Preparation And Properties Of TiN/Al Matrix Composites

In view of TiN’s high strength,high hardness,wear resistance,high temperature resistance and good electrical and thermal conductivity properties,more and more researchers have carried out research on its high-temperature structural materials,wear resistance,electrical materials and military key materials.Aluminum and its alloys are also concerned because of their low density,good electrical conductivity,low coefficient of thermal expansion and high thermal stability.In this paper,combining the advantages of TiN and Al,using pure aluminum as matrix and TiN as reinforcing phase,TiN reinforced aluminum matrix composites with better performance were prepared.TiN reinforced aluminum matrix composites with high performance were prepared by powder metallurgy method in vacuum molybdenum wire hot pressing furnace.The phase of TiN reinforced aluminum matrix composites was qualitatively analyzed by XRD,and the microstructure characteristics of TiN reinforced aluminum matrix composites were studied by scanning electron microscopy（SEM）and energy dispersive spectroscopy（EDS）.Finally,the properties of the synthetic TiN reinforced aluminum matrix composites were analyzed in detail,such as the performance of hardness under different reinforcement phase content,the change of tensile properties under different reinforcement phase content,the friction and wear characteristics and wear mechanism under different friction frequencies and loads.The following conclusions are drawn:（1）The optimum process of TiN reinforced aluminum matrix composites is as follows:sintering temperature 610℃,pressure strength 30 MPa,holding time 1 h,Al content 85 wt%and TiN content 15 wt%.（2）The grain boundary of pure Al is clear.After TiN is added,the microst ructure distribution of the composite is uneven,and the enhanced phase particles appear at the grain boundary.At the grain boundary,with the increase of TiN c ontent,agglomeration occurred,TiN particles gradually grew larger,and the distri bution in Al matrix was not so uniform.When the TiN content was 10 wt%,th e agglomeration of TiN particles gradually became obvious,and when the TiN c ontent reached 15 wt%and 20 wt%respectively,the agglomeration phenomenon became more obvious,mainly concentrated around the Al matrix.Compared with other contents,TiN distribution in the composites with 5 wt%TiN was more u niform,and there was no agglomeration phenomenon.（3）The tensile strength of titanium nitride reinforced aluminum matrix composites is improved compared with that of the matrix materials.The enhancement effect increases first and then decreases with the increase of the mass fraction of titanium nitride.When the TiN mass fraction is 15 wt%,the enhancement effect is the most obvious,and the tensile strength is 23.70%higher than that of pure aluminum matrix materials（4）TiN can effectively reduce the abrasion degree of the friction surface of composites.The main wear mechanisms are adhesive wear and abrasive wear,and fatigue wear appears when the load is large.During friction,more Ti O₂ and Al₂O₃ films are formed on the surface due to the accumulation of friction heat,which can reduce the wear degree of the wear area.（5）The thermal expansion coefficient of TiN/Al matrix composites gradually decreases with the increase of the mass fraction of titanium nitride,and the thermal stability gradually increases with the decrease of the thermal expansion coefficient.Therefore,the thermal stability of TiN/Al matrix composites is the highest when the Tin content is 20 wt%,and the thermal stability is improved by 29%compared with that of pure aluminum matrix materials.