Classification of Refractory Materials by Refractoriness, Shape, Composition, Properties, and Density

Classification of Refractory Materials

Refractory materials can be classified in various ways, primarily based on refractoriness, shape, chemical composition, chemical properties, and bulk density, as detailed below:

Classification by Refractoriness:

1. Ordinary refractory materials, with a refractoriness of 1580~1770°C;
2. High-grade refractory materials, with a refractoriness of 1770~2000°C;
3. Super-grade refractory materials, with a refractoriness above 2000°C.

Classification by Product Shape:

1. Shaped refractory products (further divided into standard bricks, special-shaped bricks, and custom-shaped products);
2. Unshaped refractory materials (such as refractory concrete, plastic refractories, refractory fibers, etc.).

Classification by Chemical and Mineral Composition:

1. Silica-based products
   • Silica bricks, containing not less than 93% SiO₂;
   • Quartz glass products, containing more than 93% SiO₂.
2. Aluminosilicate products (classified by SiO₂ and Al₂O₃ content)
   • Semi-silica bricks, containing more than 65% SiO₂ and less than 30% Al₂O₃;
   • Fireclay bricks, containing 30%~48% Al₂O₃;
   • High-alumina bricks, containing more than 48% Al₂O₃;
   • High-purity alumina products, such as corundum bricks and corundum-mullite bricks.
3. Magnesia-based products
   • Magnesia bricks, containing more than 85% MgO and less than 3.5% CaO;
   • Magnesia-alumina bricks, containing more than 80% MgO and 5%~10% Al₂O₃;
   • Magnesia-chrome bricks, containing more than 48% MgO and more than 8% Cr₂O₃;
   • Dolomite bricks, containing more than 40% CaO and more than 30% MgO;
   • Magnesia-silica bricks, containing more than 82% MgO, more than 11% SiO₂, and not more than 2.5% CaO;
   • Magnesia-carbon bricks, containing more than 70% MgO and more than 14% C.
4. Chrome-based products, containing approximately 30% Cr₂O₃.
5. Carbon-based refractory materials, containing 20%~70% graphite carbon or 70%~90% coke carbon.
6. Other high-grade refractory materials, including zirconia-based materials (ZrO₂, SiO₂), carbides (zirconium, hafnium, tungsten, etc.), and nitrides (titanium, zirconium, tantalum, etc.).

Classification by Chemical Properties:

1. Acidic refractory bricks, primarily composed of SiO₂, susceptible to attack by basic slags, such as silica bricks;
2. Basic refractory bricks, primarily composed of MgO and CaO, susceptible to attack by acidic slags, such as magnesia bricks;
3. Neutral refractory bricks, resistant to both acidic and basic slags, such as magnesia-chrome bricks.

Classification by Bulk Density:

1. Dense refractory bricks, with a bulk density of 2.2~2.75 g/cm³;
2. Lightweight refractory bricks, with a bulk density of 0.4~1.3 g/cm³;
3. Ultra-lightweight bricks, with a bulk density of 0.3~0.4 g/cm³, suitable for insulation purposes.