Abstract
Achieving densification in sintering of titanium diboride (TiB2) is challenging due to its high covalent bonding and low self-diffusion coefficient, necessitating the use of external pressure and high temperature. To enhance densification, a combination of reaction sintering and liquid phase sintering was employed in this study. Different ratios of sintering aids were tested via vacuum sintering. B4C and Ti3SiC2 were chosen as sintering aids, reacting to produce TiB2, TiC, and SiC. Co, known for their good wettability with TiB2, were used as metal sintering aids, along with Mo, which contributes to grain refinement in TiB2-based ceramic composites. A core-rim structure was observed after first holding at 1100–1150 °C, where B4C reacted with Ti3SiC2, and subsequently sintering at 1900 °C and 1950 °C facilitated densification. Mo diffused into TiC, surrounding the original TiB2 grains along with trace amounts of Co, thereby inhibiting TiB2 growth. The recipe of 90 wt% TiB2+10 wt% (B4C + Ti3SiC2+Co + Mo) achieved the highest relative density at 94.37 % and a hardness of 28.56 GPa. The observed crack propagation exhibited transgranular cracking, crack bridging, and branching, absorbing higher energy and enhancing fracture toughness.
Published Version
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