The tips for impregnating carbon graphite mainly include the following key steps and precautions:
Preliminary preparation:
Clean the graphite surface: Before impregnation, the graphite surface must be cleaned to remove impurities and oil stains to ensure the purity of the graphite material.
Blank processing: The graphite rod is processed into a tube, and the inner and outer diameters are left with a processing allowance of 2~3mm. If the blank is a large block, it is necessary to cut the material with a thin-sheet grinding wheel, and ensure that the blank is not attached with oil stains.
Low-temperature baking: Bake the graphite tube at 70~80℃ for 2 hours to remove moisture in the pores.
Impregnation process:
Impregnation equipment and process: Put the graphite tube into the impregnation kettle, vacuum it, and inhale the impregnant. Alcohol-soluble phenolic resin is usually selected because it is volatile and has high viscosity.
Impregnation conditions: 30 minutes at a vacuum of 0.1MPa, and then 0.6-0.8MPa compressed air is introduced for 4-5 hours.
Curing treatment: The impregnated products need to be naturally dried in a cool and ventilated place for no less than 48 hours, and then pressurized and heated for curing, the temperature is generally 130℃.
Subsequent treatment:
Remove excess impregnant: After the product is out of the kettle, place it for 2 hours, and wipe off the resin on the outer surface with alkaline water and sawdust.
Quality inspection: The cured product needs to be tested for air permeability to ensure that no bubbles are generated.
Common problems and solutions:
Uneven impregnation: Ensure that the vacuum and pressure are properly controlled during the impregnation process to avoid uneven penetration of the impregnant.
Incomplete curing: Control the curing temperature and time to ensure that the resin is completely cured.
Improper surface treatment: After impregnation, the surface needs to be carefully treated to ensure that there is no excess impregnant residue. Through the above steps and techniques, the performance of carbon graphite materials can be effectively improved, its mechanical strength and wear resistance can be enhanced, and it is widely used in the sealing systems of mechanical seals, pumps, compressors and other equipment.
