Pretreated al substrates for better adhesion with silicone RTV adhesive sealant

Abstract

Adhesion in peel’ tests were performed to determine the average peel strength and adhesion characteristics of silicone RTV sealant deposited on aluminium substrates pretreated by plasma deposition using hexamethyldisiloxane and hexamethyldisilazane as monomers and argon and oxygen as carrier gases. Chemically prepared films of SiO₂ were also deposited on the aluminium substrates from tetraethylorthosilic ate and tetramethylorthosilicate solutions. Test specimens were prepared following the ASTM C794–93 specification. The average peel strength necessary to peel the silicone sealant from the aluminium substrate was shown to be increased by pretreatment, however the extent of the improvement was dependent on the type and duration of pretreatment performed. Although the average peel strength was increased and the adhesion characteristics were improved, no record of 100% cohesive failure was obtained. A mixed failure mode (adhesive and cohesive) was observed in many cases.