Preparation of Ti3AlC2/Al2O3 composites based on the titanium concentrate: Gas-based reduction, acid leaching and sintering

Abstract

Ti3AlC2/Al2O3 composites exhibit outstanding physical and chemical properties, but their widespread use is hindered by the expensive raw materials. This study introduces a novel production process for Ti3AlC2/Al2O3 composites. Initially, high grade Ti(C, O) powders with purity above 90 % are obtained through the reduction and carbonization of titanium concentrate in a CH4–H2 system. Subsequently, pure Ti3AlC2/Al2O3 composites are fabricated via sintering using the Ti(C, O)/Ti/Al system. Experimental findings reveal that prolonged reduction time and high temperatures in the CH4–H2 system lead to increased carbon deposition in the titanium concentrate reduction product, adversely impacting the purity of the sintered Ti3AlC2/Al2O3 composites. The optimal conditions for reducing titanium concentrate to Ti(C, O) in the CH4–H2 system involve a 1.5-h reduction period at 1200 °C. Excess Ti and Al powders are crucial in the preparation of Ti3AlC2/Al2O3 composites from the Ti(C, O)/Al/Ti material system. Surplus Ti powders reduce the TiC content in the final product, while excess Al powders act as deoxidizers, removing oxygen from Ti(C, O) and generating Al2O3 in situ. The optimal molar ratio for Ti(C, O), Al and Ti powders is determined to be 2:1.6:1.2. This research introduces a cost-effective approach for producing pure Ti3AlC2/Al2O3 composites.