As a core component in aluminum melt purification, graphite rotors are prone to oxidation reactions due to oxygen erosion in high-temperature environments (350–730°C). This leads to shaft diameter reduction and fracture, severely impacting aluminum processing efficiency and costs. The oxidation mechanism primarily stems from two factors: direct reaction between graphite and oxygen at high temperatures, and the lack of protective inert gas for exposed parts of the rotor due to incomplete sealing of the degassing chamber.
To address this challenge, traditional technologies optimize synergistically across three dimensions: process, materials, and structure. Specific measures include:
- Controlling immersion depth (leaving ~80 mm above the liquid surface and ~60 mm submerged to reduce liquid-level fluctuation erosion);
- Maintaining a positive pressure environment with high-purity nitrogen/argon (≥99.9% purity) to block oxygen intrusion, combined with a 5–10-minute preheating treatment above the liquid surface to minimize thermal stress;
- Using high-purity graphite substrates (carbon content ≥99.9%);
- Enhancing drive system stability and structurally reinforcing vulnerable areas (e.g., nozzle holes).
The “three-in-one solution”—integrating high-purity graphite substrates, coating protection, and argon positive pressure—has successfully extended rotor service life and reduced costs, verifying the effectiveness of multi-technology integration. These measures have become the foundational protection strategy in industrial applications, significantly slowing down the oxidation process.
