“…Nucleation on pretreated surfaces is observed to occur primarily on carbon-rich particles or defects, such as scratches, grain boundaries, particle boundaries, dislocations, electron bombardment damages, and edges of etch pits/craters [39,72,75,79]. Pulsed laser irradiation + coating a-C, WC, cBN layer enhancement [106] Carburization enhancement [31,70] As schematically depicted in Figure 4 [72], nucleation enhancement by scratching is attributed to (a) seeding effect [78,98,107], (b) minimization of interfacial energy on sharp convex surfaces [20,108], (c) breaking of a number of surface bonds or presence of a number of dangling bonds at sharp edges [100], (d) strain field effects [105], (e) rapid carbon saturation (fast carbide formation) at sharp edges [72,109], and (f) removal of surface oxides [39,100]. Another possible operating mechanism [13,71] for the nucleation enhancement by scratching is that scratching produces non-volatile graphitic particles through local pyrolysis of absorbed hydrocarbons.…”