Characterization of polyacrylic acid modified zinc phosphate crystal conversion coatings

Journal Article · Fri Nov 05 04:00:00 EST 1993 · Journal of Applied Polymer Science; (United States)

DOI:https://doi.org/10.1002/app.1993.070500520· OSTI ID:5849919

Wragg, J L; Chamberlain, J E; Chann, L; White, H W ^[1]; Sugama, T ^[2]; Manalis, S ^[3]

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1. Univ. of Missouri, Columbia, MO (United States). Dept. of Physics and Astronomy
2. Brookhaven National Lab., Upton, NY (United States). Energy Efficiency and Conservation Div.
3. Digital Instruments, Inc., Santa Barbara, CA (United States)

Raman spectroscopy and atomic force microscopy have been used to investigate the composition and surface structure of polyacrylic acid modified zinc phosphate crystal conversion coatings on steel. Zinc phosphate coatings are used extensively to provide corrosion protection and to improve adherence of top coatings to steel. Within the last few years it has been demonstrated that addition of high molecular weight polyacrylic acid (PAA) to the phosphating bath can significantly improve both resistance to corrosion and topcoat adherence. It has been reported that the addition of PAA reduces the size of crystallites, which leads to greater film ductility, and therefore to fewer sites for corrosive attack, and that organic molecular segments from the PAA are incorporated into the surface structure and provide additional adhesive bonding with polymeric topcoats. In this work Raman spectra show the compositions of both unmodified and PAA modified films to be zinc phosphate dihydrate, Zn[sub 3](PO[sub 4])[sub 2] [times] 2H[sub 2]O. Atomic force microscopy (AFM) was used to measure the morphologies of single crystallite surfaces. Morphologies of the unmodified and modified films obtained by AFM are in general quite similar, but subtle differences are apparent.

• DOE Contract Number: AC02-76CH00016
• OSTI ID: 5849919
• Journal Information: Journal of Applied Polymer Science; (United States), Journal Name: Journal of Applied Polymer Science; (United States) Vol. 50:5; ISSN 0021-8995; ISSN JAPNAB
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360105 -- Metals & Alloys-- Corrosion & Erosion
360602* -- Other Materials-- Structure & Phase Studies
ALLOYS
COATINGS
CORROSION PROTECTION
IRON ALLOYS
IRON BASE ALLOYS
MICROSTRUCTURE
MORPHOLOGY
OXYGEN COMPOUNDS
PHOSPHATES
PHOSPHORUS COMPOUNDS
POLYMERS
PROTECTIVE COATINGS
STEELS
ZINC COMPOUNDS
ZINC PHOSPHATES