灭茬刀具刃口表面制备Ni-Co-TiN复合镀层的组织与性能

Microstructure and properties of Ni-Co-TiN composite coatings prepared on the surface of stubble cutters

  • 摘要: 为了提升灭茬刀具的表面硬度及耐腐蚀性能,进而延长其使用寿命,文中采用超声辅助喷射电沉积法在灭茬刀具常用45钢表面制得Ni-Co-TiN复合镀层。通过正交试验方法,确定镀层制备的最优工艺参数。利用透射电镜(TEM)、扫描电镜(SEM)、X射线衍射仪(XRD)和能谱仪(EDS)测试镀层的微观结构、表面形貌、相结构及元素组成,并采用显微硬度计和电化学工作站对镀层显微硬度和耐腐性能进行测试。正交试验结果表明,Ni-Co-TiN复合镀层制备的最优工艺参数为:镀液喷射速度4 m/s,超声波功率120 W,TiN纳米粒子含量10 g/L,极间距8 mm。采用最优工艺参数制备的Ni-Co-TiN复合镀层,其镍晶粒尺寸得到明显细化,TiN粒子弥散分布于镀层中。该镀层的显微硬度高达489.82 HV,其自腐蚀电位为-0.342 V和自腐蚀电流密度为2.15×10-6 A/cm2

     

    Abstract: In order to improve surface hardness and corrosion resistance of stubble cutters, and then to extend their service life, the Ni-Co-TiN composite coatings were prepared by ultrasonic-assisted jet electrodeposition on the surface of 45 steel used in stubble cutters. The optimal process parameters for producing Ni-Co-TiN coatings were determined by orthogonal experiment. The microstructure, surface morphology,phase structure and elemental composition of the coatings were observed by scanning electron microscope(SEM), transmission electron microscopy(TEM), X-ray diffractometer(XRD) and energy dispersive spectrometer(EDS), respectively. Moreover, the microhardness and corrosion resistance of coatings were tested by microhardness tester and electrochemical workstation. The orthogonal experiment results demonstrated that the optimal process parameters for producing Ni-Co-TiN coatings were listed as follows, the jet speed of the plating solution 4 m/s, the ultrasonic power 120 W, the content of TiN nanoparticles 10 g/L and the electrode spacing of 8 mm. The nickel grain sizes of the Ni-Co-TiN coating prepared with the optimal process parameters were obviously refined and TiN particles were dispersed in the coating. The microhardness of the coating was as high as 489. 82 HV, the self-corrosion potential(Ecorr) was-0. 342 V and self-corrosion current density(Icorr) was 2. 15×10-6 A/cm2.

     

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