摘要
Chromium coatings with and without Al_2O_3 or Y_2O_3 particles were prepared by chromizing the as-deposited Ni-film with and without Al_2O_3 or Y_2O_3 particles using a conventional pack-cementation method at 800 ℃. The cyclic oxidation at 800 ℃ and hot corrosion in molten 75% Na2SO4＋25% NaC1 at 800 ℃ of the three different chromizing coatings were investigated. The effects of Al_2O_3 or Y_2O_3 on the cyclic oxidation and hot corrosion behavior of the chromizing coatings were discussed. Microstructure results show that the codeposited Al_2O_3 or Y_2O_3 particles significantly retard the grain growth of the chromizing coating, which increases the cyclic oxidation and hot corrosion resistance of the chromizing coatings, due to the more rapid formation of purer and denser chromia scnle
采用在Ni基上复合电镀Ni-Al2O3和Ni-Y2O3复合涂层后在800°C下扩散渗铬的方法,分别制备了Al2O3和Y2O3改性渗铬涂层。采用相同的工艺在单Ni镀层上直接渗铬,获得一种不含氧化物粒子的渗铬涂层。分析了Al2O3和Y2O3影响渗铬涂层的氧化和腐蚀性能的机理。组织结构分析表明,Al2O3和Y2O3能明显抑制在渗铬过程中涂层晶粒的长大。800°C循环和75%Na2SO4+25%NaCl混合盐腐蚀试验结果表明:与在单Ni镀层上直接渗铬相比,Al2O3和Y2O3改性的渗铬涂层所具有的细晶结构促进了保护性氧化物形成元素Cr沿晶界向氧化前沿的快速扩散,从而有利于致密保护性Cr2O3氧化膜的快速形成,使得改性的渗铬涂层表现出更优异的抗循环氧化和混合盐热腐蚀性能。
基金
Project(11531319)supported by Scientific Research Fund of Heilongjiang Provincial Education Department,China
