Abstract
NiTi coatings were sprayed on AISI 1045 steel coupons by air plasma spraying. Two types of amorphous/nanocrystalline NiTi powders, one of nominal size range (–63 to +20 μm) and the other of nominal size (–125 to +63 μm), were used. Open circuit potential EOC measurements and Tafel polarisation tests were employed to study corrosion behaviour of the coatings in 3·5% NaCl solution at 23°C. These tests indicated that the corrosion performance of the coating produced by using finer powder was better than that of the coating produced by using coarser powder. After 10 h of immersion, the steel substrate had not been corroded in the former case, while it had been corroded in the latter case. In addition, it was shown that corrosion current densities are six times lower in the coating produced by using finer powder than in that sprayed by using coarser powder.
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