Spray-coated barrier coating on copper based on exfoliated vermiculite sheets

High-temperature barrier coatings protect metals and alloys from oxidization, delay property degradation and increase their service lifetime. Here we demonstrate a vermiculite clay-based oxidation-resistant coating on metal, using copper as an example. Dispersions of few-layer vermiculite sheets with lateral dimension in the range of microns to tens of microns are obtained in a two-step mechanical-chemical exfoliation approach, using vermiculite mineral as the starting material. The dispersion of these high aspect ratio two-dimensional sheets can be directly spray-coated on Cu foils to form a continuous and transparent thermal barrier film without the need for any binder materials. After heating in air at 400 °C for 24 h, vermiculite protected Cu foils did not show any significant sign of oxidation or degradation in mechanical and electrical properties, while uncoated Cu foils were completely destroyed.