The calcination temperature of Molai powder needs to be adjusted according to the specific production process and raw material characteristics. The following are the calcination temperature ranges and suggestions in different research and practice:

I. General calcination temperature range

The calcination temperature of Molai powder is usually between **1100℃ and 1500℃**. This temperature range can ensure the full formation of mullite phase and avoid melting or structural damage caused by excessive temperature.

II. Optimum calcination temperature

Studies have shown that in the temperature range of **1200℃ to 1300℃**, the crystallinity of mullite is high, and the mullite phase formed is relatively pure.

Another study pointed out that when the calcination temperature is **1175℃**, the mullite phenomenon is obvious and the crystallinity is good.

For some special production processes, such as preparing mullite from fly ash, the calcination temperature can be as low as 1150℃.

III. Effect of calcination temperature on properties

In the temperature range of **1250℃ to 1400℃**, a large number of mullite crystals are formed, but they have not grown sufficiently. At this time, the shrinkage and properties of the green body are relatively stable.

When the temperature is further raised to 1400℃ to 1500℃, mullite crystals grow rapidly, which may lead to loose bodies and lower strength.

IV. Suggestions in actual production

In actual production, the calcination temperature should be adjusted according to the specific use and quality requirements of Molai powder. For example, Molybdenum powder used in precision casting may require higher calcination temperature to ensure fire resistance and strength.

For raw materials with high kaolinite content, the calcination temperature can be controlled between **1100℃ and 1300℃** to ensure the formation of mullite phase.

To sum up, the calcination temperature of Molai powder should be optimized according to the raw material composition, production technology and final product requirements. It is generally recommended to calcine at **1200℃ to 1300℃** to obtain ideal mullite phase and product properties.