CO2超临界流体中制备镍基复合电铸层的微观组织和显微硬度

Microstructure and Microhardness of Nickel Composite Electroforming Films under CO2 Supercritical Fluids

摘要:

简单介绍CO2超临界流体（SCF-CO2）复合电铸的实验方法，采用扫描电镜(SEM)、数字显微硬度计对Ni-Al2O3和Ni-金刚石复合电铸进行研究，分析SCF-CO2环境下制备的Ni-Al2O3复合电铸层(N1)和Ni-金刚石复合电铸层(N2)的表面微观组织，探讨强化颗粒（纳米Al2O3和微米金刚石颗粒）、压力对N1和N2显微硬度的影响。结果表明，SCF-CO2环境下制备的N1表面光亮、平整，Al2O3颗粒的分散效果好；随着Al2O3颗粒添加量增加，N1的显微硬度先逐渐上升后快速下降，在其添加量为60 g/L、压力为14 MPa时，N1显微硬度最大，为11.4 GPa，是大气环境下制备的Ni-Al2O3复合电铸层的2倍多，此时N1中Al2O3颗粒的复合量为9.9%(质量分数)。SCF-CO2环境下制备的N2表面含有黑色金刚石颗粒、微观组织呈胞状均匀分布；随着金刚石颗粒添加量增加，N2的显微硬度呈现先快速上升后逐渐下降的趋势，在金刚石颗粒添加量为60 g/L、压力为10 MPa时，显微硬度最大，可达到9.1 GPa，当压力高于14 MPa后，N2的显微硬度快速下降

Abstract:

The experimental method of composite electroforming under CO2 supercritical fluids (SCF-CO2) was brief introduced. The experiment of nickel-Al2O3 and nickel-diamond composite electroforming were investigated using scanning electron microscope (SEM) and digital microscope hardness tester. The surface microstructures of nickel-Al2O3 and nickel-diamond composite electroforming films were analyzed. The effect of strengthening particles (nano Al2O3 particle and micro diamond particle) and pressure on microhardness of nickel-Al2O3 and nickel-diamond composite electroforming films were discussed. The results show that the bright and uniform surface of nickel-Al2O3 composite electroforming coating can be prepared under SCF-CO2 environment, and the dispersion of Al2O3 grains has optimal state. The microhardness of nickel-Al2O3 composite electroforming films gradually increases and then rapidly decreases with the increasing of Al2O3 addition. Its maximum can reach 11.4 GPa when the addition is 60 g/L and the pressure is 14 MPa, which is twice as much as that of the nickel-Al2O3 conventional composite electroforming layer. The content of Al2O3 grain in nickel-Al2O3 composite electroforming film under SCF-CO2 is 9.9 wt%. The microstructure of nickel-diamond composite electroforming films with black diamond grains and cellular distribution can be prepared under SCF-CO2. The microhardness of nickel-diamond composite electroforming films rises fast and then decreases gradually with the increasing of diamond particles. Its maximum can reach 9.1 GPa when the diamond grains content and working pressure are 60 g/L and 10 MPa respectively, but the microhardness will rapidly decrease when the pressure is higher than 14 MPa