Analysis Of Laser Texture Edge Splashing Bulge And Study Of Bonding State Of Post Coating

As a surface pretreatment method which can effectively improve the bonding strength of plasma sprayed coatings,surface texture technology has gradually become one of the important research directions at home and abroad.The existing research focuses on the overall texture morphology and the influence of grooves on the bonding state of coatings,but the research on the splashing crater formed by the accumulation of molten materials around grooves or pits during the textural processing is less.Based on sine type texture as the research object,through the nanosecond laser processing technology on the material surface texture,and adopt the way of plasma spraying coating on the surface texture processing,through the way of combining theoretical analysis and experimental research,the optimization of texture processing parameters,promoted coating combined with state of the excellent crater morphology,the main research content is as follows:Through single factor experiment for the design of the laser parameters,the effects of laser power,scanning frequency,pulse frequency,scanning speed four parameters influence on crater morphology,in-depth analysis of the influence of laser parameters on the crater forming mechanism,establish the mapping relationship of laser parameters and crater morphology,through to the crater morphology observation and analysis,it is concluded that the experiment conditions to obtain good crater morphology of laser processing parameters,lay the foundation for the research of the state of the coating.By means of comparative experiments,two types of substrates with and without craters were set under the same parameters.Plasma spraying was carried out on the treated substrates.Combined with the pull-out experiments and the comparative analysis of data,the increase of the bonding strength of the coating by the craters was obtained,and it was found that the increase effect was more than 70%.When the scanning times were more than 5 times,the bonding strength of the coating could not be obtained because the interlayer fracture occurred during the drawing process,but the cohesion strength of the coating was 20.32 MPa.It is found that the crater can greatly increase the contact area of the interface,and the anchoring points on the surface of the crater can make the substrate and the coating combine in a mechanical way,which indicates that the crater is an important structure to improve the bonding strength of the coating.Through the observation and analysis of the cross-section morphology of the sample,and the coating morphology characteristics of the crater and its vicinity were extracted,respectively from the spray droplet filling and spreading mode and state,porosity contrast,crack distribution and formation mechanism of several aspects of the study,the impact of the crater on the coating bonding state.It was found that the filling defects of the coating were mainly concentrated on the outside of the crater,and the porosity of the coating near the crater increased compared with other locations.Moreover,the top of the coating would produce stress concentration,which led to cracks in the forming process of the coating.Therefore,it is found that when the scanning times are 5 times,the crater morphology and bonding strength and quality of the coating obtained are better,which can maximize the bonding performance of the coating.