Adherent diamond coatings on cemented carbide substrates with different cobalt contents

A new process has been employed for preparing diamond coatings on cemented carbide substrates. Before depositing the diamond coatings, a diffusion bar rier interlayer was prepared by solid diffusing boron into the substrates a nd this interlayer has the function of suppressing catalytic effect of Co o n non-diamond formations. It was confirmed that on cemented carbide substra tes with Co contents ranging from 3 to 8%, high quality adherent diamond co atings could be deposited. The formation of the boronized interlayer change d the catalytic character of the substrate surface and the interlayer funct ioned as a diffusion barrier layer against outward Co diffusion. The latter beneficial effect was found to be accompanied by phase transformations in the interlayer, from one composed of mainly WC, CoW2B2, and CoB phases to t hat of CoWB, WC and Co2B phases, during the high temperature diamond deposi tion processes. (C) 2001 Elsevier Science B.V. All rights reserved.