Improvement of Film-to-Substrate Adhesion for Diamond and Related Films by Plasma-Based Technologies

Diamond films become an ideal candidate for tool-coating materials because of its unique properties: 1) highest hardness and heat conductivity; 2) a low friction coefficient; and 3) good chemical stability. Due to their high hardness and toughness, cemented-carbide tools coated with diamond have profound potential applications in industries and currently drawn intensive attention among the academics worldwide. However, the poor adhesion inhered between a diamond coating and a cemented carbide shortens the working life and jeopardizes the tooling accuracy of the coated tools. This paper attempts to reveal systemically some mechanisms likely causing the poor adhesion, illuminates and compares some approaches by using energetic particles to form a multilayered gradient coating system so as to improve the adhesion, which demonstrates certain superior merits.