급속응고한 Ag-Sn-In 합금의 미세조직에 미치는 Bi의 영향

Abstract

Contact material is widely used as electrical parts. Ag-CdO has a good wear resistance and stable contact resistance. But the disadvantages of Ag-CdO alloy are coarse Cd oxides and harmful metal, Cd. Then Ag-Sn alloy that has stable and fine Sn oxide at high temperature has been developed. In order to investigate the effect of Bi addition that affects the formation of the oxide layer on the surface and the formation of oxide in matrix Ag, we studied the microstructures and properties of Ag-Sn-In(-Bi) material fabricated by rapid solidification process. The experimental procedures were melting using high frequency induction, melt spinning, and internal oxidation. We have shown that the size of Sn oxide at no additional Bi is 20nm and the effect of Bi for high hardness is 0.3wt%Bi. Bi was concentrated to grain boundary and Bi made precipitation free zone (PFZ). Then Bi caused poor properties of alloy.