Friction And Wear Behavior Of Ti₂SnC Reinforced Copper Matrix Composite Materials

The rapid development of electric contact materials has put forward higher requirements for self-lubricating composite materials.One of the standards to measure self-lubricating copper composite materials is friction and wear performance.In addition,taking the pantograph slide of consumables as an example,reducing its wear is of great benefit to energy conservation.As a conductive ceramic material,Ti₂SnC has excellent self-lubrication and conductivity due to its ternary layered structure,which makes Ti₂SnC/Cu composite material become a potential application material for electric contact and pantograph slide.The Ti₂SnCreinforced copper matrix composite has a great application prospect.Therefore,it is of great significance to study the friction and wear properties of Ti₂SnC reinforced copper matrix composites for the development of electric contact materials.In this thesis,the Ti₂SnC/Cu composite was prepared by Powder sintering with direct-heating and orthogonal experiment.The microstructure,composition and morphology of the composite were observed by optical microscopy（OM）,scanning electron microscopy（SEM）,phase analysis（XRD）and Electron Probe Microanalyzer（EPMA）.In this experiment,the effect of forming process on the friction properties of Ti₂SnC/Cu composite was studied.On the other hand,the effects of load,velocity and grinding pair on the friction properties of the composite also were studied.Main achievements are listed below:1)A series of Ti₂SnC reinforced with cooper matrix composites were prepared by Powder sintering with direct-heating and orthogonal table design with different process parameters.The optimal preparation process was determined to be 2μm,8wt.%,45 MPa and kept for 30 min.The study of forming process parameters based on the optimal process combined with the control variable method is as follows:with the increase of holding time,the wear mechanism gradually changes from adhesive wear to abrasive wear.With the increase of pressing pressure,the wear mechanism changes from abrasive wear to adhesive wear.With the increase of Ti₂SnC particle size,the wear mechanism changes from abrasive wear to adhesive wear.2)With the increase of Ti₂SnC content,the overall decrease of volume wear rate is related to the increase of hardness.The overall wear rate of 8wt.%Ti₂SnC/Cu composite is the smallest（0.197-0.264）×10^-33 mm³/（N·m）under different loads,which is related to its good interface adhesion.With the increase of load,the wear mechanism changes from adhesive wear to peeling wear.At different wear speeds,the friction coefficient of 10wt.%Ti₂SnC/Cu composite decreases with the increase of friction speed,and there is a period of friction running-in and sliding stability.The overall wear rate shows a downward trend,and the wear mechanism changes from oxidation wear to adhesion wear and then to oxidation wear.3)After the rolled deformation of Ti₂SnC/Cu composite was 20%,the friction coefficient of Ti₂SnC/Cu composite with a pressure of 45 MPa was stable and the volatility was improved The wear rate did not change much,and the wear mechanism was slight adhesive wear.With the increase of rolling deformation at 20%,the microstructure of Ti₂SnC/Cu composites prepared at a pressure of 55 MPa presents densification and the wear mechanism is mainly abrasive wear due to severe particle fragmentation.