Accession Number : ADA303998

Title :   Surface Modification, Organometallic and Polyaryl Coatings, and Flame Spray Technologies for Preventing Corrosion of Metals.

Descriptive Note : Final rept. 15 Jul 92-31 Dec 94,

Corporate Author : BROOKHAVEN NATIONAL LAB UPTON NY

Personal Author(s) : Sugama, T.

PDF Url : ADA303998

Report Date : MAY 1995

Pagination or Media Count : 25

Abstract : To improve adherent properties of electrogalvanized steel (EGS) to polymeric topcoats, the surfaces of EGS were modified by polyelectrolyte-modified zinc phosphating solution. The electrochemical reaction between phosphating solution and EGS led to the complete coverage with fully grown hopeite crystals after only 5 sec treatment, thereby improving adhesion to topcoating and providing protection of EGS against corrosion. To evaluate the ability of polyphenylene sulfide (PPS) coatings to protect zinc phosphate (Zn.Ph)-treated steels from corrosion in a wet, harsh environment, we exposed them in autoclave to attempt heating-cooling cyclic fatigue tests (1 cycle = 12 hr at 200C + 12 hr at 25C) up to 90 times. The major chemical reaction at the interfaces between the PPS and Zn in the Zn.Ph layer during cycling led to the formation of ZnS reaction product, which enhanced the Zn.Ph-to-PPS adhesive bond; correspondingly, there were no signs of peeling and separation of the coating after 90 cycles. Organometallosiloxane polymer (OMSP) was synthesized through the hydrolysis-condensation reaction of the mixed precursor solutions of the N-3-(TRIETHOXYSILY)PROPYL!-4,5,-DIHYDROIMIDAZOLE AND B-trimethoxysilylethyl-2-pyridine sols in liquor medium and the metal alkoxides and metallocene dichloride dissolved in water or tetrahydrofurane. The OMSP films (thickness, 0.3 to 1.0 microns) deposited by simple dip-withdrawing coating methods to aluminum alloys displayed the 3000 hr-salt spray resistance. Using a flame spray coating process, the methacrylic acid-modified polyethylene copolymer was overlaid onto cold rolled steel surfaces.

Descriptors :   *SURFACE FINISHING, *ELECTROCHEMISTRY, *STEEL, *PROTECTIVE COATINGS, ALUMINUM ALLOYS, SOLUTIONS(MIXTURES), MODIFICATION, POLYMERS, SYNTHESIS(CHEMISTRY), AIR FLOW, COPOLYMERS, CORROSION INHIBITION, ORGANOMETALLIC COMPOUNDS, CERAMIC COATINGS, SILOXANES, OXIDATION, ELECTROLYTES, HYDROLYSIS, THERMAL CYCLING TESTS, SULFIDES, DELAMINATION, FATIGUE TESTS(MECHANICS), PHOSPHATES, ADHESIVE BONDING, POLYETHYLENE, PLASTIC COATINGS, ACRYLIC ACID, ALKOXY RADICALS, POLYPHENYLENES, ELECTROPLATING, COLD ROLLED PROCESS, GALVANIC CORROSION, DIP COATING, ZINC COATINGS, ZINC COMPOUNDS, FLAME SPRAYING.

Subject Categories : Coatings, Colorants and Finishes
      Properties of Metals and Alloys
      Physical Chemistry
      Polymer Chemistry

Distribution Statement : APPROVED FOR PUBLIC RELEASE