Unicoat Airplane Coatings Systems: Corrosion Resistant Ceramer Coatings

摘要

The objective of this research project is to provide better adhesion and corrosion protection to metal substrates utilizing a self-priming Unicoat system. The overall goal of this project is to replace the environmentally hazardous chromium treatment with the environmentally friendly ceramer coatings without sacrificing corrosion protection. In our approach, new Unicoat formulations were prepared using a polyurethane/siloxane ceramer system. The ceramer coatings were formulated with HDI isocyanurate, TEOS oligomers and functionalized isocyanurate. The functionalized isocyanurate was added as a coupling agent between inorganic and organic phases. The ceramer coatings were moisture-cured through the reactions of alkoxysilane (SiOR) and isocyanate (NCO) with water. Two crosslinking mechanisms occurred simultaneously in the presence of atinospheric water. The organic/inorganic moisture- curing mechanism results in a polyurea/polysiloxane crosslinked coating and the functionalized isocyanurate couples organic phase with the inorganic phase via a urea and a siloxane linkage. Control of phase boundaries and inorganic phase size were achieved via addition of catalyst and phase coupling agent Both the TEOS oligomers and the alkoxysilane functionalized isocyanurate improved adhesion and corrosion resistance. The addition of TEOS oligoiners also resulted in improved tensile properties, scratch and abrasion resistance.