NiAl/NiCoCrAlY/8YSZ复合喷涂层的微观结构与性能研究

目的提高金属/陶瓷隔热涂层体系在海洋环境下的耐腐蚀性能。方法利用冷喷涂方法制备NiAl复合打底层和Ni CoCrAlY粘结层,与等离子喷涂制备的8YSZ陶瓷层构成适用于海洋环境的多层结构耐蚀隔热涂层体系。利用FE-SEM分别观察喷涂态粘结层和陶瓷层的表面、横截面形貌,通过EDS分析涂层元素分布;利用XRD分析表征涂层的物相组成;借助万能材料试验机,采用拉伸法测试涂层结合强度;利用热循环试验和焰流冲刷试验测试涂层的耐高温性能。结果微观分析表明,冷喷涂制备的NiAl复合打底层和Ni CoCrAlY粘结层形貌致密,涂层材料未发生明显氧化,颗粒变形程度不一,粘结层与基体间的结合强度约为18.4 MPa,粘结层与8YSZ陶瓷层界面结合紧密。陶瓷层物相结构和成分稳定,涂层经12次热震循环和1000个周期的高温焰流冲击后,表面未出现开裂、起皮和脱落。结论采用冷喷涂法和等离子喷涂法联合制备的耐蚀隔热复合涂层体系具备良好的耐热性和耐腐蚀性。冷喷涂制备的金属涂层结构致密,孔隙率低,与陶瓷层结合良好,能够有效提高涂层体系在腐蚀性环境中的耐蚀性能。NiAl复合涂层可以缓解Ni CoCrAlY粘结层和铝合金基材间的热匹配问题,增强涂层的结合性能。

Microstructure and Properties of NiAl/NiCoCrAlY/8YSZ Composite Coatings

The work aims to improve the corrosion resistance of metal/ceramic thermal insulation coatings in marine envi-ronment. NiAl composite coating and NiCoCrAlY bonding layer were prepared by cold spraying and formed to a multi-layer structure corrosion resistant and heat insulating coating system suitable for marine environment with 8YSZ ceramic coating prepared by plasma spraying. The surface and cross-section microstructure of bonding layer and ceramic layer were observed by field emission scanning electron microscopy (FE-SEM), and the elements distribution was analyzed by energy dispersive spectral (EDS). The phase compositions of coatings were characterized by X-ray diffraction (XRD). Bonding strength test was carried out by tensile test with universal material testing machine. Thermal cycle test and high temperature flame erosion test were used to investigate the high temperature resistance of the coating. Microscopic analysis showed that the morphology of NiAl composite coating and NiCoCrAlY bonding layer was compact, there was few obvious oxidation observed in the coating and the degree of particle deformation was different. Bonding strength between bonding layer and matrix was about 18.4 MPa. The interface of bonding layer and 8YSZ ceramic layer was closely bonded. The components of the ceramic layer were stable. No cracking, peeling or shedding occurred on the coating surface after 12 thermal shock tests and 1000 cycles of high temperature flame erosion. The composite coating prepared by cold spray and plasma spray has excellent thermal resistance and corrosion resistance. The metal coating prepared by cold spray has compact structure, low porosity and good bonding with ceramic layer, which can effectively improve the corrosion resistance of the coating system in corrosive environment. NiAl composite coating can alleviate the thermal matching problem between NiCoCrAlY layer and aluminum alloy substrate, thus enhancing bonding performance of the coating.