NiCrAlY涂层在1050℃下的微观结构演变及抗氧化性能研究

Investigate on microstructural evolution and oxidation resistance of NiCrAlY coatings at 1050℃

为了进一步研究NiCrAlY涂层高温氧化过程中的微观结构演变,分析涂层结构与抗氧化性能之间的内在作用机理,为新型耐高温长寿命涂层的研制提供理论与数据参考.采用电弧离子镀技术,在镍基高温合金基体表面沉积NiCrAlY涂层,并将真空热处理后的涂层在1050℃进行恒温氧化200 h后,通过扫描电子显微镜、X射线衍射和X射线能谱仪等检测手段,对NiCrAlY涂层在氧化过程中的微观结构演变和抗高温氧化机理进行研究.研究结果表明,真空热处理能够有效改善涂层的组织结构和均匀化涂层成分.涂层氧化过程中形成的α-Al_(2)O_(3)和Cr_(2)O_(3)对涂层具有良好的防护作用,能够降低涂层的氧化速度,抑制NiCr_(2)O_(4)尖晶石有害相的形成.氧化过程的持续进行,使得涂层中近氧化层侧的Al浓度降低,导致非保护性氧化物的形成,使得氧化层发生剥落,涂层的抗氧化性能降低,氧化物层出现分层现象,由疏松较厚的外氧化层和致密较薄的内氧化物层组成.涂层增重随氧化时间的变化曲线遵循抛物线规律,恒温氧化过程中涂层的平均氧化速率为0.0856 g·m^(-2)·h^(-1).该文对深入理解涂层的抗高温氧化机理及新型涂层的研制提供了理论与实验数据参考.

NiCrAlY coating was deposited on Ni-based superalloy substrate using arc ion plating(AIP)technology and then was subjected to isothermal oxidation in air at 1050℃for up to 200 h with the purpose of further investigating the microstructural evolution during high-temperature oxidation and analyzing the intrinsic mechanism between the microstructure and oxidation resistance performance,which can provide theoretical and data references for the development of new high temperature resistant and long-life coatings.The microstructure evolution and high-temperature oxidation resistance mechanism of NiCrAlY coating during the oxidation process were investigated by scanning electron microscopy,X-ray diffraction and X-ray energy spectrometry.The results revealed that vacuum heat treatment could effectively improve the coating structure and homogenize the composition.Theα-Al_(2)O_(3)and Cr_(2)O_(3)formed during the oxidation process could reduce the oxidation rate of the coating and inhibit the formation of NiCr_(2)O_(4) spinel harmful phases,prolonging the service life of NiCrAlY coating.The concentration of Al element in the near-oxide scale side of the coating was reduced with the further oxidation process,leading to the formation of non-protective oxides,which made the oxide scale flake off and reduced the oxidation resistance of the coating.The oxide scale was composed of a loose thicker outer oxide layer and a dense thinner inner oxide layer and the curve of coating weight gain with oxidation time followed a parabolic law.The average oxidation rate of NiCrAlY coating after oxidation was 0.0856 g·m^(-2)·h^(-1).The research could provide theoretical and experimental data reference for in-depth understanding of the mechanism of high temperature oxidation resistance and the development of new coatings.