Abstract: Using 250g/L H2SO4 and 15g/L H2C2O4 as the basic electrolyte， by adding 2g/L surface modified nanoSiC particles and 15ml/L PTFE emulsion， a kind of double particle composite anodizing electrolyte was composed. A composite anode oxide film with double particles was prepared on the surface of LC4 aluminum alloys using pulse power supply. The results showed that under the anodic oxidation processing condition such as the oxidation temperature of 0℃， the current density of 30Adm-2， the duty ratio of 80%， and the oxidation time of 40min， a double particle Al2O3SiCPTFE composite anodic oxide film with thickness of 20μm and the hardness 4340MPa was successfully prepared on the surface of the LC4 aluminum alloy. There were a lot of micron pore defects in the structure of the composite oxide film， which provided composite places for the composite deposition of the double particles. A double particle composite film that has nano SiC particles reinforced hardness and PTFE particle reinforced self lubricating properties was formed.

Key words: LC4 aluminum alloys, composite anodic oxidation, particle reinforced, oxide film structure, hardness