摘要
采用CO2激光在45钢表面制备镍基纳米WC/Co复合熔覆层,在激光单道熔覆的基础上进行激光搭接熔覆。通过SEM、XRD、EDS以及显微硬度测试,分别对激光单道及搭接熔覆层的显微组织、物相、成分及硬度进行比较研究。结果表明：选择合适的激光熔覆工艺,可以在45钢表面获得基本上消除了裂纹和孔洞,并与基体呈冶金结合的镍基纳米WC/Co复合熔覆层及其搭接熔覆层。熔覆层的物相为γ（Fe-Ni）基体上分布着以WC、W2C为主的碳化物相。其中激光单道、搭接熔覆层显微硬度分别为779.3-1315.0HV0.1、600.3-1560.0HV0.1。尽管单道及搭接熔覆层中碳化物的种类不变,但其形态和分布有较明显差异,搭接熔覆层较单道熔覆层中碳化物形态多样性及分布不均匀性更大一些。无论激光单道或搭接熔覆层中,都存在含相当数量的粒度≤100nm的纳米颗粒,分析认为这些纳米颗粒最有可能为WC、W2C为主的碳化物,对于熔覆层的抗裂止裂起了关键的纳米效应作用。本文研究的结果对重要零部件的较大面积局部表面改性或修复再制造的工程应用具有重要的探索意义。
CO2 laser was adopted to prepare nickel based nanometer WC/Co composite clad coating on the surface of 45 steel. Laser overlapping was used on the base of laser single cladding. The microstructure, phase, composition and hardness in the single and overlap clad coatings were analyzed by SEM, XRD, EDS and microhardness test. The results indicate that Ni based nanometer WC/Co composite coating metallurgically bonded with the base and eliminated with cracks and pores can be prepared on the surface of 45 steel by selecting appropriate laser single and overlap cladding technology. The mierohardness of the laser single and overlap clad coatings are 779. 3 - 1315.0 HV0. 1 and 600. 3 - 1560. 0HV0. 1. In the laser single and overlap coatings, though the kinds of carbides are not changed, the shape and distribution of carbides are different remarkably. The shape and distribution variety in laser overlap clad coating are more obvious than that in laser single clad coating. There is a considerable quantity of nanometer particles visible with granularity small than 100 nm both in the laser single clad and overlap clad composite coatings. Through analysis the nanometer particles, most of them may be carbides of WC and W2C. The nanometer WC/Co particles introduced into the composite coatings play an important nanometer-effect role in resisting crack of the laser cladding processes. The research results have an important exploration significance in laser engineering applications to improve and refurbish large surface area on important parts.
出处
《金属热处理》
CAS
CSCD
北大核心
2008年第10期40-46,共7页
Heat Treatment of Metals
基金
上海市重点学科建设项目(J51402)
关键词
激光熔覆
激光搭接熔覆
陶瓷涂层
显微组织
纳米效应
laser cladding
laser overlap cladding
ceramic coating
mierostructure
nanometer-effeet
