Polysilicon reducing furnace is key equipment to refine the polysilicon rod, first  high-voltage breakdown when high
pressure start , make pure silicon as the low resistance conductor, and thus enhance the conduction current speed, so that the internal temperature of the silicon core rise fast , greatly shorten the start-up time and improve production efficiency. Therefore, high temperature resistant  si3n4 ceramic insulating ring is needed to prevent insulation failure under high temperature and high pressure. Due to alumina ceramic own limited performance, the service life is very short, so the silicon nitride ceramic insulation ring has become the first choice.