激光熔覆纳米La_2O_3/Ni基合金涂层

Laser Cladding Nano-La_2O_3/Ni-based Alloy Coatings

采用横流5kWCO2激光在低碳钢基体表面制备纳米La2O3/Ni基激光熔覆涂层。采用光学显微镜(OP)、扫描电子显微镜(SEM)、X射线衍射仪(XRD)分别对熔覆涂层进行显微组织和相组成的观察。用显微硬度计和滑动磨损试验机对熔覆涂层的硬度和耐磨性进行测试。试验结果表明:熔覆层主要由γ-(Ni,Fe),Cr23C6,LaNi10.5Si2.5等相组成,随离结合面距离增大,熔覆层的组织逐渐变细。随着纳米La2O3加入量及扫描速度增加,熔覆层组织变细。加入纳米La2O3后,平均硬度由未加时500HV0.5提高到约700HV0.5,耐磨性也得到不同程度的提高。在本试验条件下,添加质量分数为1.0%纳米La2O3熔覆层的耐磨性明显高于质量分数为1.5%纳米La2O3熔覆层的耐磨性。扫描速率采用250mm/min的熔覆层,其综合性能最佳。

Composite coatings made of La2O3 nano crystalline/Ni-base powder is prepared by transverse flow CO2 laser on the substrate of low carbon steel. Phase constitution and microstructure of the coatings were investigated by Olympus Pine 3 type optical microscope （OP）, JSM-35C type scanning electronic microscope （SEM） and XD- 3A type X-ray diffraction meter （XRD）. The micro-hardness and the wear resistance also were tested. The results showed that there existed γ-（Ni,Fe）,Cr23C6 and LaNi10.5Si2.5 in the coatings. Finer microstructure was observed with the increasing of laser scanning speed and the amount of nano additives and the distance from the substrate. With nano-La2O3 addition, the average micro-hardness changed from 500 HV0.5 to 700 HV0.5.The wear resistance of the coatings with w（La2O3）= 1.0% was higher than that of w（La2O3）= 1.5%.