Skip to content 
The Role of Silicon Carbide Plates in Kilns
Silicon carbide plates are flat materials made from silicon carbide and typically designed for use in the high-temperature areas inside kilns. These plates are engineered to withstand high-temperature environments, chemical corrosion, thermal expansion, and other factors, ensuring the stable operation and efficient heating of kilns. They serve multiple functions, including heating, support, and protection, making them suitable for various industrial applications such as ceramic product production kilns, melting furnaces, high-temperature experiments, and metal smelting, among others. Silicon carbide plates are widely used in industrial kilns, particularly in the fields of ceramic arts and sanitary ware production, due to their high-temperature strength, excellent thermal conductivity, and resistance to thermal shock.
Table of Contents
Performance Advantages of Silicon Carbide Plates
- Silicon carbide plates used in kilns are typically employed in the furnace chamber, heating zones, support platforms, and other areas to ensure the stability and efficiency of heating and heat treatment processes within the kiln. Compared to other materials, silicon carbide plates offer several advantages that enable them to withstand corrosion and thermal stress in high-temperature environments, thereby extending the kiln’s lifespan and improving production efficiency.
High-Temperature Resistance: Silicon carbide plates exhibit outstanding high-temperature resistance, making them suitable for various high-temperature kiln operations. - Corrosion Resistance: Silicon carbide plates demonstrate excellent stability in many chemical environments, with the ability to withstand corrosive gases and liquids such as acids and alkalis.
- Thermal Expansion Adaptability: Silicon carbide plates have a relatively low coefficient of thermal expansion at high temperatures, helping to reduce thermal stress and the occurrence of cracks.
- Superior Thermal Conductivity: Silicon carbide plates possess excellent thermal conductivity, allowing for uniform heating within the kiln.
- Mechanical Stability: While silicon carbide is a brittle material, well-designed silicon carbide plates can maintain a certain degree of mechanical stability at high temperatures.
- Wear Resistance: Silicon carbide plates offer some degree of wear resistance, allowing them to be used in kilns processing abrasive or particle-containing materials without significant wear.
- Good Insulation Performance: Silicon carbide plates have good insulation properties, reducing heat conduction and energy loss.
- Thermal Shock Resistance: Despite their low coefficient of thermal expansion, silicon carbide plates typically exhibit good resistance to thermal shock, enabling them to withstand temperature variations in kilns.
Common Issues with silicon carbide plates
Silicon carbide, as a non-oxide material, is prone to oxidation under high-temperature cyclic conditions, which can affect its lifespan. Here are some common issues that can occur with silicon carbide plates during use:
- Cracking and Fracture: Silicon carbide plates may develop cracks or fractures due to thermal stress in high-temperature environments. This can result from non-uniform heating, rapid temperature changes, or mechanical stresses.
- Deformation, Oxidation, and Corrosion: The thermal expansion coefficient of materials used in kilns may not match that of silicon carbide plates, leading to deformation. Additionally, at high temperatures, silicon carbide can react with oxygen and other chemicals, causing oxidation and corrosion.
- Slagging and Gas Permeation: Some gases can permeate into the interior of silicon carbide plates at high temperatures, leading to the formation of pores or increased brittleness, which can affect the mechanical properties and durability of the plates.
- Sintering and Thermal Loss: Silicon carbide plates may undergo sintering at high temperatures, resulting in dimensional changes. Prolonged use can also lead to thermal losses, reducing their performance.
Precautions for using Silicon Carbide Plates
Silicon carbide plates are used in diverse environments, and their effects and resulting damage can vary greatly. When using silicon carbide plates, it’s essential to carefully select, install, and maintain them based on the characteristics and operational requirements of the kiln to ensure their stability and safety in high-temperature environments. The following precautions will help reduce the likelihood of issues with silicon carbide plates:
- Material Compatibility: Ensure that the chosen silicon carbide plates are compatible with ceramic materials, glazes, or other ceramics to prevent potential chemical reactions or contamination.
- Temperature Suitability: Silicon carbide plates can withstand high temperatures, but make sure their high-temperature resistance matches the kiln’s operating temperature to avoid damage from excessive heat.
- Avoid Rapid Temperature Changes and Proper Heating/Cooling: While silicon carbide plates have a low coefficient of thermal expansion at high temperatures, it’s still crucial to avoid rapid temperature changes, especially overly fast cooling, to minimize the risk of thermal stress and cracking.
- Proper Support: When using silicon carbide plates, ensure they are as level as possible, supported at three points, and that the supporting pillars are aligned vertically to prevent breakage.
- Keep Dry: Keep the plates dry, and before loading products into the kiln, ensure they are as dry as possible. The contact area between the products and the plates should not be too large. New plates may need to stabilize after several uses, so it’s advisable to place them in a location with a relatively uniform temperature when first using them.
- Avoid Mechanical Impact: Silicon carbide plates are brittle and susceptible to mechanical impact and vibrations. Avoid collisions, shocks, and vibrations during operation, as they can lead to cracks or damage.
- Regular Inspection, Cleaning, and Maintenance: During use, regularly inspect the surface of the silicon carbide plates for cracks, damage, or wear. If any issues are detected, replace the plates promptly to prevent further deterioration.
Real-life Cases of Damage to Silicon Carbide Plates
1.Specific Damage Description of SiC plates issues
This batch of silicon carbide plates was produced using a reaction-sintering process and was intended for use in daily ceramic kilns. After some usage, certain silicon carbide plates exhibited varying degrees of cracking and deformation (see Figure 1). Additionally, some silicon carbide plates experienced spalling after multiple uses, leading to contamination of certain tableware products (see Figure 2).
2.Cause analysis of SiC Plates issues
- Cracking of Silicon Carbide Plates: One of the most common defects observed in silicon carbide plates is cracking. This occurs due to the susceptibility of silicon carbide to oxidation, which undergoes two significant expansions during heating: one between 180-270°C and another between 570-600°C. These expansion processes are rapid and highly disruptive. To prevent product cracking within these temperature ranges, it is essential to slow down the heating and cooling processes. Upon analyzing the materials responsible for cracking, it was found that there were no initial defects such as internal pores or uneven crystal structures that could have led to cracking. As a result, the investigation focused on the operational aspects of the site. It was discovered that the kiln in question primarily produces everyday ceramic products like bowls, plates, and cups, and there were no established standards for heating and cooling operations. Sudden temperature changes could cause different sections of the silicon carbide plates to expand or contract at different rates, resulting in thermal stress. If this thermal stress exceeds the material’s tensile strength, it can lead to cracking.
- Improper Handling During Production: Inadequate handling during the production process can also lead to uneven stress on the products, resulting in cracking. From the on-site operations, it was observed that non-standard assembly procedures caused damage to the silicon carbide plates, which likely increased the chances of cracking due to thermal stress during firing.
Environmental Factors: The damage to the silicon carbide plates is closely related to the oxygen content in the environment. Excessive levels of oxygen in the atmosphere can promote the oxidation and expansion of silicon carbide, leading to cracking. Additionally, high levels of moisture in the kiln can accelerate the oxidation of silicon carbide plates. This can occur due to high moisture content in the fuel or the introduction of products that have not been properly dried, causing rapid heating and an inability to vent moisture. The kiln was operating during a high-temperature rainy season, resulting in an unusually humid working environment. This was also a contributing factor to the rapid oxidation and subsequent cracking of the silicon carbide plates.
- Overloading Leading to Deformation: If silicon carbide plates are subjected to excessive loads, they can deform or crack under high-temperature conditions. Silicon carbide has high-temperature strength and is generally resistant to deformation due to excessive loads. However, in cases where each layer of plates is not properly supported during use, the weight of the upper layers may need to be considered, which can lead to overloading. Therefore, during the installation and firing process, it is essential to ensure that all supports are firmly in place. In the actual production process of this kiln, layers of silicon carbide plates were stacked unevenly, and as silicon carbide gradually oxidized, deformation occurred.
- Residue and Contamination Issues: When there is insufficient combustion air, silicon carbide plates can produce hard-to-burn carbon particles due to incomplete combustion. These carbon particles can fall onto the product surface through visible flame gaps, causing defects like black spots on the products. Additionally, as mentioned earlier, improper heating, kiln operation or sample loading, mechanical vibrations or impacts, and rapid oxidation issues not only lead to cracking of silicon carbide plates but also result in the shedding or detachment of particles from the plates in high-temperature environments, leading to residue and contamination of the kiln’s products.
3.Improvement Measures for Plates issues
- Gradual Use of Silicon Carbide Plates: When initially using silicon carbide shelving, the surface area of silicon carbide particles exposed to the external environment is the highest, resulting in more oxidation of silicon carbide and stronger volume expansion. Additionally, a small amount of binder binds the silicon carbide. As the number of uses increases, the oxidation film on the surface of silicon carbide gradually fuses together, and the strength of the plate increases. Considering that the middle section of the kiln has relatively uniform temperature changes, it is recommended to place new plates in the middle section of the kiln during their initial use.
- Standardize On-Site Operations: Avoid abrupt temperature changes and operate by gradually raising and lowering temperatures. During manufacturing and assembly, prevent mechanical impacts and collisions and use appropriate operational and protective measures. Choose the appropriate size and geometry of silicon carbide plates to reduce stress concentration. Regularly inspect the surface of silicon carbide plates to promptly detect cracks and take repair or replacement measures.
- Optimize and Improve the Oxidation Environment: Adjust the work schedule during the summer high-temperature rainy season, and keep the products inside the kiln dry to reduce the oxidation rate of silicon carbide.
- Adjust the Loading Method of Silicon Carbide Plates in the Kiln: Ensure that each support pillar is directly aligned with the load to avoid overloading of silicon carbide plates.
- Strictly Control the Combustion Atmosphere Inside the Kiln: Avoid incomplete combustion and the resulting increase in heat.
Conclusion
In conclusion, if Silicon Carbide Plates（setter/batt） encounter various issues such as breakage during use, it is influenced by multiple factors. Specific investigations and determinations need to be made based on the on-site conditions and the characteristics of the product itself. If you are looking for Silicon carbide Plates or related products, feel free to browse our related products or contact us directly.
Committed to excellence, we have consistently delivered high-quality solutions that cater to the diverse needs of our clients.
