Plateholder design for deposition of uniform diamond coatings on WC-Co substrates by microwave plasma CVD for efficient turning application.

Polycrystalline diamond coatings have been grown on cemented carbide WC-6% Co substrates with different aspect ratios by microwave plasma CVD in CH 4 /H 2 gas mixtures. Special plateholder with holes for group growth has been used to protect the edges of the substrates from non-uniform heating due to the plasma edge effect. The difference in heights Δh of the substrates and plateholder, and its influence on the diamond film mean grain size, growth rate, phase composition and stress was investigated. Diamond growth rate of 0.3–1 μm/h and compressive stress of 2.2–2.5 GPa, respectively were determined in the optimal Δh region. The substrate temperature range of 740–760 °C, within which uniform diamond films are produced with good adhesion, is determined. The diamond-coated samples produced at optimized process conditions exhibited a reduction of cutting force and wear resistance by a factor of two, and increase of cutting path length up to 8150 m or by 4.3 times upon turning А390 Al-Si alloy as compared to performance of uncoated tools. Prime novelty Polycrystalline diamond coatings with uniform structure and thickness distribution are grown by microwave plasma CVD (MPCVD) on WC-6% Co substrates using an optimized pocket-type substrate holder. Edge effect during MPCVD on high substrates (height/diameter > 0.1) was suppressed. Influence of distance between the substrate holder and substrate surface on deposition temperature and other parameters was investigated. Cutting force and wear rate of the coated samples upon cutting of Si-Al abrasive alloy were twice less than that of uncoated WC-6% Co. [ABSTRACT FROM AUTHOR]