Erosion resistance refers to the ability of refractory bricks to resist the erosion and impact of various corrosive media at high temperatures. These corrosive media include various slags (blast furnace, electric furnace, converter, refining furnace, non-ferrous metal smelting furnace, calcining furnace, reactor), fuel, ash, fly ash, iron filings, lime, cement clinker, alumina clinker, waste, molten metal, molten glass, acids and alkalis, electrolyte solutions, and various gaseous substances (coal gas, CO, sulfur, zinc, and alkaline vapors), etc. Erosion resistance is a very important indicator for measuring the resistance of refractory bricks to chemical erosion and mechanical wear, and it is of great significance for formulating correct production processes and rationally selecting refractory bricks.

I. Factors Affecting the Erosion Resistance of Refractory Bricks

The factors affecting the erosion resistance of refractory bricks are both internal and external. The internal factors mainly include: the chemical and mineral composition of refractory bricks, the microstructure and other properties of refractory bricks, etc.; the external factors include: the nature of the corrosive medium, the service conditions (temperature, pressure, etc.) and the interaction between the corrosive medium and the refractory bricks under the service conditions. (1) Chemical and mineral composition of refractory bricks. Materials with different chemical compositions have different resistance to corrosion. Acidic refractory bricks have better resistance to acidic corrosive media, while basic refractory bricks have a weak ability to resist the corrosion of acidic corrosive media. Refractory bricks are multiphase aggregates, composed of main crystalline phase and matrix. The main crystalline phase has high refractoriness, large grains, and few grain boundaries, and its resistance to corrosion is relatively better; if the impurity content in the matrix is ​​high, it is easy to form a liquid phase. If the viscosity of the formed liquid phase is low, it is not conducive to the corrosion resistance of the material. (2) Microstructure of refractory bricks. This mainly refers to the distribution and bonding of various phases in refractory bricks, as well as the number, size, shape and distribution of pores, etc. (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 significant impact on their erosion resistance. Dense materials with high bulk density and low porosity have better erosion resistance than loose materials; materials with poor thermal shock resistance will crack or peel off when subjected to thermal shock, allowing the corrosive medium to enter the material and reducing its erosion resistance; carbon-containing refractory bricks with poor oxidation resistance will form a decarburized layer after surface oxidation, and the loose structure will easily fall off, reducing erosion resistance; materials with poor high-temperature volume stability will generally also have poor erosion resistance. (4) The influence of corrosive media. This mainly refers to the chemical composition, acidity, alkalinity, and viscosity of the corrosive medium, the temperature and flow rate (static or dynamic), pressure, and atmosphere (oxidizing and reducing properties for gaseous corrosive media). (5) The interaction between refractory bricks and corrosive media. Refractory bricks react with corrosive media to form a high-melting-point or high-viscosity phase, which is beneficial to reducing the erosion of the material. (6) The influence of usage conditions. The main factors include temperature and fluctuation, pressure, atmosphere, contact time, and area. Higher temperatures, larger fluctuations, higher pressure or vacuum, stronger corrosive atmospheres, longer contact time, and larger contact areas all contribute to more severe corrosion of the material.

II. Methods to Improve Corrosion Resistance

Based on the above analysis, the following measures can be taken to improve the corrosion resistance of refractory bricks: (1) Improve the purity of raw materials and the chemical and mineral composition of the product, minimizing the content of low-melting-point substances and impurities; (2) Pay attention to the selection of refractory bricks, using those with a chemical composition similar to the corrosive medium; in addition, during use, it is important to ensure that the chemical properties of the materials used are similar to prevent or reduce interfacial damage reactions between materials under high-temperature conditions; (3) Select appropriate production methods to obtain products with a dense and uniform microstructure. Due to the diversity and complexity of corrosive media, the test methods for studying the corrosion resistance of refractory bricks should also vary. Henan Refractory Materials Factory recommends test methods for slag resistance, acid resistance, alkali resistance, glass melt corrosion resistance, and CO corrosion resistance.