National Science Council

National Science Council of R.o.c.

Sheng-Long Lee

Jing-Chie Lin

Yung-Bao Deng

Jyuhn-Yih Wu

Jainn-Yuan Lin

A method for producing fine silver-palladium alloy powder includes the steps of: (A) preparing separately a silver nitrate solution and a palladium nitrate solution and mixing the solutions, and then adding a neutralizing and complexing agent to the mixed solutions to adjust the pH thereof to about 2.5-3.5, whereby a first mixture containing silver and palladium ions is obtained; (B) preparing a second mixture containing a reductant and a surfactant; (C) bringing the first mixture into contact with the second mixture at a reaction temperature of 15.degree.-50.degree. C. under stirring in order to permit the silver and palladium ions to be reduced and to coprecipitate so as to form silver-palladium alloy particles; and (D) recovering the coprecipitated silver-palladium alloy particles, thereby obtaining the fine silver-palladium alloy powder.

Method for producing fine silver-palladium alloy powder

Silver powder with a controlled surface area is made by introducing a silver ion containing solution and a mixed solution containing reducing agents and surfactants into a low temperature tank of 5.degree.-20.degree. C. and holding for a period of 7-60 minutes, followed by introducing the resulting reaction solution into a high temperature tank and holding further. The rest potential of the reaction solution is monitored to determine the end point of the reaction.

Process for the preparation of silver powder with a controlled surface

A process of recovering tungsten carbide from cemented tungsten carbide scraps by selective electrolysis is disclosed. A chelating agent is added to the electrolyte for complexing with tungsten ion to prevent passivation of tungsten carbide, and thus the dissolution rate of the cementing agent is increased.

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Chung-Li, Taiwan

Sheng-Long Lee