Refractory Kiln Furniture in the Ceramic Tableware Firing Process

1. Types of Refractory Kiln Furniture

Refractory kiln furniture is typically made from high-temperature-resistant materials such as silicon carbide (SiC), alumina (Al₂O₃), cordierite (2MgO·2Al₂O₃·5SiO₂), and mullite (3Al₂O₃·2SiO₂). Each material has distinct properties that make it suitable for different firing conditions:

• Silicon Carbide (SiC) Kiln Furniture: Known for its exceptional thermal conductivity, high mechanical strength, and resistance to thermal shock, SiC is widely used in high-temperature firings (up to 1400°C or higher). It is ideal for fast-firing processes and heavy-load applications. However, it is more expensive than other options.

• Alumina (Al₂O₃) Kiln Furniture: Alumina-based kiln furniture offers excellent chemical stability and high-temperature resistance, making it suitable for advanced ceramics and technical applications. It is often used in oxidizing atmospheres but can be brittle under rapid thermal cycling.

• Cordierite Kiln Furniture: Cordierite is valued for its low thermal expansion coefficient, which provides excellent thermal shock resistance. However, it has a lower maximum service temperature (around 1200°C) and is less durable than SiC or alumina. It is commonly used in traditional ceramic firing.

• Mullite Kiln Furniture: Mullite combines good thermal shock resistance with high-temperature stability (up to 1600°C). It is chemically inert and widely used in both oxidizing and reducing atmospheres.

2. Key Properties of Kiln Furniture

To perform effectively in the kiln, refractory kiln furniture must possess several critical properties:

• High-Temperature Resistance: The material must maintain structural integrity at firing temperatures (typically 1100–1400°C for ceramics).

• Thermal Shock Resistance: Rapid heating and cooling cycles can cause cracking, so the material must withstand thermal stress.

• Mechanical Strength: Kiln furniture must support the weight of multiple ceramic pieces without deformation or breakage.

• Chemical Inertness: It should not react with ceramic glazes or kiln atmospheres (oxidizing or reducing).

• Low Thermal Expansion: Minimizing expansion prevents warping and cracking during temperature changes.

3. Functions of Kiln Furniture in the Firing Process

Kiln furniture serves multiple essential functions during ceramic tableware production:

• Support and Stacking: Shelves, posts, and setters hold ceramic pieces in place, allowing efficient use of kiln space.

• Separation and Protection: Spacers and batts prevent ware from sticking together and protect glazed surfaces from damage.

• Heat Distribution: Properly designed kiln furniture ensures uniform heat transfer, reducing firing defects like warping or uneven sintering.

• Durability and Reusability: High-quality kiln furniture can endure multiple firing cycles, reducing production costs over time.

4. Challenges and Innovations

Despite their critical role, kiln furniture faces challenges such as thermal fatigue, contamination risks, and high costs. Recent advancements include:

• Composite Materials: Combining SiC with alumina or mullite improves strength and thermal shock resistance.

• 3D-Printed Kiln Furniture: Additive manufacturing allows customized designs for complex ceramic shapes.

• Coatings and Treatments: Protective coatings reduce wear and extend the lifespan of kiln furniture.

Conclusion

Refractory kiln furniture is a vital component in ceramic tableware production, ensuring efficient and high-quality firing. The choice of material depends on firing conditions, cost considerations, and required performance. As ceramic manufacturing evolves, innovations in kiln furniture will continue to enhance efficiency and sustainability in the industry.