Formation mechanism and synthesis of Fe–TiC/Al2O3 composite by ilmenite, aluminum and graphite

Abstract Al 2 O 3 /TiC composites are used as cutting tools for machining gray cast iron and steels. The addition of iron improves the toughness of Al 2 O 3 /TiC composites. Ilmenite, aluminum and graphite can be used to produce in-situ Al 2 O 3 /TiC–Fe composites. However the formation mechanism and reaction sequences of the system are not clear enough. Therefore, the present research is designed to determine the formation mechanism and the reaction sequences of the foresaid system. In this research, ilmenite was synthesized to prevent the presence of impurities in the system and then the critical temperatures of ilmenite, aluminum and graphite powder mixture were determined by DTA analysis. The milled and pressed samples, prepared from this mixture, were heat treated at the critical temperatures. The final products were analyzed with XRD. It was found that at the first exothermic peak of DTA curve (720 °C), aluminum reacts with FeTiO 3 , forming Fe, TiO 2 , Al 2 O 3 and Fe 2 Al 5 . Further increase in the temperature, up to 930 °C, results not only in the transformation of TiO 2 to Ti 2 O 3 and TiO, but also in the conversion of Fe 2 Al 5 to FeAl. Moreover, titanium carbide will also be formed. With the rise in temperature, Ti 2 O 3 , TiO and iron aluminides disappear and TiC, Al 2 O 3 and Fe will be the final compounds.