浸渍强化对氮化硅组织和性能的影响

浸渍强化处理是提高反应烧结氮化硅性能的有效措施。影响浸渍强化效果的主要因素有浸渍剂的品种;多孔坯体的结构特征:以及浸渍剂与氮化硅之间的润湿性能和相互作用关系等。本文通过系统性实验,确定了进行浸渍处理的最佳条件。

THE INFLUENCE OF INFILTRATION STRENGTHENING ON THE STRUCTURE AND PROPERTIES OF SILICON NITRIDE

Infiltration strengthening is an effective means to improve the mechanical properties of Reaction Bonded Silicon Nitride(RBSN). In this paper, porpous RBSN compacts are infiltrated with three kinds of salt solutions: Re(NO3)yZr(NO3)4and A12(SO4)3. The thermodynamics of infiltration is that the wetting angle is less than 90 The infiltration amount obeys Poiseill Law, After the compacts are infiltrated with Re(NO3)4and Ai2(SO4)3, the fexural strength is increased largely, but Zr(NO3)4decreases the strength. This is because RexOyand Al2O3from the respective decomposition of Re(NO3)yand Al2(SO4)3can promote the sinter of Si3N4powders, decrease the sizes of pores and blunt the tips of cracks. On the contrary ZrO2from Zr(NO3)4enables Si3N4to decompose at high temperature.