The manufacture of infrared detectors needs to use high-purity single crystal materials such as CdZnTe. When producing such high-purity single-crystal materials, zone melting purification methods are required to increase the purity of raw materials from 6N (99.9999%) to 7N (99.99999%). In order to prevent the adhesion of purified raw materials to the wall of the quartz boat vessel at high temperatures, it is necessary to form a carbon film with uniform thickness and strong adhesion on the surface of the quartz boat. The traditional method of coating carbon film method on the surface of the quartz boat has the problem of uneven coating and difficult removal of impurities. A carbon fumigation furnace based on methane pyrolysis in a vacuum environment with carbon particles adhering to the outer surface of the quartz boat was designed. The heating temperature and consuming time of methane decomposition were calculated. The heating temperature control performance and carbon fumigation experiments were carried out. When the heating temperature is between 1000 ℃ and 1200 ℃, 25% methane pyrolysis takes 1.734 s to 0.014 s, which is short and easy to achieve carbon film bonding. When the carbonization heating temperature is 1106 ℃, the temperature control accuracy in the middle of the carbonization zone is ±0.1 ℃. Between 400--780 mm in the transverse position of the furnace cavity, the temperature of the inner cavity of the quartz tube is greater than or equal to 1100 ℃. It′s heating temperature control stability and carbon fumigation performance are good, the adhesion between the carbon film and the quartz boat is good. The carbon film is pollution-free and the thickness is uniform.