Fe_3Al/Al_2O_3陶瓷复合梯度涂层抗热震性研究

STUDY ON THERMAL-SHOCK RESISTANCE OF Fe_3Al/Al_2O_3 COMPOSITE GRADED COATINGS

通过800℃—压缩空气冷却热循环实验,对Fe_3Al/Al_2O_3梯度涂层的抗热震性和热震机制进行了研究。结果表明:涂层的主要热震损坏形式是随着循环次数的增加而产生的剥落。当裂纹在Al_2O_3中出现时,涂层将沿着基体-涂层界面迅速剥离,而对梯度涂层则具有相当的抗热震能力。实验证明:Fe_3Al中间层和涂层成分的梯度变化缓解了热循环应力,提高了抗热震损坏能力,同时,有利于涂层结合强度的提高。

The thermal-shock resistance and the thermal-shock mechanism of Fe3 Al/Al2 O3 graded coatings were studied by thermal-cycling experiment at 800℃ and cooled by compressed air. Results indicate that the main thermal-shock failure mode of coatings is coatings spoilage and the graduate loss of adhesive strength with the increasing times of thermal cycle. When the cracks form in Al2 O3 coatings, the coatings are spoiled quickly along the substrate - coating interfaces. But the graded coatings stili have some abilities of thermal-shock resistance when the cracks form. It is proved that Fe3 Al intermetallic intermediate lay-er and the gradient distribution of coating composition can relax the thermal-cycling stress in different degree and increase the a-bility of thermal-scathing mode, such as crack's forming in layers and between layers and growing continuously. The gradient distribution of coating composition also benefits to thermal-shock resistance of the coatings, and has definite connection to the adhesive strength of the coatings.