Castable precast is a functional material developed on the basis of traditional indefinite refractory materials and is a high temperature material within the category of refractory castables. It is made of refractory aggregate, powder, bonding agent, additive, water or other liquids, and is cast into a fixed shape by casting method. According to the bonding agent, it is divided into refractory cement bonding, phosphate bonding, water glass bonding, cementless bonding, etc. According to the material, it can be divided into high alumina, corundum, clay, mullite, etc.
The product can be arbitrarily prefabricated into a variety of shapes, good thermal shock stability, high strength, good resistance to spalling; refractoriness with sintered refractory bricks as high as 1750 ℃, and in the application of heavy metal smelting furnace can effectively resist penetration, the formation of erosion layer, no joints, good airtightness, less heat loss, energy saving; can quickly repair the furnace, improve the furnace operating rate; can achieve direct lifting mechanized furnace construction, construction High efficiency. We can solve the technical problems in the process of furnace construction for users; and we can consider the liner design and various construction plans for users according to their requirements and furnace conditions. The castables are supplied in time, generally within two weeks, and can be produced in a hurry, and there is no mold fee for large quantities. Refractory prefabricated parts are being widely used in various industrial furnaces with the irreplaceable superiority of refractory bricks. Its biggest advantage is that it can be pre-baked and directly lifted, which greatly shortens the construction period and controls the quality stably.
Casting material prefabricated parts are an important variety of refractory materials, which accounts for an increasingly high proportion. The prefabricated parts of castables are divided into small pieces in advance and designed with special shapes for the parts to be constructed in high-temperature furnaces, and molds are made according to the shapes.
Baking is an important process in the production of castables. In the process of baking, most of the free water and combined water of the precast itself is discharged and high strength is produced. Baking has a great influence on the quality of precast parts, especially the dense and high strength refractory precast parts with large volume, because the precast parts themselves have high density and large size. The joint action of water vapor pressure and thermal stress in the baking process can easily lead to the spalling of the precast, which can cause the precast to blow up in serious cases. The baking of prefabricated parts of castables generally adopts temperature control method. When baking, several temperature measurement points are arranged in the drying kiln and a baking curve is preset. The baking curve includes several heating and holding sections. By monitoring the temperature of the temperature measurement points, the baking system is carried out according to the preset baking curve. This control method is simple and easy to implement, and is the main control method for baking refractory precast parts and even other materials at present. Casting material prefabricated parts in the baking process is prone to burst, manifested as casting material suddenly and violently from the surface of its structure peeled off or exploded into a number of broken pieces. The baking temperature is higher or faster to cause the precast bursting. Baking in addition to the normal discharge of water, due to the higher or faster baking temperature, produced a negative effect that the water vapor pressure is too large resulting in the bursting of precast parts.
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