激光熔覆高熵合金涂层的耐腐蚀性能研究进展

利用激光熔覆技术制备的高熵合金涂层已成为一种新兴的绿色清洁耐腐蚀涂层.为了最大程度发挥高熵合金涂层的耐腐蚀防护性能,需要探究激光熔覆高熵合金涂层耐腐蚀性能的影响因素及影响机理.首先阐述了高熵合金理论以及利用激光熔覆技术制备高熵合金涂层的优势,总结了高熵合金激光熔覆涂层优异耐腐蚀特性及耐腐蚀强化机理.重点综述了高熵合金元素组成、激光熔覆工艺参数、涂层后处理工艺以及服役温度4个因素,对高熵合金激光熔覆涂层耐腐蚀性能的影响规律与影响机理.高熵合金中适当添加Ni、Al、Ti等元素,在一定程度上可以提高涂层的耐腐蚀性,但是随着元素含量的进一步增加,由于高熵合金涂层的物相组成改变、晶格畸变严重、元素偏析加剧,可能导致涂层的耐腐蚀性能降低.适宜的激光加工参数可以使涂层具有较好的耐腐蚀性,原因在于涂层的缺陷较少、组织细密均匀.退火、激光重熔、超声冲击处理等涂层后处理工艺,通过改变高熵合金涂层的物相组成以及微观组织特征,来提高其耐腐蚀性.激光熔覆高熵合金涂层的服役环境温度越高,则腐蚀速率越快.最后,对激光熔覆高熵合金涂层的耐腐蚀性能强化方法进行了总结与展望.

Advances in Corrosion Resistance of High Entropy Alloy Coatings Prepared by Laser Cladding

The high entropy alloy coating prepared by laser cladding technology has become a new kind of green, clean and corrosion resistant coating. In order to maximize the corrosion resistance of high entropy alloy coatings, it is necessary to explore the influencing factors and mechanism of the corrosion resistance of high entropy alloy coatings. The theory of high entropy alloy and the advantages of high entropy alloy coatings prepared by laser cladding technology are described, and the excellent corrosion resistance characteristics and corrosion strengthening mechanism of high entropy alloy coatings prepared by laser cladding are summarized. The influence law and mechanisms of the elements composition of high entropy alloy, laser cladding process parameters, coating post-treatment technology and service temperature on the corrosion resistance of high entropy alloy coatings prepared by laser cladding are emphatically reviewed. The corrosion resistance of the coatings can be improved by adding Ni, Al, Ti and other elements to the high entropy alloy. However, with the further increase of element content, the corrosion resistance of the high entropy alloy coatings may decrease due to the change of phase composition, serious lattice distortion and aggravated elemental segregation. The suitable laser processing parameters can make the coatings have better corrosion resistance, because the coatings have fewer defects, fine and uniform microstructure. Post-treatment processes such as annealing, laser remelting and ultrasonic shock treatment can improve the corrosion resistance by changing the phase composition and microstructure characteristics of high entropy alloy coatings. The higher the service temperature, the faster the corrosion rate of high entropy alloy coatings prepared by laser cladding. Finally, the enhancement of corrosion resistance of high entropy alloy coatings prepared by laser cladding is summarized and prospected.