Accession Number : ADA316852

Title :   Growth and Microstructure of Protective Ceramic Films on Aluminum.

Descriptive Note : Final technical rept. 1 Aug 92-31 Jul 95,

Corporate Author : MISSOURI UNIV-COLUMBIA

Personal Author(s) : White, Henry W.

PDF Url : ADA316852

Report Date : 29 SEP 1996

Pagination or Media Count : 7

Abstract : The motivation for this collaborative work with T. Sugama and co-workers at Brookhaven National Laboratory is to develop a low temperature ceramic coating process suitable for aluminum and magnesium. Their method uses sol-precursor solutions with polygermanosiloxane (PGS) or polytitanosiloxane (PTS) additive. Crosslinked networks are formed by pyrolytic reactions near 350 deg C. The surface microstructure of these films were investigated by Raman spectroscopy, AFM, SEM and EDAX. AFM scans of a 30% TSPI, 20% PTS ceramic film on Al 6061 showed prominent cracks, indicating imperfect match of Al and ceramic film thermal expansion coefficients. Single element scans of the surface reveal highest levels of Al occurring in the cracks, as would be expected because the ceramic film is thinnest at the cracks. However, the ceramic film may not be zero in the cracks, and may afford some level of corrosion protection, if the crack is not too wide. These studies indicate that obtaining crack free films is difficult. Optical spectroscopy showed evidence for Si-O-Ge linkages, and for interfacial oxane bonding with the substrate in the PGS films.

Descriptors :   *CERAMIC MATERIALS, *ALUMINUM, *PROTECTIVE COATINGS, MAGNESIUM, LOW TEMPERATURE, MICROSTRUCTURE, RAMAN SPECTROSCOPY, CRACKING(FRACTURING), THIN FILMS, CORROSION INHIBITION, CERAMIC COATINGS, SILOXANES, CROSSLINKING(CHEMISTRY), THERMAL EXPANSION, TITANIUM, CRYSTAL GROWTH, PYROLYSIS, SOL GEL PROCESSES.

Subject Categories : Ceramics, Refractories and Glass
      Coatings, Colorants and Finishes

Distribution Statement : APPROVED FOR PUBLIC RELEASE