【摘要】 采用大气等离子喷涂技术制备Cr₃C₂-NiCr复合涂层,并对制备的Cr₃C₂-Ni Cr涂层试样进行800℃×100 h氧化和熔盐（Na₂SO₄+25wt%NaCl）热腐蚀试验。利用X射线衍射仪（XRD）和带能谱的扫描电镜（SEM/EDX）分析氧化、腐蚀涂层表面和截面的成分及结构变化,探讨其高温氧化、腐蚀机理。结果表明:等离子喷涂Cr₃C₂-Ni Cr涂层具有层状组织结构,喷涂过程中无明显相分解或氧化。高温氧化后的Cr₃C₂-NiCr涂层表面及层片界面形成了连续、致密的Cr₂O₃保护膜,涂层表现出优异的抗高温氧化性能。在热腐蚀过程中,腐蚀盐破坏了涂层表面及层片界面形成的氧化膜,腐蚀性元素沿着涂层中的孔洞及层片界面扩散到涂层内部,涂层发生"活化氧化",耐腐蚀性较差。更多还原

【Abstract】 Cr₃C₂-NiCr composite coatings were fabricated by atmospheric plasma spraying technology. Oxidation and molten salt（ Na₂SO₄+25wt% Na Cl） corrosion tests of the coating were conducted at 800 ℃ for 1 h. Phase compositions and microstructure of the surface and crosssection of the coating after oxidation / corrosion tests were analysed by using X-ray diffraction（ XRD） technique and scanning electron microscopy（ SEM） equipped with an energy dispersive spectrometer（ EDX）. The oxidation and corrosion failure mechanisms of the Cr₃C₂-NiCr coating were explored. The results show that the as-sprayed coating presents lamellar structure without visible phase decomposition during spraying process. The coating exhibits excellent oxidation resistance at 800 ℃,which are attributed to the formation of continuous and dense Cr₂O₃ layers on the surfaces and the splat boundaries. Oxides on the surfaces and splat boundaries are attacked by chlorine under corrosion condition,and chlorine is able to diffused through the coating along splat boundaries. Corrosion is extremely severe in oxidizing conditions because of active oxidation,which can lead to great degradation of the coating.更多还原