Reaction path of the synthesis of α-Al2O3-TiC-TiB2 in an Al-TiO2-B4C system

Differential thermal analysis was undertaken to determine the reaction path of the synthesis of α-Al2O3-TiC-TiB2 in an Al-TiO2-B4C system under argon. The Al content plays a significant role in controlling the reaction path and product. When the Al content is no more than 26.7 wt.%, TiO2 first reacts with B4C to yield TiB2 with TiBO3 being the intermediate phase, and then increasing temperature leads to the subsequent reactions between Al and TiO2 or its sub-oxides to yield α-Al2O3 and Al3Ti, and the resultant Al3Ti then reacts with B4C to produce TiC and TiB2. When the Al content is high (e.g. ≥ 34 wt.%), the reaction between Al and TiO2 for the formation of α-Al2O3 and Al3Ti occurs initially, and then the Al3Ti reacts with B4C. With the increasing Al content, the onset of the exothermic reaction in the Al-TiO2-B4C system shifts to lower temperature and the degree of reaction conversion is enhanced.

► We investigated the reaction path in an Al-TiO2-B4Csystem by DTA and XRD. ► Al content plays a significant role in controlling the reaction path and products. ► The reaction of TiO2 with B4C occurs first for Al content no more than 26.7wt%. ► With an increase in Al, the prior reaction of TiO2 with Al becomes more favorable. ► Ideal products could be obtained for high Al content even under DTA condition.