A Study Of Cermets By In-Situ Synthesis From Natural Ilemenite

TiC/Fe and TiC-Al₂O₃/Fe cermets are good machinery materials with excellent properties and wear resistance. So far, the most common metallurgy method has the deficiency of contamination between the hard phase and the adherence phase influencing the mechanical performances, and a high cost. Those are all bottle necks of its applications. The job of finding a cost effective new technology with a great improvement of cermets properties becomes very important.Our country is abundant in ilmenite and it was chosen as the raw material. Self-propagating high-temperature synthesis (SHS) was used to in-situ fabricate TiC-Al₂O₃/Fe blends of powders. A novel in-situ processing combining SHS with vacuum sintering and hot-pressing was first used to prepare dense TiC/Fe, TiC-Al₂O₃/Fe cermets and steel-bonded cemented carbide GT35. This work contributes a lot to theoretical and industrialization of in-situ processing of natural mineral to fabricate cermets.High energy ball milling, hot processing, vacuum sintering as well as machining and heat treatment were used in this work. After processing, the microstructure and phase composition of the synthesized composites were characterized employing differential thermal analysis(DTA), thermal gravimetric analysis(TG),X-ray diffraction (XRD), scanning electron microscopy(SEM) and chemical bond calculation methods. The thermal dynamics of carbon deoxidization and aluminum deoxidization to in-stiu synthesis, dynamics of phase formation were studied. Influences of raw material and processing techniques on combustion and granularity of SHS products, types and quantities of additives as well as sintering process on the microstructure and mechanical properties of the composites were also investigated. Controlling rules and optimum mixture and processing techniques were proposed. Main results:1) The thermal dynamically stable phase of ilmenite in-stiu synthesis cermets was TiC-Al₂O₃ and Fe;...