蒸着Al-Cr合金めっき鋼板の耐食性

抄録

The corrosion resistance of steel sheets continuously vapor-deposited with Al-Cr alloy and the crystal structure of the deposited layer were studied. Furthermore, investigation of the electrochemical corrosion behavior and an analysis on the morphology and the state of the corrosion products were conducted. Al-Cr alloy deposited steel sheets with Cr content of about 10wt% had superior corrosion resistance and revealed about eight times higher corrosion resistance in salt spray environments when compared to steel sheets vapor-deposited with pure Al. Increase of the corrosion potential and the pitting potential and improvement in the corrosion resistance of the deposited layer itself were confirmed with an increase of Cr content. It is considered that the drastic decrease in the corrosion resistance of Al-Cr alloy deposited steel sheets with Cr content of over 10wt% is caused by the reduction of the galvanic protection of the deposited layer to the steel sheet. The corrosion products mainly consist of dense bayerite (β-Al(OH)₃) and do not contain Cr compounds. The corrosion behavior was also discussed in connection with the crystal structure.