P92钢单渗铝涂层与Ni-Al复合涂层高温抗氧化性能的对比研究

Comparative study of high-temperature oxidation resistance of the single aluminized coating and Ni-Al composite coating of P92 steel

为了提高P92钢的高温抗氧化性,在其表面分别制备了单渗铝涂层和Ni-Al复合涂层,并测试了2种涂层在使用温度(650℃)下的恒温抗氧化性能,总的氧化时间为120 h.采用光学显微镜和扫描电子显微镜分析涂层氧化过程中的组织形貌变化,利用能谱仪对氧化试样进行截面元素线扫描,使用X射线衍射仪对涂层氧化产物进行物相分析.结果表明:Ni-Al复合涂层的氧化增重较低(1.853 g/m^2),且在氧化120 h时尚未形成完整氧化膜,而单渗铝涂层的氧化增重为2.225 g/m^2;在氧化120 h后,单渗层的Al元素扩散至距表面24.53μm,得到的氧化产物主要为Fe2O3和Al2O3,复合涂层的Al元素扩散至距表面19.04μm,氧化产物主要为Al2O3.由于复合涂层中的纯Ni层能够有效减缓Al元素向基体扩散,从而比单渗铝涂层具有更好的高温抗氧化性.

In order to improve the high-temperature oxidation resistance of P92 steel,the aluminized coating and Ni-Al composite coating were prepared on the surface of P92 steel.The constant temperature oxidation resistance of the two coatings at 650℃was tested and the total oxidation time was 120 h.The morphology of the coatings during the oxidation was analyzed by using optical microscope(OM)and scanning electron microscope(SEM).The element lines scanning of the oxidation samples were carried out by using energy dispersive spectrometer(EDS),and the phase of the oxidation products was identified by X-ray diffractometer(XRD).The results showed that the oxidation weight gain of Ni-Al composite coating was relatively low(1.853 g/m^2),and no complete oxidation film was formed after being oxidized for 120 h,while the oxidation weight gain of the aluminized coating was 2.225 g/m^2.After the above-mentioned oxidation,Al element in the aluminized coating diffused to 24.53μm from the surface with the main oxidation products being Fe2O3 and Al2O3.While Al element diffused to 19.04μm from the surface in the composite coating,the oxidation products were mainly Al2O3.As the Ni layer of the composite coating can effectively slow down the diffusion of Al element to the matrix,it has a high-temperature oxidation resistance better than that of the single aluminized coating.