电火花沉积高熵合金涂层的研究现状与展望

Research Status and Prospect of High Entropy Alloy Coating Prepared by Electrospark Deposition

基于高熵效应的多主元合金克服了传统高熵合金(HEA)的弊端,形成了综合性能优异的简单固溶体。最初,高熵合金的设计理念主要通过块状高熵合金来实现,随着人们对高熵合金的深入研究,高性能高熵合金涂层的概念被提出来。但是,现有的磁控溅射、热喷涂和激光熔覆技术制备高熵合金涂层存在厚度低、孔隙率高、对异形关键部件涂层可达性差等问题,严重阻碍了高熵合金涂层在航空航天领域的应用。电火花沉积技术不但具有绿色、节能、省材等优势,而且针对细长管内壁和弯曲弧面等结构特征的关键件,电火花沉积高熵合金涂层的厚度均匀、可达性良好。除了对涂层制备工艺的探索外,众多学者还通过高熵合金涂层设计的五大效应之一“鸡尾酒效应”改变组元进行调配以及添加WC等硬质颗粒和稀土元素来达到涂层所需的组织和性能。最后,研究者往往会在涂层制备之前采用正交试验等手段优化高熵合金涂层制备的工艺参数,提高涂层所需要的性能。本文详细介绍了高熵合金设计原理及不同技术制备高熵合金涂层的研究进展,总结了不同高熵合金涂层体系结构与性能之间的关系,并指出利用电火花沉积高熵合金涂层作为表面改性手段的发展前景。

The multi-principal component alloy based on high entropy effect overcomes the disadvantages of traditional high entropy alloy and forms a simple solid solution with excellent comprehensive properties.At first,the design concept of high entropy alloy is mainly realized through the block high entropy alloy.With the in-depth research of high entropy alloy,the concept of high performance high entropy alloy coating is put forward.However,the existing techniques of magnetron sputtering,thermal spraying and laser cladding to prepare high entropy alloy coatings have many problems,such as low thickness,high porosity and poor accessibility to special-shaped key parts,which seriously hinder the application of high entropy alloy coatings in aerospace field.EDM deposition technology not only has the advantages of green,energy saving and material sa-ving,but also has the advantages of uniform thickness and good accessibility for the key parts of the structure characteristics such as the inner wall of long and thin pipe and curved cambered surface.In addition to the exploration of coating preparation process,many scholars also through the high entropy alloy coating design one of the five effects of the“cocktail effect”to change the composition of mixing,and the addition of WC and other hard particles and rare earth elements to achieve the required structure and properties of the coating.Finally,researchers often optimize the process parameters of high entropy alloy coating preparation by means of orthogonal test before coating preparation,so as to improve the performance required by the coating.In this paper,the design principle of high entropy alloy and the research progress of preparing high entropy alloy coatings by different technologies are introduced in detail,the relationship between the structure and properties of different high entropy alloy coa-tings is summarized,and the development prospect of electrospark deposition of high entropy alloy coatings as surface modification means is pointed out.