摘要
研究了激光送粉熔覆WC Co硬质合金的气孔问题。结果表明 ,激光熔覆WC Co形成气孔的倾向较大 ,细粉熔覆层的气孔率比粗粉高 ,多道叠加的气孔率比单道高。熔覆层组织为未熔化的WC颗粒、鱼骨状枝晶和Co固溶体基体。熔覆层含有WC、Co、FeW3C、Fe2 W ,CW3,Co3O4 等相。激光熔覆WC Co出现气孔的主要原因归结于高温熔池中的氧与碳反应形成CO或CO2 气体。在WC Co中添加一定量的金属还原剂Ti后 ,Ti能还原熔池中的氧化物 ,阻止O与C的化合 ,抑制CO或CO2 气体的生成 ,从而减少气孔率甚至消除气孔。加Ti后 ,熔覆层中的Co3O4 相消失而出现了Ti2 O和Co6 W6 C相。
This paper presents the porosity investigation in laser cladding WC/Co cemented carbide with continuous powder feeding. The results demonstrated that laser cladding WC/Co was of large porosity tendency. The porosity rate was higher when laser cladding fine WC/Co powder and multi layers compared to the coarse WC/Co powder and single layer. The basic microstructure was composed of unmelted WC particles, the Co solid solution matrix and some fish bone shaped dendrites, which contained WC, Co, FeW 3C, Fe\-2W, CW\-3 and Co\-3O\-4 phases. The main reasons for the occurrence of porosity in laser cladding WC/Co cemented carbide was attributed to the oxidation reaction of C and O 2 in high temperature molten pool, which resulted in CO and/or CO 2 gases. When adding appropriate amount of Ti into the WC/Co powder, Ti can deoxidize the oxides in molten pool, inhibit the reaction between O 2 and C, suppress the production of CO and CO 2, so the porosity was decreased. X ray analysis proved that original Co\-3O\-4 phase disappeared and Ti 2O and Co\-6W 6C appeared when Ti was added into the powder.
出处
《材料热处理学报》
EI
CAS
CSCD
北大核心
2002年第2期49-53,共5页
Transactions of Materials and Heat Treatment
基金
清华大学 985重点基金资助 (No.0 81 1 0 0 50 0 )
关键词
送粉激光熔覆
硬质合金
气孔
金属还原法
powder feeding laser cladding
WC/Co cemented carbide
porosity
metal deoxidization
