- Patching refractory linings: Refractory plastics are commonly used to patch cracks, holes, and damaged areas in refractory linings of furnaces, kilns, ovens etc. This helps extend the service life of the lining.
- Bonding refractory bricks: Refractory plastics can be used as a mortar to bond refractory bricks and shapes. They help create a strong bond and seal joints between bricks.
- Insulating fill: Lightweight refractory plastics can be used as an insulating fill behind refractory linings. They help reduce heat loss and improve energy efficiency.
- Trowelable coatings: Provide a durable high-temperature surface coating.
What is refractory plastic?
Refractory plastic, commonly known as refractory putty, is an unshaped material that hardens when heated. Alumina, silica, magnesia, zirconia, or their combinations, are mixed with a binder and a plasticizer to make refractory plastics.
They are used for various applications, including repairing and patching furnace linings, ladles, and other high-temperature equipment. They can also be used for constructing new furnace linings and other refractory structures. Therefore, Selecting the appropriate type is crucial based on the application’s specific requirements, including temperature, chemical resistance, and mechanical strength.
Types of plastics refractory
- Alumina-based: These consist of alumina (Al2O3) as the primary raw material. They are resist high temperatures, wear, and chemical attack. They are commonly used in furnace linings, kiln furniture, and crucibles.
- Silica-based: Silicon dioxide (SiO2) is the main component of this plastic refractory. They are resist high temperatures and acidic chemicals. Glass and ceramic furnace linings employ them.
- Magnesia-based: Composed of magnesia (MgO) as the primary raw material, they have good resistance to high temperatures and basic slags. They are commonly used in applications such as furnace linings in the steel and cement industries.
- Zirconia-based: Use zirconia (ZrO2) as its principal basic ingredient, and have great resistance to high temperatures, corrosion, and wear. They are frequently employed in high-temperature furnaces and thermal barrier coatings that require strong thermal stability and chemical resistance.
- Mixed or composite refractory plastics: Created by mixing two or more distinct refractory materials. Alumina-silica, alumina-chrome, alumina-zirconia-silica (AZS), alumina-magnesia, and silicon carbide-alumina refractory plastics are some examples. Mixed refractory polymers can have better thermal stability, mechanical strength, and resistance to wear corrosion and chemical attack than their separate components.
Additionally, additives like graphite, silicon carbide, or metal fibres can also to improve their qualities such as electrical conductivity, thermal conductivity, and mechanical strength. Remember, the application and the required qualities determine the type of refractory plastic used.
- High-temperature resistance: Depending on the composition, refractory plastics can endure temperatures from 1000°C to 1800°C (1832°F to 3272°F). They can handle rugged steel, cement, glass, and petrochemical applications.
- Thermal shock resistance: They exhibit good resistance to thermal shock, which is the ability to withstand rapid temperature changes without cracking or spalling. This property is crucial for materials used in high-temperature environments where temperature fluctuations are typical.
- Chemical resistance: Refractory plastics resist chemical attacks from various substances, such as acidic or basic slags, gases, and molten metals. The specific type of chemical resistance depends on their composition.
- Wear and abrasion resistance: Refractory plastics can provide good resistance to wear and abrasion caused by mechanical stress, erosion, or contact with abrasive materials. This property is essential for applications where the refractory material is subject to high levels of mechanical wear, such as furnace linings and kiln furniture.
- Mechanical strength: Refractory plastics have good mechanical power, which is their ability to withstand mechanical stress without deforming, cracking, or failing. This property is crucial for materials used in structural applications, such as furnace linings and high-temperature equipment.
- Ease of application: Hand or with simple tools can apply refractory plastics. They can fill uneven gaps and create complicated shapes at room temperature, making them flexible.
- Good adhesion: Refractory plastics stick well to existing refractory surfaces or themselves when applied in layers. This avoids refractory structure delamination.
- Low shrinkage: Refractory plastics shrink slightly during drying and heating, preventing cracking and spalling.
Refractory plastics can fix and repair furnace linings, ladles, and build new refractory structures. Their composition and processing processes determine their attributes and performance, thus it’s important to pick the right kind for the application.
- Furnace linings: Steel, cement, glass, and petrochemical industries implement refractory plastics to repair, repair, and build furnace linings. Also, fill gaps, seal joints, and create complicated shapes to defend against high temperatures, mechanical stress, and chemical assault.
- Ladles and tundishes: In the steel industry, they are often used to maintain and repair the linings of ladles and tundishes, which are containers used for holding and transporting the molten metal. They provide resistance to high temperatures, wear, and chemical attack from molten metal and slag.
- Kiln furniture: Supporting, shelves, and setters made from refractory plastics can withstand high temperatures and chemical assault during burning.
- Burner blocks and nozzles: Mainly used to make burner blocks and nozzles for industrial furnaces.
- Incinerators and waste-to-energy plants: Used in the linings of incinerators and waste-to-energy plants, where they defend against heat, wear, corrosive gases and ash.
- Boiler and heater linings: For high-temperature resistance, thermal insulation, and protection from corrosive gases and combustion byproducts.
- Non-ferrous metal processing: Such as in the aluminum and copper industry, they can use to line furnaces, crucibles, and other equipment exposed to high temperatures and corrosive environments.
- Repair and maintenance: They are an excellent material for repair and maintenance work, as they can be easily applied to existing refractory surfaces or used to patch damaged areas. Their moldable nature allows for quick and efficient repairs, reducing downtime and minimizing the risk of equipment failure.
These applications are just a few examples of the many uses for refractory plastics in various industries. The choice of refractory plastic and proper installation and curing procedures are crucial to ensure the material’s long-term performance and durability in these demanding environments. Are there no disadvantages to them? Come and see with me.
Refractory plastics have multiple disadvantages that must be discussed when choosing them for high-temperature applications. Include:
- Limited resistance to specific chemicals: Depending on its composition, refractory plastic may be chemically susceptible. Basic slags target alumina-based refractory polymers, whereas acidic compounds attack magnesia-based ones. The chemical environment and refractory plastic composition must be considered.
- Curing and drying requirements: Refractory plastics must be properly cured and dried to achieve their desired properties. This process can be time-consuming and requires careful attention to ensure uniform drying and avoid cracking or spalling.
- Higher cost than other refractory materials: Refractory plastics can be more expensive than other refractory materials, such as castables or bricks. This may be a consideration for cost-sensitive applications.
- Limited service life: Although Refractory plastics can perform well in high-temperature applications, they have a shorter lifespan than other materials. So, you may need regular inspection, maintenance, and replacement to last.
Despite these disadvantages, refractory plastics can still be an effective solution for many high-temperature applications due to their ease of application, moldability, and other desirable properties. Careful consideration of the application’s specific requirements and selection of the appropriate refractory plastic composition can help address these disadvantages and ensure reliable performance.
Where to buy plastic refractory?
As a factory of origin with over 26 years of experience, Hongtai Refractory can create a wide range of refractory products, including refractory plastics, and provide end-to-end services. This will not only answer your purchasing and use issues, but will also help you better understand this industry. Don’t hesitate to get in touch with us if you would like to speak with refractory experts.