The uneven surface of the coating has a significant negative impact on its wear resistance, which is mainly reflected in the following aspects: 1. Increase in Friction Resistance The uneven surface of the coating will increase the friction resistance. When an object slides or rubs on the coating surface, the raised parts of the surface will come into direct contact with the rubbing object, resulting in more energy consumption and wear. This increased friction resistance makes the coating more prone to scratching or wearing, thus reducing its wear resistance. 2. Stress Concentration The uneven surface will lead to stress concentration. At the raised parts or defects of the coating, the frictional force will act concentratedly, causing these areas to bear higher local stress. This stress concentration will accelerate the wear of the coating, especially under high-load or frequent friction conditions. 3. Aggravation of Coating Defects The uneven surface of the coating is usually accompanied by defects such as pinholes, craters and orange peel. These defects not only damage the integrity of the coating, but also expand further during the friction process, resulting in local damage to the coating. For example, pinholes may be further scratched during the friction process to form larger cracks or holes, thereby reducing the overall wear resistance of the coating. 4. Reduction of Coating Life The coating with an uneven surface is more vulnerable to the external environment, such as dust and particulate matter. These impurities will embed in the uneven areas of the coating, further aggravating the friction and wear. In addition, the uneven surface is also more likely to accumulate water or chemical substances, thereby accelerating the aging and corrosion of the coating and further reducing its wear resistance. 5. Impact on Coating Adhesion The uneven surface of the coating may mean that the bond between the coating and the substrate is not tight enough. Insufficient adhesion will cause the coating to peel off more easily during the friction process, especially under high-load or frequent friction conditions. This decrease in adhesion will significantly reduce the wear resistance of the coating. 6. Poor Visual and Tactile Effects From the visual and tactile perspectives, the uneven surface of the coating gives the impression of roughness and poor quality. This decline in surface quality not only affects the appearance of the product, but also affects its actual performance, especially in application scenarios with high requirements for surface quality. In conclusion, the flatness of the coating surface is one of the important factors affecting wear resistance. A flat coating surface can reduce friction resistance, disperse stress, reduce the occurrence of defects, and enhance the overall adhesion and durability of the coating. Therefore, improving the flatness of the coating by using additives such as leveling agents is one of the important means to improve the wear resistance of the coating.