化学镀高Cu含量Ni-Cu-P镀层的组织结构及显微力学性能研究

Study on Microstructure and Micromechanical Properties of Cu-Rich Ni-Cu-P Coating Synthesized by Electroless Plating

为了探究化学镀高Cu含量Ni-Cu-P镀层的组织结构及显微力学性能,通过化学镀法在45钢基体表面镀覆了高Cu含量的Ni-Cu-P镀层,通过扫描电镜、X射线衍射仪、EDS能谱分析仪、显微硬度计、纳米压痕仪等测试了未经热处理和经过热处理的镀层的微观组织及显微力学性能。结果表明:获得的高Cu含量Ni-Cu-P合金镀层厚度均匀,与基体结合良好;随着施镀时间的延长,镀层中Cu含量降低而Ni、P含量增加;未经热处理的镀层主要由Ni及Cu基固溶体组成,经200℃/2 h、300℃/2 h热处理后镀层相组成无明显变化,经400℃热处理后有NiP_(2)、Cu_(3)P等磷化物析出;化学镀初期(10 min),随着施镀时间的延长,镀层硬度显著增加,之后增加不明显;热处理可促进磷化物的析出,进而提高镀层硬度,经400℃/2 h热处理后镀层硬度显著增加.

In order to explore the microstructure and micromechanical properties of Cu-rich Ni-Cu-P coating synthesized through electroless plating,such coating was synthesized on the 45 steel substrate by electroless plating.The SEM,XRD,EDS,microhardness tester and nanoindenter were used to test the microstructure and micromechanical properties of the coating without heat treatment and after heat treatment.Results showed that a uniform Cu-rich Ni-Cu-P coating was obtained,which showed good adhesion with the 45 steel substrate.With the prolongation of plating time,the content of Cu in the coating decreased while the content of Ni and P increased.The coating without heat treatment was mainly composed of Cu-and Ni-based solid solutions.After a heat treatment at 200℃or 300℃for 2 h,the phase composition of the coating showed no obvious change.However,after a heat treatment at 400℃,NiP_(2) and Cu_(3)P were precipitated from the coating.In the early stage of plating(10 min),the hardness of coating increased obviously with the prolonging of the plating time,but after that a sluggish increase appeared.In all,a heat treatment,especially at 400℃for 2 h,could promote the precipitation of phosphide and thus increase the hardness of coating.