Preparation process of nano-diamond coated mold

Hot-wire CVD deposition method:
The excitation source (hot wire) is passed through the die inner hole and placed at the axial position. By controlling parameters such as hot wire temperature, gas flow rate, and reaction time, uniform deposition of the nanodiamond coating is achieved. For example, in the nucleation stage, the hot wire reaction pressure is adjusted to 4.0～6.0 kPa, a mixed gas of hydrogen and methane is input, the flow rate is 1800～2300 ml/min, the methane volume fraction is 2～4%, and the reaction time is 40～80 min; in the growth stage, the reaction pressure is adjusted to 2.5～3.5 kPa, the mixed gas flow rate and methane volume fraction are adjusted accordingly, and the reaction time is 300～420 min.
Multi-hot wire braiding technology:
A braided wire composed of multiple hot wires is used to replace a single straight hot wire, achieving uniform coating of the diamond coating on the inner surface of a large-aperture (inner hole 15～70 mm) drawing die. According to the drawing die with different diameters, different combinations of braided wires are selected to ensure that the diamond film is uniform and of good quality.
Nanodiamond composite coating technology:
Conventional diamond and nanodiamond are organically combined. Based on the deposition of a conventional diamond coating, a layer of nanodiamond film is in-situ deposited to form a composite coating. This makes the coating have the advantages of wear resistance and strong adhesion, as well as a smooth surface, low friction coefficient, reduced hardness, and easy grinding and polishing. The nanodiamond coating particles are 20～80 nm in size.