Controlled Preparation and Thermal Conductivity of Highly Oriented Graphite Blocks

Using cheap and available natural flake graphite with high crystallinity and mesophase pitch as raw materials, graphite block materials with high bulk density, highly preferred orientation and high thermal conductivity, were prepared by a hot-press molding at mild temperatures and subsequent carbonization and graphitization treatments at high temperatures. XRD, SEM and PLM analyses indicate that the prepared graphite block has a highly preferred structural orientation, the graphitic layers of the graphite flakes inside are clearly oriented perpendicular to the hot-pressing direction. The components of various sized flake graphite and different types of pitch binders, and the proportions of raw materials, as well as the preparation process parameters (including hot-pressing temperature and pressure, heat treatment temperature, etc.), have great influences on the room-temperature in-plane thermal conductivity of the resultant graphite blocks. Graphitized blocks prepared from 86wt% NG (+32 mesh) and 14wt% AR mesophase pitch through hot-pressed at 500℃ at a fixed pressure of 10 MPa for 5 h and subsequently underwent 1000℃ carbonization and 2800℃ graphitization, have a good comprehensive thermophysical property. Their bulk density reaches above 1.91 g/m³, and room-temperature in-plane thermal conductivity is measured as high as 550 W/(m·K), and improved to 620 W/(m·K) after 3000℃ graphitization treatment.