Effect of precursors on the combustion synthesis of TiC-Al₂O₃ composite

Abstract

In the combustion synthesis of TiC-Al2O3 composites from TiO2, Al, and C, different types of precursors, i.e., anatase and rutile TiO2, and graphite and carbon black were used. The measurements of combustion wave velocity showed that the reactivity was higher with graphite as a carbon source and anatase as a TiO2 source. This was also confirmed by analyzing the degree of conversion of reactants to products. For the precursors investigated, the wave propagation of the 3TiO2-4Al-3C system diluted by A12O3 showed that the limit of wave propagation was more dependent on carbon source than on TiO2. The wave front of all the samples proceeded in unstable combustion mode. Temperature profiles in the reaction zone suggested that the heat-affected zone was broader in the case of graphite carbon source than carbon black. The microstructures and chemical composition of the products were also studied.

Structure Formation in the Combustion Synthesis of Al2O3–TiC Composites

“…Since the starting TiO 2 phase has the anatase modification, the presence of rutile in the quenched-reaction zone is an indication of a solid-solid transformation of titania, a process that takes place at 918 K. The presence of titanium in this zone is consistent with the two-step mechanism mentioned above and is in agreement with reports in the literature. 3,12,13 The differential thermal analysis (DTA) study by Sundaram et al 16 on the system 4Al⅐3TiO 2 has shown that the reaction between Al and TiO 2 at 1165 K leads to the formation of Ti 3 Al according to…”

“…The formation of the Ti 3 Al phase is also believed to take place before the primary combustion reaction. This suggestion is based on the observation of AlTi 3 in DTA experiments which are done typically at a much lower heating rate than that experienced in SHS. Another justification for this proposal is based on previous observations on the synthesis of TiC/Ni-Al composites.…”

“…C ERAMIC-CERAMIC composites of Al 2 O 3 -TiC have been the focus of significant attention primarily because of their potential application in cutting tools and tape-head materials. [1][2][3] Their utilization in these and similar applications is motivated by such attractive properties as high wear resistance, high strength and fracture toughness, and good electrical conductivity. 1,2 Commercially available Al 2 O 3 -TiC ceramics are generally manufactured by the pressureless sintering or hot-pressing of Al 2 O 3 and TiC powder mixtures at a temperature in the range of 1873-2073 K. 2,4,5 More recently, these and similar composites have been prepared by combustion synthesis, a process noted for its simplicity and feasibility of using low-cost raw materials.…”

“…Cutler et al, 5,9,10 Rabin et al, 11 and Adachi et al 12 reported results on the synthesis of and subsequent densification of these composites. Choi et al 3 used different types of precursors to investigate the effect of reactants on the properties of the products, and Bowen et al 13 examined the microstructures of the combustion-synthesized composites. The combustion synthesis of Al 2 O 3 -TiC composites can be achieved by the following reaction:…”

Ambient‐Temperature Mechanochemical Formation of Titanium Nitride‐Alumina Composites from TiO2 and FeTiO3

“…The lower temperature is sufficient for grain growth, but is below the ignition temperature of 900°C which is commonly found for pressed pellets in the formation of composites of titanium carbide and alumina from TiO 2 , C, and Al. [11][12][13][14][15][16][17][18][19][20][21][22][23][24] Differential thermal analysis was performed on selected powders using approximately 30 mg samples which were heated up in either a nitrogen or argon atmosphere to 1200°C at a heating rate of 20°Cиmin −1 using a Shimadzu DTA-50 instrument. Thermogravimetric analysis was also performed using the same parameters in a Shimadzu TGA-50.…”