Selection of optimum parameters to obtain Ag–TiB₂ composite electrical contacts

Abstract

A simple method of obtaining Ag–TiB₂ composite electrical contacts has been worked out. A silver powder with unique properties was obtained by cathodic reduction of Ag⁺ ions from AgCl in a Zn|0·5M H₂SO₄, AgCl|Ag cell. This method enables the recycling of silver containing secondary materials or wastes. Silver was joined with titanium boride via powder metallurgy (pressing–sintering). The influence of the composition and compacting pressure on the mechanical and electrical properties of the composites obtained was studied. A composite containing 2% of titanium boride, which was pressed under 700 MPa of pressure, and then sintered at 1123 K for 45 min in an argon atmosphere, possesses a density of 8·82 g cm⁻³, hardness HB = 23, conductivity κ = 49·01 MS m⁻¹, and a contact resistance that is independent of the applied current intensity, in turn ranging from about 8·4 to 5·3 μΩ at contact forces in the range of 30–100 N.

Keywords:

• CATHODIC REDUCTION OF SOLID COMPOUNDS
• SILVER POWDER
• POWDER METALLURGY
• AG-TIB2 COMPOSITES
• ELECTRICAL CONTACTS