等离子喷涂YSZ/NiCrAlY涂层及抗熔融Al-Si腐蚀性能研究

热浸镀Al-Si合金涂层是一种高效的耐蚀技术。然而,其生产过程中与Al-Si熔液直接接触的部件存在严重的Al-Si熔蚀问题。采用大气等离子喷涂(APS)制备了YSZ/NiCrAlY涂层,研究了主气流量对YSZ(Y-Si-Zr)涂层微观组织结构、力学性能的影响规律、涂层的高温稳定性和耐Al-Si熔液腐蚀行为。结果表明,随着主气流量的提升,粒子熔滴的铺展均匀性、涂层致密度、力学性能均先升高后降低。在主气流量(Ar)为40L/min时,涂层显示出最佳的表面平整度、最大的致密度以及最优的力学性能。在1000℃热处理100 h后YSZ涂层的界面结构稳定,孔隙率下降,致密度显著提高。此外,将试样在700℃熔融Al-Si液腐蚀50h后,在YSZ涂层与熔融Al-Si合金的界面没有发现互反应区和元素互扩散现象,并且Al-Si熔液没有渗透进涂层内部而是被阻挡在涂层表面,表明APS制备YSZ/NiCrAlY涂层能够有效地抵抗Al-Si熔液腐蚀,可作为与高温Al-Si熔液接触部件的最有潜力的防护涂层之一。

Plasma-sprayed YSZ/NiCrAlY protective coating and its resistance to molten Al-Si corrosion

Hot dip Al-Si alloy coating is an efficient corrosion resistant technology. However, there are serious Al-Si corrosion problems in some parts of the production line, such as sunk rolls, which are in direct contact with the Al-Si alloy melt. In this paper, YSZ/NiCrAlY protective coating system was prepared by air plasma spraying (APS). The influence of main gas flow on the microstructure, mechanical properties, high-temperature stability and Al-Si alloy corrosion resistance of YSZ coating were also investigated. The results showed that the spreading uniformity, coating density and mechanical properties of the droplet firstly increased and then decreased with the main gas flow rising. The coating exhibited the best surface smoothness, maximum density and optimal mechanical properties when the main flow is 40 L/min. The interface structure of YSZ coating is stable, the porosity is decreased, and the density is significantly increased after heat treatment at 1000°C for 100 h. In addition, no diffusion or reaction zone was found at the interface between YSZ coating and Al-Si alloy melt when the coated sample was immersed in the Al-Si alloy melt for 50 h. Al-Si melt did not penetrate into the coating, but was blocked on the YSZ coating surface, indicating that APS YSZ/NiCrAlY coating can effectively resist Al-Si melt corrosion, which can be used as one of the most potential protective coatings for parts contacting with high temperature Al-Si melt.