The Development of High-Performance CVD Diamond Coated Cutting Tool Inserts

摘要

The use of diamond as a thin-film or coating enables us to exploit the wear resistant properties of the thin-film while taking advnatage of the bulk mechanical properties (toughness) of the underlying substrate base material. However, in order to reudce this goal to practice, it is important to optimize both the physical properties of the diamond film and the properties of the film/substrate interface. Early efforts to produce diamond coated WC-Co products did not improve the adhesion strength to a level which provides a diamond coated material which is of sufficient utility to the end-user in highly abrasive applications such as machining aluminum alloys with high silicon content. This paper describes the essential characteristics of the diamond/substrate interface which, acting together, have recently led to significant improvements in the adhesion strength of the diamond film to the underlying substrate. These characteristics fall under three general categories: a) chemical composition, b) phase composition, c) microstructural composition. All of these features are produced using essentially one process step developed to produce these characteristics in such a way that does not compromise other important physical features. Finally, this paper will review the results of our efforts to optimize the physical characteristics of the diamond deposits for metal cutting applications and overview results of world-wide testing of these diamond coated WC-Co based cutting tool inserts.