Sintering is a thermally activated and time dependent process, which occurs below the melting point of ceramics. Boron carbide is a highly covalent non-oxide ceramic with a high melting temperature. Therefore, the densification of boron carbide via thermally activated process is extremely hard and requires additional driving forces. Boron carbide based composite ceramics are produced by the direct addition of secondary phases into the structure or via reactive sintering using sintering additive. In this study, an additive effect on the spark plasma sintering behavior of boron carbide ceramic was investigated. 5 vol% silicon hexaboride and 5 vol% titanium silicon carbide are used to investigate the sintering behavior of boron carbide. Boron carbide with additive was densified by SPS at 1800°C for 10min under 70 MPa. The addition of 5 vol.% silicon hexaboride to boron carbide enhanced densification and increased the relative density of ceramic from 76% to 92%. 5vol.% titanium silicon carbide addition increased the relative density from 67% to 73%. Both additive decomposed at elevated temperatures and resulted in situ reaction with boron carbide. The crystallographic phases were characterized by X-ray diffraction using copper Kα radiation. The micrographs of fractured surfaces for specimens were determined by scanning electron microscopy (SEM). Vickers hardness of the specimen were also reported.
Anahtar Kelimeler: boron carbide, sintering additive, spark plazma sintering
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