Which is better, high alumina refractory bricks or clay bricks?

In the field of refractory materials, high alumina refractory bricks and clay bricks are two common products. Many customers often ask when choosing, which one is better? The answer to this question is not absolute, but depends on the specific usage conditions and cost budget.

1.Core difference: Al₂O₃ content determines the starting point

The Al₂O₃ content of high alumina bricks is ≥48%, while that of clay bricks is around 30%.

Simply put, for every 10% increase in Al₂O₃, the load softening temperature increases by approximately 60–80°C. Therefore, for bricks of the same shape, high-alumina bricks can be the first to obtain the “high-temperature pass”.

2.Advantages and application scenarios of high alumina bricks

In the tunnel kiln and rotary kiln firing zone with a temperature of >1250℃, the load softening temperature of high alumina bricks (≥1450℃) directly surpasses that of clay bricks (≥1250℃).

In addition, high alumina bricks have low creep rate and good flexural strength retention rate. When the kiln is kept warm for a long time, the deformation of the furnace lining is small.

However, its thermal conductivity is 20–30% higher than clay bricks. Therefore, if the heat recovery of the furnace is not good, the energy consumption will increase slightly.

Furthermore, the cost of raw materials increases linearly with the Al₂O₃ content. Therefore, in the medium and low temperature range, the “performance margin” of high alumina bricks becomes a budget burden.

At the same time, its excellent performance also means relatively higher manufacturing costs and purchase prices, which is an economic factor that must be considered when making a choice.

3.Economic efficiency and traditional applications of clay bricks

Although the performance of clay bricks is inferior to that of high-alumina refractory bricks, they are fully capable of meeting the requirements of working conditions with low temperature requirements and weak chemical corrosion.

For example, clay bricks are widely used in the furnace walls of blast furnaces, hot blast furnaces and other kilns, as well as in the insulation layer of kilns or the working layer that is not in direct contact with flames.

At the same time, the apparent porosity of clay bricks is generally higher than that of high alumina bricks. The elastic modulus is low, but the residual strength retention rate after 100 thermal shock cycles is slightly better.In other words, when the temperature requirement is not high, clay bricks can complete the task by using the two advantages of “cheap + resistance to sudden cooling”.

However, its performance shortcomings will become apparent when faced with ultra-high temperature or strong chemical corrosion environments. At this time, it is necessary to upgrade to high-alumina bricks or other more advanced refractory materials, such as silica bricks or magnesia-carbon refractory bricks.

In short, there is no absolute distinction between the two types of refractory bricks in terms of superiority or inferiority, but each has its own applicable “battlefield”.

Choosing which refractory brick to use requires a comprehensive assessment of the kiln operating conditions and the overall budget. Therefore, a reliable supplier is also crucial.

Henan Ruitai Lianxin Refractory Materials Co., Ltd. has been focusing on refractory materials for 20 years. It not only provides high-quality refractory bricks of qualified quality, but also provides customers with the most suitable kiln working condition solutions based on professional knowledge. Choosing Ruitai Lianxin means choosing strength.