Factors affecting the erosion resistance of refractory bricks

Influencing factors of erosion resistance of refractory bricks

Erosion resistance refers to the ability of refractory bricks to resist erosion and erosion by various erosive media at high temperatures. These erosion media include various slag, fuel, ash, fly dust, iron filings, lime, cement clinker, alumina clinker, garbage, liquid molten metal, glass melt, acid and alkali, electrolyte liquid, various gaseous substances (gas, CO, sulfur, zinc and alkali vapor), etc. Therefore, the reasonable selection of refractory bricks is of great significance.

There are two main factors affecting the erosion resistance of refractory bricks.

Intrinsic factors:

(1) Chemical and mineral composition of refractory bricks. Different chemical composition of materials have different erosion resistance, acid refractory bricks have good erosion resistance to acid erosion medium, while alkaline refractory bricks have a weak ability to resist acid erosion media.

Refractory bricks are multiphase aggregates consisting of a main crystal phase and a matrix. The main crystal phase has high refractory, large grains, less grain boundaries, and relatively good erosion resistance; If the content of impurities in the matrix is high, it is easy to form a liquid phase, and if the formed liquid phase viscosity is low, it is not conducive to the erosion resistance of the material.

(2) The organizational structure of refractory bricks. It mainly refers to the distribution and bonding of each phase in refractory bricks, as well as the number, size, shape and distribution of pores.

(3) Other properties of refractory bricks. The bulk density, apparent porosity, thermal shock resistance, oxidation resistance, and high temperature volume stability of refractory bricks have a great influence on their erosion resistance. Dense materials with high bulk density and low porosity have better erosion resistance than loose materials. When the material with poor thermal shock resistance is subjected to thermal shock, cracks or cracking peeling will occur, so that the erosion medium enters the inside of the material, resulting in reduced erosion resistance; Carbon-containing refractory bricks with poor oxidation resistance form a decarburized layer after surface oxidation, and the structure is loose and easy to fall off, so that the erosion resistance is reduced; Materials with poor volume stability at high temperatures generally make their erosion resistance worse.

External factors:

(1) The influence of erosion medium. It mainly refers to the chemical composition, acidity and alkalinity, viscosity, temperature, flow speed (static or dynamic), pressure and atmosphere of the medium (for gaseous erosion medium, oxidation, reduction, etc.).

(2) The interaction between refractory bricks and erosion medium. Refractory bricks react with the erosion medium to form a high melting point or high viscosity phase, which is conducive to reducing the erosion of materials.

(3) Influence of conditions of use. It mainly includes temperature and fluctuations, pressure, atmosphere, contact time and area. The higher the temperature, large fluctuations, high pressure or vacuum, strong atmosphere corrosiveness, longer contact time, large area, the more serious the erosion of the material.

Therefore, the measures to improve the erosion resistance of refractory bricks are:

(1) Improve the purity of raw materials and minimize the content of low melts and impurities;

(2) Pay attention to the selection of refractory bricks, and try to choose refractory bricks with a chemical composition similar to the erosion medium;

(3) Select the appropriate production method to obtain products with dense and uniform organizational structure.