Improvement in thermal fatigue behavior of Si–Mo–Cr coated C/C composites through modification of the C/C-coating interface

Pre-oxidation is used as a treatment to carbon/carbon (C/C) composites for improving the thermal fatigue behavior of Si–Mo–Cr coated C/C composites. Si–Mo–Cr coating was prepared on C/C composites by pack cementation, and the thermal fatigue behavior of the coated samples was studied. After thermal cycling in air between 1773K and room temperature for 15 times, the mass losses of the coated C/C substrate without and with pre-oxidation were 6.3% and 3.8% respectively. Also, percentages of the remaining flexural strength of the coated C/C substrate without and with pre-oxidation were 71.78% and 82.97%. The improvement of the thermal fatigue properties of the coated samples with pre-oxidation was mainly attributed to the formation of a transition interlocking structure at C/C-coating interface, which is advantageous in alleviating the CTE mismatch between Si–Mo–Cr coating and C/C substrate, decreasing the crack size in the coating. •Pre-oxidation was put forward to treat C/C composites.•A mechanical inlaid structure was constructed at C/C-coating interface.•By pre-oxidation, the coated C/C samples show a better thermal matching performance.•Pre-oxidation can improve the thermal fatigue behavior of the coated C/C samples.