Friction and wear properties of C/C composite materials in nitrogen and air atmospheres

The friction and wear behaviors of C/C composites in nitrogen and air environments under simulating normal landing energy condition were investigated on the MM-1000 friction tester.The results show that C/C composites exhibit the higher friction coefficient(0.32～0.4) but the smaller wear rate in N2,mass wear rate and linear wear rate are 18 mg/times and 1.4 μm/times,respectively;however,C/C composites shows the lower friction coefficient which is 0.2～0.3 but the larger wear rate in air,mass wear rate and linear wear rate are 48 mg/times and 3.8 μm/times,respectively.The SEM morphologies of worn surface and wear debris show that in air,wear debris which carbon fiber separates from carbon matrix appear on the worn surface,wear mechanism is mainly oxidation wear.However,in N2,large-size debris which carbon fiber is well-connected with carbon matrix appear,wear mechanisms are mainly abrasive wear and adhesive wear.