Study On Friction And Wear Topography Of Bionic Coating Surfaces Based On Fractal Theory

Wear is one of the main reasons for failure of most components, the feature of surface topography greatly influences friction and wear properties, so it is necessary to study the friction and wear properties from the surface topography aspect, but the research process between these two aspects is slow, due to measurement conditions, cost, characterizations methods etc. The bionic non-smooth SiC coating is research object, The relationship between surface topography and friction and wear properties was studied through fractal Brownian random field(FBRF).First, the fractal Brownian motion was introduced into the study of frictional surface topography, and the FBRF model was proposed based on gray image, then the stability of FBRF was analyzed in order to get an appropriate frictional surface model with random and self-affine fractal feature, besides, the physical significance of fractal parameters H was studied, the morphology tended to be smooth as H increased.Second, solution concentration and temperature were main factors of forming surface topography, based on the theory that gas-liquid interface flow deformation controls morphology forming. The bionic non-smooth SiC coatings were prepared at different diluents content and heat curing temperature in16sets of experiments, When diluents content was between14%-16%and heat curing temperature was at35oC-40oC, the surface topography presented best biomimetic structure, the maximum width dimension range of convex hull was20n m-45u m, and the convex hull and pits distributed uniformly. The abrasion index raised to109.9when the load was9.8N and the friction rotation was lOOOr after the wear resistance test of SiC coating, and the fractal dimension was computed based on FBRF model.Third, the data of frictional morphology of SiC coating was collected in different load and surface topographyi, and the fractal dimension D was computed based on FBRF model, its relevance of fitting line raised to0.9992after experimental verification. The change rules of D in wear processing were summed up, and the friction and wear properties were analyzed through fractal dimension fluctuation, and results showed that the fluctuation period of D reflected the material’s wear resistance and the amount of wear at a certain extent. The period of D was Dc>Dd>Db>Da>De>Df in every conting, and wear resistance of c coating was the best. Results showed Appropriate D of wear resisting performance in different load test, D was nearby2.46When F stood for9.8N, D located in around2.43in the meanwhile F was14.7N, and when F was19.8N, the range of D was about2.42. This method showed foundation of practices for predicting friction and wear information of materials.At last, from the statistics, frictional morphology was statistically analyzed with GLCM, and the image texture features of morphology in wear processing were studied. Four unrelated parameters, angular second moment, contrast, correlation and entropy, could scientifically and reasonably describe the friction and wear properties of coating to some extent after experimentally verified. Results indicated the change rules of parameters and wear properties, at the early stages of wear, the surface texture feature following changed from coarse to fine, the depth of texture became shallower and shallower, the complexity of texture was complexer and complexer, but with the extension of time or the strengthening of load, the bionic non-smooth body in surface was damaged for contact fatigue failure, so the next hard particles and soft layer exposed in materials, parameters appeared opposite change and then started to appear repeatedly phenomenon of variation. As it mentioned above the research methods of texture characteristics could scientifically and reasonably tools as describing the friction and wear properties of coating to some extent.