Structure and tribological properties of MоN vacuum-arc coatings

The influence of the deposition mode and test conditions on the structure and tribological properties of vacuum-arc MoN coatings was investigated. It was found that at bias voltages in the range of –30 – –70 V, coatings with a thickness of 10 mkmm based on hexagonal molybdenum nitride δ-MoN with high nanohardness (up to 34.7 GPa) and elastic modulus (up to 471 GPa) are formed on a substrate made of 15Kh12VNMF steel. Tests of “coated plate–ball” tribopairs using ceramic (Al2O3) and steel (ShKh15) balls diameter 10 mm without and with CrN, TiN and MoN coatings with a thickness of 10 mkmm show that the coating deposited at a bias voltage of –70 V has the best properties, and by the tribological characteristics at 20°С the “plate with MoN coating–ball with TiN coating” pair is optimal. At 500°С the wear resistance of the MoN coating decreases rapidly, which is associated with its thermal instability and transformation under the influence of contact stresses into molybdenum oxide.