Properties Of Silica Bricks

The core characteristics of silica bricks are their excellent high-temperature volume stability and high refractoriness, making them a key refractory material for high-temperature industrial applications above 1500℃. However, they also have limitations, such as relatively low strength at room temperature.

I. Core Advantages and Characteristics

High Refractoriness and Load Softening Temperature: Silica bricks have a refractoriness of 1690-1730℃, and their load softening onset temperature is typically above 1620-1650℃, far exceeding that of ordinary clay bricks and high-alumina bricks. They can operate stably for extended periods in high-temperature environments around 1500℃.

Good High-Temperature Volume Stability: At high temperatures, silica bricks slowly undergo the transformation from tridymite to cristobalite. This process involves uniform and pre-controllable volume changes, preventing cracking due to rapid expansion or contraction and ensuring the integrity of the kiln lining.

Low thermal conductivity that decreases with increasing temperature: Silica bricks have low thermal conductivity at room temperature. This effectively reduces heat loss from the kiln interior, improving energy efficiency and reducing energy consumption in industrial production.

Good thermal shock resistance: In industrial kilns with slow heating and cooling (such as coke ovens), silica bricks can withstand the stress caused by temperature fluctuations. However, their thermal shock resistance decreases under conditions of rapid heating and cooling, and such conditions should be avoided.

II. Main limitations:

Low strength at room temperature: Silica bricks have low compressive and flexural strength at room temperature, making them prone to damage from collisions and compression during handling and installation. Special care must be taken to protect them during construction.

Poor resistance to alkaline corrosion: The main component of silica bricks is SiO₂, which reacts chemically with alkaline substances to form low-melting-point substances, leading to structural damage. Therefore, they are not suitable for use in kilns with a strong alkaline atmosphere.

Silicon bricks are prone to absorbing moisture at low temperatures. If the ambient humidity is high during storage, the surface of the bricks will easily absorb moisture. When used at low temperatures, the moisture may evaporate and cause cracks. Therefore, they need to be stored in a dry environment and preheated.