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为提高7YSZ纳米热障涂层的热震性能,实验中采用超音速火焰喷涂(HVOF)在涡轮叶片模拟工件上制备了粘结层NiCrCrAlYTa,再使用大气等离子喷涂(APS)在粘结层上制备了7YSZ纳米陶瓷层。采用磁控溅射在7YSZ热障涂层样品表面镀铝,并在不同压力下(200、250、300 Pa)对镀铝样品进行热处理表面改性。对喷涂态样品和镀铝改性后样品进行水淬热震实验,1050℃保温10 min+水冷5 min为一个热循环,观察热障涂层镀铝改性前后样品在水淬热循环过程中形貌和结构演变。实验结果表明,镀铝改性后样品表面存在铝薄膜蒸发、凝固后形成的疏松纳米Al晶粒表层以及由Al和ZrO_2原位反应形成的致密α-Al_2O_3底层。在镀铝样品热处理过程中,随着压力升高,疏松层致密度逐渐增加。不同热处理压力下镀铝表面改性后样品经过73次水淬热循环后剥落面积均小于喷涂态样品,显示出良好的抗热震性。
In order to improve the thermal shock resistance of 7YSZ nano-thermal barrier coatings, NiCrCrAlYTa was prepared on a turbine blade simulated workpiece by means of HVOF, and then plasma-sprayed (APS) on the adhesive layer 7YSZ nano ceramic layer. The samples of 7YSZ thermal barrier coatings were magnetized with aluminum and the aluminized samples were heat-treated at different pressures (200, 250 and 300 Pa). Water spray quenching and thermal shock experiments were carried out on the sprayed samples and the modified samples after aluminum plating. The thermal insulation at 1050 ℃ for 10 min and the water cooling for 5 min were observed as a thermal cycle. Appearance and structure evolution. The experimental results show that there is aluminum film evaporation on the surface of the sample after aluminized modification, the surface layer of loose nano-Al formed after solidification and the dense α-Al_2O_3 bottom layer formed by in situ reaction of Al and ZrO_2. During the heat treatment of the aluminized samples, as the pressure increases, the density of the loose layer gradually increases. After heat treatment under different heat treatment pressure, the surface area of the sample after the aluminum plating modification is less than that of the sprayed sample after 73 times of water quenching and thermal cycling, which shows good thermal shock resistance.