The purpose of impregnation is to fill the pores and open pores in the aggregate coke particles with impregnants such as molten pitch. After secondary roasting, the porosity or ventilation porosity is reduced, and at the same time, the billet’s Density, strength, modulus of elasticity, linear expansion coefficient, or can improve corrosion resistance and wear resistance, reduce gas and liquid permeability, improve conductivity, etc.
The so-called impregnant is a substance used to fill pores. The choice of impregnant is very important. The impregnant affects the chemical stability, thermal stability and mechanical strength of the finished product. The impregnant has the following basic requirements:
(1) It has high chemical stability;
(2) The fluidity is easy to enter the micropores of the carbon graphite material;
(3) It has good adsorption and good airtightness after immersion;
(4) It can maximize the mechanical strength of the material.
Usually the roasted product is impregnated, and sometimes impregnation can be added to the last process depending on the situation. At this time, various impregnating agents such as synthetic resins, metals and alloys, inorganic or organic substances, and grease can be used according to the purpose of use. In addition to the above-mentioned purposes, impregnation can also improve airtightness, wear resistance, corrosion resistance, oxidation resistance, and sliding properties.
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