In extreme environments characterized by ultra-high temperatures and strong corrosion—such as glass tank furnaces, steel continuous casting, and precious metal smelting—traditional refractory materials often fall short. Zirconia bricks , leveraging their extremely high melting point, superior corrosion resistance, and outstanding thermal stability, have become the ultimate choice for critical components in super-high-temperature industrial kilns.

What are Zirconia Bricks?

Zirconia bricks are high-performance refractory materials primarily composed of zirconium oxide (ZrO₂). With a melting point reaching 2650-2700℃, zirconia remains stable in both oxidizing and reducing atmospheres and exhibits strong resistance to erosion by various molten metals and slags. However, pure zirconia undergoes a phase transformation at high temperatures leading to volume instability. Therefore, commercial products typically incorporate stabilizers such as CaO, MgO, or Y₂O₃ to form partially stabilized or fully stabilized zirconia.

Core Performance Characteristics

• Ultra-High Refractoriness: Service temperatures can reach approximately 2500℃, demonstrating exceptional performance in glass environments containing sodium, boron, lead, or fluorine.
• Superior Corrosion Resistance: Exhibits high chemical inertness against glass melts, molten metals, and acid/alkali slags; difficult to wet by liquid metals.
• Excellent High-Temperature Strength: Capable of withstanding a 200kPa load for 0.5-1 hour at 2000℃ without deformation; creep resistance is far superior to ordinary refractories.
• Good Thermal Shock Resistance: Low coefficient of thermal expansion (approx. 4.2×10⁻⁶/℃ from 20-1000℃), allowing it to withstand certain temperature fluctuations.
• High Density: Fused cast products can achieve an apparent porosity as low as 0%-1%, effectively blocking melt penetration.

Main Types of Zirconia Bricks

• Fused Cast Zirconia Bricks: Melted in a three-phase electric arc furnace and cast into molds. With extremely low porosity and strong corrosion resistance, they are suitable for critical areas like glass tank furnace walls, crowns, and throat areas.
• Zircon Bricks: Made from natural zircon (ZrSiO₄) with a ZrO₂ content of approximately 65%. They offer excellent thermal stability and shock resistance, used for regenerators (checkerwork) in glass furnaces and ladle linings in metallurgy.
• Zircon-Mullite Bricks: A composite of zircon and mullite, combining structural strength with thermal shock resistance. Suitable for ceramic kiln linings and upper structures of glass furnaces in medium-to-high temperature scenarios.
• Zirconia Hollow Sphere Bricks: Sintered at high temperatures using fused zirconia sand. They feature low bulk density and excellent insulation properties, ideal for insulating layers in super-high-temperature kilns.

Key Application Areas

• Glass Industry: Used for tank walls, crowns, throats, regenerator checkerwork, and fiberglass furnaces. They resist glass liquid erosion intensely without contaminating glass quality.
• Iron & Steel Metallurgy: Applied in continuous casting定径水口 (fixed nozzle), long nozzle slag lines, and sliding gate linings. They resist high-temperature steel erosion and thermal shock, ensuring steel purity.
• Precious/Rare Metal Smelting: Used for induction furnace linings, melting crucibles, and special alloy smelting equipment. Capable of withstanding temperatures ≥2600℃ with high chemical inertness.
• Special Ceramics & Electronics: Utilized in semiconductor equipment parts, electronic kiln high-temperature linings, and laser crystal furnaces due to acid/alkali resistance and high insulation.
• Petrochemical Industry: Used in high-temperature chemical reactors and gasifier linings, offering resistance to reducing atmospheres and chemical erosion.
• Research & Military: Applied in ultra-high-temperature experimental furnaces, oxygen probes, and thermal barrier coatings for extreme conditions.

Key Technical Parameters

• ZrO₂ Content: 65%-99% (High purity products ≥95%)
• Refractoriness: ≥1825℃ (Premium products can exceed 2600℃)
• Bulk Density: 3.6-5.8 g/cm³ (Fused cast products can reach >5.8)
• Apparent Porosity: 0%-18% (Fused cast products ≤1%)
• Cold Crushing Strength: ≥100 MPa (Premium products can reach 310 MPa)
• Refractoriness Under Load (0.2MPa): ≥1630℃ (Premium products ≥1680℃)
• Thermal Expansion Coefficient (20-1000℃): Approx. 4.2×10⁻⁶/℃

With its ultra-high refractoriness, excellent corrosion resistance, and thermal stability, zirconia bricks occupy an irreplaceable position in high-end sectors like glass, steel, precious metal smelting, and special ceramics. Correct selection and usage can significantly extend kiln life, improve product quality, and reduce overall costs.