Carbon self-diffusion in tungsten carbide

High-temperature properties of joint interface of VPS-tungsten coated CFC

“…The carbon diffusivity in a grain of tungsten carbide is very low (2.25 · 10 À15 cm 2 s À1 at 2000°C), but that along the grain-boundary is much higher (5.10 · 10 À5 cm 2 s À1 at 2000°C) [8]. The present results indicate that the rapid formation of the tungsten carbide layer was caused by the fast diffusion of carbon along the grainboundary.…”

Chemical vapor deposition of phase-rich WC thin films on silicon and carbon substrates

“…Such a diffusion-based model agrees with the observed increase in carbon content with temperature. The diffusion of C in WC has a high activation barrier (E D N 88 kcal/mol, [43]) and it is thought that, at low temperatures, nucleation of WC inhibits further diffusion of C leading to a film with primarily W-rich phases. At higher temperatures, more carbon is incorporated into the bulk as the diffusion activation barrier is overcome; hence a phase-rich WC film is deposited.…”

Self-assembling WC interfacial layer on diamond grains via gas-phase transport mechanism during sintering of metal matrix composite

“…This fact once again supports the hypothesis that a layer based on tungsten carbide can be spontaneously formed on the surface of diamond grains during annealing of hotpressed segments after a mixture was doped with WC nanopowder. This interlayer increases diamond adhesion to the metal binder and acts as a barrier, preventing diamond graphitization due to a relatively low coefficient of carbon diffusion through it [37].…”