Method of forming a coating with controlled grain size and morphology for enhanced wear resistance and toughness

摘要

Wear resistance of the prior-art Ti(C,N) layers can be considerably enhanced by optimizing the grain size and microstructure. This invention describes a method to obtain controlled, fine, equiaxed grain morphology in Ti(C,N) layers produced using moderate temperature CVD (MTCVD). The method includes the step of doping using CO, CO₂, ZrC1₄ and A1C1₃ or combinations of these to control the grain size and shape. Doping has to be controlled carefully in order to avoid nanograined structures and oxidization. Doping is further controlled to produce grain size that is from about 50 to about 300 nm, preferably from about 50 to about 150; a lack of any strong preferred growth orientation; and a length-to-width ratio (L/W) of less than 3 and only with a slight to moderate XRD line broadening.