电爆喷涂方法的研究进展

Research progress of electrical explosion spraying method

摘要:

电爆喷涂是一种新兴的热喷涂方法,它是利用高电压对喷涂材料脉冲放电,瞬时大电流将其加热并发生爆炸,产生高温粒子伴随冲击波喷射到基体表面形成涂层。其特点是喷射粒子速度高,设备尺寸小,适用于孔腔内壁喷涂。本文综述了电爆喷涂方法的发展现状,其经历了自由、定向和约束电爆喷涂,自由喷涂的电极直接接触,烧损严重,并对管径有限制,仅用于小直径管/孔内壁；定向喷涂的约束腔常用陶瓷材料,在爆炸冲击时易破裂或烧蚀；约束喷涂采用消融材料制作约束腔,气体放电导入电流,使这些问题得以解决。其次,阐述了该方法制备的涂层特性,即涂层与基体呈冶金结合；形成了超细晶、纳米晶结构的致密涂层,且具有良好的耐磨和抗腐蚀性及较高的硬度。给出了过程参数与涂层的关系,能量密度和喷涂距离是影响涂层性能的主要因素。最后分析了将来需要研究的问题,展望了电爆喷涂方法的发展趋势。

Abstract:

Electrical explosion spraying is a new method of thermal spraying, which uses high voltage to pulse discharge the spraying material, and the instantaneous high current heats and explodes it. High temperature particles are produced and sprayed to the surface of substrate with shock wave to form coating. It is characterized by high particle velocity and small equipment size, which is suitable for spraying on the inner wall of the cavity. In this paper, the development status of electrical explosion spraying method is reviewed, which has experienced free, directional and constrained electric explosion spraying. The free spraying electrode is directly contacted, which causes serious burning damage and limits the pipe diameter. It is only used for the inner wall of small diameter pipe/hole. Ceramic materials are commonly used in the confinement chamber of directional spraying, which are easy to break or ablate during explosive impact. These problems can be solved by using ablation material to make the confinement cavity and introducing current into the gas discharge in constrained spraying. Secondly, the characteristics of the coating prepared by this method are described, that is, the coating is metallurgical bonded with the substrate. The compact coating with ultra-fine grain and nano-crystalline structure is formed, which has good wear resistance, corrosion resistance and high hardness. Then the relationship between the process parameters and the coating is given. The energy density and spraying distance are the main factors affecting the coating performance. Finally, the problems to be studied in the future are analyzed, and the development trend of electric explosive spraying method is prospected.