DEVELOPMENT OF AN IMPROVED RINSE SOLUTION FOR PHOSPHATE COATING THROUGH ADDITION OF ORGANIC ACIDS

摘要

This work was undertaken in order to Improve the salt spray resistance capabilities of phosphate coatings through Innovations In the post treatment of the phosphate coatings and specifically through Improve¬ments In the supplementary rinse solutions. Various compounds, both organic and inorganic, were tested in solution, both by themselves and in combination with each other and with the existing chromic acid rinse solution, as possible rinses for phosphate coatings. It was found that four different 1-4 and 1-5 dlcarboxyllc acids, when used in the proper concentration with the existing 0.6 go/liter (0.08 oz/ gal) chromic acid rinse increased the salt spray life of a phosphate coating by at least one hour over the salt spray life of a coating treated in the standard 0.6 gm/1 chromic acid rinse. These four acids are: citric acid, glutaric acid, maleic acid and succinic acid. It was also found that one aromatic dlcarboxyllc acid tested, phthallc acid, had the same effect on the salt spray life as the above mentioned aliphatic acids.