THE MECHANICAL PERFORMANCE OF DLC FILMS ON STEEL SUBSTRATES

The thermomechanical properties of thin DLC films on steel substrates have been measured and related to their structure. The modulus and the rmal expansion coefficient have been determined from beam curvature me asurements conducted on Si and steel substrates. The fracture toughnes s and the adhesion have been characterized by using probes that introd uce controlled strains into the DLC, through the substrate. Multistrai n and sphere impression methods have been used for this purpose. The s trains cause multiple cracking and local spalling events that can be a nalyzed to obtain the toughnesses. The DLC toughness is found to be si milar to that for typical carbides. The interfaces have a much greater toughness, attributed to the use of a thin Cr adhesion layer. (C) 199 8 Elsevier Science S.A. All rights reserved.