▎ 摘　　要

NOVELTY - A system comprises a gas refining quartz glass tube; a silicon carbide (SiC) substrate arranged at the center of a vacuum cavity; an induction heating graphite boat; and a carbon felt insulating layer. The SiC substrate is arranged in a sample groove of the graphite boat. The graphite boat is arranged at the center of the carbon felt insulating layer. A hydrogen source, a hydrogen needle valve and a mass flow meter are in series connection to form a hydrogen bypass. An argon source, an argon needle valve and a mass flow meter are in series connection to form an argon bypass. USE - System used in preparing graphene by silicon carbide thermal cracking method (claimed). ADVANTAGE - The system can achieve high-quality graphene production at relative high atmospheric pressure (0.1-1 atm). DETAILED DESCRIPTION - A system comprises a gas refining quartz glass tube; a SiC substrate arranged at the center of a vacuum cavity; an induction heating graphite boat; and a carbon felt insulating layer. The SiC substrate is arranged in a sample groove of the graphite boat. The graphite boat is arranged at the center of the carbon felt insulating layer. The carbon felt insulating layer is close to tube wall of the vacuum cavity to form a hollow structure. One end of the vacuum cavity is provided with a vacuum cavity door for opening or closing it. Below the vacuum cavity door, a flapper valve, a molecular pump and a mechanical pump are connected sequentially, where the three together compose a vacuum gas circuit for vacuumizing the vacuum cavity as necessary. The other end of the vacuum cavity is installed with infrared detection window passing through a glass out of the infrared. The induction heating coil is sleeved out of the tube wall of the vacuum cavity corresponding to the carbon felt insulating layer and does not contact the tube wall. The induction heating coil is sequentially connected with a medium-frequency induction heater, a PID temperature controller, an infrared temperature detector, and an infrared temperature probe, which forms an automatic heating feedback circuit. The infrared temperature probe, by the medium-frequency induction heater, detects the temperature of the induction heating graphite boat and feeds back the signal by the infrared temperature detector to the PID temperature controller to control the medium-frequency induction heater and the induction heating coil so that control of heating temperature is realized. A hydrogen source, a hydrogen needle valve and a mass flow meter are in series connection to form a hydrogen bypass. An argon source, an argon needle valve and a mass flow meter are in series connection to form an argon bypass. Both the hydrogen bypass and the argon bypass are communicated with one end of the vacuum cavity by the mass flow meter. The other end of the vacuum cavity is communicated with an exhaust bypass which is composed of a series connection of a bypass damper and a bypass mechanical pump, for controlling atmospheric pressure in the vacuum cavity and exhausting the residual gas in the cavity. An INDEPENDENT CLAIM is included for preparation of graphene by SiC thermal cracking method, comprising: (A) placing SiC substrate into the sample groove of graphite boat, pushing the Sic substrate from the vacuum cavity door in the gas refining quartz tube as a vacuum cavity, and placing at the center of the carbon felt insulating layer; (B) closing the vacuum cavity, opening bypass mechanical pump and bypass flapper valve, closing the bypass flapper valve when vacuum degree is less than 10 Pa, then opening the mechanical pump, the flapper valve and the molecular pump when vacuum degree is more than 1x 10-5; (C) respectively opening infrared temperature detector, PID temperature controller and medium-frequency heater, and under the control of the PID temperature controller whose program is preset, heating to 850 degrees C for 20 minutes for exhausting the residual gas in the vacuum cavity; (D) sequentially closing the flapper valve, the molecular pump and the mechanical pump; sequentially opening the hydrogen source, hydrogen needle valve and bypass flapper valve, filling hydrogen at 500 standard cubic centimeter per minute (sccm) in the vacuum cavity and regulating the pumping speed by the bypass flapper valve to keep the pressure in the vacuum cavity at 0.7-0.9 atm; (E) heating the graphite boat continuously to 1550 degrees C for 15 minutes at vacuum cavity pressure of 0.7-0.9 atm, after heat preservation, cooling to room temperature under protection of hydrogen, and at this time, completing the etching of SiC substrate; (F) closing the hydrogen needle valve and hydrogen source, adjusting the bypass flapper valve to maximum, closing the bypass flapper valve when vacuum degree of vacuum cavity is less than 10 Pa, sequentially opening the mechanical pump, the flapper valve and the molecular pump when vacuum degree is more than 1x 10-5, and repeating the closing step to avoid residual gas exhaustion from the vacuum cavity; (G) closing flapper valve, molecular pump and mechanical pump, opening the argon source, argon needle valve and the bypass flapper valve, filling argon at 100 sccm in the vacuum cavity, and adjusting pumping speed by the bypass flapper valve to keep pressure in the vacuum cavity to 0.7-0.9 atm; and (H) heating the graphite boat continuously to 1600 degrees C for 20 minutes, keeping pressure of vacuum cavity to 0.7-0.9 atm, after heat preservation, cooling the SiC substrate under protection of argon naturally to room temperature, and finishing thermal cracking of epitaxial graphene growing on the SiC substrate.