To provide an electric contact material minimal in consumption in a light- load medium-current region by subjecting a dry-type powder mixture, prepared by uniformly dispersing a pulverized carbon powder of respectively specified average grain size and content in a silver material powder, to compaction and then to sintering in vacuum, etc.
A carbon powder of ≤0.1μm average grain size is blended with a silver or silver alloy powder of ≤ about 10μm average grain size by the dry process so that its content becomes 0.01-0.5wt.%, and the carbon powder is uniformly dispersed in the silver or silver alloy powder, by which a dry-type powder mixture is prepared. Further, it is preferable to incorporate 0.01-10wt.% of a powder of one or more kinds among Cu, Ni, Pd, In, and Sn into the silver powder and also to incorporate 0.01-0.5wt.% of a powder of one or more kinds among Ni, Co, and Fe into the silver alloy powder. This dry-type powder mixture is compacted at a pressure of about (500 to 2000)kg/cm2 and sintered in vacuum or in a reducing atmosphere at a temp., lower by about 50-100°C than the solidus temp. By this method, the electric contact material, capable of plastic working sililar to that in the case of the conventional one and applicable in the medium-load (about 70-200g by contact force) medium-current region, can be obtained.
TAKAHASHI SATORU
ICHINOSE KAZUHITO
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