Application of diamond-like carbon coatings on steel tools in the production of precision glass components

The application of highly wear-resistant diamond-like carbon (DLC) coatings with an extremely low friction coefficient and a low wettability with regard to glass melt has been performed on steel substrates. These coatings are of high interest for the glass industry to improve the performance of high precision glass forming tools for various products like high precision glass tubes for laboratory equipment or in the fabrication of wine glasses. Me-DLC coatings are a special type of DLC coating and consist of a metal-rich carbon phase near the metal substrate interface, which is graded into a carbon-rich diamond-like phase towards the interacting surface. The metal-rich phase optimises the adhesion to the ground substrate and the metal type can be varied (Ti, Cr, Si, etc.). The metal content influences the surface properties of the coating like its wettability. For the glass-producing industry there are mainly two advantages: environmentally hazardous release agents can be abandoned and the purity and surface quality of the produced glass products can be drastically improved. The presentation describes related vacuum deposition techniques and gives examples for industrial applications.