NiCr-Cr3C2 陶瓷涂层在锌铝腐蚀中的失效分析

运用超音速火焰喷涂技术在304不锈钢沉浸辊上喷涂NiCr-Cr₃C₂ 陶瓷涂层。将制备后的试样置于600℃铝质量分数为55%的熔融锌铝混合液中,并分析涂层在其中的腐蚀机理和失效过程。采用SEM 观察了原始粉末的形态并对涂层被腐蚀前后的形貌进行对比观察,采用EDS检测了NiCr-Cr₃C₂ 粉末的原始构成以及涂层被腐蚀后其中的元素变化。结果表明,NiCr-Cr₃C₂ 陶瓷涂层的孔隙率为2.9%,平均结合强度为82.76MPa,显微维氏硬度的平均值为1078.67HV。NiCr-Cr₃C₂ 陶瓷涂层在被沉浸1d后,在涂层中发现了元素构成的变化且有层次区分,NiCr-Cr3C2 涂层失效原因是Ni-Cr基体被Zn溶解,导致了涂层溃散,涂层中的Cr₃C₂也同时失去保护作用,并漂移到Zn-Al熔体中。

Zinc-Aluminum Corrosion Resistance and Inactivation Process ofNiCr-Cr3C2Cermet oating

Cermet coatings ofNiCr-Cr₃C₂ were thermally sprayed on 304 sink roll by high velocity oxygen fuel spraying technique. The corrosion resistance of prepared sample was tested at 600 ℃ in a molten zinc-aluminum containing 55% of aluminum. The inactivation process of sink roll was studied. SEM was used to determine the morphology changes of initial powder and the sample after the corrosive experiment. EDS was used to determine the element composition of initial powder and the coating after corrosion. The data showed that the porosity, bonding strength and micro hardness were 2.9%, 82.76 MPa and 1 078.67 HV respectively before corrosion. While after 1 day's corrosion, NiCr inNiCr-Cr₃C₂ cermet was found to be dissolved in Zn, thus the protection ability ofCr₃C₂was lost.