Wear resistance of refractory materials in practical applications
2019-12-27
The abrasion resistance of refractory materials is their ability to resist mechanical wear on their surfaces from solids, liquids, and dust-laden gas flows.
In many cases, the damage to the surface of refractory materials caused by mechanical wear is often very serious. It is often the direct cause of the loss of refractory materials from their working surface. Sometimes it is greater than the damage from chemical erosion, or the damage caused by chemical erosion is often exacerbated by mechanical action. For example, the refractory lining in the upper part of a blast furnace and the iron runner are often damaged due to insufficient abrasion resistance. Refractory materials in coke oven carbonization chambers are also susceptible to coke abrasion. Steelmaking converter mouths, tapholes, and other areas subject to airflow and various molten liquid flows are often damaged due to poor material abrasion resistance. Therefore, the abrasion resistance of refractory materials is an important property.
The abrasion resistance of refractory materials depends on the composition and structure of the material. When the material is a dense polycrystal composed of a single crystal, its abrasion resistance mainly depends on the hardness of the mineral crystals that make up the material. High hardness means high abrasion resistance. When the mineral crystals are non-directional, the finer the grains, the higher the abrasion resistance of the material. When the material is composed of multiple phases, its abrasion resistance is also directly related to the bulk density or porosity of the material, as well as the bonding strength between the components. Therefore, for a certain refractory material at room temperature, its abrasion resistance is proportional to its compressive strength, and well-sintered products have better abrasion resistance. The abrasion resistance of refractory products is related to temperature. For some materials, such as silica-alumina refractory products, it is generally believed that their abrasion resistance decreases with increasing temperature within a certain temperature range (such as within the elastic range below 700~900℃), that is, it can be considered that as the temperature increases, the abrasion resistance decreases with the increase of the elastic modulus. When the temperature rises and reaches the maximum value of the elastic modulus, the abrasion resistance increases instead with the decrease of the elastic modulus. For example, the abrasion resistance of aluminosilicate refractory products at 1200~1350℃ is even better than that at room temperature. When the temperature is further increased to above 1400℃, the abrasion resistance decreases as the liquid phase viscosity in the refractory products decreases sharply. For some refractory materials, such as chromium-containing products, the abrasion resistance increases with increasing temperature.
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