Showing papers on "Powder metallurgy published in 1968"
TL;DR: In this paper, the effects of fabrication by powder processes on the density and thermoelectric properties of an n-type pseudo-binary Bi2Te2.55Se0.45 alloy have been examined.
Abstract: The effects of fabrication by powder processes on the density and thermoelectric properties of an n-type pseudo-binary Bi2Te2.55Se0.45 alloy have been examined. The large effects on the thermoelectric properties are ascribed primarily to the generation and removal of point defects, together with the doping effects of atmospheric contamination in finer powders (−50 mesh).
36 citations
Patent•
08 Apr 1968
TL;DR: The ALUMINUM BASE POWDER METALLURGY ALLOY ARTICLE as mentioned in this paper is an article about the combination of high-transverse yIELD strength and stress resistance.
Abstract: ALUMINUM BASE POWDER METALLURGY ALLOY ARTICLE HAVING AN IMPROVED COMBINATION OF HIGH TRANSVERSE YIELD STRENGTH AND STRESS CORROSION CRACKING RESISTANCE. THE ALLOY CONTAINS THE BASIC PRECIPITATION HARDENING ELEMENTS ZINC, MANGSIUM AND COPPER. IT MAY ADDITIONALLY CONTAIN COBALT OR MANGANESE. THE ALLOY IS PREPARED BY ATOMIZATION OF A MELT OF THE ELEMENTS HOT WORKING, SOLUTION HEAT TREATING, QUENCHING AND TWO-STAGE ARTIFICIAL AGING. COMPONENTS OF THE ALLOY IN PERCENT BY WEIGHT ARE, IN ADDITION TO THE ALUMINUM, 5 TO 13 ZINC, 1.75 TO 6 MANGNESIUM, 0 TO 2.5 COPPER, AND UP TO ABOUT TO COBALT OR MANGANESE. UP TO 0.75 BY WEIGHT CHROMIUM AND UP TO 0.25 BY WEIGHT ZIRCONIUM MAY BE PRESENT WHEN COBALT OR MANGANESE IS ALSO PRESENT.
19 citations
Patent•
05 Apr 1968
TL;DR: The method of fabricating spheroid-shaped particles of porous carbon with metal or metallic compound powder dispersed therein, which particles have controlled size, shape and porosity as discussed by the authors.
Abstract: The method of fabricating spheroid-shaped particles of porous carbon with metal or metallic compound powder dispersed therein, which particles have controlled size, shape and porosity, by dispersing powdered metal or metallic compound material that may comprise fissionable material in precured resin particles, heating the particles in a suspended condition in a fluid medium to spherically shape and cure the particles and then pyrolyzing the cured particles to produce the spheroid-shaped porous char matrix binding the metal or metallic compound powder together.
16 citations
Patent•
18 Mar 1968
TL;DR: A fibre-reinforced composite consists of aluminium powder containing 5-25% by weight of aluminium oxide dispersed within individual particles of the powder as mentioned in this paper, and fibres may be of silicon nitride or carbide, alumina or carbon.
Abstract: 1,236,012. Fibre-reinforced composites; powder metallurgy. AVIATION SUPPLY, MINISTER OF. June 17, 1968 [March 16, 1967] No. 12465/67. Heading C7A and C7D. The matrix of a fibre-reinforced composite consists of aluminium powder containing 5-25% by weight of aluminium oxide dispersed within individual particles of the powder. The fibres may be of silicon nitride or carbide, alumina or carbon, and comprise up to 20% by weight of the composite. In the example, a composite containing silicon nitride whiskers is made by heating to 500‹ C. and applying a pressure of “-¢ t. s. i., and then increasing the temperature and pressure to 625‹ C. and 3-4 t. s. i. Pressure may be achieved by extrusion.
10 citations
7 citations
01 Aug 1968
5 citations
Patent•
19 Sep 1968
TL;DR: In this paper, a method of making beryllium or beryellium alloy shapes from powder metal by first pressing the shape either by isostatic pressing or conventional mechanical compacting methods at room temperature to 60 percent to 95 percent of theoretical density at a pressure of between 30,000 and 90,000 psi or above and subsequently pressing and heating to final size and density.
Abstract: A method of making beryllium or beryllium alloy shapes from powder metal by first pressing the beryllium or beryllium alloy shape either by isostatic pressing or conventional mechanical compacting methods at room temperature to 60 percent to 95 percent of theoretical density at a pressure of between 30,000 and 90,000 psi or above and subsequently pressing and heating to final size and density at temperatures between 1,400 DEG F and 2,150 DEG F (preferably 1,550 DEG F to 1,900 DEG F) and pressures of from 100 to 10,000 psi effective pressure on the compacted powder, preferably at 100 to 2,500 psi The second pressing of the shape is done with mechanical pressure simultaneously with the application of heat under vacuum or inert environment
5 citations
01 Jan 1968
TL;DR: In this article, the effect of alloying on the ductile-brittle transition temperature and on the high temperature tensile and creep strength of tungsten base alloys is discussed.
Abstract: Advances made in the manufacturing of tungsten base alloys by powder metallurgy, fusion and chemical vapor deposition techniques are reviewed. The mechanical properties of many alloys are discussed in terms of the effect of alloying on the ductile-brittle transition temperature and on the high temperature tensile and creep strength.
01 Jan 1968
TL;DR: In this article, the grain structure of sintered materials has been studied, and it has been shown that the grain size in sinted metals is usually smaller than that of the corresponding cast material heat-treated in a similar way.
Abstract: For many years powder metallurgy has been known as a method for fabrication of sintered materials with special physical properties not obtainable by any other more conventional metallurgical method. Reference is made, for example, to materials with controlled porosity, combinations of metals which do not form alloys, and sintered products with special electrical properties. Little attention, however, has been given heretofore to the grain structure of sintered materials, and hardly anything more is known with respect to the structure than the general fact that the grain size in sintered metals is usually smaller than that of the corresponding cast material heat-treated in a similar way.
01 Jan 1968
TL;DR: In this paper, the powder properties of the powder used as raw material have a considerable influence on the properties of sintered compact, as well as on the ease of making it, close control of powder properties is essential for successful operation.
Abstract: Increasing interest is now being taken in the technique of powder metallurgy for the manufacture of small engineering components that are generally made by machining from bar stock. Since the properties of the powder used as raw material have a considerable influence on the properties of the sintered compact, as well as on the ease of making it, close control of the powder properties is essential for successful operation.
01 Oct 1968
TL;DR: Substructural void formation in tungsten powder metallurgy as function of annealing temperature for doped, undoped and electron beam melted material was studied in this article.
Abstract: Substructural void formation in tungsten powder metallurgy as function of annealing temperature for doped, undoped and electron beam melted material
Patent•
06 Jun 1968
TL;DR: In this paper, a mixture of silicon powder and an epoxy resin is used to volatilize a non-metallic powder material and then it is sintered in nitrogen to form silicon nitride bodies.
Abstract: Brittle non-metallic powder materials such as ceramic oxide and silicon are mixed with an epoxy resin, a hardener and an organic solvent, dried, compacted and sintered to volatilize the resin. In the example, minus 60 mesh silicon powder is mixed with an epoxy resin, acetone and a hardener, dried, screened, compacted, cured at 50-250 DEG C. and then sintered in nitrogen to form silicon nitride bodies.ALSO:Brittle non metallic powder materials such as ceramic oxide and silicon are mixed with an epoxy resin a hardener and an organic solvent, dried, compacted and sintered to volatilise the resin. In the example minus 60 mesh silicon powder is mixed with an epoxy resin, acetone and a hardener, dried, screened, compacted, cured at 50-250 DEG C. and then sintered in nitrogen to form silicon nitride bodies.ALSO:Sintered silicon nitride is produced by mixing silicon powder with an epoxy resin, a hardener, and an organic solvent, e.g. acetone, then drying, compacting, and sintering in N2 to volatilize the resin and form silicon nitride. In the example, the particle size distribution of the Si is specified, and the compact is cured at 50-250 DEG C.
TL;DR: In this paper, a method has been developed for reducing the charge in porous drip pans made from rolled powders, which improved heat transfer and gas permeability of the charge and so increase the productivity of the reduction process as a whole by 55%.
Abstract: 1.
Study of the reduction and carburization kinetics in iron powder furnaces exposed and led to the removal of several shortcomings in these units.
2.
A method has been developed for reducing the charge in porous drip pans made from rolled powders. Trials using this method showed that the porous drip pans improve heat transfer and gas permeability of the charge and so increase the productivity of the reduction process as a whole by 55%. Moreover, this method will provide the basis for mechanized and automated charged pallet preparation and discharge of the sponge iron from the pallets. Preliminary calculations indicate that even a 10% rise in productivity obtained by using the porous drip pans is enough to make these an economic proposition.
01 May 1968
TL;DR: In this paper, a dependence of strength on raw powder particle size and also on thermal history is shown, and the present report shows that beryllium generally contains an oxide dispersoid, due to particle surface scale.
Abstract: : Powder metallurgy beryllium generally contains an oxide dispersoid, due to particle surface scale, and thus the material actually is a system subject to particle strengthening. The present report shows a dependence of strength on raw powder particle size and also on thermal history.
TL;DR: In this paper, the concentration of free acid is maintained sufficiently high to inhibit co-deposition of Ni(OH)2 in a nitrate solution, and cathodic reduction of nitrate and deposition of Ni[OH]2 predominates.
Abstract: : Adherent and coherent deposits of nickel sponge similar to sintered nickel may be made from sulphate, chloride, fluoborate or sulphamate nickel plating solutions containing nickel powder in suspension, providing the concentration of free acid is maintained sufficiently high to inhibit co-deposition of Ni(OH)2. In nitrate solution, cathodic reduction of nitrate and deposition of Ni(OH)2 predominates. (Author)
01 Jan 1968
TL;DR: The largest tonnage of raw materials used in powder metallurgy fabricating are iron powders as discussed by the authors, which are highly engineered metallurgical end products that must meet strict chemical and physical specifications.
Abstract: Iron powder represents the largest tonnage of raw materials used in powder metallurgy fabricating. Not simply chips or scraps of wrought materials, iron powders are highly engineered metallurgical end products that must meet strict chemical and physical specifications.
Patent•
14 Feb 1968
TL;DR: In this paper, the authors described a powder metallurgy process in which particles of an austenitic stainless steel powder are coated with Ni and the coated powder is then sintered below the melting point of the steel and then worked as by rolling, forging or extrusion so that the coating layers form corrosion barriers orientated along the working direction.
Abstract: 1,217,004. Powder metallurgy. AVESTA JERNVERKS A.B. Feb. 16, 1968 [Feb. 16, 1967], No.7809/68. Heading C7D. Particles of an austenitic stainless steel powder are coated with Ni and the coated powder is then sintered below the melting point of the steel and then worked as by rolling, forging or extrusion so that the coating layers form corrosion barriers orientated along the working direction. The stainless steel powder contains 5-15% Ni, 16-25% Cr and optionally Si, Cu, Mn, Ti and Mo. The particle size is -5 +0A05 mms. The Ni coating may be applied by electrolysis, decomposition of the halide or carboxyl or by evaporation. The coating may also contain Cr, Mo, Si, Ti, Mn, Cu in addition to the Ni and in one example the stainless steel powder is first coated with Cr prior to coating with Ni. The sintering of the powder at 950‹-1300‹C. may be carried out prior to or in conjunction with the working which should give a minimum reduction of cross-section of 4:1. The coating metal forms 1-10% by weight of the powdered steel.