Title: Uniform diamond coatings on WC-Co hard alloy cutting inserts deposited by a microwave plasma CVD,
Abstract: Polycrystalline diamond coatings have been grown on cemented carbide
substrates with different aspect ratios by a microwave plasma CVD in
methane-hydrogen gas mixtures. To protect the edges of the substrates from
non-uniform heating due to the plasma edge effect, a special plateholder with
pockets for group growth has been used. The difference in heights of the
substrates and plateholder, and its influence on the diamond film mean grain
size, growth rate, phase composition and stress was investigated. The substrate
temperature range, within which uniform diamond films are produced with good
adhesion, is determined. The diamond-coated cutting inserts produced at
optimized process exhibited a reduction of cutting force and wear resistance by
a factor of two, and cutting efficiency increase by 4.3 times upon turning A390
Al-Si alloy as compared to performance of uncoated tools.