graphite rotor

1. The graphite rotor works continuously in the aluminum melt at about 750°C at a speed of 200r/min~400r/min, and the general service life is required to reach more than one month. The graphite rotor of our company is made of high-purity graphite. The quality of graphite itself has a significant impact on the service life of the rotor. At the same time, an anti-oxidation protective coating is applied on the surface, and the service life can be extended to 50-60 days.

2. Working principle of graphite rotor:

The graphite rotor is composed of rotor rod and nozzle. The transmission system drives the graphite rotor to rotate, and argon or nitrogen is blown into the aluminum melt through the rotor rod and nozzle. The high-speed rotating graphite rotor breaks up the argon or nitrogen gas entering the aluminum melt to form many small bubbles, which disperse them in the molten metal. When the bubbles are in contact, the bubbles in the melt rely on the gas partial pressure difference and the principle of surface adsorption to absorb hydrogen in the melt, adsorb oxidized slag, and be taken out of the melt surface as the bubbles rise to purify the melt.

Use and maintenance of graphite rotor:

1. The rotating nozzle is made of high-purity graphite. In addition to considering the structure of the nozzle to break up the air bubbles, it also uses the centrifugal force generated by stirring the aluminum alloy melt to make the melt enter the nozzle and mix with the horizontally ejected gas to form a gas or the liquid flow is ejected to increase the contact area and contact time between the bubbles and the aluminum alloy liquid, and improve the degassing and purification effect.

2. The general service life requirement is more than one month. The durability is 3-4 times better than that of the non-oxidizing rotor. It can last up to 55-65 days at about 700 °C, and can last up to 25-35 days at temperatures above 1000 °C. With an anti-oxidation protective coating on the surface, the service life can be extended to 50-60 days.

3.Before immersing the graphite rotor in the aluminum liquid, preheat it for 5 minutes to 10 minutes at about 100 mm above the liquid surface to avoid the impact of rapid cooling on the material; before the rotor is immersed in the liquid, the gas must be passed through;The air supply can be stopped only after the rotor lifts out of the liquid level, so as to prevent the air hole of the rotor nozzle from being blocked.

4. The main cause of graphite rotor damage is high-temperature oxidation: the main component of graphite is carbon, and graphite can be visibly oxidized under air conditions exceeding 600 ° C. The products of carbon oxidation reactions are CO and CO2 gases, which cannot protect the rotor. Generally speaking, the degassing box cannot be completely sealed, and most of the inner cavity of the box is not filled with protective gas, so the oxidation of the graphite rotor is inevitable. As a result of its oxidation, the shaft diameter of the rotor shaft gradually decreases until it breaks and is scrapped.