Improvement in the universality of high-performance CVD diamond coatings on different WC-Co substrates by introducing multilayered diamond/beta-SiC composite

摘要

Usually, the mechanical properties of the diamond coatings deposited on various WC-Co substrates with different gain sizes and Co contents are quite uneven, which is not beneficial to the industrial manufacture of the diamond coated cutting tools. For the intention of eliminating selectivity problem on diamond coatings growing on different cemented carbide substrates in this research, high-performance diamond coatings have been successfully synthetized through the strategy of diamond/beta-SiC composites and multilayer using hot filament chemical vapor deposition (HFCVD) technique. The comparative study chooses three sets of WC-Co with different grain sizes and Co contents as substrates. Through the combination of diamond/beta-SiC and microcrystalline diamond (MCD) structures, all coatings on different substrates possess lower residual stress (<-0.5 GPa), higher critical load (>50 N) and less spalling (<0.16 mm(2)). More importantly, the interfacial analysis has been carried out to illustrate universality enhanced mechanism. The introduction of multilayered diamond/beta-SiC composite structure can eliminate the uneven mechanical discrepancy of interface between diamond coatings and different WC-Co substrates due to non-selective nucleation of beta-SiC phases can quickly fill up residual holes on the substrates after pretreatment and form compact interfacial structure with low residual stress. Therefore, it is of the essence for industry produce of the diamond coated cutting tools due to diamond/beta-SiC composite multilayer coatings can realize the deposition of non-selective high-performance diamond coatings on various WC-Co substrates.