The Effect of De-Cobalt Pretreatment of PDC on the Deposition of Diamond Coatings

Abstract

During the preparation of polycrystalline diamond compact (PDC), Co is often added as a binder, which reduces the material’s heat resistance and catalyzes the transformation of diamond to graphite at high temperatures, thereby reducing the material’s mechanical properties. After the removal of Co, the exposure of holes beside the diamond grains could also affect the wear resistance of PDC. This article provides a new approach for the surface enhancement of PDC, which involves depositing a layer of diamond coating using the hot filament chemical vapor deposition (HFCVD) method after the removal of Co and investigating the effect of the pretreatment time of PDC on the deposition of diamond. The optimal pretreatment was obtained using the surface morphology, composition, and content of Co for a cross-section of the diamond coatings. A H2SO4-H2O2 solution was mixed in a ratio of 1:10 as the acid corrosion reagent, and the best etching time was 5 h. When the time was short, the residual amount of Co was high, which affected the quality of the diamond coatings. When the time was long, the area fraction of the substrate was high, and the deposited diamond was not able to easily fill the holes caused by corrosion.