高温处理对单向碳纤维增强无机聚合物复合材料力学性能的影响

Effect of Heat Treatment on Mechanical Properties of Unidirectional Carbon Fiber Reinforced Geopolymer Composites

采用料浆浸渍辅助超声处理工艺成功制备了单向碳纤维增强无机聚合物基复合材料,并在1100℃、1200℃、1300℃和1400℃下对其进行高温处理。研究了无机聚合物和复合材料的热稳定性、相演变过程、力学性能变化等。结果表明,经高温处理后复合材料和无机聚合物均完成陶瓷化过程,析出白榴石晶相,并且由于碳纤维和基体之间界面反应的存在,与无机聚合物相比复合材料具有较差的热稳定性。随处理温度的提高,复合材料力学性能先升高再降低,经1200℃高温处理后复合材料达到最高的弯曲强度和断裂功,比处理前复合材料分别提高了28%和11%;高温处理后复合材料强度的提高主要是由于基体完成陶瓷化,基体和纤维的界面结合强度提高,界面能够有效传递载荷;随处理温度继续升高,界面反应造成碳纤维损伤严重,并且由于基体和碳纤维热失配形成的残余应力也逐渐升高,二者共同作用造成复合材料性能急剧下降。

Unidirectional carbon fiber reinforced geopolymer composites （Cuf/Geopolymer） are prepared by the simple ultrasonic-assisted slurry infiltration method, and then treated at different temperature in order to further enhance their mechanical properties. Thermal stability/phase evolution and room temperature mechanical properties of the composites are investigated, and fracture features of composites are observed. TGA analysis shows that interface reaction in the composite starts at about 1200 ℃, and XRD confirms SiC phase appears after treated at 1400 ℃. For the composite treated at 1100℃, flexural strength and work of fracture get their highest values. With increasing heat treatment temperature, the mechanical properties of composites degrade gradually and substantially worsen for the composite treated at 1400℃. TGA, XRD and SEM investigations show that carbon fibers degrade due to their reaction with geopolymer matrix. Moreover, residual stress in the composites increases with increasing heat treatment temperature, and plays a negative role in the mechanical properties.