Self-Propagating Reactions for Synthesis of High Temperature Materials.

摘要

Hard ceramics including TiB2, produced by conventional methods such as sintering and hot pressing require expensive high temperature process steps and machining which add significant cost to the material. The use of exothermic, self-propagating reactions (SHS), have recently received interest especially by the Soviet to form high purity refractory compounds especially in the boride and carbide systems. The cost effective production of abrasive compounds, cutting tools and high hardness monolithic, refractory materials has been claimed. The SHS process, at its basic level, involves the intimate blending of elemental powders at stoichiometric levels (in this case titanium and boron). Once blended, the materials are pressed into monolithic shapes and heated at one point to a reaction temperature (700 - 1200 C). Upon achieving the reaction temperature, the remaining body is transformed via self-propagating thermal wave into intermetallic or ceramic body based upon the original binary mixture (Ti + 2B yields Ti B2). Lightweight ceramics which can be prepared by SHS reactions are being considered as candidates for armor. Limited testing to date has identified the generic properties which can maximize armor performance.