부산대학교 도서관

The main objective of this paper is to investigate the corrosion behavior of electrodeposited N-P coatings in a 5% NaCl solution. Potentiodynamic polarization curves obtained for the coating showed transition characteristics from active, passive, to transpassive as the applied potential increased. In the meantime, the weight 10ss and the measured P-content on the surface of the tested specimens were observed to increase with increases in applied potential and solution temperature Under the examination of FESEM, it was observed that the corrosion pits on the specimen at higher potentia1 and solution temperature evo1ved from smaller sizes to the ones of near1y 30μmm diameter. Moreover, within the developed corrosion pit, which penetrated through the coating, there existed cracks and delaminations. Results from XPS analysis showed that a passivated film which was richer in phosphor content was formed during corrosion. The microstructure of the corroded Ni-P coating was found to be porous and nanocrystalline under TEM examinations.