A simple, cost effective, environmentally friendly conversion-coating process has been developed for protecting a variety of metals against wear and corrosion and to increase adhesion of paints. This process results in the deposition of a thin, adherent coats of iron phosphate on treated metal substrates. This process is expected to supplant the environmentally hazardous chromate-based conversion- coating process heretofore used in the automotive and aerospace industries. It is also expected to supplant a process in which bearing races made of 440C stainless steel are pretreated with tricresyl phosphate.
In the improved process, a pre-cleaned metal substrate of 440C stainless steel or other metal is dipped into a solution comprising 1 weight percent of Durad (or equivalent phosphate ester) and 1 weight percent of ferric acetylacetonate in ethanol. The dip is done at room temperature for 1 minute. After the dip, the ethanol is allowed to evaporate, leaving a thin film of the phosphate ester and the ferric acetylacetonate. The substrate is then inserted for 1 minute in an oven that has been preheated to ≈300 °C. This heating causes the formation of a thin film of iron phosphate, as confirmed by x-ray photoelectron spectroscopy.
This work was done by Wilfredo Morales of Glenn Research Center.
Inquiries concerning rights for the commercial use of this invention should be addressed to
NASA Glenn Research Center,
Commercial Technology Office,
Attn: Steve Fedor,
Mail Stop 4–8,
21000 Brookpark Road,
Cleveland, Ohio 44135.
Refer to LEW-16680.
