Formation mechanism and controllable preparation of Ti(C,N) in Al–TiO2–Al2O3 composite at 1673 K in flowing N2

Abstract

In this paper, the Ti(C,N)–Al2O3 refractory was successfully prepared at 1673 K in flowing N2 by using brown fused alumina, rutile and Al as the raw materials, phenolic resin as the binding agent. The formation mechanism of Ti(C,N) in the Al–TiO2–C matrix and resin-bonded Al–TiO2–Al2O3 refractory was investigated by the means of XRD, SEM and EDS, respectively. Results showed that the synthesis of Ti(C,N) in Al–TiO2–C matrix required (TiO2:C)mol>1, and this condition was achieved in the Al–TiO2–Al2O3 refractory by using phenolic resin as the carbon source. When the resin-bonded Al–TiO2–Al2O3 refractory was heat-treated under high temperature and nitrogen conditions, the stability of TiO2 in the refractory decreased and gradually transformed into Ti-containing nano particles (TiO, (Al, Ti)O2 and TiC), Al3Ti and (Al–Ti)melt. Then the TiC was further transformed into Ti(C,N) by the reaction TiC(s)+TiAl–Ti(l)+N2(g)→Ti(C,N)(s) after the refractory was transformed into an Al2O3–TiC-(Al–Ti)melt system at high temperatures.