An important process of ceramic production is firing, which is carried out in the thermal equipment, which here refers to the advanced ceramic production kiln and its auxiliary equipment. There are many types of kilns for roasting ceramics. The same product can be burned in different types of kilns, and the same kiln can also bake different products. The development process of advanced ceramic production, the kiln is from low level to high level, from low output, low quality, high fuel consumption, high labor intensity, low firing temperature, can not control the atmosphere, developed to high output, high quality, low fuel consumption, high burning temperature, can control the atmosphere, and mechanization and automation. According to the operation of the kiln, it can be divided into two categories: intermittent kiln and continuous kiln. The intermittent kiln furnace can be divided into electric furnace, high-temperature inverted flame kiln, shuttle kiln, bell cover kiln and SPS sintering furnace.
The first kind is the electric furnace, the electric furnace is the general term of the electric thermal kiln. Generally, it is through the electric heating components to transform the electric energy into heat energy, which can be divided into electric resistance furnace, induction furnace, electric arc furnace, electron beam furnace and ion furnace and other five categories.
(1) Resistance furnace, when the power supply is connected to the conductor, the conductor has a current through, due to the resistance of the conductor and heat of an electric heating equipment. According to the temperature of the furnace can be divided into low temperature (working temperature less than 700℃), medium temperature (working temperature of 700~1250℃) and high temperature (working temperature more than 1250℃).
① box type resistance furnace: shape like a box, the furnace chamber is a long hexahedron, close to the inner wall of the furnace chamber placed electric heating body. Mainly used for a single small batch of large, medium and small products burning.
② well-type resistance furnace: the furnace cavity height is greater than the length and width (or diameter), and the furnace door is opened on the furnace top surface, and sealed with the furnace cap. The electric heating body is usually arranged on the side wall of the furnace chamber. Most are round, square or rectangular. Suitable for firing tubular products, deep well electric furnace is usually divided into several heating areas along the height, and the temperature of each area is adjusted by controlling power control, so that the electric furnace is distributed along the whole height temperature
(2) Induction furnace, due to electromagnetic induction action in the conductor produces induction current, and this induction current produces heat energy because of the resistance of the conductor and one kind of an electric furnace. It can be divided into induction smelting furnace and induction heating furnace, often use the induction furnace to develop silicon nitride and other heat is mainly produced by the arc of the electric heating furnace. It is used for artificial synthesis of mica, the production of alumina hollow ball and aluminum silicate refractory fiber high-quality thermal insulation materials.
(3) Electron beam furnace, the use of high-speed moving electronic energy as a heat source to heat the electric furnace, also known as the electronic bombardment furnace. Electron bombardment heater has been used to heat samples in high temperature X-light powder camera, prepare high melting metal single crystal such as melting point of ultra-pure Jun single crystal purity 99.9975% by electron beam heating floating area melting method), and heat silicon single crystal furnace and electron beam furnace. In addition, the electron beam is used for welding, evaporation coating, heat treatment, etc.
(4) Ion furnace, the electric furnace that uses the plasma energy generated by electric energy for heating. Flame kilns have limits to their temperature, usually not more than 2000℃. However, the plasma uses a part of the ionization energy, so it can easily reach a temperature above 10,000℃.