Research Of Composite Modification On Aluminum Alloy Surface

Aluminum alloy with lightweight、better strength、high toughness as well as goodconductive thermal conductivity is widely used in modern industry, but because of itspoor wear-resisting and corrosion resistance, it is more and more difficult to meettechnical requirements. Nowadays, Micro-arc Oxidation and High Current PulsedElectron Beam are the more popular surface modification methods for aluminum alloy.They improved the property, such us strength、hardness、corrosion resistance and wearresistance，by the formation of ceramic membrane or the remelting effected of highenergy electron beam. This topic is based on the aluminum alloy micro-arc oxidation,and then composite processed by electron beam. It aims to study the mechanism ofcomposite modification as long as the composite coating preparated on the surface ofaluminum alloy. The changes of morphology and phase composition could observed oranalyzed by scanning electron microcope(SEM)、X-ray diffraction(XRD)、thicknessgauge and so on.The results showed: In silicate electrolyte system, LY12aluminum alloy couldgenerated dozen microns ceramic oxidation film on its surface, which distributed of theholes; A smooth and density metal ceramic composite coating generated after compositetreatment by electron beam. The higher voltage、density or pulse frequency of electronbeam, the deeper melting of aluminum alloy surface, and the holds produced bymicro-arc oxidation disappeared gradually. There were micro cracks appeared on thematerial surface result of internal stress after electron beam effect.Phase composition showed: LY12aluminum alloy, which effected by micro-arcoxidation and electron beam composite treatment, had matrix Al diffraction peakincreased at a specific angle and most decreased. At the same time, the new phase ofα-Al2O3got higher, and β-Al2O3got smaller. This phenomenon shows that: Phasecomposition would transform to stable state in the composite processing for metalmaterial. Friction and wear experiments show that the oxide coating after compositeprocessing still exists groove, but compared with the substrate or the micro-arcoxidation coating, it becomes shallow,and there is no large area falls off phenomenon;At the same time, wear capacity reduced, friction coefficient reduced, and wearresistance increased; Those also confirmed that the Al supersaturated solid whichgenerated through the electron beam’s rapidly melting and condensation increased thestrength、hardness of composite coating.