Browsing by Author "Yu, Min"
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Item Open Access Enhanced strength and thermal oxidation resistance of shaddock peel-polycarbosilane-derived C–SiC–SiO2 composites(Elsevier, 2022-06-13) Li, Guo-Qing; Yu, Min; Lin, Guo-Wei; Wang, Yun-Long; Yang, Li-Xia; Liu, Ji-Xuan; Gucci, Francesco; Zhang, Guo-JunBiomorphic ceramic materials have potential high-temperature applications, owing to their low density, good corrosion resistance and excellent shape capability, but achieving both high specific strength and excellent thermal oxidation resistance is challenging. In this report, shaddock peel-derived C–SiC–SiO2 composites were successfully prepared by the polymer precursor infiltration (PPI) technique with an optimized heating program. The composites prepared at 1600 °C exhibit the highest compressive strength (∼14.0 MPa) and specific strength (∼1.5 × 107 N m/kg), while those sintered at 1200 °C exhibit the highest bending strength (∼27.4 MPa). The composites exhibit good thermal oxidation resistance (up to 1400 °C) with a low weight loss ratio (<0.11 g/cm3), moreover, the compressive strength of the composites sintered at 1200 °C after thermal oxidation at 1400 °C surprisingly increased from 11.6 ± 2.7 MPa to 21.5 ± 3.5 MPa. The PPI technique provides a viable route to introduce Si source into natural materials and the shaddock peel-derived C–SiC–SiO2 composites are light materials with high strength and excellent high-temperature thermal oxidation resistance.Item Open Access Low-temperature thermally modified fir-derived biomorphic C–SiC composites prepared by sol-gel infiltration(Elsevier, 2023-02-10) Li, Guo-Qing; Yu, Min; Luo, Hang; Huang, Ze-Ya; Fu, Ren-Li; Gucci, Francesco; Saunders, Theo; Zhu, Kong-Jun; Zhang, DouIn order to solve the problems (i.e. low infiltration efficiency, cracks, interface separation and poor mechanical properties) in the process of wood-derived C–SiC composites, the thermal modification of fir at low temperatures (300 °C ∼ 350 °C) combined with sol-gel infiltration was used to successfully produce biomorphic ceramics. The prepared materials were comprehensively characterized and exhibited improved interfacial bonding between C and SiC and mechanical properties. The weight gain per unit volume (0.123 g/cm3) of SiO2 gel in the fir thermally modified at 300 °C is 167.4%, higher than that (0.046 g/cm3) of the unmodified fir. A well-bonded interface was formed between the SiO2 gel and the pore wall of the fir thermally modified at 300 °C. With the increase of modification temperature from 300 °C to 350 °C, the distance between SiO2 gel and the pore wall increases, and a gap (1–3 μm) is observed between SiO2 gel and the pore wall of the fir carbonized at 600 °C. The C–SiC composites sintered at 1400 °C exhibited the highest compressive strength and bending strength of 40.8 ± 5.8 MPa and 11.7 ± 2.1 MPa, respectively, owing to the well-bonded interface between C of fir thermally modified at 300 °C and SiC. However, the composites sintered at 1600 °C for 120 min exhibited the lowest compressive strength and bending strength of 28.1 ± 13.4 MPa and 5.7 ± 1.6 MPa, respectively, which are 31.1% and 51.3% lower than those sintered at 1400 °C for 120 min, respectively. This might result from the porous structure formed by the excessive consumption of fir-derived carbon during the reaction between C and SiO2 at 1600 °C for 120 min. Therefore, thermal modification in the preparation of biomorphic C–SiC composites can promote slurry infiltration and the formation of a well-bonded interface between C and SiC, thus improving the mechanical properties of the composites.