Abstract: Fluorine content of tantalum and niobium hydroxides is reduced to under 0.5 weight % by washing such hydroxide precipitates (as obtained by HF digestion and solvent extraction) with dilute ammonia (1 to 10%) and then water in two washing stages. The first washing stage includes a partial neutralization and the used wash water of the second stage is advantageously recycled, after adjustment of its ammonia concentration, for use as the first stage washing liquid.

Abstract: Sintered composite abrasive material useful in abrasives (grinding wheels, abrasive discs and paper, etc.) and cutting tools, comprising an .alpha.-Al.sub.2 O.sub.3 matrix of sub-micron crystallite size made by sol-gel processing with a dispersed phase therein of mechanically resistant material, preferably essentially isotropic grains, added directly to the sol or gel stage of matrix formation.

Abstract: Cobalt-bound diamond tool (e.g. for cutting, drilling polishing) composite materials comprising diamond particles in uniform matrix of cobalt-boron alloy with 1-5 weight percent and uniform, stable and controllable matrix hardness of about 200 to 650 HB.sub.30.

Abstract: MCrAlY composite material with platinum and/or rhodium alloying elements as 5-15 wt. % thereof and containing included particles of carbides vanadium, niobium, tantalum, titanium, zirconium, hafnium, chromium, molybdenum and/or tungsten and/or mixtures thereof, enhancing the corrosion- and wear-resistance of such materials at high temperatures.

Abstract: In an advantageous process for producing powdered aluminium alloys which have a catalytic action or are capable of acting as precursors of catalysts, good results are obtained if the alloy is atomized with water and/or a gas at a temperature of 50.degree. to 500.degree. C. above its melting point and then cooled and dried.

Abstract: A molybdenum metal powder having an outer shell coating of MoO.sub.2 is useful in flame spray or plasma spray processes and is prepared by partially oxidizing molybdenum powder in a carbon dioxide atmosphere at temperatures of up to 1200.degree. C.

Abstract: Metal powder agglomerates of individual particles comprising (i) more than 70% by weight of one or more metals selected from the group consisting of the elements molybdenum, rhenium and tungsten and (ii) one or more binder metals selected from the group consisting of iron, cobalt, nickel, copper, silver, gold, palladium, platinum, rhodium, chromium and rhenium, wherein the individual particles have grain sizes of less than 2 .mu.m and all the metal particles lie side by side in uniform random distribution are useful as the powder required for producing shaped, sintered articles in a powder metallurgical preparation.

Abstract: The invention relates to an improvement of the flowability and an increase in the bulk density of high-surface area valve metal powders by means of the addition of finely divided extraneous metal oxides in quantities of up to 5000 ppm, relative to the quantity of metal, before the powder-metallurgical processing of the valve metal powder.

Abstract: The invention relates to a process for treating the surface of valve metals, in particular niobium and tantalum, in the form of agglomerated or non-agglomerated powders, thin foils or molded articles prepared from powder, for use as electrolytic capacitor electrodes, these metals being heated in at least one stage to temperatures of 300.degree. to 2,000.degree. C. under a high vacuum or an inert gas atmosphere and in the presence of chalcogens or chalcogen compounds, excluding oxygen.

Abstract: To produce valve-metal anodes for electrolytic capacitors, reducing agents are added to the already sintered and/or unsintered anode bodies to improve the electrical properties, whereupon heating is carried out at temperatures above the melting point of the reducing agents and below the temperatures conventionally used for sintering the valve-metal anodes.

Abstract: A process for the production of valve metal powder, which is doped with boron or boron compounds, for electrolytic capacitors having a low relative leakage current and a high specific charge. The doping with boron or boron compounds in amounts of up to 0.5 percent by weight, relative to the metal content, can take place either during the production of the metal powder or the green valve metal anodes.

Abstract: A process for the production of agglomerated valve metal powder which comprises heating an admixture of a valve metal powder and a reducing agent in the presence of an inert gas or under high vacuum for a sufficient time and at a sufficiently elevated temperature that agglomeration of the valve metal powder occurs, and removing the reaction products of the reducing agent and the valve metal and any unreacted reducing agent from the agglomerated valve metal powder by subsequent reaction with an inorganic acid. The agglomerated powder can be sintered to prepare valve metal electrodes, e.g., anodes, which can also be prepared by direct sintering of the admixture of the metal powder and the reducing agent.

Abstract: A process for the recovery of valuable metals from spent desulfurization catalyst wherein the catalyst, which has not been subjected to oxidative roasting, is thermally reduced in the presence of carbon and calcium oxide.

Abstract: A method for producing tungsten compounds low in phophorus. Calcium tungstate is precipitated from a tungstate solution possibly containing phosphate with a calcium compound. The resulting precipitate is reacted with an alkali carbonate solution under pressure of preferably 15 to 25 bar and the solution resulting is separated from the residue containing substantially all of the phosphate. The resulting solution is collected and is suitable for production of tungsten compositions low in phosphorus.

Abstract: An electrode having an electrical capacitance in excess of 10,000 .mu.C/g prepared by sintering a tantalum powder having a grain size finer than 2.5 .mu.m, and the process of preparation.

Abstract: Raw materials containing tantalum or niobium are treated to obtain aqueous solutions containing fluoroacid complexes of niobium or tantalum. These solutions are decomposed by pyrolysis and calcined to obtain pure oxides of niobium or tantalum. The hydrofluoric acid separated during pyrohydrolysis is recovered and reused. A niobium or tantalum-free raffinate solution obtained, on extraction, with the above aqueous solutions contains dissolved metalloids which are recovered as oxides which are deposable waste products.

Abstract: An anhydrous mixture of extrudable viscosity of an activated alkali metal tantalum or niobium halide powder, an alkali metal halide powder, and a molten alkali metal in about 1:0.75-2.0:4.75-5.5 molar ratio is formed into a paste which is extruded and formed into masses of critical dimensions and temperature. The mass is ignited and a self-sustaining reduction reaction ensues. The reaction product is powdered, washed and dried. The product is pure tantalum or niobium powder in almost quantitative yield. The powder is specially suited for use as electrolytic capacitor anodes. The powder is improved by passage through a plasma of an inert gas.The process can be performed on a continuous scale.

Abstract: A process for obtaining metal rich in tantalum and niobium from ore having a high titanium content comprising stepwise electrothermal ore reduction in the presence of aluminum, calcium oxide and barium sulfate.

Abstract: The production of highly porous sintered bodies useful for the manufacture of electrolytic capacitors by using as a lubricant for the base metal powder, usually tantalum, about 0.01 to about 10% by weight of an inorganic lubricant, particularly a sulfide, selenide or telluride of a metal of subgroup V or VI of the Periodic Table or nitrides of boron or silicon.