Structural And Properties Of TiAlN-based Multilayer Composite Coatings Fabricated By Plasma

Ta layer was used as the transition layer,and TiAlN/Ta composite coating and TiAlN/TaN/Ta multilayer composite coating with different modulation periods were deposited on the surface of monocrystalline silicon?100?and carbide?YG8?by magnetron sputtering?MS?technology.In order to study the influence of process parameters and modulation period on the structure and properties of the composite coating,the phase structure,microstructure of surface and cross-section were characterized,and the hardness,elastic modulus and friction and wear properties were tested.?1?TiAlN/Ta composite coatings were prepared by DC pulsed magnetron sputtering?DCPMS?,Ta transition layers were prepared by RF magnetron sputtering?RFMS?,and double glow plasma surface alloying?DGPSA?.The effects of negative bias of substrate,mass flow ratio of Ar to N₂,and preparation process of transition layer on the structure and properties of TiAlN/Ta composite coatings were studied.Studies have shown that the coating structure and mechanical properties were improved with the increase of negative bias.The composite coating with the best properties including the hardness,elastic modulus and wear resistance was fabricated by the negative bias at-320V.The composite coating structure showed defects and mechanical properties decreased during negative bias above-320V.Under a certain working pressure,the mass flow ratio of Ar and N2 mainly affects the content of N2,leading to a significent difference in the phase structure of the coating,microscopic morphology and mechanical properties.When the mass flow ratio of Ar to N2 is of 3:1,the composite coating shows the best the mechanical properties.When Ta transition layer was prepared by DGPSA technology,the adhesion and toughness of composite coating were greatly improved.?2?Ta transition layer was prepared by DGPSA technology,and TiAlN/TaN/Ta multilayer composite coating was prepared by DCPMS technology combined with RFMS technology.The effect of modulation period?>100nm?on the structure and properties of composite coating was further studied.The results show that a clear multilayer modulation structure can be observed inside the composite coating.The phase structure is different from that of TiAlN coating and TaN coating,and its elastic modulus is higher than that of TiAlN/Ta composite coating.When the modulation period is 350nm,the hardness and elastic modulus of the composite coating were the maximum,and the wear resistance was the best.?3?TiAlN/TaN/Ta nano-multilayer composite coatings with nano-level modulation period?<50nm?were prepared by reducing the prepare time to TiAlN and TaN sublayers.The effect of the modulation period on the structure and properties of the composite coating was studied.The results showed that Ta phase was enhanced,TiN?220?and TaN?300?phases were decreased.Columnar crystal structure was grown in the composite coating under small modulation period.Compared with TiAlN/Ta composite coating,the hardness of nano-multilayer coating generally decreased and the elastic modulus increased.Compared with TiAlN/TaN/Ta multi-layer coating,the wear resistance becomes worse,among which the nano multi-layer coating with modulation period of 5.2nm and 13nm hasthe higher wear resistance.