This Small Business Innovation Research (SBIR) Phase I project will conduct research to replace current environmentally damaging metal pretreatment processes with an environmentally benign process. In the approach the metal surface is etched then coated with a sub-micron film of plasma polymerized SiO2. Current metal pretreatment processes for painting and adhesive bonding perform well, but generate tremendous volumes of wastes, including hexavalent chromium and various inorganic acids. To obtain performance superior to the current state-of-the-art wet chemical surface treatments, the surface chemistry and morphology of the plasma polymerized films need to be tailored for specific interactions with the adhesive. Effects of variables including substrate chemistry, monomer chemistry, and ion kinetic energy on surface chemistry and morphology of plasma polymers will be determined. Then, the effect of the resulting structure on the strength and durability of adhesive joints will be determined. By combining in-situ analytical techniques with accelerated aging and mechanical testing of adhesive specimens, a superior, environmentally benign process based on plasma polymerization will be developed and commercialized. These primers will have well understood morphologies and surface compositions tailored to the adhesive chemistry through control of the deposition conditions and/or chemical derivitization of the plasma polymer surface.
