Al涂层对Ni基合金高温氧化性能的影响

为了研究Al涂层对Ni基合金高温氧化性能及氧化机理的影响,采用磁控溅射方法在Ni基合金表面制备了Al涂层,在600℃下对涂层进行了真空扩散退火和预氧化处理,并研究了涂层在1 100℃下的高温氧化性能.利用扫描电子显微镜和能谱仪分析了氧化膜的截面形貌及组成.结果表明,Ni基合金氧化动力学曲线近似服从抛物线规律,且合金的氧化增重最大.经过1 100℃高温氧化后,Ni基合金表面形成三层氧化膜,外层为Ni O、Cr_2O_3、Al_2O_3的混合氧化物和少量尖晶石氧化物,中间层主要为Ni的氧化物,内层为Al_2O_3.Al涂层试样的氧化增重相对较小,表明Al涂层在一定程度上提高了Ni基合金的抗氧化性能.

Effect of Al coating on high temperature oxidation properties of Ni based superalloy

In order to study the effect of Al coating on the high temperature oxidation properties and oxidation mechanism of Ni-based alloy, the Al coating was prepared on the surface of Ni-based alloy with the magnetron sputtering method. In addition, the vacuum diffusion annealing and pre-oxidation treatment were performed at 600 ℃ for the coating, and the high temperature oxidation properties of the coating at 1 100 ℃ were studied. The cross-sectional morphologies and composition of oxidation film were analyzed with scanning electron microscope(SEM)and energy disperse spectroscope(EDS). The results show that the oxidation kinetics curves of Ni-based alloy approximately obey the parabolic law, and the oxidation mass gain of Ni-based alloy is the largest. After the high temperature oxidation at 1 100 ℃, three oxidation films form on the surface of Ni-based alloy. The outer film is the mixed oxides such as NiO, Cr₂O₃ and Al₂O₃ and a small amount of spinel oxides, the medial film is mainly Ni oxide, and the internal film is Al₂O₃ oxide. The specimens with the Al coating have relatively lower oxidation mass gain. It means that the Al coating can enhance the oxidation resistance of the alloy to some extent.