Insulating refractory refers to high porosity and low bulk density, low thermal conductivity of refractories. Insulation refractories is also called lightweight refractory. It includes insulating refractory products, refractory fibre and refractory fiber products.
Heat insulation refractory is characterized by high porosity, general is 40% ~ 85%; Bulk density is low, generally less than 1.5 g/cm3; Low thermal conductivity, generally less than 1.0 W (m · k). It is used as the insulation material of industrial kiln, can decrease furnaces heat loss, save energy, and can reduce the weight of the thermal equipment. Heat insulation refractories mechanical strength, wear resistance and resistance to slag erosion sex is bad, should not be used in the furnaces of bearing structure and direct contact with molten slag, furnace charge, such as molten metal parts.
Heat insulation refractory products
Heat insulation refractory products refers to the porosity of no less than 45% of refractory products. There are many kinds of insulating refractory products. Its classification method mainly has the following kinds:
1) by using temperature is divided into low temperature heat insulating refractory (using temperature is 600 ~ 900 ° C), medium temperature and heat insulation refractory (using temperature is 900 ~ 1200 ° C) and high temperature heat insulation refractory (using a temperature greater than 1200 ° C).
2) according to the volume density is divided into general lightweight refractory (volume density of 0.4 ~ 1.0 g/cm3) and ultra lightweight refractory (bulk density less than 0.4 g/cm3).
3) according to the raw material into the clay, high aluminum, silica and magnesia insulating refractory, etc.
4) according to the production methods are divided into burning method, bubble method, chemical method and the method of porous materials such as heat insulation refractory.
5) according to the product shape is divided into setting insulating refractory products and amorphous insulating refractory products.
Insulating refractory products and dense refractory products is different, the main methods are burning joining method, bubble method, chemical method and the method of porous materials:
1) burning joining method. The method is to sawdust and other flammable or can be sublimated additives into the mud material. Mixing, and then used to squeeze billet, half dry or mud casting molding, drying after firing. Combustible or can be sublimated additive in the process of firing burn, leaving empty hole, be insulating refractory products.
2) bubble method. The method is to foaming agent into the whisk machine made by adding water mixing tiny bubbles evenly and then add the foam slurry mixing together into a foam slurry, injection model, dry, together with the model of demoulding, at 1320 ° C to 1380 ° C (for high aluminum heat insulation refractory brick) under firing, after processing plastic products.
3) chemical method. It is in the brick using chemical reaction gas in the process and a method of porous bricks. Usually use chemical reactions such as carbonate and acid, metal powder acid, caustic and aluminum powder, etc. Can make use of a chemical reaction is slow and must be able to control, or by mechanical disturbance in poured into the mold when bubbles shall disappear. Such as fast reaction, can add inhibitors such as manganese dioxide and hydrogen peroxide. In fine powder raw material slurry mixed with bubbling reagent to obtain stable foam slurry, injection model,