Adherent and low friction nanocrystalline diamond films via adsorbing organic molecules in self-assembly seeding process

摘要

Deposition of adherent and low friction nanocrystalline diamond films on cemented carbide cutting tools has been realized by application of a self-assembly seeding process with the help of lysine as stabilizing and directing agent. The colloidal stability of as-received detonated nanodiamond (DND) particles was enhanced by simply adding lysine into the nanodiamond seeding solution and adjusting the pH. Due to the two amine moieties it enhances the adsorption of oxidized nanodiamond on negatively charged cemented carbide substrate. The DND particle adsorption and adhesion of nanocrystalline diamond films on WC-Co substrate strongly depended on factors, such as concentration of lysine, pH of seeding solution and concentration of DND particles. The highest nucleation density of 6.5 x 10(10) cm(-2) was achieved with optimal colloidal stability, which was 10-100 times higher than most earlier published results on WC-Co substrate. Moreover, nanocrystalline diamond thin films were deposited uniformly and densely on cutting inserts while the film adhesion was significantly improved. Compared to diamond films prepared without the addition of lysine, the friction coefficient was 3-times lower. Therefore, electrostatic induced adsorption of diamond nanoparticles can serve to increase tool lifetime and enhance surface quality of a workpiece.