High‐Pressure Self‐Combustion Sintering of Alumina‐Titanium Carbide Ceramic Composite

Abstract

AI2O3-TiC ceramic composites were fabricated by highpressure self-combustion sintering (HPCS). The samples had a unique microstructure which was quite different from that of commercial A1203-TiC materials made by conventional processing. A possible mechanism for combustion reaction is suggested on the basis of the microstructure of the samples and the thermodynamical data. The HPCS sample had a higher KIc value than commercial A1203-TiC materials.[

Photo- and Cathodoluminescence of Combustion-Synthesized Al2O3–TiC Composites

“…3 indicate that the liquid alumina phase exists during the combustion synthesis. Adachi et al [5] and Bowen and Derby [6] reported evidence of melting of alumina in the combustion synthesis of Al 2 O 3 ±TiC composites.…”

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…”

“…(1) result in a value of 2329 K when the initial temperature is 298 K and a value of 2394 K when the latter temperature is 400 K. Although the measured maximum temperature is lower than the melting temperature of alumina, there is microstructural evidence in this work (to be discussed later) and in previously published accounts that melting of this phase does take place. Adachi et al 12 and Bowen et al 13 reported evidence of melting of alumina in the combustion synthesis of Al 2 O 3 -TiC composites. During the short duration of the main combustion reaction, liquid aluminum reacts with rutile particles and liquid Ti, Ti 3 Al, and alumina surround the fine rutile particles or rutile particles dissolved into the liquid mixture ( Fig.…”

“…6 -8 The use of combustion synthesis to prepare Al 2 O 3 -TiC composites has been reported previously. 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.…”

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

“…It can be explained by noting that the combustion wave velocity is a strong function of the combustion temperature, which is higher in the case of anatase, as shown in Fig. 6 The XRD pattern indicates that the product is composed of only two major phases, TiC and A12O3. The bond strength between Ti and O in anatase TiO2 is calculated to be approximately 6 kJ/mole lower than that in rutile TiO2, and as a result, it facilitates the aluminothermic reduction of TiO2 in the 3TiO2-4Al-3C system and enhances the reactivity of the sample.…”