Fused chrome corundum bricks are made by melting alumina in an electric arc furnace and casting it into a specified model of a specific shape. The desired product is obtained by annealing and holding, and then by processing with diamond abrasives. The product is divided into 3 types according to the different crystalline forms of alumina in it and the quantity.
Parameters of Kerui Fused Chrome Corundum Bricks
| Плавленые кирпичи из хромового корунда | KR-G92-Cr |
| Al2O3, % | ≥92 |
| SiO2, % | ≤1.0 |
| Fe2O3, % | ≤0.3 |
| CaO, % | ≤1.2 |
| Na2O, % | – |
| ZrO2, % | ≥3 |
| Cr2O3, % | ≥3 |
| Apparent Porosity, % | ≤15 |
| Bulk density, g/cm3 | ≥3.25 |
| Pressure strength, Mpa | ≥180 |
| High temperature flexural strength, 1250℃ Mpa | ≥9.5 |
| Refractoriness, ℃ | ≥1900 |
| Load softening temperature, 0.2Mpa T0.6℃ | ≥1680 |
| Burning line rate of change, %, 1500℃×2h | ≤±1.2 |
The first one has α-Al2O3 as the main crystalline phase and is called α corundum brick.
The second type is dominated by α-Al2O3 and β-Al2O3 crystalline phase, the content is basically 1:1, with slightly higher content of α phase, called α-β corundum brick.
The third one is dominated by β-Al2O3 crystalline phase, called β corundum brick.
Fused α corundum bricks
Fused α corundum brick is a high-grade fused cast refractory with α- Alumina as the main crystalline phase. It is characterized by dense structure, high erosion resistance, high refractoriness and high temperature structural strength, and good high temperature chemical stability. It is an ideal material for glass kilns in the low-temperature zone and metallurgical titanium furnaces. It is mainly used in the cooling pool part and superstructure of glass kilns as well as non-ferrous metal smelting furnaces and high temperature tunnel kilns.
Fused α-β corundum bricks
Fused α-β corundum bricks are made of high purity calcined alumina (more than 95%) and a small amount of admixture, and then put into a three-phase electric arc furnace. The bricks are melted at over 2300°C and cast into a special mold, and then tempered and annealed and removed. The bricks are cold processed, pre-assembled and inspected to meet the customer’s requirements.
Fused α-β corundum bricks are commonly used in light industry, building materials, electronics and other glass furnaces as high-grade electrofused refractories. It has more excellent performance than other materials in terms of resistance to glass liquid erosion, foaming and stone formation, and especially has a crystalline structure that is almost non-polluting to glass liquid. Therefore, it is the preferred refractory material for glass forming parts such as clarification section, working pool, runner and feed channel of glass kilns.
Fused β corundum bricks
Fused β-corundum bricks are characterized by high temperature resistance, high alkali resistance and excellent thermal shock stability. It is a new type of refractory material used in the chest wall, spit noisy and top noisy part of float glass kiln. β-corundum brick is composed of 100% β-alumina, with strong resistance to flaking, especially to strong alkali vapor shows high resistance to erosion, and almost no glass phase, no pollution to molten glass. It can be used in the superstructure part where the glass material is less scattered and its excellent characteristics can be fully developed.
| Item | α-β Alumina | α- Alumina | β- Alumina | |
| Chemical Composition,% | Al2O3 | ≥95 | 98.5 | ≥92 |
| SiO2 | ≤0.5 | 0.4 | ≤0.5 | |
| NaO2 | 3-5 | 0.9 | 5-7 | |
| Other oxides | ≤0.5 | ≤0.2 | ≤0.2 | |
| Bulk density | g/cm3 | 3.54 | 3.94 | 3.26 |
| Cold crushing strength MPa | Mpa | ≥200 | ≥250 | ≥300 |
| Thermal expansion coefficient, 1000℃ | % | 0.7 | 0.88 | 0.65 |
| Thermal expansion coefficient, 1500℃ | % | 1.09 | 1.32 | 1.01 |
| Crystallographic Analysis % | α-Al2O3 | 40-50 | 90-95 | – |
| β-Al2O3 | 50-60 | 4-10 | ＞97.5 |
