高温氧化腐蚀对热浸镀Al-Si-RE涂层表面形貌的影响

Research on the Surface Transformations of Heat Resistant Martensitic Steel Hot-dipped Al-Si-RE During High Temperature Oxidation Corrosion

为满足航空发动机叶片材料1Cr11Ni2W2MoV钢在更加苛刻的使用温度下工作的要求,本试验对其表面进行了热浸镀Al-6%Si-4%RE处理.依据GB/T13303-91标准,在700℃对浸镀件和未镀件进行了5～600h的抗高温氧化腐蚀试验,并绘制了氧化动力学曲线.采用扫描电镜和能谱仪对浸镀件的形貌、组织及成分进行分析.实验结果表明,浸镀件的抗高温氧化性能远优于未镀件,其氧化时主要经历三个阶段,即氧化初期阶段、暂态氧化阶段和稳态氧化阶段.在氧化初期,表面产生不连续的Al2O8膜并没有起到抗高温氧化的作用;暂态阶段,表面形成连续的亚稳态θ-Al2O3膜;稳态阶段,θ-Al2O3发展为具有一定厚度且致密、连续的α-Al2O3膜,对基体具有良好的保护作用,是浸镀件抗高温氧化性的屏障.同时本工作根据氧化动力学曲线交点,提出耐热用热浸镀铝件在使用前需进行扩散退火处理的可行性建议.

For improving application temperature of heat resistant martensitic steel 1Cr11Ni2W2MoV as aerial engine blade materials,its surface was hot-dipped Al-6%Si-4%RE.According to GB/T13303-91 standard,oxidation resistance tests were performed at 700℃ for 5～600h,and oxidation kinetics was investigated.The research showed the surface of 1Cr11Ni2W2MoV steel hot-dipped Al-6%Si-4%RE can be classified three phases,the beginning oxidation stage,the transition oxidation stage and the stabilization oxidation stage from analyzing the surface of coating by making use of SEM and EMPA.The discontinuous Al_2O_3 film layer was formed in the beginning stage.The uninterrupted θ-Al_2O_3 film on the surface has produced in the transition oxidation stage.During the stabilization oxidation stage,the surface become compact and uninterrupted Al_2O_3 oxidation film which is barriers of resistant oxidation from analyzing the microstructure and the surface of coating.It was suggested that resistance hot workpiece should be annealed before using in terms of the crossing point of the two kinetic curves.