Influence of preparation temperature on the properties of C/ZrC composites

• C/ZrC composites were prepared by PIP at 1500 °C, 1550 °C and 1600 °C.
• Mechanical properties of C/ZrC composites decreased severely with rising preparation temperature.
• The linear recession rate of C/ZrC composites increased with rising preparation temperature.
• The diffusion depth of Zr element into carbon fibers increased apparently with rising temperature.

The preparation temperature for C/ZrC composites was optimized by assessing the effects on their mechanical and ablation properties. The composites were prepared by precursor infiltration and pyrolysis at 1500 °C, 1550 °C and 1600 °C. With rising preparation temperature, the open porosity of the composites increased, accompanied by formation of a strong interface and aggravated damage to carbon fibers, which were adverse to the mechanical properties. As a result, the flexural strength and fracture toughness decreased from 232 MPa to 11.9 MPa m1/2 to 103 MPa and 3.4 MPa m1/2 respectively. Meanwhile, elevating the open porosity provided more passage for oxygen into C/ZrC composites, which weakened the ablation resistance. The linear recession rate increased from 21.0 μm/s to 32.0 μm/s and then to 35.7 μm/s. Taking mechanical and ablation properties into consideration simultaneously, the optimum preparation temperature was 1500 °C.

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