等离子喷涂制备MoSi_2-CoNiCrAlY复合涂层的高温氧化行为

High Temperature Oxidation Behavior of MoSi_2-CoNiCrAlY Composite Coating Prepared by Plasma Spraying

以高能球磨法制备的纳米MoSi_2-CoNiCrAlY复合粉末为喷涂材料,利用等离子喷涂技术在GH4169合金表面沉积了MoSi_2-CoNiCrAlY复合涂层,并研究了GH4169基材和复合涂层合金试样在900℃静态大气环境下的循环氧化行为。结果表明:复合涂层表现出较好的抗高温氧化性能,其氧化速率仅为1.23×10^(-7)mg^2·cm^(-4)·s^(-1),这归因于MoSi_2在氧化早期形成了SiO_2相,可以自封氧化膜。氧化后期SiO_2的脱落,Mo_5Si_3相的再次氧化生成MoO_3和MoO_2气相,以及MoSi_2的内氧化直接气化,会降低涂层的抗氧化性能。

With the ball milled nanocrystalline powders as spraying materials, MoSi2-CoNiCrAlY composite coatings were deposited on GH4169 alloy by plasma spraying technology. The cycle oxidation behavior of coated and uncoated GH4169 alloy at 900 °C in static air was investigated. The results show that the composite coating exhibits good oxidation resistance at high temperature, and the oxidation rate is only 1.23×10-7 mg2·cm-4·s-1, which is attributed to a self-sealing oxide film SiO2 with excellent protective properties formed at the early stage by oxidation of MoSi2. The oxidation resistance of the coating would be reduced by the peeling of SiO2 in the later period of oxidation and the reoxidation of Mo5Si3 phase to generate MoO3 and MoO2 gas phase as well as the internal oxidation of MoSi2.