Sn-Bronze계 마찰재료의 소결중 미세조직의 변화

Abstract

The microstrure evolution of a 78.0 Cu-7.1 Sn-12.5 Fe-2.4 Pb(wt%) alloy, metal composition of a typical Cu-Sn base friction material, has been studied during pressure (1.5 Mpa) and pressureless sintering up to 810℃ for various times. Overall microstructural changes during sintering were found to be determined by the reaction between Cu and Sn. The Sn melts upon heating spread alone the capillaries leaving pores at their sites and form ε phase. The pores collapsed during subsequent pressure sintering at higher temperatures. Upon heating ε phase appeared to transform into γ and β phases, which remelted eventually by reverse peritectic reactions. Fores, however, formed again at the sites of the intermediate phases, when the sintering pressure was relieved in the temperature range of peritectic reactions. Remelting of the intermediate phases could thus enlarge the size of pores in Cu-Sn base materials. A good homogeneous microstructure was obtained after sintering at 810℃ for about 1 hr under 1.5 Mpa.