Factors affecting erosion resistance of refractory bricks and methods for improving corrosion resistance
Release time：
2018-08-07 16:21
source：
Corrosion resistance refers to the ability of refractory bricks to resist erosion and erosion of various erosive media at high temperatures. These erosive media include various slags (blast furnace, electric furnace, converter, refining furnace, non-ferrous metal smelting furnace, calcining furnace, reaction furnace), fuel, ash, fly ash, iron filings, lime, cement clinker, alumina clinker, Garbage, liquid molten metal, glass melt, acid and alkali, electrolyte solution, various gaseous substances (gas, CO, sulfur, zinc and alkali vapor).
Corrosion resistance is a very important indicator to measure the chemical resistance and mechanical wear of refractory bricks. It is of great significance to make reasonable selection of refractory bricks for the correct production process.
Factors affecting the erosion resistance of refractory bricks are inherent and external. The internal factors mainly include: the chemical and mineral composition of the refractory brick, the structure and other properties of the refractory brick; the external ones are: the nature of the erosive medium, the conditions of use (temperature, pressure, etc.) and the conditions of use of the erosive medium and the refractory brick. The next interaction.
(1) Chemical and mineral composition of refractory bricks. The materials with different chemical compositions have different erosion resistance, and the acid refractory bricks have better corrosion resistance to acid attack media, while the ability of alkaline refractory bricks to resist acid erosion media is weak.
Refractory bricks are multiphase aggregates composed of a main crystalline phase and a matrix. The main crystalline phase has high refractoriness, large crystal grains, few grain boundaries, and relatively good corrosion resistance. If the content of impurities in the matrix is high, the liquid phase is easily formed. If the liquid phase viscosity is low, the corrosion resistance to the material is obtained. unfavorable.
(2) The structure of the refractory brick. Mainly refers to the distribution and combination of various phases 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 the corrosion resistance. A dense material with a high bulk density and a low porosity has a relatively good corrosion resistance to a relatively loose material; when a material with poor thermal shock resistance is subjected to thermal shock, cracks or cracks may occur, thereby causing the erosive medium to enter the interior of the material, resulting in erosion. The corrosion resistance is reduced; the carbon-containing refractory brick with poor oxidation resistance forms a decarburized layer after oxidation on the surface, and the structure is loose and easy to fall off, so that the corrosion resistance is lowered; the material with poor high-temperature volume stability generally also makes it resistant to erosion. difference.
(4) The influence of erosive media. Mainly refers to the chemical composition of the erosive medium, acidity and alkalinity, viscosity, temperature of the medium, flow rate (static or dynamic), pressure and atmosphere (for gaseous erosive medium, oxidizing, reducing, etc.).
(5) Interaction between refractory bricks and erosive media. The refractory brick reacts with the erosive medium to form a high melting point or a high viscosity phase, which is beneficial to reduce the erosion of the material.
(6) The influence of the conditions of use. It mainly includes temperature and fluctuation, pressure, atmosphere, contact time and area. The temperature is high, the fluctuation is large, the pressure is large or vacuum, the atmosphere is highly corrosive, the contact time is long, the area is large, and the erosion of the material is more serious.
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, improve the chemical and mineral composition of products, and minimize the content of low-melting substances and impurities.
(2) Pay attention to the selection of refractory bricks, try to use refractory bricks with similar chemical composition to the erosive medium; in addition, in the use of refractory bricks, it should also be noted that the chemical properties of the materials used should be similar to prevent or reduce the high temperature conditions. The interface between the materials used is damaging the reaction.
(3) Selecting a suitable production method to obtain a product having a dense and uniform structure.
Due to the diversity and complexity of erosive media, the test methods for studying the erosion resistance of refractory bricks should also be different. Henan Refractory Material Factory recommends test methods such as slag resistance, acid resistance, alkali resistance, resistance to glass melt erosion and CO corrosion resistance.