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分别采用超音速火焰喷涂(HOVF)和等离子喷涂(APS)在QT500球墨铸铁基体上制备Co Ni Cr Al Y粘结层(BC)和8YSZ陶瓷隔热层(TC),研究了试样在1050℃高温环境中经过2.5、8、15、50、100 h恒温氧化后体系的应力情况。利用扫描电子显微镜(SEM)对热生长氧化物(TGO)的微观形貌进行观察与分析,并用拉曼荧光光谱仪(RFS)分析了其应力的分布及变化规律,并通过力学模型进行了残余应力的数值计算。结果表明:由陶瓷层与粘结层之间的热失配而导致TGO中产生残余压应力,其最大值范围为1.9557~1.9603 GPa;残余压应力在高温氧化初始阶段逐渐减小,至15 h达到最小值,随之逐渐增大后趋于稳定;在恒温阶段,θ-Al2O3转变为α-Al2O3所引起的体积收缩是TGO中残余应力减小并趋于稳定的直接原因。
Co Ni Cr Al Y bonding layer (BC) and 8YSZ ceramic thermal insulation layer (TC) were prepared on the QT500 ductile iron substrate by means of HOVF and APS, respectively. After 2.5, 8, 15, 50, 100 h of constant temperature oxidation in high temperature environment, the stress state of the system. The microstructure of TGO was observed and analyzed by scanning electron microscope (SEM). The stress distribution and variation of TGO were analyzed by Raman fluorescence spectrometer (RFS). The residual stress Numerical calculation. The results show that the residual compressive stress in the TGO is caused by the thermal mismatch between the ceramic layer and the adhesive layer, with the maximum value ranging from 1.9557 to 1.9603 GPa. The residual compressive stress decreases gradually in the initial stage of high temperature oxidation to 15 h Reaching the minimum value, then gradually increasing and then stabilizing. During the thermostatic phase, the volumetric shrinkage caused by the transformation of θ-Al2O3 into α-Al2O3 is the direct cause of the residual stress in TGO decreasing and stabilizing.