CLEANING METAL SURFACES BY TREATMENT WITH ALKALINE CLEANING SOLUTION AND THEN WITH RARE EARTH ION-CONTAINING, ACIDIC SOLUTION; METAL SURFACES COATED WITH RARE EARTH (COMPOUNDS)

摘要

A metal surface which has been cleaned using an alkaline based solution is treated with an acidic solution which contains rear earth ions to remove any smut which may have been produced during the alkaline cleaning. A coating is formed on the cleaned surface using a different acidic solution containing rare earth cations which have multiple valence states. When the surface is reacted with coating solution, an increase in the pH at the metal surface indirectly results in precipitation of a rare earth metal such as cerium onto the surface. Alternatively, after the removal of the smut, the surface may be coated using a painting technique.