Research On Preparation And Properties Of TiN-type Hard Films

Hard films has broad application prospect as it can effectively increase the service life,reduce machining cost, and improve the processing efficiency and precision. The hard filmsrequire better properties due to the advance of industrial technology, they should not onlyhave high hardness and adhesion strength, but also have smooth surface. For theserequirements, we deposited TiN, TiAlN hard films by PVD technology, studied theirproperties through the methods of process optimization and the combined technology. Theresults were presented as follows:Based on the research of our team, we optimized the process of magnetic filter arc ionplating (MFAIP) and magnetron sputtering (MS) coating machine. For MFAIP, TiN filmshowed larger deposition rate, maximum hardness and adhesion when the bias was-150v andthe magnetic filter current was4.5A. For MS, when the nitrogen flow was2sccm, TiAlN filmshowed the highest hardness, when the nitrogen flow was4sccm, TiAlN film’s adhesion was:LC1=18N, LC2=22.5N. The results of high temperature oxidation experiments to MS-TiAlNfilms indicated that, when the temperature up to800℃, the film could still effectively preventthe diffusion of Fe, O, but it would lose the protective effect when the temperature increasedto850℃.This article innovatively integrated the advantages of AIP technology (high ionization rateand high energy of incident particles) and MS technology (homogeneous membrane layer andsmooth surface, etc), deposited the Ti/TiN/TiAlN composite films on the surface ofhigh-speed steel substrates. From the substrate, transition layer Ti/TiN to the surface TiAlNfilm, the thermal expansion coefficient and hardness showed gradient transition, which caneffectively relieve the film’s inner stress and improve the film’s performance. In addition, themacroparticles on surface of AIP-TiN transition layer could crystallized and grew during thedeposition of MS-TiAlN film, and the grain morphology was similar with TiAlN film, whichimproved the adhesion with surrounding film. So the Ti/TiN/TiAlN composite film depositedby AIP and MS combined technology not only have high hardness, smooth surface,but alsohave an exellent adhesion between films and substrate, the adhesion could get to: LC1=21.3N,LC2>30N. This article innovatively combined AIP with MFAIP technology, ground and polished theAIP-TiN interlayer, then coated the MFAIP-TiN surface layer, deposited TiN double films onthe surface of high-speed steel substrate and cemented carbide material. The double TiN filmshad smooth surface, low roughness and high adhesion, the adhesion on the high speed steelwas as high as: LC1=20.3N, LC2=23.7N, on the cemented carbide it reached to: LC1=11.4N, LC2>30N. This method can also be used in the re-coating field when the films notdeposited effectively or being used repeatedly, which can meet the requirements of green,environmental protection and energy conservation, has an important economic andengineering significance.