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Effect of TiO2 and TiB2 on Pressureless Sintering of B4C

This paper presents results of experiments on pressureless sintering of boron carbide (B4C) with addition of titânia (TiO2) and titanium diboride (TiB2). The TiB2 powder was added as a second phase and the TiO2 powder for reactive sintering and in-situ formation of TiB2. The final concentrations of TiB2 in the composites were 0 to 10 vol%. Sintering was performed at 2050 °C/30min in argon atmosphere. TiO2 was completely transformed into TiB2 with fine equiaxed grains distributed homogeneously. Composites obtained by in-situ reaction showed a densification increase with the concentration increase, while the composites with TiB2 powder mixture showed low densification in all compositions. Relative Density of the composite with 10 vol% of TiB2 obtained in-situ was 91% (TD) compared to 86 % for B4C only. Vickers hardness was about 29 GPa.