Andalusite Castable Material for Glass Kiln

Andalusite Castable Material for Glass Kiln

Andalusite castable is an amorphous refractory material made of andalusite as the main raw material. It has the characteristics of good slag resistance and thermal shock resistance. The linear change rate is smaller at high temperature, which can make the volume of the castable more stable. It has strong oxidation resistance. The glass phase produced by the decomposition of andalusite can fill the pores, hinder the entry of oxygen, and reduce the porosity. As the particle size of andalusite aggregate decreases and the sintering temperature increases, the oxidation resistance is enhanced. In addition, andalusite aggregate can improve the high-temperature strength of the castable, and the secondary mullite produced by decomposition can promote the combination of aggregate and other raw materials, further improving the medium and high temperature strength.

The specific performance parameters of andalusite castable are as follows:

Room temperature performance: The apparent porosity is low, generally lower than that of high-alumina castables, and the volume density is relatively high. Its room temperature compressive strength and room temperature flexural strength vary due to the formula and preparation process, but can usually meet the requirements of conventional use.

Heating line change rate: After heat treatment at 1300℃ for 3h, the andalusite castable and andalusite-high-alumina castable will expand in volume due to the mulliteization of andalusite, while the high-alumina castable will shrink significantly; after heat treatment at 1500℃ for 3h, all samples show expansion, and the expansion of andalusite castable is relatively large , which helps to offset the volume shrinkage of the castable during long-term use at high temperature, showing good volume stability.

Creep resistance: Andalusite castables and castables containing andalusite have strong creep resistance, among which andalusite castables have the best high-temperature creep resistance. For example, the compressive creep rate of andalusite castables at 1300℃ for 25h can be as low as -0.06%, which is much better than -1.93% of high-alumina castables.

High-temperature strength: The high-temperature flexural strength of andalusite castables is good, and increases with the increase of andalusite addition. For example, at 1300℃, its high-temperature flexural strength is higher than that of high-alumina castables. This is because the structure formed by andalusite mullite strengthens the matrix bonding, and the secondary mullite generated at the same time makes the interior tighter.

Thermal shock resistance: Andalusite castables and their composite castables have more thermal shock times, generally more than 65 times, which is better than the 47 times of high-alumina castables. This is because the linear expansion coefficient of andalusite is smaller than that of high-alumina bauxite, the thermal stress generated during thermal shock is smaller, and the structure is more stable.

Thermal conductivity: The thermal conductivity of andalusite castable at 1000℃ is about 1.8 W·m⁻¹·K⁻¹, which is lower than the 2.2 W·m⁻¹·K⁻¹ of high-alumina bauxite castable. It can reduce heat loss when used as kiln lining.

Antioxidation: The oxide layer of andalusite aggregate is thin, and the glass phase produced by its decomposition can fill the pores, hinder the entry of oxygen, reduce the porosity, and enhance the antioxidation performance. As the particle size of andalusite aggregate decreases and the sintering temperature increases, the antioxidation performance will be further enhanced.

Product Parameters