How to distinguish the quality of a magnesia-alumina crucible tube?

Muffle furnace alumina tubes are high-temperature electrical equipment with two points to note. They are generally used to generate temperatures above 300℃, with normal operating temperatures reaching 800-1000℃, or even 1800℃. As commonly used heating instruments, they are frequently found in laboratories, testing rooms, and factory workshops. Many manufacturers offer alumina crucibles, with a wide variety of products available. Choosing a suitable one is not easy! It requires considering general indicators and then personalized needs.

What indicators should generally be considered? Below are some references on muffle furnace alumina tubes provided by the editor.

Muffle furnace alumina tubes are high-temperature electrical appliances used to generate temperatures above 300℃. They typically generate 800-1000℃, or even 1800℃. We feel the heat at 60°C and it becomes painful at 80°C, so burns should be avoided when using faulty equipment.

Most muffle furnace alumina tubes still use a single-shell structure, where the iron shell directly wraps the furnace lining.

Used to measure temperatures in Celsius. This type of equipment is commonly used in research institutions and features simple operation and reliable stability. This equipment usually issues an alarm when problems occur. Let's discuss frequently occurring malfunctions.

1. Overtemperature. As equipment providing a working environment, it has strict constant temperature requirements. These requirements should vary depending on the properties of the experimental materials. If the control fails and cannot maintain the set constant temperature, it will damage the materials and the box-type resistor.

2. Timing prompt. It can be used for sintering, heating, and heat treatment in coal, power, chemical, building materials, research institutes, and colleges and universities. Based on the heating time of the experimental materials, the required constant temperature time is set, automatically controlled, and time prompts are given. The constant temperature is stopped simultaneously, and natural cooling occurs, eliminating the need for dedicated personnel monitoring, thus improving work efficiency. Therefore, a timing device should be included to improve work efficiency.

3. Malfunction. Controlled by a temperature controller to achieve setting, heating, and constant temperature. Data is collected by a sensor. If damaged, it will lead to inaccurate collection, resulting in experimental failure and equipment damage. Therefore, an alarm device should be equipped to ensure safety.

4. New or long-unused tubes should be baked at 300-400℃ for 5-6 hours to remove moisture, which can prolong their lifespan. Water is a major cause of breakage.

5. Maintain continuous cleanliness inside the furnace. The furnace tube should not contain any residual substances that react with Al2O3. When burning materials, to extend the lifespan, do not place materials directly on the tube; use a boat-shaped crucible.

6. When heating, be sure to place alumina plugs, two on each side, for a total of four. The distance between the inner ends of the plugs on both sides is approximately 360 mm. If plugs are not used, the temperature at both ends will be higher, and the O-rings in the flange cannot withstand the higher temperature, resulting in reduced airtightness. Plugging both ends will help create a balanced temperature field.