| 摘要 |
PROBLEM TO BE SOLVED: To improve the corrosion resistance of a steel not only in atmospheric corrosive environments but also in seawater-splashed parts and in seawater by coating the surface of the steel with denseα-(Fe,Cr)OOH contg. a specified amt. of Cr, low in free energy and excellent in serf-recoverability. SOLUTION: The surface of a steel is coated withα-(Fe,Cr)OOH contg. 1.5 to 28.0 mass% Cr. Thisα-(Fe,Cr)OOH is the one low in free energy, stable and not deteriorated even in seawater, and in which the bonding among the crystals is strengthened to increase the cohesiveness thereof, and the state that seawater in filtrates and reaches the surface of the steel is prevented to improve the corrosion resistance of the steel to seawater. Moreover, even in the case defects are generated in theα-(Fe,Cr)OOH layer caused by any damage, Cr is diffused to be supplied from the layer into FeOOH formed at the defected part to recover the defected part. The coating of theα-(Fe,Cr)OOH is formed by applying an aq. soln. of chromium (III) sulfate on the surface of the steel for plural times.
|
