Development of a Reactive-diluent-based Dual-cured Hybrid Organic/Inorganic Coating for Aircraft Corrosion Protection

Abstract                In this work, a reactive-diluent-based hybrid organic/inorganic coating was developed for aircraft corrosion protection.  Since this precursor of the coating contains two forms of functional groups (acrylate functionality and trimethoxysilane functionality), two different crosslinked networks can be produced.  A polyacrylate network can be produced using a radiation-cure mechanism while a polysiloxane network can be produced by the following sol-gel reaction. Of six forms of acrylate with different number of functionalities, two are selected as reactive diluents for the novel precursor by evaluating their physical, rheological, and barrier properties.   Dual-cured process analyses for the two forms of the coatings were further conducted as a function of curing conditions through a series of technique, including FT-IR, confocal Raman microscopy, photo-DSC, DSC, EIS, and TGA. By understanding the relationships between coating properties and curing condition, a rapid-cure, and corrosion protective aircraft coating based on a dual cure mechanism is expected to be developed.  It has been found that the formation of the siloxane crosslinks was dependent upon the crosslinking network induced by the UV-curing process, which controlled the water uptake in the coating in the initial period of time.   Furthermore, a great number of “Si-O-Si enriched regions” were observed distributing over the coating surface after long time of immersion in electrolyte.  A possible mechanism that can explain this phenomenon is proposed.