Brief analysis of porosity and water absorption of refractories

What is the definition of the porosity of refractory materials and what is the basis for determination?
 

The ratio of the porosity volume to the total material volume in a material is divided into true porosity, closed porosity, and apparent porosity. Usually, the porosity in the refractory industry in China refers to the apparent porosity. The pores in refractories can be roughly divided into three categories: closed pores, open pores, and through pores. Generally, the three types of pores are combined into two types, namely, open pores (including through pores) and closed pores. Apparent porosity refers to the bulk density of all open pores in a material is the ratio of the dry mass of the refractory material to its total volume (the sum of the volume of solids, open pores, and closed pores), that is, the mass per unit volume of the material. Or kg / m '.
 

The bulk density of dense shaped refractory products shall be measured according to the national standard GB / T2997-2000. The bulk density of shaped heat-resistant refractory products shall be determined according to the national standard GB / T2998 2001. The bulk density of dense refractory castables shall be measured in accordance with YB / T5200- -1993.
 

Porosity is the basic technical index of most refractory materials. It affects almost all properties of refractory products, especially strength, thermal conductivity, corrosion resistance, thermal shock resistance, etc. Generally speaking, porosity increases, strength decreases, thermal conductivity decreases, and erosion resistance decreases.
 

The porosity of refractories is affected by various factors such as all raw materials and process conditions. Generally speaking, the use of dense raw materials, the use of reasonable particle grading according to the principle of tightest packing, the use of suitable binders, the materials are fully mixed, high-pressure molding, increasing the firing temperature and extending the holding time are all conducive to reducing the material's Porosity.

What is the definition of refractory water absorption and what is the basis for determination?
 

The water absorption rate is the ratio of the mass of water absorbed by all open pores in the material to its dry mass. It is expressed in percent. It is essentially a technical indicator that reflects the amount of open pores in the product. Because of its simple measurement, it is often used in production Identify the calcined quality of raw materials. The raw materials with good sintering should have low water absorption value.