稀土CeCl3对耐热钢Ni2Al3/Ni复合涂层抗氧化性的影响

Effect of rare earth(CeCl3) on oxidation resistance of Ni2Al3 / Ni composite coatings on heat-resistant steel

摘要:

本文采用电镀镍、低温包埋渗铝在P92铁素体耐热钢表面制备不同稀土Ce含量的Ni-Al化合物复合涂层，并对复合涂层进行650 ℃×132 h的抗氧化实验。利用OM、SEM、EDS、XRD，分析涂层氧化前后的截面微观形貌，化学元素分布及物相变化规律。结果表明：涂层的氧化动力学曲线均符合抛物线规律。不含Ce的复合涂层平均氧化速率为0.4412×10-6 g/cm2/s，渗铝剂中加入2%CeCl3的涂层抗氧化性明显增强，平均氧化速率为0.2957×10-6 g/cm2/s，而加入过量CeCl3（4%、6%）则会在氧化过程中产生更多的孔洞，恶化了涂层的高温抗氧化性能，氧化速率相对加入2 % CeCl3的涂层有所升高。另外涂层中加入Ce元素增加了氧化膜的粘附性，对Al元素的向内扩散具有抑制作用。

Abstract:

Ni-Al composite coatings were successfully prepared on the surface of P92 ferritic heat-resistant steel by electroplating nickel and low temperature packing cementation aluminum. The anti-oxidation experiment of the composite coating was carried out at 650 °C for 132 h. The micrograph of cross section, chemical element distribution and phase transformation of the coating before and after oxidation were characterized by OM, SEM, EDS and XRD. The experimental results show that all the oxidation kinetics curves of the coatings are in accord with the parabolic law. The average oxidation rate of the composite coating without introducing Ce is 0.4412×10-6 g/(cm2·s). By contrast, the average oxidation rate of the coating with 2% CeCl3 added in the aluminizing agent is 0.2957×10-6 g/(cm2·s), which indicates that the oxidation resistance is obviously improved. However, the addition of excess CeCl3 (4%, 6%) will produce much more holes in the oxidation process and deteriorate the high-temperature oxidation resistance of the coating. In these cases, the oxidation rates of samples are higher than that with 2% CeCl3 addition. Moreover, the addition of Ce element in the coating increases the adhesion of the oxide film and has an inhibitory effect on the inward diffusion of the Al element.