Heating process of refractory materials

Refractory material during this period of time that from room temperature rise to the highest sintering temperature is called temperature rise period, in order to meet the performance requirements of the product quality, the heating speed as quickly as possible.

In this period must consider the following questions:

1. Considering the product size and charge mode, bulky, wall thickness, complex structure and different thickness of the refractory products were firing, heating rate should be slower, so as to avoid the local temperature difference is too large, the expansion is not caused by deformation or crack.
2. From the firing process products to consider, should pay attention to the following several ways: 

• Such as blank in the gas suction, heating speed is slower. Such as adsorption water volatile, organic binder decomposition, hydroxide decomposition is different degree of aspiration. Therefore, when the heating rate should be slower, the temperature can be found on thermal analysis data.
  
   
• Body composition of the billet are crystal transformation, the heating speed should slow down. If the transformation is an exothermic reaction, you should slow heating, in order to avoid hot mutation caused by refractories cracking; if the endothermic reaction, it may be appropriate to strengthen the heat, stay after finishing the transformation should be slow heating, do not allow the temperature rising speed. The phase transition temperature can also be found in the data of thermal analysis. 
• Liquid phase appearance to be careful when heating, the liquid phase appears to increase the contact between particles, improves the transmission speed of body heat, reduce the temperature gradient, to accelerate the speed of temperature rise. But if the heating speed is too fast, too much local liquid phase, there may be due to the self weight or internal force and the body deformation, collapse.