钢表面激光熔覆Ni基ZrO_2（4Y）陶瓷层的研究

Study of Laser Clad Ni-base Alloy/ZrO_2(4Y)Ceramic Layer on the Surface of 45 Steel

本文用ＳＥＭ、ＥＤＡＸ、ＸＲＤ和显微硬度计分析了４５钢表面激光熔覆Ｎｉ基ＺｒＯ_２（４Ｙ）陶瓷层的组织结构与性能。结果表明：激光熔覆的Ｎｉ基ＺｒＯ_２（４Ｙ）陶瓷层出现分层现象，表层为致密的ＺｒＯ_２陶瓷层，与钢基体结合的中间层为Ｎｉ基合金；陶瓷层主要由ｔ－ＺｒＯ_２相与少量Ｎｉ基γ固溶体组成，激光的快速熔凝过程抑制了ＺｒＯ_２的ｔ→ｍ相转变；在最优激光参数条件下，可获得与钢基结合良好的致密ＺｒＯ_２陶瓷熔覆层，其硬度值达到ＨＶ_（０．２）１７２０；激光参数偏离最优值时，熔覆的陶瓷层出现微孔、裂纹，且硬度大幅度下降。

n this paper the microstructure and hardness of laser clad Ni-base/ZrO_2 (4Y) ceramic layer on the surface of 45 steel are examined by SEM、EDAX、XRD and microdurometer. A layering phenomenon is observed in laser cladded zone, in which there are two layers:ZrO_2 ceramic surface layer followed by solidi-fied Ni-base solid solution. The ceramic layer mainly consists of t-ZrO_2 and γ-Ni phases. The quick melting and solidifying caused by laser processing restrains T→m-ZrO_2 phase transformation. under appropriate pro-cessing parameters,a homogeneous and non-porous ZrO_2 ceramic layer is obtained, and its microbardness is up to HV_(0.2) 1720.