Experiments were conducted in order to elucidate the formation mechanism of TiB₂by the simultaneous magnesio-thermic reduction of TiO₂- B₂O₃mixture. TiB₂was formed at 897 K or more, and its X-ray diffraction intensity increased with increasing temperature. In addition to MgO and MgTi₂O₄, which were main by-products, Mg₃(BO₃）₂ and (Mg, Ti) O were produced at lower temperature and at higher temperature, respectively. In the magnesio-thermic reduction of TiO₂, Ti₂, O was identified at 1273 K or more, and its X-ray diffraction intensity increased to a maximum at 1373 K, but finally disappeared at 1573 K. In reduction of short time period, however, the formation of TiO₂ was observed even at 1573 K. On the other hand, in the magnesio-thermic reduction of B₂O₃, the formation of boron could not be identified by X-ray diffraction, but weak diffraction peaks of B₄C were detected. It was inferred from these results that amorphous boron had been formed. Thermodynamic consideration clarified that TiO₂is easily reduced to TiO with magnesium, but the additional reduction of TiO to Ti is difficult at higher temperature. Therefore, since the formation of boron precedes in the simultaneous magnesio-thermic reduction of TiO₂- B₂O₃ mixture, it was concluded that TiB₂is finally formed according to the next reaction : TiO + Mg + 2B = TiB₂ + MgO.
TiO₂- B₂O₃混合物のMg熱還元によるTiB₂の生成反応
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