• CN:11-2187/TH
  • ISSN:0577-6686

›› 2011, Vol. 47 ›› Issue (2): 95-101.

• 论文 • 上一篇    下一篇

高硬度多微孔小型零件激光表面精密熔覆钴基合金涂层提高耐冲蚀性能研究

石岩;张宏;刘双宇;徐春鹰   

  1. 长春理工大学机电工程学院
  • 发布日期:2011-01-20

Improving Resistance of Cobalt-based Alloy Coating Formed Laser Fine Cladding on High-hardness and Microporous Small Parts

SHI Yan;ZHANG Hong;LIU Shuangyu;XU Chunying   

  1. School of Electromechanical Engineering,Changchun University of Science and Technology
  • Published:2011-01-20

摘要: 高硬度多微孔小型零件的结构特点为其表面熔覆强化带来了较大难题。采用辅助工艺装置及同轴送粉激光熔覆方法对以阀座为代表的高硬度多微孔小型零件进行激光表面熔覆钴基合金涂层强化处理。采用扫描电镜、X射线衍射仪、显微硬度计及激光显微镜等分析、测试仪器对激光熔覆层宏观形貌、微观组织及显微硬度进行表征,采用燃油喷射试验台对激光熔覆及未熔覆处理阀座使用寿命进行对比考核测试。结果表明,采用纯铜辅助工艺装置,在保证熔覆层良好成形的同时,避免了高硬度小型零件在激光熔覆过程中烧蚀、高温回火等现象的产生,有效解决了小型零件激光熔覆难题。采用镶嵌碳棒的方法有效地解决了熔覆层堵塞微孔的难题。激光熔覆后的钴基合金涂层主要由γ-Co、CoCx、Cr23C6、W5Si3等相组成,微观组织表现为由枝晶及共晶组成的亚共晶组织。熔覆层与基体之间形成了良好的冶金结合。激光熔覆处理后的阀座表面耐油流冲蚀性能明显增强,使用寿命提高40%。

关键词: 钴基, 激光熔覆, 耐冲蚀性能, 微观组织, 微孔, 小型零件

Abstract: The surface hardening of high-hardness and microporous small parts is difficult owing to its special structure characteristics. The valve seat, as a representative of such small parts, is hardened by laser fine cladding Cobalt-based alloy coatings by using the auxiliary processing device and the co-axial powder feeding system. The macromorphology, microstructures and microhardness are characterized by using laser microscope, SEM, XRD and microhardness tester . Comparison tests of service lives of the laser cladding specimens and the uncladding specimens are carried out on the fuel injection test rig. The results show that the phenomena of ablation and high tempering of the valve seat during the process of cladding are avoided while good forming of clad layer is ensured by using the pure copper auxiliary processing device . The problem of micropores blocked by cladding layer is solved by the method of inlaying kryptols. The laser cladding layer is comprised of a hypoeutectic structure, which contains primary dendrites and interdendritic eutectics. The primary phases are γ-Co, CoCx, Cr23C6, W5Si3 and etc. The metallurgical bonding forms well between the cladding layer and the matrix of GCr15 steel. Compared with the uncladding specimens, the erosion resistance of the laser cladding specimens is increased by 40%.

Key words: Cobalt-based, Erosion resistance, Laser cladding, Micropore, Microstructure, Small parts

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