Changxing jinyuan refractory material co. LTD
Contact: Mr. Zhou
Hand machine: 18657298080
Email address: email@example.com
Address: wang bang tou industrial park, taihu street, changxing county, huzhou city, zhejiang province
Mullite is a crystalline phase of al2o3-sio2 system with many excellent properties, especially good creep resistance at high temperature, so it has been widely used. Mullite castable is difficult to produce because of the harsh requirements on the binder, which requires that the binder can not reduce the excellent performance of mullite, using Al2O3, silica gel and pure calcium aluminate cement as the binder can get excellent performance of mullite castable.
The properties of light mullite castable are listed in table 1. This castable works well, but the lightweight clay aggregate limits its use at higher temperatures.
There are two main factors that determine the performance of lightweight castable: one is the performance of lightweight aggregate, and the other is the binding mode and the type of binder. Once a lightweight aggregate is selected to produce a lightweight castable, the performance of the lightweight castable depends on the type of binder and the additive. Traditional lightweight castable is added with 20%? 30% cement, or 10%? 15% water glass as binder. With cement and sodium silicate as binders, the strength of the castable decreased during the heating process, which affected its performance.
At present, the combination of low cement and ultra-low cement has been widely used in the production of dense castable. For lightweight mullite, a premium material, the amount of cement added, though small, is always introduced by some harmful magazines. The best combination is the application of composite aluminum - silicon adhesive. The composite si-al adhesive mainly contains Al2O3 and SiO2, among which Al2O3:SiO2 =3:2, and a small amount of additives to promote the formation of mullite is added.
Since si-al adhesive contains neither low melting additives nor hydration binders, nor other forms of inorganic and organic binders, the pouring material will not produce the strength reduction caused by the disappearance of hydration binding, nor the strength reduction caused by the burning loss of binders. At high temperature, the binding site is mainly refractory properties and bonding properties are excellent mullite phase, the light mullite particles closely together. Because of the expansion of mullite at high temperature, the linear shrinkage of light mullite castable decreases.
The heat insulation mechanism of the light castable is similar to that of the light fire brick, both of which are caused by the higher porosity of the material.
In recent years, energy sources are becoming increasingly scarce, and the development of energy saving materials has been paid more and more attention. Lightweight castable is more and more important in high temperature applications. Light castable material has high porosity, small volume density and low thermal conductivity. On the one hand, it has great thermal resistance to heat transfer from high temperature to low temperature, which reduces heat loss in continuous production equipment. On the other hand, because of its small heat capacity, less heat storage, thus improving the short-term production and intermittent production of thermal equipment utilization and thermal efficiency. In addition, it also can be the same as ordinary castable, both integral pouring, also can be made into prefabricated parts, very convenient to use.