不锈钢基体NiCrBSi/NiCrBSi(SiC-Mo)合金层的激光熔敷

Laser remelting of NiCrBSi/ NiCrBSi(SiC-Mo) alloy coatings on stainless steel

为提高不锈钢叶片的耐磨损和气蚀的性能,在材料表面以激光熔敷NiCrBSi合金层。对合金层的显微结构、与不锈钢基体结合方式和SiC等颗粒增强改性对组织结构的影响进行了研究。采用5kW连续二氧化碳激光器对不锈钢上等离子喷涂预置NiCrBSi合金层进行表面熔敷。扫描电子显微镜和X射线衍射分析结果表明:涂层显微结构为细化树枝晶,由γ基体与γ/γ′和NiB的共晶组成。合金粉中添加SiC-Mo颗粒后,熔敷层显微组织更加细化,成为与基体具有一定取向关系的枝晶组织,形成过饱和固溶体和极细的共晶体。SiC弥散分布于自溶性镍基合金中,熔敷不出现裂纹,可进一步提高涂层抗磨蚀性。该激光熔敷自溶性NiCrBSi合金挂片在黄河三门峡3号水轮机中环上现场测试结果表现出优良的抗磨蚀性。

A 5 kW continuous wave CO2 laser was used to produce NiCrBSi alloy coatings on stainless steel to improve the gas abrasion and mechanical resistance of steel blades. The powders were adhered to the surface by plasma spraying before the laser cladding. SEM and XRD analyses showed that the coating microstructure was fine dendrites composed of γ matrix phases and eutectic phases including γ/γ′ and NiB phases. A homogeneous microstructure with finer dendrites consisting of variously oriented grains was found after chemical modification of the NiCrBSi alloy coating by SiCMo hard particles. Laser surface remelting somewhat improves the abrasionerosion wear resistance of the plasmasprayed NiCrBSi(SiCMo) coatings.