What are the characteristics of graphite rotors and the causes of damage?
First, what are the characteristics of graphite rotor compared with other rotors?
1. In aluminum processing industries such as aluminum plate and aluminum foil casting, aluminum alloy wheels, etc., the service life of graphite rotor is as long as 2 months.
2. Rotary refining deaerator can be divided into mobile type and fixed type, which are suitable for different operating environments.
3. The degassing rate is more than 50%, which shortens the smelting time and reduces the production cost.
4. Suitable for crucible furnace, ladle and static box aluminum liquid purification.
5. The surface is treated with oxidation resistance, and the service life is about 5 times that of ordinary products, which is widely used in the aluminum alloy casting industry.
There is a special application in graphite products, that is, graphite rotors. The purification treatment of liquid aluminum alloy is the main means to improve the comprehensive performance of aluminum alloy. In the purification process, the purified gas is mixed with the solvent and the mixture is blown into the aluminum melt through the rotation of the graphite rotor, which is currently the most advanced treatment method in the world.
The graphite rotor rotary nozzle is made of high-purity graphite. In the nozzle structure, in addition to bubble breaking, the centrifugal force generated by stirring the aluminum alloy melt is also used to make the melt enter the nozzle and evenly mix with the horizontally sprayed gas to form a gas/liquid jet, increase the contact area and contact time between the bubble and the aluminum alloy liquid, and improve the degassing and purification effect.
The speed of the graphite rotor can be infinitely adjusted by adjusting the speed of the frequency converter. The specifications of the graphite rotor and impeller are, and the high-purity anti-oxidation graphite rotor has the characteristics of high strength, high temperature resistance and aluminum flow corrosion resistance. In the process of purification and degassing, nitrogen is introduced to the surface of the aluminum alloy liquid in the box for covering protection, so that the part of the graphite rotor exposed to the aluminum alloy liquid is in inert gas, which prevents the high temperature oxidation of the rotor and prolongs the service life of the rotor.
Second, the main reason for the damage of the graphite rotor
1. High-temperature oxidation: The main component of graphite is carbon, and graphite has visible oxidation in the air above 600. The products of the carbon oxidation reaction are CO and CO2 gases, which do not protect the rotor. Generally speaking, the degassing box cannot be completely sealed, and most of the chamber cavity is not protected by protective gas, so the oxidation of the graphite rotor is inevitable. As a result of oxidation, the diameter of the rotor shaft gradually decreases until it breaks and is scrapped.
2. Molten aluminum washout: The graphite rotor is immersed in the molten aluminum in the degassing box, and generally rotates at a speed of 200 rpm ~ 400 rpm and strongly agitates the molten aluminum, which will cause strong scouring and friction to the rotor. In particular, the contact part between the liquid surface and the rotor rod gradually thins, and it will break and be scrapped.
3. The influence of the transmission system: The transmission system of the degassing device is unstable, especially the connection with the rotor is not at the same center, and the rotor swings when running. On the one hand, the friction between the rotor and the sealing plug causes damage; On the other hand, with the increase of liquid level tumbling, rotor oxidation and corrosion intensify, and rotor loss accelerates.
Qingdao Sanlian Graphite Products Co., Ltd