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采用电弧离子镀沉积Cr和粉末包埋法渗Al的联合工艺制备了Al-Cr涂层,并利用粉末包埋法制备了渗Al涂层,分析了2种涂层的组织结构和成分,研究了镍基高温合金DSM11基体、渗Al涂层和Al-Cr涂层在1000和1100℃下的恒温氧化行为.结果表明:渗Al涂层和Al-Cr涂层组织致密,与基体结合良好且成分分布均匀.2种涂层都明显分为2个区域:外层和互扩散区.渗Al涂层外层由b-NiAl相和Ni2Al3相组成,Al-Cr涂层外层由b-NiAl相、Ni2Al3相、a-Cr相和AlCr2相组成.AlCr涂层可以显著改善基体合金的抗氧化性能,且明显优于渗Al涂层.Al-Cr涂层优良的抗氧化性能源于在氧化过程中出现了Cr(W)析出带,能够一定程度阻碍涂层中的Al元素向基体扩散,降低了涂层退化速度,而Cr的存在可以促进Al的选择性氧化,提高涂层的自修复能力.
Al-Cr coating was prepared by a combined process of arc ion plating deposition Cr and powder impregnation Al infiltration. The Al-Cr coating was prepared by powder embedding method. The microstructure and composition of the two coatings were analyzed. The oxidation behavior of DSM11 matrix, infiltration Al coating and Al-Cr coating at 1000 ℃ and 1100 ℃ were investigated. The results show that the infiltration Al coating and Al-Cr coating are dense and well bonded to the matrix The two coatings were obviously divided into two regions: outer layer and inter-diffusion layer.The outer layer of Al infiltration coating consisted of b-NiAl phase and Ni2Al3 phase, the outer layer of Al-Cr coating was composed of b-NiAl Phase, Ni2Al3 phase, a-Cr phase and AlCr2 phase.AlCr coating can significantly improve the oxidation resistance of the matrix alloy, and significantly better than infiltration Al coating.Al-Cr coating excellent oxidation resistance from oxidation Cr (W) precipitation occurs in the coating, which can hinder the diffusion of Al in the coating to the matrix to some extent and reduce the degradation rate of the coating, while the presence of Cr can promote the selective oxidation of Al and improve the self-repair of the coating ability.