There are three types of pores in refractory bricks
1. Closed air hole: it is closed in the product and is not connected with the outside world
2. Open air hole: one end is closed and the other end is connected with the outside world
3. Through hole: through both ends of the product
The apparent porosity of refractory brick refers to the total volume of open pores and through pores and the percentage in the total volume of products
Apparent porosity is the basic technical index of refractory brick, which affects almost all properties of refractory brick, especially strength, thermal conductivity, corrosion resistance, thermal shock resistance, etc. Generally speaking, the apparent porosity increases, the strength decreases, the thermal conductivity decreases and the corrosion resistance decreases.
The apparent porosity of refractory brick is affected by the raw materials used, process conditions and other factors. Generally, the selection of dense raw materials, reasonable particle grading, selection of appropriate binder, high-pressure molding, increasing firing temperature and prolonging holding time are conducive to reducing the apparent porosity.
