Graphite stickThe electric heater commonly used in high-temperature vacuum furnaces can be used up to 3000 ℃, which is easy to oxidize at high temperatures. Except for vacuum, it can only be used in neutral atmosphere or reducing atmosphere. Then, how to use the graphite rod and heating tube of the vacuum furnace? Let's share with you:

1. Select graphite rod with good red heat uniformity at the heating part. The poor uniformity of red heat of the rod will affect the uniformity of furnace temperature and shorten the service life of the rod. In the process of use, the red heat uniformity of the rod will gradually deteriorate, and in serious cases, the rod will be broken.

2. The service life of the graphite rod will be shorter with the use of higher temperature. Especially after the surface temperature of the rod exceeds 1500 ° C, the oxidation speed will be accelerated and the service life will be shortened. Please try not to let the surface temperature of the graphite rod be too high during use.

3. After the graphite rod is heated in the air, a dense silicon oxide film is formed on the surface, which becomes an antioxidant protective film and plays a role in prolonging the service life. Intermittent use, with the furnace temperature

The rise and fall of the degree will lead to the rupture of the protective film on the surface of the rod, the weakening of the protective effect, and the increase of the resistance value of the accelerating rod. In order to ensure the stable temperature of the kiln and meet the demand of rapid temperature rise, the supporting electrical control system should have sufficient voltage adjustment margin - that is, when the new rod is used, it can meet the design and use power of the kiln at a lower voltage; As the use time goes on, the resistance value of the rod becomes larger. At this time, the use voltage needs to be increased accordingly to meet the design and use power of the kiln.

Voltage margin value: the voltage of the graphite rod at the later stage of use is generally 1.5-1.7 times that of the new rod. According to the Xiaobian of Henan graphite rotor, the upper limit of voltage in the later stage is generally 220V or 380V according to the voltage regulation mode and wiring mode.

Graphite stickPower adjustment mode: Xiaobian of Henan graphite rotor suggests adjusting the power by adjusting the voltage. It is recommended to select silicon controlled voltage regulator or voltage regulator for voltage regulation of graphite rod. Generally, it is not adjusted by changing the power regulator of the cycle number.

4. When graphite rods are used continuously, it is desirable to increase the voltage slowly to maintain a long life.

5. Graphite rods shall be connected in parallel as much as possible. If the resistance values of the graphite rods are different, the load of the graphite rods with high resistance in series is concentrated, resulting in a rapid increase in the resistance of a certain graphite rod and a shorter life. At the same time, it is necessary to strengthen the grouping of resistance values, that is, the resistance values of the same group of bars should be as close as possible. Generally, the resistance value deviation of the same group of rods in parallel is within 10% - 15%, and the resistance value deviation of the same group of rods in series is within 5% - 10%. The higher the furnace temperature, the smaller the required resistance deviation.

6. In general,Graphite stickThe surface load density is obtained from the relationship between the temperature in the furnace and the surface temperature of the graphite rod. It is recommended to use the power of 1 / 2-1 / 3 of the maximum surface load density of the graphite rod. The higher the current applied to the graphite rod, the higher the surface temperature of the graphite rod. It is recommended to use the surface load density (power) as small as possible. Please note that the value recorded at the cold end of the graphite rod is the current and voltage measured in the range of 1050 ℃ + - 50 ℃ in the air, which may not be consistent with the actual use.