CeO2颗粒对铌合金表面镀渗复合涂层抗氧化性能的影响

Effect of CeO2 addition on high temperature oxidation resistance of composite coating on Niobium alloy

摘要:

为了提高铌合金的高温抗氧化性，采用化学镀结合包埋渗技术在铌合金表面制备了含有CeO2颗粒的复合涂层，研究了复合涂层的微观结构和高温抗氧化性能。结果表明，不含CeO2的Al/Ni涂层以NiAl相为主，Al/Ni-CeO2涂层则含NiAl、NiAl3、Al3Nb和CeO2等相。经1000℃氧化测试，Al/Ni复合涂层氧化50h后增重为8.0 mg/cm2，表面主要生成Al2O3、AlNbO4相；Al/Ni-CeO2复合涂层50h后氧化增重为4.0 mg/cm2，表面以Al2O3、CeO2、NiAl、NiAl3、Al3Nb、AlNbO4相为主。高温氧化后，两种涂层样品表面均生成连续致密的Al2O3膜，涂层与基体结合良好；含CeO2的涂层，其稀土氧化物主要在Ni膜拖拽力作用下富集于涂层互扩散区。稀土氧化物颗粒的添加细化涂层组织，降低涂层中Al元素的消耗，填补涂层中的孔洞，增强了氧化膜与涂层的粘附力，有效提高了涂层的抗氧化性。

Abstract:

In order to improve high temperature oxidation resistance of niobium alloy, electroless plating combined with pack cementation technologies was used to obtain composite coatings with or without CeO2 particles. The microstructure and high temperature oxidation resistance of the composite coatings were investigated. Al/Ni coating contains NiAl phase, while Al/Ni-CeO2 coating is made up of NiAl, NiAl3, Al3Nb and CeO2, etc. The oxidation test of the composite coatings was carried out at 1000℃. The results show after 50 h oxidation mass gain of the Al/Ni composite coating was 8.0 mg/cm2, with the formation of Al2O3 and AlNbO4 phase; The mass gain of the Al/Ni-CeO2 composite coating after 50 h oxidation was 4.0 mg/cm2, with Al2O3, CeO2, NiAl, NiAl3, Al3Nb and AlNbO4 phase. On the surface of two coating systems continuous dense Al2O3 scales were detected with good adhesion to the coating. CeO2 particles were mainly aggregated in the interdiffusion zone under the drag force of Ni. The addition of CeO2 particles refines the coating structure, reduces the consumption of Al element in the coating, fills the holes, and enhances the adhesion of the scales to the coating, so as to improve the oxidation resistance of the coating.