Study Of Properties On TiAlN Based Nano-Multilayer Coatings Deposited By Multi-Arc Ion Platings

With the rapid development of the mechanical processing industry,more advanced cutting technology has also progressed rapidly.As a result,the performance requirements for coated tools have become increasingly demanding.Nowadays,traditional binary coatings such as TiN and TiC can hardly meet the needs of society,which makes the development of hard coatings more and more diversified.Among the many diversified hard coatings,TiAIN coating has been widely noticed due to its high hardness and excellent adhesion and other characteristics.With the increasingly harsh working environment,some of its shortcomings have been exposed,such as hardness,high temperature oxidation resistance and so on.TiAlSiN,which is formed by doping Si elements into TiAIN coating,has high hardness,wear resistance,chemical stability and high temperature oxidation resistance and has become an excellent coating material for improving the performance of cutting tools in the machining industry,and has received widespread attention in the field of scientific research.However,with the in-depth study of TiAlSiN coatings,it has been found that TiAlSiN coatings have significant interfacial effects due to their amorphous Si3N4 wrapped nanocrystalline TiAlN structure,which inhibits grain growth and plays a role in refining grains,while the increase in grain boundaries also increases the stress in the coating,so the spalling of single-layer TiAlSiN coatings is difficult to avoid,which also leads to poor adhesion of TiAlSiN coatings.TiAlN coatings are characterised by high adhesion and hardness,but the AI content of TiAlN has a significant influence on the coating properties.In order to optimize the performance of TiAlSiN coatings,TiAIN singlelayer films,Ti(1-x)AlxN/TiAlSiN bilayer films and Ti(1-x)AlxN/TiAlSiN nano-multilayer films were prepared by multi-arc ion plating technology in this paper,and the preparation process of TiAIN,different Al content of the TiAIN transition layer and the structure of the multilayer film system on the properties of TiAlSiN.The specific research works are as follows:(1)TiAlN coatings were prepared by multi-arc ion plating at different arc currents and pulse bias voltages,and the effects of arc current and pulse bias voltage on the properties of TiAlN and some of their magnitudes were analysed.As the pulse bias voltage increases from-200 V to-600 V,the coating thickness,hardness and adhesion increase and then decrease,and the wear rate decreases and then increases,and the pulse bias voltage has a greater effect on the coating performance than the arc current.The best overall performance of the TiAIN coating was achieved at an arc current of 60 A and a pulse bias of-400 V,with the hardness of 32.1 GPa,a wear rate of 2.747×10-6 mm3·N-1m-1 and adhesion of 105.9 N.(2)Ti(1-x)AlxN/TiAlSiN bilayer structures with different Al content transition layers and TiAlSiN monolayers were prepared and their effects were analysed.With the increase of Al content in the transition layer,the number of large particles on the surface of the coating increases;the hardness of the coating increases and then decreases,with the maximum hardness of 34.9 GPa for x=0.5,which is slightly lower than that of 35.4 GPa for TiAlSiN monolayer;the bilayer structure substantially improves the adhesion of the coating,with the maximum at 98.6 N for x=0.5.The results show that the best overall performance is achieved with the Al content in the transition layer of 0.5,the overall performance is optimal.(3)Six groups of Ti0.5Al0.5N/TiAlSiN nanomultilayers with modulation periods in the range of 120 nm-8 nm were prepared,and the effect of modulation period on the mechanical properties of the multilayers was investigated.The results show that the prepared multilayers have a clear cross-section of multilayer structure with a clear interface,and the multilayers have a dense and uniform structure with no obvious defects;the hardness of the multilayers increases and then decreases as the modulation period decreases,reaching a maximum at Λ=24 nm with a hardness of 42.1 GPa and an adhesion force of 95.0 N.The wear rate and the average friction coefficient of the multilayers show a trend of decreasing and then increasing,with a minimum at Λ The wear rate and the average friction coefficient of the multilayer film both tend to decrease first and then increase,with a wear rate of 3.1468×10-6 mm3·N-1m-1 and an average friction coefficient of 0.5226 at Λ=24 nm.The best performance of the Ti0.5Al0.5N/TiAlSiN nano-multilayer film was achieved at Λ=24 nm.