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In the realm of industrial furnaces, the frequent start - stop cycles pose significant challenges to the refractory materials lining these high - temperature devices. This article delves deep into the failure mechanisms of refractory materials under such conditions and presents effective anti - thermal shock design strategies. Particular attention is given to the high - alumina insulating bricks, analyzing their microstructures and outstanding performance in high - temperature equipment.
To understand the anti - thermal shock performance of refractory materials, it is essential to start from the scientific principles. The internal stress and fracture mechanism of the materials play a crucial role. When an industrial furnace starts and stops frequently, the refractory materials experience rapid temperature changes, which generate internal stress. If this stress exceeds the material's strength, fractures occur.
Let's compare the microstructural changes and physical properties of high - alumina bricks, clay bricks, and corundum bricks under repeated thermal cycles. Clay bricks, for example, have relatively poor thermal shock resistance. During repeated heating and cooling, their microstructures may break down, leading to a decrease in strength. Corundum bricks, on the other hand, have high hardness but may be brittle under thermal shock. High - alumina bricks, however, strike a good balance.
| Material | Thermal Expansion Coefficient (×10⁻⁶/°C) | Fracture Toughness (MPa·m¹/²) |
|---|---|---|
| High - Alumina Bricks | 4 - 6 | 2 - 3 |
| Clay Bricks | 6 - 8 | 1 - 2 |
| Corundum Bricks | 7 - 9 | 1 - 1.5 |
The composite structure of high - alumina insulating bricks, consisting of mullite/corundum + glass phase, is the key to their excellent performance. This structure results in low thermal expansion and high toughness. The mullite and corundum phases provide strength, while the glass phase can absorb energy and prevent crack propagation. As a result, the risk of crack expansion is significantly reduced.
In high - frequency start - stop industrial furnaces such as electric arc furnaces and annealing furnaces, the selection of refractory materials is crucial. For these applications, high - alumina insulating bricks are often a preferred choice. Based on practical cases, when selecting high - alumina bricks, parameters such as alumina content (usually above 70%), thermal conductivity (less than 1 W/(m·K) at high temperatures), and refractoriness under load (above 1600°C) should be considered.
Our company's high - alumina insulating bricks have been widely used in various industrial furnaces. In an electric arc furnace project, after replacing the original clay bricks with our high - alumina insulating bricks, the furnace's energy consumption was reduced by 15%, and the service life was extended by 20%. These results demonstrate the reliability and effectiveness of our products.
If you are facing challenges in selecting refractory materials for your high - temperature equipment, don't hesitate to explore our high - alumina insulating bricks. They can provide you with a reliable solution to withstand thermal shock and ensure the stable and efficient operation of your industrial furnaces. Click here to learn more about our high - alumina insulating bricks.
