Fabrication Of Antifouling And Self-Cleaning Surface Of Aluminum Alloy Based On Multi-Factor Coupled Bionic Theory

With the demand of saving energy and reducing emissions improved gradually,lightweight has been an inevitable trend in global automobile industry.Aluminum and aluminum alloys are widely used in aerospace,transportation,marine and other fields due to their proportion of small,specific strength,good formability and properties of mechanics,physics and process,especially that they have played an important role in lightweigh of automotive industry.While most automobile manufacturers mainly focus on the functional performance of aluminum alloy surfaces,such as wear resistance,corrosion resistance and so on,they neglect the requirements of surface antifouling and self-cleaning.In recent years,people have discovered a new way to solve this problem with further study of bionic engineering constantly.Some parts of animal’s body surface such as earthworms,dung beetle and other animals have multi-scale microstructures that reduce the contact area between liquid and animal body surface and increase the liquid contact angle on the body surface,which it is similar to "lotus leaf effect" of some plant leaf area extremely.The "lotus leaf effect" is the coupling of surface morphology,structure and materia essentially,namely that synergistic action of the surface waxy material and the micro-rough structures makes the biological surface antifouling and self-cleaning.Thus,this paper uses shot blasting process and electrochemical oxidation technology to prepare corrosion resistant and antifouling and self-cleaning surface of aluminum alloy based on the multi-factor coupled bionic theory and self-cleaning theory,which is of great significance for improving the performance of aluminum alloy and speeding up the application of aluminum alloy in automobile lightweight field.The specific research contents are as follows:At first,the paper studies the relevant theories and modles of antifouling and self-cleaning surface and uses Cassie model as the fundanmental model to prepare antifouling and self-cleaning surface of aluminum alloy.In addtion to,the paper analyzes the correlative theories and application of biomimetic and comes out with multi-coupling bionic that is the process of constructing micro/nano-multilayer structures on non-smooth morphological surface,then making surface low energy.The theory is the theoretical basis and reference of preparing aluminum alloy antifouling and self-cleaning surface.The micro-pit structures of the aluminum alloy surface is fabricated by the shot blasting process.The paper studies the effect of shot blasting process parameters to surface properties such as surface morphology,surface contact angle and surface adhesion energy and optimizes the process paramters.And the contact angle and rolling angle of optimized aluminum alloy surface is 148.4° and 2.5° respectively.While the rolling angle of aluminum alloy specimen is far less than 10°,the contact angle is less than 150° after the process of shot blasting and fluorided treatment,indicating that the one-dimensional micro-scale structure cannot have an ideal hydrophobic performance as low surface energy treated.The nano-coral structures of the aluminum alloy surface is prepared by the electrochemical oxidation process.The paper studies the effect of electrochemical oxidation process parameters to surface properties such as surface morphology,surface contact angle and surface adhesion energy and optimizes the process paramters.And the contact angle and rolling angle of optimized aluminum alloy surface is 163.5°and 13° respectively.While the contact angle of aluminum alloy specimen is far more than 150°,the rolling angle is more than 10° after the process of shot blasting and fluorided treatment,indicating that the one-dimensional micro-scale structure cannot have an ideal hydrophobic performance as low surface energy treated.The shot blasting and electrochemical oxidation are combined,which means that the coral-like nano structures is constructed by the process of electrochemical oxidation on aluminum alloy surface with the micro-pit structure construted by the shot blasting and the micro/nano composite structures are fabricated eventually.Some surface properties such as microscopic morphology,contact angle of water droplet,adhesion energy and hardness of surface of fluorinated aluminum alloy surface are analyzed.After the process of shot blasting,electrochemical oxidation and fluorided on aluminum alloy surface,the contact angle is up to 153°,the rolling angle drops to 5°.The contact angle and the rolling angle meet the requirements of super hydrophobic surface so that the fluorided micro-nano composite structures have a good antifouling and self-cleaning performance.Besides,the result of surface EDS energy spectrum analysis and eletrochemical test show that the prepared antifouling and self-cleaning surface in this paper has excellent corrosion resistance properties.