New diamond turnable coatings of ternary systems for ultraprecision cutting

Moulding tools for optical components need optical surface quality. To reach this high quality surface the machining with monocrystalline diamond tools is most suitable. Steels which are used as materials for moulding tools are not diamond machinable due to heavy chemical wear of the diamond tool. Therefore diamond machinable coatings have to be deposited on the moulding tools before final cutting. Up to now electroless nickel phosphorus coatings are the only diamond turnable coatings, but their hardness and temperature stability is limited. For this reason new diamond machinable coatings with higher hardness and improved temperature stability have to be developed. One promising coating is substoichiometric titanium nitride (TiN x