Introduction of high temperature box type resistance furnace
Time：2020-12-25 16:20 Click：
Among the high-temperature experimental electric furnaces, high-temperature box furnaces, box-type muffle furnaces, atmosphere box-type furnaces, box-type heating furnaces, box-type heat treatment furnaces, etc. can all be called high-temperature box-type resistance furnaces, which are generally made of silicon carbide rods. It is an electric heating element with a maximum working temperature of 1350℃. The silicon carbide rods are vertically arranged on both sides of the furnace, rarely on the top and bottom of the furnace.
Silicon carbide is a non-metallic material. The resistance value changes greatly during the heating process. In order to avoid damage to the silicon carbide rod, the heating speed should not be too fast below 850°C. Silicon carbide rods will gradually age during use, and the resistance value will increase significantly, making the temperature rise slow or even unable to reach the required temperature. Therefore, in order to adjust the input power, the voltage of the box heat treatment furnace should be increased accordingly, so a small gear is required. Multi-stage voltage regulating transformer. Silicon carbide rods have poor resistance to rapid cold and heat, low high-temperature strength, and high brittleness. This limits the length and furnace size of the silicon carbide rods and can only handle smaller-sized workpieces, which affects the scope of application of the furnace.
The lining of high-temperature box-type resistance furnaces is relatively thick, usually with three layers: refractory layer built with high alumina bricks; middle layer built with insulation bricks; outer layer is insulation filler; it can also be sandwiched between the refractory layer and the insulation layer Aluminum silicate refractory fiber. The furnace floor adopts silicon carbide products.
Molybdenum disilicide is another high-temperature non-metallic electric heating element material with a maximum operating temperature of 1600°C. The high-temperature box furnace also requires a voltage regulating transformer.
At present, there are also box-type muffle furnaces that use high-temperature resistance alloys as electric heating elements, with a rated temperature of 1200°C. Although the maximum operating temperature is slightly lower than that of non-metallic (silicon carbide) heating elements, the high-temperature resistance furnace, but its power and furnace chamber size are larger, which can heat treat larger-sized workpieces.
At present, this kind of high-temperature furnace is equipped with furnace tank and drip-type protective atmosphere, which can realize heating with little or no oxidation and no decarburization.
Box heating furnace with full fiber lining, less heat storage, fast heating, and energy saving. If chromium-containing zirconium fiber is used, the furnace temperature can reach 1200～1300℃ (special high-temperature and high-resistance electric heating alloy patented products are required to ensure the use of heating elements life). Two-way furnace door, two-way loading and unloading of workpieces, a wide range of applications. Less oxidation devices can be added to realize less oxidation heating.
The finalized product has a 1100℃ all-fiber trolley furnace.