Performance Classification and Application Effects of High-aluminum Refractory Materials

Sintered high alumina bricks are the main member of the aluminosilicate refractory family. Aluminosilicate materials are divided into the following four categories based on their alumina content.

1. Semi-siliceous refractory material: alumina content 15% to 30%.

2. Clay refractory materials: alumina content 30% to 48%.

3. High-aluminum refractory materials: alumina content 48% to 89%.

4. Corundum refractory material: alumina content ≥90%.

The physical and chemical properties of high-aluminum refractory materials generally depend on the ratio of Al2O3/SiO2, the content of impurities, the density of raw materials, the particle size distribution of bricks, the type and amount of binders, and the conditions of mixing, molding, and sintering. For special high alumina bricks, the type, grade, particle size, and content of special refractory raw materials determine the mineral composition, microstructure, and destruction mechanism of the refractory materials, affecting the physical and chemical properties and application effects of the refractory materials.

Ordinary high alumina bricks have good high-temperature resistance, but poor thermal shock resistance.

In the 1970s, the China Building Materials Research Institute developed phosphate-bonded high-alumina bricks (hereinafter referred to as phosphate bricks), which solved the problem of poor thermal shock resistance of high-alumina bricks. However, phosphate bricks have poor high-temperature resistance. In the future, the development of high temperature-resistant and thermal shock-resistant materials has become the development direction of high aluminum refractory materials.

In the 1980s, the China Building Materials Research Institute developed zircon-bonded anti-flaking high-alumina bricks. Since then, the China Building Materials Research Institute has developed lightweight high-alumina bricks by reducing the amount of phosphoric acid and adding “three stones”. Kyanite bricks were developed by Luoyang Refractory Materials Research Institute using high-temperature firing and the “three-stone” process.

In the 1990s, the China Building Materials Research Institute developed second-generation anti-flaking bricks, and some refractory companies also developed silicon carbide bricks by adding silicon carbide. At present, sintered high alumina bricks for cement kilns are mainly composed of silica fume bricks and anti-stripping bricks. It should be pointed out in particular that anti-flaking bricks and silicon special-shaped bricks are new products independently invented by our country’s refractory materials scientists.