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钼镧合金表面FeCrAl涂层耐腐蚀性能

Corrosion resistance of FeCrAl coatings on Mo–La alloys

  • 摘要: 采用非平衡磁控溅射工艺在Mo–La合金表面沉积FeCrAl涂层,研究所制备涂层的耐腐蚀性及涂层的腐蚀机理。结果表明:FeCrAl涂层样品在360 ℃、18.6 MPa、纯水的高压釜中腐蚀72 h,平均腐蚀速率为3.8 mg·dm‒2,低于同条件下锆合金以及未沉积涂层的钼镧合金的腐蚀速率,且涂层中的Al与外界环境介质中的氧发生反应,在涂层表面形成致密的Al2O3薄膜,在一定程度上减缓了涂层的腐蚀速度,有效保护了基体材料。FeCrAl涂层样品在1200 ℃、0.1 MPa的高温水蒸气环境下腐蚀8 h,Al2O3氧化膜厚度在4.0 μm左右,涂层维持保护效果,钼镧合金基体未暴露在腐蚀环境中;经淬火后,Al2O3氧化膜厚度减小至2.5 μm左右,涂层依旧维持结构完整性,没有出现贯穿性脱落,满足Mo–La合金表面耐腐蚀性的使用要求。

     

    Abstract: FeCrAl coatings were deposited on the surface of Mo–La alloys by the non-equilibrium magnetron sputtering process. The corrosion resistance and corrosion mechanism of the FeCrAl coatings were investigated. The results show that, the average corrosion rate of FeCrAl coatings is 3.8 mg·dm‒2 in the autoclave under 360 ℃, 18.6 MPa, and pure water corrosion condition for 72 h, which is lower than that of zirconium alloys and Mo–La alloys without coating. Al in the coating reacts with the oxygen in the environment medium, forming a dense Al2O3 film on the surface of the coatings, which slows down the corrosion rate of the coatings and effectively protects the substrate materials. The thickness of Al2O3 film is about 4 μm after the FeCrAl coatings are corroded for 8 h at 1200 ℃ and 0.1 MPa, the coatings maintain the protective effect, and the Mo–La alloy substrate is not exposed to the corrosion environment. After quenching, the thickness of Al2O3 film reduces to about 2.5 μm, the coatings keep the structural integrity, and there is no penetrating shedding in Mo–La alloy surface, which meets the requirement of corrosion resistance.

     

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