PROPERTIES OF Ti3XC2(X=Al, Si) WITH PLASMA SPRAYED ZrO2 THERMAL BARRIER COATING
LIU Jing, SHENG Hongfei, ZHANG Baoshan, PENG Liangming
School of Engineering Science, University of Science and Technology of China, Hefei 230026
Cite this article:
LIU Jing SHENG Hongfei ZHANG Baoshan PENG Liangming. PROPERTIES OF Ti3XC2(X=Al, Si) WITH PLASMA SPRAYED ZrO2 THERMAL BARRIER COATING. Acta Metall Sin, 2011, 47(9): 1141-1146.
Abstract There has been a great interest in the synthesis and characterization of Ti3AlC2 and Ti3SiC2 lamellar ceramics due to their striking combination of merits of both metals and ceramics, such as good high-temperature strength, excellent oxidation resistance. In this study, dense and high purity polycrystalline Ti3AlC2 and Ti3SiC2 lamellar ceramics were prepared from Ti, Al(Si) and C powders by reactive hot pressing in vacuum at 1450 ℃ for 1.5 h under 30 MPa. Their phase constitution, mechanical characterization and thermal properties were investigated. In addition, plasma-sprayed monolayer ZrO2 thermal barrier coatings free of metallic transition layer were prepared on the two ceramic substrates. The purity of the Ti3AlC2 and Ti3SiC2 were 91.5% and 90.3%, and the main impurity was TiC. The flexural strength and fracture toughness were 536 MPa, 7.8 MPa·m1/2 and 457 MPa, 6.8 MPa·m1/2 for Ti3AlC2 and Ti3SiC2, respectively. They took a respective average value of 8.77×10-6 and 9.14×10-6/℃ for the coefficient of thermal expansion (CTE) without remarkable temperature dependence between 25 and 1000℃. Furthermore, the coatings contributed to a more than 60\% decrease in the high temperature thermal conductivity compared to the two matrices. In general, Ti3AlC2 and ZrO2-coated Ti3AlC2 displayed superior comprehensive properties to Ti3SiC2 and ZrO2-coated Ti3SiC2. The temperature differences between the outside surface and the coating/matrix interfaces created by the thermal barrier coating were calculated to be 341 and 358 ℃ for Ti3AlC2 and Ti3SiC2 substrate, respectively.
