The medium temperature zone of refractory castable is between 800-1000℃, and the strength of castable in this temperature zone is the most awkward temperature for castable weakness. If you want to increase the intensity of the medium temperature, there are several methods.
Method for increasing the medium temperature strength of refractory castable
The first is the chemical reaction that can be added α-Al2O3 fine powder in aluminate refractory cement to make the product expand at medium temperature, in order to make up for the decline in medium temperature strength caused by the volume contraction of castable. Adding a certain proportion of α-Al2O3 fine powder to the castable increases the shrinkage compensation effect, so the weakness of the medium temperature strength of the material can be adjusted. Whether the binder is used by CA-50 or CA-60 high-aluminum cement, the strength of the medium temperature will be greatly reduced, if the binder is CA-70 high-aluminum cement, after adding α-Al2O3 fine powder, the medium temperature strength will not only not decrease, but also improve.
The sintering agent is added to the refractory castable
Another method is to add sintering agent in refractory cement, can also improve the medium temperature strength of castable, sintering agent is soft clay, etc., the proportion of 3-6%, its effect can make castable sintering at a lower temperature, prevent or change the structure of castable change, in order to improve the medium temperature strength of castable. Some even have improved effects than drying strength.
In addition, adding water reducing agent to monolithic refractory castable can also improve the interim temperature strength, but the addition of water reducing agent can not change the decline of the middle temperature strength.
After the castable passes the medium temperature zone, due to the increase of the liquid phase, the sintering will make the castable form a ceramic bond, so the compressive strength will increase with the increase of the heating temperature, under normal circumstances, the high-aluminum cement of CA-60 will be slightly higher than the high-aluminum cement of CA-50 refractory castable load softening temperature and refractorability.
Therefore, the medium temperature strength of refractory castable can be improved by adding α-Al2O3 fine powder, sintering agent or water reducing agent.
