Electrostatic self-assembly seeding strategy to improve machining performance of nanocrystalline diamond coated cutting tools

To tackle the issue of insufficient adhesion low wear resistance of diamond coated WC-Co inserts during machining Al-13 wt% Si alloy, nanocrystalline diamond films were deposited by HFCVD employing electrostatic self-assembly seeding strategy. The diamond film adhesion, wear resistance, tool lifetime and surface quality were extraordinary enhanced by increasing the diamond nucleation density via stabilizing the seeding solution by [2‑(Methacryloyloxy)ethyl]trimethylammonium chloride (TMAEMC). Due to the unprecedented high nucleation density of 1.2 × 10¹¹ cm⁻² on the tools, obtained with this stabilizing agent at pH 4, its flank wear after 90 min machining is at least 15 times lower than the commercially diamond coated insert and the diamond coating seeded without additive. The tool lifetime of the diamond film seeded with TMAEMC at pH 4 was at least 7 times higher than uncoated one and 4 times higher than the untreated one. A long tool lifetime with long phase of nearly constant low flank wear (46 μm till 150 min) was achieved at a diamond nucleation density higher than 10¹¹ cm⁻². Meanwhile, the surface roughness of the workpiece machined by optimized insert was 4 times lower than the untreated one. Therefore, the self-assembly seeding approach with the assistance of organic molecule represents a potent solution in order to achieve adherent and high wear resistant diamond coatings for industrial applications.