Sintered mullite has excellent thermal stability, which is mainly reflected in the following aspects:

I. High fire resistance

The fire resistance of sintered mullite is high, which can reach above 1790℃. Its load softening temperature is between 1600℃ and 1700℃, which means that the sintered mullite can keep its structure stable and is not easy to soften and deform at high temperature.

II. Good thermal shock resistance

Sintered mullite has good thermal shock resistance and can remain stable in frequent temperature changes. This characteristic makes it perform well in high-temperature equipment such as hot blast stoves, and can withstand rapid temperature changes without cracks or damage.

III. Low coefficient of thermal expansion

The thermal expansion coefficient of sintered mullite is low, which makes its volume change little at high temperature, and can effectively reduce the stress caused by thermal expansion. For example, at 800℃, the linear expansion rate of mullite is about 0.4%, and it has non-uniformity of axial expansion, which is helpful to improve the thermal stability of the material.

IV. Low creep value at high temperature

Sintered mullite has a small creep value at high temperature, which means that it can maintain the stability of shape and structure in long-term high temperature use. For example, at 1550℃, the 50-hour high temperature creep rate of sintered mullite is only 0.796%.

V. Low thermal conductivity

Sintered mullite has low thermal conductivity, which can effectively reduce heat transfer, thus improving the heat insulation effect. This feature not only helps to save energy, but also reduces the heat loss of hot blast stoves and other equipment.

VI. Good chemical stability

Sintered mullite has high chemical stability and can resist chemical erosion in high temperature environment. Its impurity content is low, such as iron and alkali metal oxides, so it can maintain good performance in reducing atmosphere.

To sum up, sintered mullite, with its characteristics of high refractoriness, low thermal expansion coefficient, good thermal shock resistance and low thermal conductivity, performs well in high-temperature equipment such as hot stoves and has excellent thermal stability.