Carbon felt is a graphite felt treated at a high temperature above 2000℃ in vacuum or inert atmosphere, and its carbon content is higher than that of carbon felt, reaching more than 99%. At the end of 1960s, graphite felt appeared in the world. Graphite felt can be divided into asphalt-based, polyacrylonitrile-based graphite felt and adhesive-based graphite felt because of the different choices of original felt.

Among them, the asphalt represented by Japanese Wuyu Chemical Industry is the mainstream of the thermal insulation industry, and the thermal insulation felt in Europe and America is mainly adhesive, while in China, most of them are mainly acrylic resin. In this process, polyacrylonitrile-based carbon felt or viscose-based carbon felt is cut into the required size, rolled into a cylinder, placed in a container made of graphite material, placed in a high-temperature furnace (graphite tube furnace, medium-frequency induction furnace, high-frequency induction furnace or other heating forms), vacuumized or protected by introducing high-purity inert gas, and heated to 2200-200 at a heating rate of100-300℃/h.