Method of an Ag/metal oxide material for electrical contacts

摘要

This invention relates to a silver / metal oxide material for electrical contacts containing no Cd which essentially consists of Ag and 5 to 30% by weight of at least one of oxides of Sb, Sn, Zn, In, Cu, Mn, Bi and Pb, and further, if necessary, 0.05 to 2% by weight of at least one of oxides of Mg, Al, Fe, Ni, Co, Si, Ga, Ge, Te, Ca and Li, the total amount of said metal oxides being 5 to 32% by weight, wherein fine particles of said metal oxides are substantially uniformly distributed in a matrix whose main component is Ag in a sintered state, and wherein there are no grain boundaries formed by agglomerations or agglomerated layers of said metal oxides. Further, the method of producing the same is provided including steps of: changing in steps the hydrogen ion concentration in an aqueous solution of Ag Ions and at least one of metal ions of Sb, Sn, Zn, In, Cu, Mn, Bi and Pb, and further, if necessary, at least one of metal ions of Mg, Al, Fe, Ni, Co, Si, Ga, Ge, Te, Ca and Li so as to form precipitates of Ag-oxygen compound and oxides and/or hydroxides of said metals; drying and thereafter heat-treating said precipitates to form mixed powder of Ag and oxides of said metals and shaping and sintering said mixed powder; and further, if necessary, heat-treating the sintered material to stabilize.