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以激光工艺制备了添加纳米La_2O_3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La_2O_3粉床预置于基体30CrM nS i Ni2A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。
A nickel-based coating with nano-La2O3 raw material was prepared by laser process. Prior to laser cladding, a fully intermixed Ni60A and La_2O_3 powder bed from a high energy ball mill was placed on the surface of the substrate 30CrMnSiNi2A. La segregates between the dendrites and thus limits the growth and ripening of the secondary dendrites. Microstructure has been refined. The above explanation of this phenomenon is corroborated by the EPMA results due to the higher La enrichment and the more significant microstructure refinement on the upper surface of the coating. Cladding coating after RE microstructure refinement and purification, hardness and wear resistance were significantly increased relative to the base metal, and cracks in the coating and no pores appear. COF of the friction coefficient curve of the coating is obviously lower than that of the matrix, and the volume loss rate and the microhardness value of the coating are respectively 1/10 and 4 times of the matrix value.