How to Choose Refractory Materials for High-Frequency Start-Stop Industrial Furnaces? Analysis of Thermal Shock Resistance as a Key Indicator

Sunrise

2025-11-14

Technical knowledge

High-frequency start-stop industrial furnaces pose severe challenges to the thermal shock resistance of refractory materials. This article delves deep into the physical mechanism of thermal shock resistance, compares the structural stability differences of high-alumina bricks, clay bricks, and corundum bricks under temperature fluctuations, and reveals why the composite structure of mullite or corundum + glass phase can significantly enhance fracture toughness and low thermal expansion performance. Combining typical application scenarios such as electric arc furnaces and annealing furnaces, it provides material selection suggestions with an Al₂O₃ content ≥ 48% and a thermal conductivity < 1.2 W/(m·K). It implicitly recommends the company's high-alumina insulating bricks, which have a long-term service temperature of up to 1650°C, excellent thermal shock resistance, and energy-saving advantages, making them an ideal choice for high-frequency start-stop furnace bodies.

In the industrial landscape, high-frequency start-stop industrial furnaces present a unique set of challenges, especially when it comes to selecting the right refractory materials. The ability of these materials to withstand rapid temperature changes, known as thermal shock resistance, is a critical factor that can significantly impact the performance and longevity of the furnace.

The Principle of Thermal Stress Damage

When an industrial furnace is started and stopped frequently, the refractory materials inside are subjected to extreme temperature fluctuations. This causes thermal stress, which can lead to cracking and spalling of the materials. The principle behind this lies in the fact that different parts of the material expand and contract at different rates during heating and cooling cycles. If the material cannot accommodate these dimensional changes, internal stresses build up, eventually leading to failure.

Performance Comparison of Different Refractory Bricks

Let's take a look at how different types of refractory bricks perform under the repeated heating and cooling cycles typical of high-frequency start-stop furnaces:

Clay Bricks: Clay bricks have relatively low thermal shock resistance. During repeated temperature changes, they tend to crack easily due to their high thermal expansion coefficient. Their structure may also become unstable, leading to a shorter service life in high-frequency start-stop applications.
Ordinary High-Alumina Bricks: These bricks offer better thermal shock resistance compared to clay bricks. However, in extreme temperature fluctuation scenarios, they may still experience some degree of cracking and spalling, especially if the Al₂O₃ content is not optimized.
Corundum Bricks: Corundum bricks have high refractoriness and good thermal shock resistance. But they are often more expensive, and their performance may vary depending on the specific composition and manufacturing process.

In contrast, our company's high-alumina insulating bricks stand out. With an Al₂O₃ content of ≥48% and a thermal conductivity of < 1.2 W/(m·K), they offer excellent thermal shock resistance and energy-saving advantages. Their long-term service temperature can reach 1650°C, making them suitable for a wide range of high-frequency start-stop industrial furnaces.

$Microstructure comparison of different refractory bricks$

Case Studies in Real-World Applications

To better illustrate the importance of thermal shock resistance in high-frequency start-stop furnaces, let's look at some real-world examples:

Application Scenario	Problem	Solution
Steel Mill Electric Arc Furnace	Frequent lining replacement due to cracking and spalling of the refractory materials caused by high-frequency start-stop operations.	Replacing the original refractory bricks with our high-alumina insulating bricks. The excellent thermal shock resistance of these bricks significantly reduced the lining replacement frequency, saving both time and cost.
Ceramic Annealing Furnace	Spalling of the refractory lining due to rapid temperature changes during frequent start-stop cycles, affecting the quality of the ceramic products.	Using our high-alumina insulating bricks as the lining material. The bricks' ability to withstand thermal shock ensured a more stable furnace environment, improving the quality of the ceramic products and reducing production losses.

The Role of Microstructure Design

The microstructure of the refractory material plays a crucial role in enhancing its thermal shock resistance. Our high-alumina insulating bricks feature a composite structure of mullite or corundum + glass phase. This unique structure can significantly improve the fracture toughness and low thermal expansion properties of the material.

The mullite or corundum phase provides high strength and refractoriness, while the glass phase acts as a buffer, absorbing and dissipating the thermal stress generated during temperature changes. This combination allows the material to better withstand rapid temperature fluctuations without cracking or spalling.

Microstructure diagram of high-alumina insulating bricks

Conclusion and Product Recommendation

Selecting the right refractory material for high-frequency start-stop industrial furnaces is a complex decision that requires a deep understanding of the thermal stress damage principle and the performance characteristics of different materials. By considering factors such as thermal shock resistance, Al₂O₃ content, and thermal conductivity, you can make an informed choice that will optimize the performance and longevity of your furnace.

Our company's high-alumina insulating bricks, with their excellent thermal shock resistance, energy-saving advantages, and long-term service temperature of up to 1650°C, are the ideal choice for high-frequency start-stop industrial furnaces. They can help you reduce energy consumption, extend the service life of your furnace, and improve overall production efficiency.

Explore Our High-Alumina Insulating Bricks for Your Furnace Now!