How to Choose Corundum Bricks?

When selecting corundum bricks, focus on the application scenario, focusing on four core dimensions: composition, performance indicators, appearance, and production process, to ensure they are suitable for specific working conditions.

1. Prioritize the Core Application Scenario

The performance requirements for corundum bricks vary significantly across different applications, making this the primary consideration when selecting.

For high-temperature kilns: Focus on refractoriness and corrosion resistance. Choose bricks with a high refractoriness under load temperature and the ability to withstand erosion from molten glass or kiln slag.

For wear-resistant applications: Prioritize room-temperature compressive strength and bulk density. The higher the strength and the denser the structure, the better the wear resistance.

For environments with large temperature fluctuations: Additional consideration should be given to thermal shock resistance. Choose corundum bricks with modified ingredients such as Cr₂O₃ to prevent cracking due to sudden temperature changes.

2. Key Performance Indicator Verification

Performance indicators directly determine the effectiveness of corundum bricks. Suppliers should be requested to provide test reports and focus on the following:

Alumina (Al₂O₃) content: This is a core indicator of corundum bricks. Higher Al₂O₃ content (e.g., 95% or 99% corundum bricks) increases refractoriness, strength, and chemical stability, but also increases the price. The appropriate content should be selected based on the application conditions to avoid excessively high content, which can lead to costly waste.

Bulk density: Required to be ≥3.6 g/cm³. Higher density indicates a denser brick, greater resistance to corrosion and wear, and higher thermal conductivity.

Room-temperature compressive strength: Standard sintered corundum bricks require ≥70 MPa, while fused corundum bricks require ≥150 MPa. Insufficient strength can lead to breakage during installation or use.

Softening under load temperature (T0.6): Required to be ≥1700°C. Higher temperatures increase the brick’s resistance to deformation under high-temperature loads, making it suitable for ultra-high-temperature environments. Thermal shock stability: Measured by the number of water cooling cycles, e.g., 1100°C water cooling cycles ≥10 times. A higher number indicates better crack resistance under temperature fluctuations. The selection should be based on the operating temperature range.

3. Appearance and Dimension Inspection

Appearance directly reflects the level of production process quality, ensuring that cosmetic defects do not affect performance.

Surface Quality: The surface should be smooth and flat, free of visible cracks, chipped corners, bulges, or impurities. Cracks present may rapidly expand under high temperatures, causing brick failure.

Dimensional Deviation: Measure length, width, and height using a tape measure or caliper. Deviations must meet industry standards (e.g., length deviation ≤ ±1mm). Irregular dimensions can result in excessive masonry gaps, compromising kiln sealing.

4. Verify Production Process and Supplier

The production process determines the inherent quality of corundum bricks, and the supplier’s qualifications influence after-sales service.

Supplier Selection: Prioritize qualified and reputable manufacturers. Require product certificates and test reports. If necessary, conduct on-site inspections of the production process to avoid purchasing inferior products.