to be more costly to mine than other seams in the same district? (9) Is there an active market demand for coal from the seam being assessed? (10) Is the coal held only as protection to surface structures and in such location that it can never be mined? (11) Is the coal in a solid piece or is it in pillars that have been standing for some years as a result of incomplete mining in an old operation? (12) Expected percentage of recovery from the seam being assessed as determined by present mining practice in similar properties. (13) Value of the seam as indicated by sales of similar mineral rights in the immediate district. (14) Current royalty rates of leases for coal in the seam under consideration.

Jan 1, 1939

By Albert E. Wiggin

PagE I. Early History of Boston & Montana Mill at Great Falls (1891 to 1905). 210 a. Original Mill Built in 1891.........210 b. Coarser Concentration Tried...211 c. Screen Sizing of Fine Jig Feed Introduced..211 d. Installation of Finer Grinding.......211 e. Steam Stamp Tried in Place of Blake Crushers..... 211 j. Mill Increased from Three to Six Sections........ 213 g. Tonnage Increased from 300 to 450 Tons per Section... 212 h. Round Tables Replaced by Wilfley Tables....212 I1. Hancock Jig Replaces Evans Jig...212 a. Description of Hancock Jig...213 - b. Tests Made on- Hancock Jig..213 1. Treating Natural Feed..215 2. Treating Sized Feed..215 3. Treating Classified Feed .215 c. Tests Made on Evans Jig...216 III. Richards Pulsator Classifier System...218 a. Experimental Work.....218 b. Installation of System in Section No. 4,....... 220 IV. Woodbury Classifier and Jig System.............222 V. The Great Falls System................ 222 a. As Installed at Anaconda............ 224 1. Coarse Crushing and Jigging Division...... 225 2. Hancock Jig Division........... 226 3. Fine Middling Division.......... 229 4. Table Division............. 230 5. Slime Division.........230 b. Special Features of Great ails Flow sheet....... 231 1. Development of Hancock Jig Flow Sheet..... 231 2. Development of Finishing Table Flow Sheet.... 232 3. Treatment of Coarse Middling Table Products .. 232 4. Results of Test Made on 500-Ton Section at Great Falls Mill...........234 VI. Comparison of Great Falls and Evans System at Anaconda.... 236

Jan 1, 1914

By T. H. Oxnam

INTRODUCTION. THE predominating value of the ores now being treated by the Palmarejo and Mexican Gold Fields, Ltd., is silver, although some gold is also carried. The present method of treatment consists of wet-crushing and concentrating, followed by the cyanidation of the unroasted sands and slimes. The sands are treated by leaching and the so-called accumulated slimes by a system of agitation and decantation. It is only within very recent years that the cyanidation of unroasted silver-ores has been commercially successful. In fact, at the time operations were begun at the cyanide-plant at Chinipas, February, 1902, I knew of no other leaching-plant treating similar ores successfully. The cyanide treatment of the Palmarejo ores differs but little from the ordinary practice in cyaniding gold-ores; and perhaps but little, if any, new information concerning the metallurgy of silver is to be gleaned from it. PALMAREJO MINE. The Palmarejo mines are located in the southwestern part of the State of Chihuahua, Mexico, on the foothills of the Sierra Madre mountains, at an elevation of 3,200 feet. The mills, 12. miles distant, are situated on the Chinipas river, near the town of Chinipas, which is about 150 miles northeast of Agiabampo, on the Gulf of California. Supplies are shipped via this port as this route is the best and most direct to the property. The ore-bodies in the Palmarejo mines have been deposited. along a series of rock-fractures, caused by an intrusion of eruptive rock. The most important of these fractures or fissures, both in width and value, are the Prieta and Blanca veins, which.

Jul 1, 1905

By W. L. Remick

THE hydrotator coal-cleaning process was developed as an economic necessity to meet the ever-increasing demand for an inexpensive method of cleaning coal down to the sizes ordinarily referred to as "dust." As the most urgent demand seemed to be in the anthracite field, all experimental work has been conducted in that territory during the past 2 years, with the exception of a few months during the strike of 1925-26, when some experiments were performed in the Alabama bituminous fields. The first commercial plant was constructed at the Middle Creek Colliery of the Philadelphia & Reading Coal & Iron Co., Pottsville, Pa. This plant is now operating. APPLICATION The field of application of the process is: 1. Cleaning anthracite fines, ordinarily described as "slush" or "silt." Slush contains all sizes from %2 in. down to and including "dust." (Anthracite passing a 32-in. mesh is also referred to as No. 2 Barley and No. 4 Buckwheat.) 2. Cleaning sizes too fine for recovery by other methods. 3. Removal of coal from sand circulated in the Chance sand-flotation process. 4. Cleaning of bituminous sizes. from 3/8 in. down to "dust. 5. As equipment for the performance of the froth flotation process. 6. Other separating, extraction and _washing. processes which may be considered outside the realm of coal cleaning. PRINCIPLE OF OPERATION Fig. 1 shows the method of classification practised under the Hydrotator patent:1 In coal cleaning the machines are operated as "hindered settling" classifiers, the flow of solids and liquids being so controlled that the units may be combined in series.

Jan 1, 1927

By O. C. Wheeler

In order that the series of reports on oil and gas in Colombia may be complete, the report for the year 1941, which was not available for Volume 160 of the TRANSACTIONS, is given here. The report for 1945 begins on page 4o6.

Jan 1, 1946

By J. F. KENP

THE White Knob copper-deposits are situated about three miles south of Mackay, on the Salmon River .branch of the Oregon Short Line Railroad, in Custer county, Idaho. An outline-map of this district is given in Fig. 1. The deposits have been known and spasmodically worked for many years, and a total of over 3.5 miles of tunnels, shafts and other workings has been driven with a view to their development. These extensive excavations have exposed the deposits sufficiently to permit a careful geological examination. The peculiar features which give special interest to this paper are the branching, free-like form of the ore-bodies; the absence of zones of secondary enrichment in the partly oxidized pyritic deposits, and the fact that while the deposits are associated in a general way with the contact of an eruptive rock with limestone, which it penetrates, the garnetization has taken place not in the limestone, as is the usual case, but in the igneous

Mar 1, 1907

Jan 1, 1970

By David J. Mack

A SURVEY and critical appraisal of published information about Young's modulus was originally made by the writer because of a complete lack of information about this very important quantity in works on mechanics, physical metallurgy, physics, and other sciences. It was felt that a comprehensive summary of such information about Young's modulus might be of general interest and may suggest new problems or lines of attack on other problems that involve E. Hence this paper has been prepared even though it is only a review, with no new ideas or experimental data. The references are only those used in assembling the paper. No attempt was made to compile a complete bibliography on the subject of Young's modulus. CALCULATION OF YOUNG'S MODULUS FROM THEORETICAL OR EMPIRICAL CONSIDERATIONS Many attempts have been made to compute E from theoretical considerations. The earliest calculations were probably those of Tomlenson (1883) and Southerland (1891), but Fessenden 41,42 made extensive calculations a few years later and arrived at the relationship: [2E = 78. 101 (_L V] where V is the atomic volume. In 1923, Peczalski,43 working from the same stand-point but with more information available on atomic structure, arrived at an identical relationship, which he expressed as: [E=B(m) 2] where B is a constant of value about 8 • 10 7, p is density and m is atomic weight; the atomic volume, of course, being m/p. Portevin44 immediately pointed out that while the equations of Fessenden and Peczalski were true of the common metals, they gave low values for the refractory metals with high moduli (Fig. I). He showed (Fig. 2) that much better concordance was obtained by means of an empirical equation of the form: [E _ KT'Vb] where K is a constant; T the absolute melting point; V, atomic volume, and a and b constants of value approximately I and 2 respectively. This constant K in the Portevin equation is not necessarily the same for all elements, as shown by Thompson.45 Other equations for E based upon theoretical considerations have been derived by Honda and Yamada49 and Lasareff. 50 The most recent calculations of elastic moduli based upon quantum mechanics are probably those of Fuchs.46-48 He extended the method of Wigner and Seitz for calculating the lattice energy and compressibility of monovalent metals and computed the elastic constants of lithium,

Jan 1, 1945

By J. Gordon Parr, D. H. Polonis

The formation and subsequent decomposition of metastable phases in Ti-Ni alloys containing up to 11 pet (atomic) Ni have been studied. The decomposition of a completely retained ß phase and of a completely transformed 8 phase in a 6 pet alloy has been followed by X-ray diffraction and metallographic methods and by hardness determinations made during the process. The possible mechanisms of the reactions are discussed. PREVIOUS investigations of the Ti-Ni system have usually been limited to phase diagram studies; but little attention has been given to metastable phases and tempering processes. These are important, however, since equilibrium conditions are rarely achieved—nor, perhaps, are they desired—in practice. Up to the present time the available transformation data for titanium alloys appear to be restricted to isothermal transformation curves for selected binary and ternary systems. No quantitative studies have been made of the mechanism by which equilibrium is approached. Several independent investigations have been carried out to determine the Ti-Ni phase diagram. Early work by Wallbaum' and later by Long et al.' produced tentative phase diagrams which were not representative of true binary conditions, since the alloys were contaminated with oxygen and nitrogen. The most recent diagram (Fig. 1) is due to Margolin et al.," and a slight modification of the a + ß/ß boundary (shown dotted) has been proposed by McQuillan.' The structure of the phase Ti,Ni was shown by Duwez and Taylor" to be face-centered-cubic, with 96 atoms per structure cell. The formation of a martensitic ß phase (close-packed-hexagonal) in Ti-Ni alloys has generally been observed when specimens of low nickel content are rapidly cooled from the 0 (body-centered-cubic) range. Margolin et al. reported an increasing tendency for P to be retained in lump specimens as the nickel content increases. McQuillan' has studied the effect on the microstructure of delay time in quenching, and has reported the formation of pro- eutectoid a precipitate in a quenched hypoeutectoid alloy. In a previous study of Ti-Fe alloys," experiments were made on powder specimens produced by filing alloy ingots. Techniques were devised for the preparation and heat treatment of alloys, and X-ray diffraction methods were used both for structure determinations and phase ratio estimations. A similar approach has been made in this study of Ti-Ni alloys. Experimental Methods Ten alloys ranging from 0.25 pet to 18 pet Ni* * All compositions are in atomic percentages unless otherwise stated. were prepared from iodide titanium bar stock (hardness Rf 72) and Johnson-Matthey spectrographic standard nickel by levitation melting.' As a check

Jan 1, 1957

By W. M. Albrecht, W. D. Klopp, R. I. Jaffee, B. G. Koehl

Kinetic studies were made of the reactions of tantalum with oxygen, nitrogen, and air at 400o to 1500°C. The tantalum-oxygen reaction is linear from 500° to 1250°C. The tantalum-nitrogen reaction follows a cubic rate law at 400° to 700°C and a parabolic rate law at 800" to 1475°C. The reaction behavior in air is initially parabolic followed by a transition to linear behavior. In the search for high-temperature materials, considerable interest is being shown in the refractory metal, tantalum. It is the third highest melting metal with a melting point of 2996°C. Also, tantalum has excellent ductility, making it one of the most workable refractory metals. In considering high-temperature applications of tantalum, the oxidation kinetics of the metal must be known. Such information also serves as a basis for the development of corrosion resistant tantalum-base alloys. Therefore, this study was made to investigate the reaction of tantalum with air, nitrogen, and oxygen. LITERATURE Several oxides of tantalum have been reported. The pentoxide, Taz05, is the only oxide of tantalum whose identity has been established. A high-temperature modification, aTa2Os, has been reported by several investigators.1-4 A low-temperature phase, ßTa2O5, undergoes an allotropic transformation at 1320o to 1350oC. 5-8 Four other oxides of tantalum have been reported. The oxides TaO2, TaO, and Ta4O have been reported by schonberg.9 A suboxide Ta2O, was observed by Wasilewski 6. However, the presence of oxides lower than Ta2O5 is questioned by Lagergren and Magneli.7 In oxidation studies, vermilyeal0 and Peterson, et al.,12 reported one possible phase intermediate between Ta and Ta2O5. Only Ta2O5 was formed in the tantalum air reaction, as reported by Michae1.l3 Several studies have been made on the kinetics of the tantalum-oxygen reaction. vermilyeal4 investigated the range 50° to 300°C and found that the rate of growth of a thin adherent oxide film could be described by the Cabrera-Mott theory. Gulbransen and Andrew15,18 studied the reaction kinetics of tantalum in oxygen pressure of 1/10 atm at 250° to 450°C. At all temperatures the reaction followed the parabolic rate law for periods up to two hours. The oxidation behavior in the range 500" to 1000°C was found to be linear at oxygen pressures of 0.2 to 600 psi according to Peterson. et al.l1 At very low pressures (1 x 10-3 to 2 X lo-' mm of Hg) Gebhardt and seghezzi17 reported linear oxidation at 800° to 1500°C. The reaction of tantalum with air is similar to the reaction with oxygen. Studies have been made by Waber, et a1.,12 and Michae1.l3 Two nitrides of tantalum, TaN and Ta2N are known. Their structures have been determined by Brauer and Zapp 18,19 The tantalum-nitrogen reaction kinetics have been investigated by Gulbransen and Andrews. 15, 16 The reaction follows the parabolic rate law at 500° to 850°C at a nitrogen pressure of 1/10 ,atm. At the same temperature, the tantalum-nitrogen reaction is much slower than the tantalum-oxygen reaction. EXPERIMENTAL TECHNIQUES Material— The material used in this study was high-purity, electron-beam-melted tantalum obtained from the Temescal Metallurgical Corp. The hardness of the as received ingot was 76 Vhn. The analysis of the material is given in Table I. Methods—Cylindrical specimens of tantalum approximately 0.9 cm in diam and 0.5 cm in length

Jan 1, 1962

By HENRY M. HOWEL

1. Introduction.-The first part of this papers treats of the causes and the restraining of piping in steel ingots; the second& considers the causes and the restraining of -segregation; and the third proposes certain precautions in engineering specifications concerning these two defects. Into their causes I have looked carefully, with the purpose of arriving at rational methods of restraining them, and at efficient ways of detecting. and measuring the harm which they cause, so as to benefit the public by reducing this harm at once effectively and with the least expense to the manufacturer, and therefore in the end with the least expense to the consumer. In Part I., I infer that the pipe is chiefly due to what I, call the virtual expansion of the outer walls of the ingot in the early part of the freezing. I find that the upper and smooth-faced part of the pipe probably forms while the interior is still molten, but that the lower, steep, and crystal-faced part probably forms in metal which is already firm. Of the five causes which may co-operate to limit the depth of the pipe, I find that three-blow-holes, sagging, and the progress of freezing from below upwards-are usually effective. I find that the pipe may be lessened by casting (1) in wide ingots,; (2) in sand molds, especially if these are pre-heated (this is rarely expedient); (3) at the tops instead of at the bottom; (4) slowly; (5) and with the large end up; (6) by the use of a sinking-head or other means of retarding the cooling of the top; (7) by permitting blow-holes to form; and (8) by liquid compression.) Most of these I consider in some detail, and in particular I dwell on the advantages of casting with the large end up, and I propose certain administrative arrangements to permit this.

Mar 1, 1907