中文摘要：

以激光工艺制备了添加纳米La2O3初料的镍基涂层。激光熔覆之前,高能球磨机充分混合的Ni60A和La2O3粉床预置于基体30CrMnSiNi2A表面。La偏聚于枝晶间从而限制了二次枝晶的成长和熟化。显微组织得到了细化。由于更高的La富集,涂层上表面显微组织细化更为显著,这一现象的上述解释得到EPMA结果佐证。熔覆涂层经过RE显微组织细化和净化,硬度、耐磨性均相对基体金属显著提升,而涂层中裂纹和孔隙均未出现。涂层的摩擦系数曲线COF明显低于基体,磨擦体积损失率和显微硬度值分别是基体数值的1/10和4倍。

英文摘要：

Ni-based coatings with nano-sized feedstock rare earth element（RE, La2O3） addition were produced by laser cladding. Bed of high energy ball milling mixed Ni60 A and La2O3 powders were pre-placed onto the substrate 30 CrMnSiNi2 A before laser cladding. Results show that La segregates in inter dendrite and thus secondary dendrites growth and ripening are limited. The microstructure is refined. Top surface of the cladded coatings displays better refined microstructure which is caused by high La concentration, and this phenomenon is verified in EPMA results. The cracks and pores cannot be found in cladded coatings in which microstructure refinement and purifying effect caused by RE is clearly reflected in SEM microstructure, hardness and especially the wear resistance test results. The COF（coefficient of friction） of the coatings is apparently lower than that of substrate steel; the wear volume loss rate and the microhardness of coatings are less than 1/10 and about 4 times higher than that of substrate metal, respectively. This research forms the basement of metal surface anti-wear layer on the work surface of high speed heavy duty gear set in helicopter transform system.