【作者】 胡雪磊；

【导师】 王佳； 李相波；

【作者基本信息】 中国海洋大学 ， 海洋化学， 2010， 硕士

【摘要】 随着航空、航海技术的快速发展,对发动机、内燃机材料强度的要求也不断提高。热障涂层凭借良好的隔热效果、耐磨、耐腐蚀及热冲击性能,在高温工作环境中得到了广泛的应用。冷喷涂技术利用低温、预热高压气流携带粉末颗粒以超高速撞击基体。制备的涂层孔隙率低、结合强度高、显微硬度高、不易发生化学反应及相变。在一定程度上弥补了传统热喷涂技术的缺陷,为改善热障涂层耐高温耐腐蚀性能开辟了新的道路。本论文的主要目的是利用X射线衍射技术(XRD)、扫描电镜及EDS能谱分析、显微硬度、结合强度、抗热震性及耐腐蚀性试验等手段对冷喷涂技术成功制备的NiCoCrAlY/ZrO2复合涂层的物理及电化学性能进行研究。同时也对磨损及人工破损后的NiCoCrAlY/ZrO2复合涂层进行物理和腐蚀电化学性能进行测试,探讨磨损和破损问题对涂层性能的影响。研究结果显示,XRD分析未发现氧化相峰；涂层与基体结合致密分界面不明显,孔隙率低(2.6%左右)；显微硬度较高(NiCoCrAlY/ZrO2涂层：HV400-600; NiCoCrAlY单层:HV 400-500)；冷喷涂涂层内部、涂层与基体结合力都很高,NiCoCrAlY/ZrO2涂层与钢基体结合强度超过40.4 Mpa, NiCoCrAlY涂层与钢基体之间的结合强度达到37.5 Mpa。涂层总体性能良好,但还是差于氦气做载气制备的试样(孔隙率1.2%左右,显微硬度HV 600-800)涂层在海水中浸泡两小时后,阳极极化曲线就出现钝化区,随着浸泡时间的延长复合涂层钝化区变得明显,单层钝化区则变得不明显。冷喷涂涂层腐蚀电流密度很小,极化电阻较大,涂层的耐蚀性能较好。海水浸泡过程中涂层阻抗谱先呈现单个时间常数,容抗弧半径先增大后逐渐稳定。有氧化锆存在的涂层,海水浸泡一定时期,其阻抗谱时间常数由一个转为两个,103天后变为三个。涂层致密性极好,浸泡137天,涂层表面并未发现Fe的腐蚀产物。在900℃的热震性试验过程中,冷喷涂CoNiCrAlY/ZrO2涂层经过7次热震试验后在涂层表面出现了龟裂纹,NiCoCrAlY涂层经过4试验后在涂层表面出现了龟裂纹,单层表面出现的龟裂纹比双层更为细密。人工破损的冷喷涂NiCoCrAlY/ZrO2涂层在海水浸泡过程中的电化学阻抗谱测试结果显示：涂层浸泡两小时后,阻抗谱便出现了两个时间常数。随浸泡时间延长,第二个时间常数变的明显,基体的腐蚀加剧。更多还原

【Abstract】 With the rapid development of aviation and navigation, the demands for the materials with high performance for gas turbine and the internal combustion engine are increasing. Due to the high temperature-and corrosion-resistance, the thermal barrier coatings (TBCs) are extensively used for the protection of aircraft blades and industrial gas turbines.In the cold gas dynamic spraying (CGDS) process, solid particles are accelerated in a supersonic inert gas flow and directed towards the object to be coated. The main coating characteristics are:low porosity level; absence of oxidation; good adherence to the substrate; high microhardness; absence of chemical reaction and microstructural changes. The cold spraying technology, which makes up the deficiencies of the tradition thermal spraying, improves the performances of the TBCs.In this paper, the characters of the NiCoCrAlY/ZrO2 coating were studied through XRD, SEM, micro-hardness test, combination test, thermal shock resistance test and anticorrosion experiment. In order to discuss the relationship between the abrasion, defection and the properties of the coating, the performances of the defected NiCoCrAlY/ZrO2 coatings were also investigated.The results showed:little or no microstructural changes occurred in the CGDS deposition process; as-deposited coatings presented the dense microstructure, high hardness and high tensile strength (the NiCoCrAlY/ZrO2 coating:HV 400-600, 40.4 Mpa; the NiCoCrAlY coating:HV 400-500,37.5 Mpa). The performances of the as-deposited coatings were good, but not better than those of the coatings which were deposited when He was as process gas (porosity level:about 1.2%, microhardness:HV 600-800). At the beginning of anodic polarization, the coatings reflected a passive trend, which implied the formation of a passive film. After about 1 day’s immersion in seawater, it was evident that no clear passive trend behavior was presented in NiCoCrAlY coating, while the NiCoCrAlY/ZrO2 coating still exhibited a passive trend. The lower corrosion current and the higher polarized resistance proved the excellent anticorrosion performance.The EIS spectrums were consisted of one semicircle, whose radius enlarged continuously before stabilization. For the CoNiCrAlY/ZrO2 coating, the time constants increased to two after 38 day’s immersion, and then to three after 103 day’s immersion. There were no productions of iron corrosion from beginning to end.The thermal shock resistance tests showed that cracks appeared after seven times tests for the CoNiCrAlY/ZrO2 coating, while four times tests for the CoNiCrAlY coating. Besides, the cracks on the CoNiCrAlY coating were finer than that on CoNiCrAlY/ZrO2 coating.After about 1 day’s immersion, the EIS spectrums were consisted of two inconspicuous time constants for the defected NiCoCrAlY/ZrO2 coating. With the immersion time increasing, two time constants appeared distinctly and the corrosion of the substrate was serious.更多还原