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在1450℃真空下保温1.5 h进行热压反应烧结制备了纯度为90%以上的Ti_3AlC_2和Ti_3SiC_2层状结构陶瓷,研究了它们的物相组成、微观结构、力学性能及热物理特性,并在2种陶瓷基体上进行了无金属粘结过渡层等离子喷涂ZrO_2热障涂层处理,考察了涂层的结合强度与热冲击特性.结果表明,Ti_3AlC_2和Ti_3SiC_2基体材料的抗弯强度和断裂韧性分别为536 MPa,7.8 MPa·m~(1/2)和457 MPa,6.8 MPa·m~(1/2),在25—1000℃温度范围内的平均线膨胀系数分别为8.77×10~(-6)和9.14×10~(-6)/℃,前者的力学性能与热稳定性均优于后者;等离子喷涂后,整体材料的热导率下降幅度达60%以上,涂层与基体结合牢固且具有良好的抗热冲击特性;对2种基体的涂层隔热效应的计算表明,0.3mm厚ZrO_2涂层外表面与内界面的温差分别为341和358℃,可显著提高工件的使用温度.
Ti3AlC2 and Ti3SiC2 layered ceramics with a purity of over 90% were prepared by hot press reaction sintering at 1450 ℃ for 1.5 h under vacuum. The phase composition, microstructure, mechanical properties and thermophysical properties of Ti3AlC2 and Ti3SiC2 layered ceramics were studied. The results show that the flexural strength and fracture toughness of Ti_3AlC_2 and Ti_3SiC_2 matrix materials are respectively 536 MPa, 7.8 MPa · m ~ (1/2) and 457 MPa, 6.8 MPa · m ~ (1/2) respectively. The average coefficients of linear thermal expansion of the composites were 8.77 × 10 ~ (-6) ) And 9.14 × 10 ~ (-6) / ℃, respectively. The mechanical properties and thermal stability of the former are better than those of the latter. After plasma spraying, the thermal conductivity of the material decreases by more than 60% And has good thermal shock resistance. The calculation of the thermal insulation effect of the two substrates shows that the temperature difference between the outer surface and the inner interface of the 0.3 mm thick ZrO 2 coating is 341 and 358 ° C, respectively, which can significantly increase the working temperature of the workpiece .