激光重熔对喷射电沉积纳米镍涂层组织与性能的影响

Effect of Laser Remelting on Microstructure and Properties of Nanocrystalline Nickel Coating Prepared by Jet Electrodepositing

为了提高喷射电沉积纳米镍涂层的性能,采用激光重熔工艺对涂层进行处理,研究了激光重熔对涂层微观组织和性能的影响。用扫描电镜(SEM),X射线衍射仪(XRD)和显微硬度计分析了涂层表面形貌、微观结构和显微硬度,同时对涂层的腐蚀特性进行了考察。结果表明,在优化的工艺参数下,喷射电沉积制备的镍涂层表面比较平整,结合致密,由平均尺寸为13.7 nm的纳米晶颗粒组成,但涂层中仍存在一些孔隙及其他缺陷;经过激光重熔后,熔融区内的晶粒尺寸明显减小,使涂层致密化程度得以提高并使涂层与基体由机械结合变为冶金结合,因此激光重熔处理后涂层的显微硬度明显提高,且其耐腐蚀性能明显优于原喷射电沉积镍涂层。

To improve the properties of nanocrystalline nickel coating prepared by jet electrodepositing, laser rernelting experiment was carried out and the effects of laser remelting on microsturcture and properties on coating were researched. The surface morphology, microstructure and microhardness of coatings were investigated using scanning electron microscopy （SEM）, X-ray diffractometry （XRD） and microhardness measurement. Meanwhile, the corrosion behavior was studied. The results showed that the nickel coatings prepared by pulse jet electrodepositing owned a fine-grained structure （average grain size is 13.7 nm） with a smooth surface and high density under the optimum processing parameters. However, there were still some pores and other defects. After laser remelting, the grain size of coating was greatly diminished, the density of coating was also improved and the bonding state between the coating and substrate became metallurgical combination from mechanical combination. So the laser remelting sample had higher hardness, better corrosion resistance than jet electrodepositing coating did.