OXIDATION RESISTANCE OF PULSE ELECTRODEPOSITED Ni-W-P-SiC COMPOSITE COATING

Oxidation resistance of pulse electrodeposited Ni-W-P-SiC composite coating was studied by means of mass gain of oxidation and X-ray diffraction.The oxidation resistance of pulse composite coating was better than that of direct current composite coating.The oxide film mass of Ni-W-P-SiC pulse composite coating increased with the increase of oxidation temperature and oxidation time.The increase of oxide film mass was less when oxidation temperature was lower than 600℃ and the increase of oxide film mass was more when oxidation temperature was higher than 600℃.The effect of pulse frequency and duty ratio on oxidation resistance was relatively significant and good resistance was obtained in f=33-50Hz and r=0.4(or 0.6).Oxidation temperature had a great influence on the structure of Ni-W-P-SiC pulse composite coating.The amorphous feature of coating was weakened with the rising of oxidatiom temperature and time.