Study On The Texture Processing And Micro-friction Performance Of Ni-Co Alloy Coating

Ni-Co alloys are widely used in the micro-system. Improving of Ni-Co alloys surfacemicro-performance is the key problem to be solved. Micro/nano surface texturing caneffectively improve the friction and adhesion performance at micro/nano-scale. Laser directscanning is an efficiently processing means to manufacture micro/nano texture. So the authormade the electroplating Ni-Co alloy coating as a research target. The textured surface wasfabricated by laser controlled processing. The micro tribology properties of textured Ni-Coalloy coating surface were analyzed by the atomic force microscope.Due to its fast deposition rate, the pulse electrodeposition is a reliable method to controlthe grain size and roughness size of the coating surface. The Ni-Co alloy coating has uniformdensity electrodeposited by this method. Therefore, the author used three kinds ofelectrodeposition method (the DC electrodeposition, single pulse electroposition and periodicreversal pulse electrodeposition) to prepare the Ni-Co alloy coating. By adjusting theelectrodeposition experimental parameters and the composition of coating solution, the sizeof the grain and surface roughness, surface topograghy were controlled reliably. Therelationship of the electrodeposition experiment parameters and coating surface propertieswas established.Laser direct scanning is a efficiently processing means to manufacture micro/nanotexture. The author established the laser processing system. The shape and size of coatingsurface texture were controlled by adjusting the laser processing parameters (laser currentdensity and laser scanning velocity). The controllable manufacture of coating texture wasrealized. The size of surface texture related to the initial grain size of coating and has nothingto do with the initial chemical composition of coating surface. The relationship of the laserprocessing parameters and surface texture was set up. The fast controllable manufacture ofcoating micro/nano texture was realized.The friction properties of textured Ni-Co alloy coatings was tested by AFM. Therelationship of the laser processing parameters and the surface friction performance was build.By adjusting the laser processing parameters, the law of surface friction was achieved. Thesurface with half spherical and ellipsoidal structure has a lower friction. The frictionperformance of textured Ni-Co alloy coating under different bias condition by C-AFM wastested. The influence law and mechanism of textured surface was discussed. The relation oftribological performance and bias was set up. The dynamic control of friction was achieved.