氧燃充枪比对爆炸喷涂CoCrAlYTa涂层抗氧化性能的影响

Influence of Oxygen/Fuel In-gun Ratio on Oxidation Resistance of CoCrAlYTa Coating Prepared by Detonation Gun Spraying

采用爆炸喷涂工艺制备了CoCrAlYTa涂层,借助SEM,EDS,XRD和高温氧化实验研究了氧燃充枪比对涂层组织结构及抗氧化性能的影响。结果表明:随着氧燃充枪比的增加,爆轰温度和爆轰速率不断提高,使涂层由均匀结构向层状结构转变,涂层的孔隙率不断降低;而涂层越致密,氧化过程中涂层表面越能尽早形成连续的氧化膜,使得涂层的抛物线速率常数kP下降,从而降低形成铝氧化物的临界浓度,促进Al元素的选择性氧化,进一步阻碍氧向涂层内部的扩散,使涂层的抗氧化性能随氧燃充枪比的增加而不断增强。

CoCrA1YTa coatings were prepared by means of detonation gun spraying. The influence of oxygen/fuel in-gun ratio on the structure and oxidation resistance of the as-prepared coatings was in- vestigated by SEM, EDS, XRD and high-temperature oxidation test. The results revealed that the detonation temperature and bombardment velocity increased with the increased of oxygen/fuel in-gun ratio, which induced the transformation of coating structure from uniform structure to lamellar struc- ture and the decreased of the coating porosity. Meanwhile, the continuous oxide scale was prone to being formed earlier if the coating was more compactness, which decreased the parabolic rate constant kp of the coating. The critical concentration of A1 element in the coating to form A12 03 declined conse- quently and the selective oxidation of A1 was promoted. The formed A12Oa layer can further suppress the diffusion of oxygen into the coating and result in the enhancement of oxidation resistance with the increase of oxygen/fuel in-gun ratio.