Decoration of zinc oxide nanoparticles onto carbon fibers as composite filaments for infrared heaters

- This study adopts a microwave method to coat ZnO on carbon fibers (CF) as filament.
- The CF composite filament offers high thermal radiation power for infrared heater.
- The morphology of ZnO plays a crucial role in affecting the radiation performance.
- The ZnO crystals create emissive surface area, enhancing the thermal conductivity.

This study examines the thermal properties of ZnO-coated carbon fiber (CF) filaments for high-performance infrared (IR) heaters. An efficient pulse microwave (PM) method is applied to deposit different morphologies of ZnO crystals at various pH values of Zn2+ solutions, i.e., fragments (pH = 9), thin films (pH = 10), bulky islands (pH = 11), and nanoparticles (pH = 12). Under the applied voltage of 25 V, the CF composite filament, prepared by the PM route at pH = 10, offers the highest thermal radiation power and superior heat-storage capability among these IR heaters. Its saturation temperature and heating rate of ZnO-coated CF heater can reach to 184 °C and 28 °C/min, respectively. The enhanced thermal performance can be ascribed to the facts (i) the ZnO crystals create more emissive surface area and (ii) the composite filament illuminate more homogeneous spectral IR rays, showing the synergetic effect.