Synthesis of alumina-coated graphite using polyvinylpyrrolidone via sol-gel reaction

Although graphite has excellent thermal conductivity of 200-800 W/mK, there are definite limits when applying graphite to thermally conductive materials, such as a coating material for printed circuit boards (PCB), an additive to the adhesive for the assembly of electronic chips, and a filler for thermal spreader pads. The problems are largely attributed to the electrically conductive property. To endow graphite with an electrically insulating property, graphite was coated with a well-grown alumina layer using polyvinylpyrrolidone (PVP) as a cohesive promotor. Aluminum isopropoxide (AIP) was used as the alumina precursor and PVP was used to improve the cohesion between graphite and alumina. An alumina-coating on graphite was conducted by a base-catalyzed sol-gel reaction. The changes in the morphology and the amounts of coated alumina, as well as the electrically insulating properties were investigated. An optimized condition to make alumina@PVP@graphite was determined by changing the amounts of AIP and PVR The synthesized alumina@PVP@graphite was categorized as an electrical insulator with a high surface resistivity of about 10¹² ohm/sq.