The invention relates to a preparing method of AgSnO
electric contact materials with uniform tissues. The method comprises the steps of
smelting, surface treatment,
extrusion, drawing, pushing and
cutting,
ingot pressing, inner oxidation, re-pressing, surface treatment,
extrusion and drawing, wherein additives are any two kinds of materials or more than two kinds of materials from Cu, Ga, Ce, Zr and CO. The materials comprise the following ingredients in percentage by weight: 86 to 92 percent of Ag, 5 to 8 percent of Sn, 2 to 3 percent of In, 0 to 2 percent of Cu, 0 to 1 percent of Ga, 0 to 0.2 percent of Ce, 0 to 0.3 percent of Zr and 0 to 0.5 percent of Co. The key steps of the process include the
ingot pressing after the wire material pushing and
cutting,the inner oxidization, the re-pressing and the surface treatment. The wire materials prepared by the method have the advantages that the metallographic structure is uniform, and the
oxide aggregation and silver aggregation phenomena do not occur. Meanwhile, the
hardness of the wire materials is low, the elongation percentage is high, after the materials are made into rivets, electric performance tests are carried out, the
material transfer resistance performance is good, and the AgSnO
electric contact materials prepared by the method are suitable for being applied to various different vehicle-mounted relays.