The term “refractory” refers to a material’s mechanical strength at high temperatures. Refractory materials have a high melting point and maintain their strength and structure even when subjected to extreme temperatures. The American Society for Testing and Materials defines refractories as “non-metallic materials with the chemical and physical qualities that make them appropriate for constructions or as components of systems applied to temperatures above 1,000 °F (811 K; 538°C).”
Types Of Refractory Materials
Refractory bricks in a variety of sizes and shapes are now available at Ganesha’s for a wide range of options. Fireclay refractories, high alumina refractories, silica brick, Magnesite refractories, Chromite refractories, Zirconia refractories, insulating materials, and monolithic refractories are examples of common refractory materials. Various types of refractories are used in applications such as boilers, furnaces, kilns, ovens, etc, based on the temperatures and service conditions.
Silica Refractory
Silica brick is a refractory material that contains at least 93% SiO2. Quality rocks are used as the raw material. At temperatures close to their real fusing point, silica brick has great mechanical strength. This behavior contrasts with many other refractories, such as alumino-silicate materials, which begin to fuse and creep at temperatures far lower than their fusion points. Various types of silica brick are widely used in the glass and steel industries.
Fireclay Refractory
Fireclay refractories are primarily hydrated aluminum silicates with 25% -45% Al2O3 and 50% -80% SiO2 with minor additional minerals. Because refractory fire brick is relatively inexpensive and its raw ingredients are generally available, it is the most popular type of refractory brick and is widely utilized in most furnaces, kilns, stoves, regenerators, and other purposes.
Magnesite Refractory
Magnesite refractories are chemically basic materials that include at least 85% magnesium oxide. These are made of magnesite (MgCO3) and silica, both of which are found naturally (SiO2). The physical features of this type of brick are often weak, and their main value is their resistance to basic slags, particularly lime and iron-rich slags. These are the most important refractories used in basic steelmaking processes. Basic brick is now successfully utilized in glass tank checks, lime and cement kilns, and metallurgical burners in addition to metallurgical furnaces. At high temps, acidic refractories also may react with limes and basic oxides.
High Alumina Refractories
Alumina refractories with more than 45 percent alumina are referred to as high alumina materials. The alumina content ranges from 45 to 95 percent. Sillimanite (61%), mullite (70–85%), and corundum are the most often utilized refractory materials (99 percent) The refractoriness of high alumina refractories increases with increasing alumina concentration. The hearth and shaft of blast furnaces, lime and ceramic kilns, cement kilns, glass tanks, and crucibles for melting a variety of metals are all applications for high alumina refractories.
Zirconia Refractories
Zirconia refractories have a very good hardness at room temperature that can be maintained up to temperatures of 15000 degrees Celsius. Its thermal conductivity is found to be significantly lower than that of the majority of other refractories. Zirconia does not react directly with liquid metals or molten glasses. As a result, they can be used as high-temperature construction materials in metallurgical and glass furnaces.
Monolithic Refractory
Monolithic refractory, the general term for all unshaped refractory goods, are materials that are installed as a suspension and eventually harden to create a solid mass. The traditional type of fir is being replaced by monolithic refractories.
Chromite Refractories
Chrome magnesite refractory bricks are made from sintered magnesia and refractory chrome ore. Chrome-magnesite refractory bricks typically have 20-35% Cr2O3 and 42-50% MgO, whereas magnesite-chromite refractory bricks include at least 60% MgO and 8-18% Cr2O3. Silicate is used to connect the gap between refractory granules.
Insulating Materials
Insulating materials are refractory materials having a high porosity and low thermal conductivity that are used to reduce heat losses. When compared to firebricks, insulating materials have a lower density and a higher heat resistance. A diverse range of insulating refractories with different chemical combinations is currently accessible. It is also less expensive than high-duty bricks.
Importance Of Refractory Materials
The cost and quality of steel products are heavily influenced by refractory materials. In recent years, the diversity of steel products and their cleaning requirements have boosted the demand for high-grade refractory. Steel production demands temperatures of 1600 ° C. Furthermore, steel making deals with high-temperature phases such as molten steel, slag, and hot gases. These phases are chemically reactive, requiring the use of refractory materials in the production of steels. The key demand is for high-quality refractory at a low cost, because the cost of refractory is added to the cost of the product.
Uses Of Refractory Materials
Refractory materials are used for the following purposes:
- Providing a thermal barrier between a warm medium and the wall of a contained vessel.
- Resisting physical pressures and reducing vessel wall erosion caused by hot medium
- Anti-corrosion protection
- Thermal insulation is provided.
