The influences of ball milling processing on the morphology and thermal properties of natural graphite-based porous graphite and their phase change composites

Carbon-based phase change composites (PCCs) are excellent thermal storage materials. But the mismatch between thermal conductivity and strength limits their application. In this work, we prepared a bulk porous graphite with high strength and high thermal conductivity by using template method with natural flake graphite as raw material and NaCl as template. After modifying its structure by an optimized ball milling process, PCCs with excellent properties were prepared by loading paraffin wax with this porous graphite. Compared with the original paraffin, the thermal conductivity of the prepared PCCs can be increased by 17 times (0.58 to 10 W·m⁻¹·K⁻¹). Besides, the compressive strength is also significantly improved. That is 1.5 MPa when paraffin is melted, and 6 MPa when paraffin is solid, which can support more than 2200 times of its own weight at the phase change temperature. This work is expected to promote the application of phase change composites in high-strength temperature control building materials.