Thermal shock resistance refers to the ability of a sample to resist the effects of rapid temperature changes without being destroyed. It is also known as rapid cooling and heating, temperature change resistance and thermal stability. As we all know, during the use of materials, the temperature rises or falls inevitably, causing them to expand and contract, that is, thermal stress. When the thermal stress exceeds the structural strength of the material itself, cracking or peeling occurs, and even the lining collapses. Therefore, this performance is an important indicator for judging the quality of materials and is also one of the bases for design, material selection and operation.
Thermal shock resistance is closely related to the chemical mineral composition, microstructure, material particles and preparation process, thermal expansion and thermal conductivity of the material, and is also closely related to the organizational structure and strength of the material. For example, generally speaking, the larger the thermal expansion rate of the material, the poorer the thermal shock resistance; the higher the thermal conductivity, the better the thermal shock resistance, and so on. In general, compared with fixed fired products, amorphous refractory materials have better thermal shock resistance. For example, high-alumina phosphate castables have excellent thermal shock resistance.
Thermal shock resistant castables are made of high-quality synthetic materials as the main raw materials, with the addition of high-quality composite binders and ultra-fine powders. The product has the characteristics of excellent thermal shock stability, high refractoriness, and high strength. It can ensure the overall structure of the circulating fluidized bed furnace, and is particularly suitable for harsh environments such as the ignition air duct and water-cooled air chamber of CFB boilers with relatively large temperature fluctuations. The ability to achieve excellent thermal shock stability lies in the fact that zircon decomposes at high temperatures to produce tetragonal zirconium oxide, which transforms into monoclinic zirconium oxide when cooled, that is, the introduction of zircon forms a high-temperature stress-induced phase change toughening mechanism in the matrix, generating microcracks inside the material, thereby improving the material's ability to resist thermal shock losses.
The main physical and chemical properties of TA series castables
|
index/project |
TA-1 |
TA-2 |
|
|
chemical composition % |
AL2O₃ |
≥80 |
≥50 |
|
SiO₂ |
≤20 |
≤25 |
|
|
Bulk density g/cm³ |
110℃×24h |
≥2.80 |
≥2.50 |
|
1000℃×3h |
≥2.80 |
≥2.50 |
|
|
Flexural strength at room temperature Mpa |
110℃×24h |
≥10 |
≥9.0 |
|
1000℃×3h |
>20 |
>16 |
|
|
Normal temperature compressive strength Mpa |
110℃×24h |
≥65 |
≥60 |
|
1000℃×3h |
≥160 |
≥120 |
|
|
Line change rate after burning % |
1000℃×3h |
-0.1 |
-0.2 |
|
Abrasion resistance, according to ASTM (c-704 specification), cm³ |
≥20 |
≥16 |
|
|
High temperature flexural strength, Mpa(1000℃×1h) |
≤5.0 |
≤6.0 |
|
|
Thermal Conductivity, W/m,k |
1.9 |
1.8 |
|
|
Thermal shock stability, times, 1000℃ water cooling |
≥50 |
≥40 |
|
|
Refractoriness ℃ |
≥1770 |
≥1750 |
|
|
Maximum operating temperature ℃ |
≥1550 |
≥1500 |
|
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