摘要
微弧氧化(MAO)技术是一种在金属表面原位生长陶瓷膜层的表面改性技术,可以大幅度提高金属的耐磨、耐腐蚀、耐热冲击等性能。但膜层表面粗糙多孔且存在裂纹是限制该技术进一步发展的瓶颈。诸多研究表明在电解液中添加稀土是改善MAO陶瓷膜层性能的有效手段之一。稀土添加剂能促使基体膜层钝化,提高溶液导电率,加快基体阳离子向膜层表面迁移速度,从而降低膜层粗糙度及孔隙率,提高厚度,增强结合力,改变相组成,继而提高膜层硬度,对膜层减摩耐磨、耐腐蚀、润湿性、抗高温氧化及耐热冲击性能均有一定影响。探讨了稀土添加剂对MAO膜层性能影响机制,最后指出了稀土添加剂未来应解决稳定分散、制备催化及生物活性膜层、多种添加剂复配等研究方向。
Micro-arc oxidation(MAO)is a surface modification technology that fabricates ceramic coatings on metal surface in situ.The ceramic coating can dramatically improve the properties of metals such as wear resistance,corrosion resistance,high-temperature oxidation and heat shock resistance.However,the rough porous surface with cracks of the coating is the bottleneck that restricts the MAO’s further development.Rare earth has the characteristics of high coordination number and strong polarization ability,and it can be used to prepare materials with unique properties when combined with other chemical elements.Many studies have shown that adding rare earth to electrolytes was one of the effective means to improve the properties of MAO coating.The effects of rare earth additives on the MAO process were introduced,including rare earth oxides and rare earth salts.Rare earth oxide could be adsorbed on metals surface,which promoted the passivation of the coating,increased the discharge channel deposits,and made the discharge uniformity during the MAO process.Due to the high electrovalence and polarization capacity of rare earth ions,the rare earth salt additives could increase the conductivity of the solution and the peak current,decrease the striking voltage and current density.By adding rare earth salt into electrolytes,the oxidation time and energy consumption of the coating were reduced.Then,the effects of rare earth additives on the surface morphologies,thickness,bonding forces,and phase compositions of MAO coatings were introduced.The rare earth additive was beneficial for migrating substrate metal cations to the coating surface,adjusting reaction processes,reducing melting point and molten viscosity of substrate oxides,enhancing the liquidity and capacity to fill in the plasma channel of the oxides.Furthermore,the coating quality was improved.The thickness of MAO coating firstly increased and then decreased with increasing rare earth concentration.The diffusion strength and the lattice matching of molten metal oxide
作者
刘建
朱新河
马春生
尚少伟
Liu Jian;Zhu Xinhe;Ma Chunsheng;Shang Shaowei(Marine Engineering College,Dalian Maritime University,Dalian 116026,China)
出处
《稀有金属》
EI
CAS
CSCD
北大核心
2022年第8期1073-1082,共10页
Chinese Journal of Rare Metals
基金
国家自然科学基金项目(51779023)资助。
关键词
稀土
微弧氧化(MAO)
膜层性能
影响机制
rare earth
micro-arc oxidation(MAO)
film performance
influence mechanism
