In the solar photovoltaic industry, the quality of monocrystalline silicon is directly related to the quality of monocrystalline silicon. A qualified thermal field can grow high-quality monocrystalline silicon. Therefore, creating excellent thermal field conditions is a very important factor in the Czochralski monocrystalline process. . Graphite is the carrier for single crystal growth. High-purity graphite and isostatically pressed graphite processing parts are mainly used in graphite Czochralski single crystal growth furnaces. Based on actual needs, the size of the thermal field is divided according to the diameter of the quartz crucible. Currently, the thermal fields in our country range from φ12" to φ28", and generally φ18" to φ22" are the majority. The thermal system of the single crystal furnace we are talking about here is the so-called thermal field. The thermal field generally includes a pressure ring, an insulation cover, an upper, middle and lower insulation cover, a (three-flap) graphite crucible, a crucible support rod, a crucible tray, and an electrode. , heater, guide tube, and graphite bolts to avoid silicon leakage in the future. The furnace bottom, metal electrodes, and support rods are all equipped with protective plates and protective sleeves. 1. Heater The heater is a very important component in the thermal field. It is a direct heating element. When the temperature is high, it can reach more than 1600 degrees. Common heaters have three shapes, cylinder, cup, and spiral. Generally, the heater is made of high-purity graphite. 2. Graphite electrode The function of graphite electrode is to stably fix the heater and deliver current through other heaters. Therefore, the electrode must be thick, strong and durable, and the surface must be smooth and smooth to ensure a good contact surface and not spark when powered. The graphite electrode is also processed with high-purity graphite. 3. Graphite crucible, graphite support rod, graphite tray The crucible support rod, crucible and tray together form the support body of the graphite crucible, which needs to be firmly combined with the lower shaft. When the lower shaft rotates, the support rod and the tray must be ferried. The height of the graphite support less than or equal to 0.5mm can be adjusted. 4. Thermal insulation cover The thermal insulation cover is divided into upper, middle and lower thermal insulation covers. The thermal insulation cover is made of graphite carbon felt wrapped around an insulation cylinder. The number of layers of graphite carbon felt depends on the situation. The lower insulation cover forms the bottom insulation system. Its function is to strengthen the insulation of the bottom of the pot, increase the temperature of the bottom of the pot, and reduce heat loss. 5. Thermal insulation cover and guide tube The thermal insulation cover consists of an upper thermal insulation cover, an thermal insulation carbon felt and a lower thermal insulation cover, that is, a layer of graphite carbon felt is sandwiched between two layers of annular graphite. The guide tube is mainly used to control the temperature gradient of the thermal field and guide the argon gas flow in the future. 6. Pressure ring The graphite pressure ring is a circular annular graphite piece composed of several arcs. It is placed at the contact point between the cover plate and the furnace wall to prevent heat and gas from passing through the gap between the fireplace and the cover plate.