Interlayers for diamond deposition on tool materials

Fluidized bed micro-machining and HFCVD of diamond films onto Co-cemented tungsten carbide (WC-Co) hardmetal slabs

“…Nonetheless, the built-up of diamond films on WC-Co substrates is quite tricky because of the harmful effects of Co binder, which leads to the formation of a graphitic carbon layer at the substrate surface during the early stages of deposition, on which diamond grows later [3]. Mostly, the problem is overtaken by covering the WCCo substrate with interlayers, which act as diffusion barrier [4], etching the WC-Co substrate surface to wash superficial Co out [5], and decarburizing the substrate surface after the etching of binder [6]. In each case, a seeding process with diamond nucleation promoters and a roughening of the substrate surface are strongly required to improve the built-up of the diamond film and increase the interface contact area [7], hence speeding up the formation of a continuous film and enhancing the adhesion between the incoming diamond film and the hardmetal.…”

Hot filament chemical vapour deposition and wear resistance of diamond films on WC-Co substrates coated using PVD-arc deposition technique

“…This element promotes the formation of sp 2 carbon at the interface between substrate and diamond film, and this has a detrimental effect on film adhesion. The use of binder removal (Co etching) and interposition of diffusion barrier layers [4] results in good adherence of a diamond film onto a WC-Co substrate. However, the first solution (Co etching) generates voids in the outermost layers of WC grains, which thus induces embrittlement of the cutting edge.…”

A novel Mo-W interlayer approach for CVD diamond deposition on steel

“…Lu et al reported that critical load of diamond films on WC increases from 11.2 N for diamond films thickness of 1.5 µm to 14.5 N for samples with thickness of 4.5 µm. 30 Endler et al 31 reported the critical load of diamond coatings on steel substrates was within the region of 6-22 N for diamond films with thickness of 3-5 µm. Whilst our diamond samples (300nm thickness) using Mo-W interlayers are much thinner than others reported, they show a similar level of critical FIG.…”