Silicate coupling layer for metal to polymer adhesion improvement: Physical-chemical fundamentals and technological importance

Silicated metal surfaces may improve the adhesion of polymers to metal surfaces. Two different methods of silicate formation - a flame pyrolysis of orthosilicates and a sol-gel coating based on a Cr^III- doped SiO₂-sol - are proposed. The coupling of the SiO₂-layer on the metal oxide surface, their structure and morphology and, the effect of the silane coupling agent on the adhesion mechanism are discussed. The formation of stable and durable compounds is proved by shear strength measurements and SEM analysis of the interface after boiling tests. Additionally, the adhesion of glued joints between glasses, ceramics and metals is also improved by this method.