Fabrication of thermally robust carbon nanotube (CNT)/SiO2 composite films and their high-temperature mechanical properties

Carbon nanotube (CNT) films have shown great promise for a wide range of applications such as high-performance composites, energy devices, and environmental protection. However, the mechanical degradation of CNT films under high temperatures caused by their inherent weak oxidation resistance significantly limits their application in high-temperature environments. This paper presents a method for improving the mechanical properties and thermal stability of CNT films using SiO2-coating modification. The SiO2 precursor was first uniformly infiltrated into a CNT film via a vacuum-assisted filtration method. The SiO2 precursor was then decomposed under a controlled temperature to form an amorphous SiO2 layer wrapped on the CNTs. This treatment remarkably enhanced the mechanical performance of the CNT film, with a tensile strength of 180.9 MPa, which was 200% higher than that of the pristine CNT film. The SiO2-modified CNT film also exhibited excellent thermal stability at 500 °C, making it possible to expand its usage in high-temperature environments. The mechanism of the enhanced mechanical properties and thermal stability of the SiO2/CNT film is also discussed.