The production process of impregnated carbon graphite mainly includes the following steps:
Preparation stage:
Blank processing: Process the graphite rod into tube material, leaving a processing allowance of 2~3mm for the inner and outer diameters of the finished product size. If the blank is a large block, cut the material with a thin grinding wheel and then make it into a tube material, and ensure that the blank is not attached with oil stains.
Flushing: Use compressed air to clean the graphite dust on the surface of the tube material, or wash it with tap water to prevent blocking the impregnation surface gap and affecting the impregnation effect.
Low-temperature baking: Heat the tube material to 70~80℃, keep it for 2 hours, and then cool it naturally to remove moisture from the pores of the graphite tube material.
Impregnation treatment:
Equipment preparation: Put the graphite tube material into the wire basket, keep a certain distance, put it into the impregnation kettle, and evacuate it to about 0.1MPa for 30 minutes.
Impregnation: Inhale the resin in the resin impregnation kettle, the height should be 100mm above the workpiece, and introduce 0.6-0.8MPa compressed air for 4-5 hours.
Curing: 2 hours after the product is out of the kettle, the resin on the outer surface of the product can be wiped off with alkaline water and sawdust, and then naturally dried in a cool and ventilated place, generally not less than 48 hours.
Choice of impregnant:
Common impregnants include phenolic resin, furan resin, epoxy resin or polytetrafluoroethylene. These impregnants can improve the strength and wear resistance of carbon graphite materials through impregnation treatment.
Equipment requirements:
The main equipment required for impregnation includes preheating tank, impregnation tank and impregnation liquid heating tank. The preheating tank is used to remove the gas and moisture contained in some products, and the impregnation tank is used for vacuum and pressurized impregnation.
Technical requirements:
The impregnation liquid usually uses coal tar, and the technical requirements include ash content not more than 0.3%, moisture not more than 0.2%, volatile matter 60-70%, softening point 55-75℃, free carbon 18-22%.
Through the above steps, the porosity of carbon graphite material is reduced, the bulk density and mechanical strength are increased, and the electrical and thermal conductivity are improved, so it is suitable for various mechanical sealing occasions, such as the sealing system of pumps, compressors, reactors and other equipment.
