超音速等离子弧喷涂ZrO_2/CoNiCrAlY热障涂层界面高温氧化性能研究

Study on the high-temperature oxidation performance of ZrO_2/CoNiCrAlY thermal barrier coating interface by supersonic plasma spraying

采用超音速等离子弧喷涂设备在35Cr Mo钢基体上制备了Zr O_2/Co Ni Cr Al Y热障涂层,并将涂层加热到1 150℃进行氧化试验。利用扫描电子显微镜和X射线衍射方法对涂层的组织结构和相组成进行了分析,并对元素扩散情况进行研究。结果表明,涂层组织致密,界面结合良好,无剥落;粘结层表面存在少量尖角和钩状突出颗粒。热障涂层经过1 150℃加热后,在粘结层与陶瓷层的界面处出现少量深颜色的热生长氧化物(thermally grown oxide,简称TGO);随着氧化时间的延长,TGO层厚度明显增加并且开始连续。通过对Zr O_2-8Y2O3/Co Ni Cr Al Y界面扫描发现,该处Al元素出现了的富集峰,而Cr和Ni元素的含量远小于金属黏结层中含量,并且Cr和Ni元素的变化趋势为沿界面呈梯度下降,TGO层由亚稳态的θ-Al2O3逐渐转变为稳定态的α-Al2O3,有效地提高了涂层的抗高温氧化性能。

The Zr O_2/Co Ni Cr Al Y thermal barrier coating was prepared by Supersonic Plasma spraying on 35 Cr Mo steel and then it was heated at a constant temperature 1 150 ℃. The structure and phase composition of the coating was analyzed by SEM and XRD methods, and some studies were also focus on the element diffusion. The results showed that the coating was compact with well combined interface and had no desquamation. A little sharp-angled and hooked grains existed on the surface of the bond coating. After heated at 1 150 ℃, the microstructure of coating presented some thermally grown oxide(TGO) with deep colour. The thickness of TGO layer increased and became continuous with the increase of oxidation time. Through scanned the interface of Zr O_2/Co Ni Cr Al Y, it presented Al element peak which was assembled at oxide zone, but the content of Ni, Cr element were reduced and descend from metal felt layer to oxide zone. The Al_2O_3 phase changed from metastable θ-Al_2O_3 to steady α-Al_2O_3 in TGO layer. It could be proved that the high-temeprature oxidation resistance of coating could be improved obviously.