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采用在Ni基上分别电镀Ni-Al2O3复合涂层,单Ni镀层和Ni-Y2O3复合涂层+1100℃扩散渗铬3 h的方法,制备了3种渗铬涂层,并对其进行循环氧化实验。SEM分析表明:与Y2O3微米粒子相比,Al2O3纳米颗粒更加均匀分布在Ni纳米晶中,而且抑制了渗铬过程中涂层晶粒的长大。氧化实验表明:与普通渗铬涂层相比,Al2O3改性的渗铬涂层所具有的细晶结构促进了氧化初期保护性Cr2O3氧化膜的快速形成,随后涂层晶界处Al2O3抑制了Cr的外扩散,降低了氧化速度并提高涂层的抗剥落性能;微米Y2O3粒子通过溶解和重新析出来抑制渗层晶粒长大,且具有稀土活性元素的效应,从而提高渗层的抗循环氧化性能。
Three kinds of chromizing coatings were prepared by electroplating Ni-Al2O3 composite coating, single Ni coating and Ni-Y2O3 composite coating on Ni base at 1100 ℃ for 3 h, respectively. Three kinds of chromizing coatings were prepared and were cyclically oxidized experiment. SEM analysis shows that the Al2O3 nanoparticles are more uniformly distributed in the Ni nanocrystal than the Y2O3 microparticles, and the grain growth of the coating is suppressed during the chromizing. Oxidation experiments show that, compared with the ordinary chromizing coating, fine grained structure of Al2O3-modified chromized coating promotes the rapid formation of protective Cr2O3 oxide film at the initial stage of oxidation, and then Al2O3 at the grain boundary of the coating inhibits Cr Of the external diffusion, reducing the oxidation rate and improve the anti-spalling properties of the coating; micron Y2O3 particles by dissolving and re-precipitation to inhibit the growth of grain infiltration layer, and the effect of rare earth active elements, thereby enhancing the resistance of circulating layer oxidation performance.