材料期刊网

纳米CeO_2p是合金中最为常用的一种稀土改性材料, 可明显改善合金的抗氧化性能. 为了研究纳米CeO_2p对双层热障涂层中NiCoCrAlY粘结层抗氧化性能的影响,本文采用激光熔覆技术, 在镍基高温合金表面上制备了4种纳米CeO_2p含量不同的NiCoCrAlY粘结涂层, 分析了它们在1050 ℃空气氛围中的等温氧化行为, 并初步探讨了纳米CeO_2p的作用机制. 结果表明: 添加纳米CeO_2p的涂层的抗氧化性能均高于未加纳米颗粒的涂层, 其中添加2% (质量分数)纳米CeO_2p的涂层抗氧化性能最好. 在氧化100 h后, 添加2% 纳米CeO_2p涂层的质量增加仅为1.56 mg/cm², 较未加纳米颗粒的涂层减少一半以上; 同时, 涂层进入稳态氧化所需要的时间极短, 仅为未加纳米颗粒的涂层的1/20; 此外, 涂层氧化膜在长时间氧化后仍很致密, 涂层内部仅出现轻微的内氧化, 而相同氧化条件下的未加纳米颗粒的涂层的氧化膜已趋于失效.

Nano-CeO_2p, which is most commonly used as a kind of rare earth modified material of alloys, possesses a prominent advantage in improving oxidation resistance. To study how nano-CeO_2p will affect the oxidation resistance of NiCoCrAlY bondcoat in double--layer thermal barrier coatings, in this work, four kinds of the NiCoCrAlY coatings with different contents of nano-CeO_2p were prepared on the surface of a Ni--based superalloy using laser cladding technology, their isothermal oxidation behaviors in atmosphere under 1050℃ were investigated, and the influence mechanism of nano-CeO_2p on the oxidation resistance of coatings was preliminary discussed. The results show that all these coatings with nano-CeO_2p have better oxidation resistance than those without nano-CeO_2p, among which the coating with 2% (mass fraction) nano-CeO_2p has the best oxidation
resistance. After 100 hours of oxidation, its oxidation mass gain is only 1.56 mg/cm², reducing by more than half compared with the coatings without nano-CeO_2p; meanwhile, it takes extremely short time to enter the steady oxidation stage, only about 1/20 of the coating without nano-CeO_2p. Besides, the oxide layer of the coating is still very dense even after a long time oxidation and only a slight internal oxidation takes place within the coating, however, in that case, the oxide layer of the coatings without nano-CeO_2p is out of operation.