Gte Laboratories Incorporated

Gte Products Corporation

Gary Czupryna

Samuel Natansohn

Robin W Munn

Robert A Long

A process for the preparation of silicon nitride powders, which are suitable for the manufacture of high quality structural ceramics is described. The synthesis process is based on the reduction of silicon dioxide by carbon in a nitrogen stream at elevated temperatures to form alpha silicon nitride. Silicon nitride powders of various morphologies are obtained by this technique by varying either the type of reactants used or the process conditions. Structural ceramics with densities exceeding 99% of theoretical and having satisfactory mechanical strength and oxidation resistance were sintered from powders synthesized by the method of this invention.

Process for the synthesis of silicon nitride

A process for the growth of silicon nitride whiskers consists of reacting a mixture of carbon and silicon dioxide powders at elevated temperature in a stream of nitrogen, said reaction mixture containing small amounts of metals such as chromium, magnesium, and nickel which promote the growth of silicon nitride whiskers by vapor phase transport. The whiskers obtained as a result of this invention are of much higher purity than those obtained by prior art.

Process for the growth of alpha silicon nitride whiskers

A process for cleanly separating tungsten and the coinage metals from alloys or mixtures thereof comprises electrowinning the coinage metal from an electrolyte solution which is maintained substantially free of tungsten contamination by contacting the electrolyte solution with an organic extractant to remove the tungsten. A preferred extractant solution comprises a quaternary alkyl ammonium salt or quaternary alkyl phosphonium salt dissolved in an inert organic solvent.

Process for separating tungsten from coinage metals

A process for cleanly separating coinage metals from alloys of coinage metals and tungsten comprises electrowinning the coinage metal from an electrolyte solution which is contacted with an ion exchange resin to selectively remove the tungsten.

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Salem, MA, United States of America

Gary Czupryna