Why the water glass refractory castable could bear the high temperature?

To increase the  use temperature of water glass refractory castables, comprehensive  technical measures shall be adopted: Use modified water glass as a  binding agent to improve the grade and fineness of the matrix materials,  use sodium fluorosilicate as a coagulant, and it is important to  control the castables. The sodium content.

The  use temperature of ordinary water glass refractory castables is low due  to containing more Na 2 O and fluxes such as sodium fluoride. When  bauxite clinker is used as powder, special-grade or first-grade clay  clinker and alumina clinker are used as aggregates, when the modified  water glass and sodium fluorosilicate are used to prepare refractory  castables, the sodium content shall be strictly controlled, ie Use high modulus, low density water glass and less Na2SiF6 to improve performance.

In refractory castables, due to the use of modified water glass and  appropriate amount of Na2SiF6, less sodium is introduced into the feed,  and less NaF is generated, ie, the amount of silicic acid gel is  reduced, resulting in a reduction in the normal temperature strength of  more than 10 MPa. However, it is also sufficient  to meet the construction requirements, but the high temperature  performance has been greatly improved, thus increasing the operating  temperature. Figure 2 shows the X-ray diffraction pattern of the heated sample after 1400. From the figure, the main mineral components are mullite and corundum, as well as a small amount of cristobalite and Al2O3.

Due  to the use of modified water glass as a binding agent, the grade of the  matrix material is improved; strictly controlling the sodium content in  the refractory castable material can obtain sufficient room temperature  strength, and the active SiO2 in the water glass reacts with Al2O3 in  the matrix material under high temperature. The formation  of acicular mullite and other high-temperature minerals and a small  amount of jelly filling it, so that the structure of the refractory cast  material compact, improved performance. This is the mechanism by which the material is resistant to high temperatures.