Preparation And Properties Of TiC/TiB₂Composite Based On Pressureless Sintering

TiC-TiB2ceramics composite has been widely used in various fields, such as special electrode, cutting tool, wear-resisting parts, which is one of the most suitable structural ceramics for high temperature applications. TiC-TiB2composite is usually synthesized by SHS and hot pressing method so far. However, it is difficult to control the reaction process for SHS and is costly for the latter method to prepare TiC-TiB2ceramics, which both restrict the development of such material. Due to characteristics of simple process and low-cost energy of pressureless sintering method, it could significantly reduce production cost of material and support widely applications in the future market. In order to reduce the production cost of materials, this study was focused on preparation of TiC-TiB2composite by pressureless sintering, which is very significant for the applications and development of TiC-TiB2ceramics composite.This study used two kinds of methods to prepare TiC-TiB2ceramics composite. One is using TiC-TiB2powders resulted from cheap titanium-rich undressed ore and boron anhydride to prepare TiC-TiB2ceramics material. The other method is using in-situ synthesized TiB2(from TiO2、B4C and C raw powders) and purchasing TiC powder to prepare TiC-TiB2ceramics composite. The sintering process and the effect of sintering aid on the density, microstructure and properties of TiC-TiB2composite were investigated in detail.The experimental results were shown as follows. For the TiC-TiB2powder preparation the best sintering process was to sinter at1450℃holding for30minutes. Corresponding to the reaction equation, the optimum ratio of raw materials was120%boron anhydride. When using homemade TiC-TiB2powders as raw material, the optimum sintering process of TiC-TiB2composite was2100℃holding for90min. When Y2O3content was6%, the TiC-TiB2ceramics material showed the optimum properties. The bending strength and fracture toughness of that were151.4MPa and3.02MPa-m1/2, respectively. On the other hand, using in-situ TiB2(from TiO2、B4C and C) and purchasing TiC powders as raw materials to prepare TiC-TiB2composite, the best sintering process was1400℃×30min+2000℃×90min. When the content of Y2O3was12%, the material showed the optimum properties. The hardness, bending strength and fracture toughness of that were19.98GPa,270MPa and3.54MPa·m1/2, respectively.