1.Introduction

2.Muffle Furnace

3.Application scope

4.Maintenance and precautions

5.Development History

1.Introduction:

Muffle furnace, also known as box type resistance furnace or high-temperature muffle furnace, is a universal heating equipment that can be divided into box type furnace, tube type furnace, and crucible furnace. There are domestic muffle furnaces and imported muffle furnaces (such as American muffle furnaces and German muffle furnaces).

Muffle furnace is a translation from English. Muffle means package, and furniture means furnace. The common names for muffle furnaces in China are as follows: electric furnace, resistance furnace, muffle furnace, and muffle furnace. A muffle furnace is a universal heating device. According to its appearance, it can be divided into box type furnace tube type furnace crucible furnace.

2.Muffle furnace:

The muffle furnace is a periodic operation type, used for element analysis and determination in laboratories, industrial and mining enterprises, and scientific research institutions, as well as for heating during quenching, annealing, tempering, and other heat treatments of general small steel parts. High temperature muffle furnaces can also be used for high-temperature heating such as sintering, dissolution, and analysis of metals and ceramics.

3.Application scope:

(1) In the industries of thermal processing, cement, and building materials, carry out thermal processing or treatment of small workpieces.

⑵ Pharmaceutical industry: used for drug inspection, pre-treatment of medical samples, etc.

⑶ Analytical chemistry industry: used for sample processing in water quality analysis, environmental analysis, and other fields. It can also be used for petroleum and its analysis.

Coal quality analysis: used to determine moisture, ash, volatile matter, ash melting point analysis, ash composition analysis, and elemental analysis. It can also be improved by adding chimneys as ashing furnaces.

4.Maintenance and precautions

1. When the muffle furnace is used for the first time or is used again after long-term shutdown, it must be dried. The oven drying time should be at room temperature of 200 ℃ for four hours. 200 ℃ to 600 ℃ for four hours. When in use, the maximum furnace temperature should not exceed the rated temperature to avoid burning out the electric heating element. It is prohibited to inject various liquids and easily soluble metals into the furnace. It is best for the muffle furnace to operate below the maximum temperature of 50 ℃, as the furnace wire has a longer lifespan.

2. The muffle furnace and controller must operate in a place with a relative humidity not exceeding 85%, free from conductive dust, explosive gases, or corrosive gases. When metal materials containing grease or other substances need to be heated, a large amount of volatile gases will affect and corrode the surface of the electric heating element, causing it to be destroyed and shorten its lifespan. Therefore, during heating, timely prevention and proper sealing of containers or appropriate opening of holes should be carried out for elimination.

3. The muffle furnace controller should be limited to use within the ambient temperature range of 0-40 ℃.

4. According to technical requirements, regularly check whether the wiring of the electric furnace and controller is in good condition, whether the pointer of the indicator is stuck or stuck during movement, and use a potential difference meter to calibrate the increase in error caused by magnetic steel, demagnetization, wire expansion, fatigue of spring, and balance damage of the instrument.

5. Do not pull out the thermocouple suddenly at high temperatures to prevent the jacket from exploding.

6. Regularly keep the furnace clean and promptly remove oxides and other substances from the furnace.

7. It is prohibited to inject various liquids and easily melted metals into the furnace. When heating metal materials with oily substances, a large amount of volatile gases will affect and corrode the surface of the electric heating element, causing it to burn out and shorten its lifespan. Therefore, when heating metal materials with oily substances, sealing work of the metal materials should be done well.

8. Regular checks should be conducted to ensure that the wiring connections are in good condition.

5.Development History

In the past, small muffle furnaces were usually used for secondary firing of porcelain at lower temperatures to fix the glaze, because most of the enamel pigments used in the main body and glaze of porcelain needed to change color at high temperatures. The painted enamel on metals that we are familiar with also needs to be baked in a muffle furnace.

Nowadays, as a universal front box kiln, muffle furnaces are commonly used for high-temperature applications such as welding glass, making enamel coatings, ceramics, welding, and brazing products. In the process of making ceramics, muffle furnaces are often used for overglaze decoration, so their temperature is usually relatively low. Muffle furnaces are also used in many research facilities, such as chemical researchers using them to determine the proportion of non combustible and non volatile components in a sample. At present, some muffle furnaces have implemented programmable digital controllers that can automatically perform tilting, soaking, and sintering steps. In addition, with the advancement of heating element materials such as molybdenum disilicate, modern muffle furnaces can generate operating temperatures up to 1800 degrees Celsius (3272 degrees Fahrenheit), which will be beneficial for more complex metallurgical applications.