采用激光熔覆技术,在45#钢表面进行了镍基合金粉末添加TiO2的熔覆试验.通过对激光熔覆工艺参数及TiO2含量的优选可以获得质量良好的熔覆层.对激光熔覆层横断面进行了显微硬度测量和显微组织分析,对熔覆层表面进行了X射线衍射(XRD)物相分析及摩擦学性能测试.试验表明,当TiO2含量3 wt.-%～4 wt.-%,激光功率1.8 kW,扫描速度2～4 mm/s时,可以获得无裂纹、无气孔且与基底呈冶金结合的质量良好的熔覆层.TiO2能够提高镍基合金熔覆层的韧性、耐磨性,细化熔覆层的组织,降低熔覆层的裂纹敏感性.TiO2对G112镍基合金激光熔覆层的改善归因于TiO2对熔覆层组织的均匀细化、对粗大针状脆性硬质相的抑制以及对韧性相成分的提高作用.

The experiments of laser cladding of Ni-base composite alloy powder doped with TiO 2 were carried out. Various laser processing parameters and different TiO 2 content were chosen to obtain a perfect clad layer. The microstructure observation and microhardness test of the cross-section of the laser cladding zone were performed. X-ray diffraction analysis and tribotesting of the surface of the laser coatings were also accomplished. A good finish and crack- and porosity-free surface clad layer was obtained with the TiO 2 content of 3 wt.-%～4 wt.-% at the beam scanning velocity of 2～4 mm/s. An excelled interface between the coatings and the substrate was formed. It is shown that the addition of TiO 2 can enhance the toughness of coatings, refine the microstructure of clad layer, and reduce the cracking susceptibility obviously. The improvement of properties of the laser-clad layer is due to the effect of TiO 2 on it, in which TiO 2 with a proper content can uniformly refine the structural grains, entirely suppress the formations of big nubbly hard-phases, greatly reduce the size of dendritic phases and increase the tenacity of coatings.