Research On Preparation,microstructure And Properties Of TiC-Ti₅Si₃ Reinforced Cu Matrix Composites Base On Ti-SiC System

Cu matrix composites have been widely used in industrial production due to their excellent electrical and thermal conductivity,high strength and hardness,good wear resistance and high temperature resistance.However,single-phase reinforced Cu matrix composites often have agglomerations,which affect the performance of the composites seriously.It is found that the hybrid reinforced Cu matrix composites have an advantage on uniformity of microstructure,and the synergistic enhancement effect between the reinforcement phases can be exerted.Therefore,selected Ti powder and SiC powder as raw materials in-situ synthesizing TiC and Ti₅Si₃ in the Cu melts to prepare TiC-Ti₅Si₃ hybrid reinforced Cu matrix composites in this paper.The SEM,TEM,XRD and DSC testing methods were conducted on analyzing the microstructure of the composites and the reaction process of the Ti-SiC system in Cu melts.At the same time,the hardness and wear resistance properties of the prepared composites were investigated by Micro-hardness Tester and Friction and Wear Tester,respectively.The main conclusions are as follows:1.Based on Ti-SiC system,SiC can be effectively introduced into Cu melts by the reactive wetting of Ti-SiC and the reaction products are distributed uniformly in Cu melts.However,the types and microstructures of the reaction products are varied with SiC size changing.When the size of SiC is small,such as 5μm,SiC can absolutely react with Ti to form TiC and Ti₅Si₃.The synthesized TiC are small particles and Ti₅Si₃ are needles or rod-like.When the size of SiC is large enough,such as 20 and 50μm,SiC does not tend to react completely with Ti.As a result,besides the TiC particles and Ti₅Si₃ rods,core-shell particles,Cu@TiC,SiC@TiC,SiC-CDC@TiC（CDC refer to derive carbon）and ternary layers SiC@SiC-CDC@TiC can be formed in the composites.At the same time,Ti₅Si₃ is to develop to be larger needle-like and even dendritic.2.When the size of SiC is large enough,the Ti-SiC reaction in Cu melts has two alternative reaction path ways and different reaction stages.The one will make SiC firstly transform into TiC,while another will make SiC firstly transform into SiC-CDC,and then further react with Ti to form TiC.Although TiC is more thermally favorable than both SiC and SiC-CDC,the presence of TiC shell can prevent SiC and SiC-CDC from further transformation.3.Based on Ti-SiC system,5μm SiC was used to prepare the TiC-Ti₅Si₃ hybrid reinforced Cu matrix composites with different components.The microstructure study shows that the TiC-Ti₅Si₃ were also to form solid skeleton structure as the synthetic amount of TiC particle,and Ti₅Si₃ rod and Cu@Ti₅Si₃ are improved gradually.4.The performance test shows that,as the content of TiC-Ti₅Si₃ hybrid reinforcement increase,the wear resistance of composites is not always improved.Choosing appropriate reinforcement ratio can not only ensure the continuity of Cu matrix,but also make the reinforcement form a solid skeleton structure.When the content of TiC-Ti₅Si₃ is too high,the toughness and continuity of Cu matrix will be destroyed.So the brittleness of composites is sharply increased and the lost mass is rapidly increased.In terms of the composites with different components in the paper,the wear resistance of the Cu-6.8Ti-1.4Si-0.6C composite is the best,while the Cu-9.72Ti-2Si-0.86C composite is the worst.The research of this thesis makes reference for the prepared,microstructure controlled,reaction process and wear resisrance of TiC-Ti₅Si₃ hybrid reinforced Cu matrix composites based on Ti-SiC system.