文摘
Sub-micron sized TiB2 ceramic powders were prepared via self-propagating high-temperature synthesis (SHS) followed by HCl leaching at different temperatures. Purified powders obtained using optimum process parameters were consolidated by field assisted sintering technology/spark plasma sintering (FAST/SPS) technique. Phase and microstructural analyses of both the powder and sintered samples were carried out by X-ray diffractometer (XRD) and scanning electron microscope (SEM). The chemical analyses and particle size measurements of the specimen were conducted by inductively coupled plasma-mass spectrometry (ICP-MS) and dynamic light scattering (DLS) techniques. The final properties of the sintered sample were determined in terms of density and microhardness. The effects of different HCl leaching temperatures on the formation, microstructure, particle size, purity and sintering behavior of the SHS-produced TiB2 powders were investigated. The SHS reaction of TiO2-B2O3-Mg powders as a starting mixture yielded MgO, Mg3(BO3)2 and Mg beside the desired phase TiB2. All three magnesium containing by-products were completely removed by performing hot HCl leaching. TiB2 powders after SHS reaction and leaching with 9.3xA0;M HCl for 30xA0;min at 80xA0;°C revealed a minimum purity of 98.4% and a homogenous particle size distribution with an average particle size of 536xA0;nm. In the ultimate SPS experiment which was conducted at 1500xA0;°C for 5xA0;min under a pressure of 50xA0;MPa, a relative density of 94.9% and a micro-hardness value of 24.56xA0;GPa were achieved.