汽车内燃机的表面等离子喷涂与高温氧化性能

Surface Plasma Spraying and High Temperature Oxidation Performance of Automotive Internal Combustion Engine

采用等离子喷涂的方法在汽车内燃机用GH4169合金表面制备了CoNiCrAlY涂层和MoSi_2-CoNiCrAlY复合涂层,对比分析了单一涂层和复合涂层的物相组成、显微形貌和抗高温氧化性能,并探讨了涂层的高温氧化机制。结果表明:CoNiCrAlY涂层主要由γ′-Ni_3Al、a-Al_2O_3和γ-Co相组成,MoSi_2-CoNiCrAlY复合涂层中还出现了MoSi_2和Mo_5Si_3相;CoNiCrAlY涂层在1 025℃条件下氧化不同时间所得氧化膜的物相组成都为Cr_2O_3、α-Al_2O_3、NiCr_2O_4和(Co,Ni)Cr_2O_4,MoSi_2-CoNiCrAlY复合涂层氧化膜中还形成了部分SiO_2相;MoSi_2-CoNiCrAlY复合涂层的硬度高于CoNiCrAlY涂层的,抗氧化能力明显优于CoNiCrAlY涂层的;CoNiCrAlY涂层"快速氧化阶段"和"稳定氧化阶段"的影响要素分别为NiO、NiCr_2O_4和(Co,Ni)Cr_2O_4尖晶石相的生长速率和Al_2O_3致密氧化膜的生长速率,而影响MoSi_2-CoNiCrAlY复合涂层高温氧化性能的关键要素为SiO_2的扩散和流动能力。

CoNiCrAlY coating and MoSi2-CoNiCrAlY composite coating were prepared on the surface of GH4169 alloy for automotive internal combustion engine by plasma spraying. The phase composition, microstructure and high temperature oxidation resistance of single coating and composite coating were comparatively analyzed, and the mechanism of high temperature oxidation of coatings was explored. The results show that the CoNiCrAlY coating was mainly composed of γ’-Ni3 Al,a-Al2 O3 and γ-Co, MoSi2 and Mo5 Si3 phases also appeared in MoSi2-CoNiCrAlY composite coatings;the phases of CoNiCrAlY coating at 1 025℃ with different oxidation times were Cr2 O3, aAl2 O3,NiCr2 O4 and(Co, Ni) Cr2 O4,while SiO2 phase was also formed in the oxide film of MoSi2-CoNiCrAlY composite coating;the hardness of the MoSi2-CoNiCrAlY composite coating was higher than that of CoNiCrAlY coating, the antioxidant capacity was significantly better than that of CoNiCrAlY coating. Influence factors in "rapid oxidation stage" and "stable oxidation stage" of CoNiCrAlY coating were NiO,NiCr2 O4 and(Co,Ni) Cr2 O4 spinel phase growth rate and the growth rates of Al2 O3 compact oxide film. and the key factors affecting MoSi2-CoNiCrAlY composite coating for high temperature oxidation were diffusion and flow capacity of SiO2.