Almost all impermeable graphite that be applied in chemical industry are manufactured via impregnation . Impregnant is not only applied to filling hole but also to improving mechanical strength of impregnated graphite. But while different impregnat is used, different mechanical strength appear, such as chemical stability, thermal ability, hardness, etc. So when you are choosing impregnant, it should conform to following characteristics:

　　Good chemical stability

　　Good mechanical ability

　　Steady Volume which can suffer impregnation

　　Low water content

　　Low viscosity

　　Peopley usually choose phenolic resin, modified phenolic resin, furfural acetone resin, furfuryl alcohol resin and coal pitch. However, sometimes, people choose organic silicon resin, sodium silicate, molten sulfur, paraffin as impregnant.

　　Impregnated impermeable graphite is simmilar with other graphite material, which have better chemical ability than other non-metallic corrosion resistant materials.

　　There are several tips should be noticed：

　　① Graphite pieces should not contain dust, oil, moisture.

　　② In order to Impregnate thoroughly, and in case of graphite expending, Vacuum degree should be as high as possible.

　　③ The quality of impregnant needs special care. If shrinkage process of resin is incomplete or dehydration is incomplete, the quality of impregnant will change.

　　④ Residual resin on the surface of graphite should be wiped.

　　⑤ Vacuum degree, pressure, time and temperature can decide whether the qualit of first impregnation is good enough.

　　Industrial production, the most widely used carbon graphite material impregnant, asphalt, resin, synthetic resin, metal and metal alloys, organic lubricant, and halogen lubricant.

　　How to choose impregnation agent should obey some basic requirements. Select impregnating agent is an extremely important task, dipping agent determines the performance of products: chemical stability, thermal stability resistance, mechanical strength and so on.

　　For dipping should have the following basic requirements:

　　1. There are approximately graphite high chemical stability;

　　2. With easy-flowing pieces immersed porous graphite;

　　3. Can maximize the mechanical strength of graphite.

　　4. Good adsorption after graphite and graphite good dip impervious;

　　When the Baptist phenolic resin, using the following system: will be filled with resin and mounted dip products into the dipping tank immersion tank, dipping tank temperature vacuum degree (9.9 ~ 10) x 104 Pa, keep 30-35 minutes, after which, In the dipping tank pressurized to 0.4 to 0.5 MPa gauge pressure, and then held for 30 to 35 minutes. Products rapidly removed after dipping 5% alkali solution treatment, then washed. The need for such a treatment is to clear the surface of the resin products. After the water will wash products, placed in dry air for several hours, the amount of graphite inhalation resin, depending on the porosity of varying sizes, about products, about 10% by weight to 20% per surface to a depth of 15-20 mm impregnated .

　　To prevent the article due to the temperature rise in the use of leaving the possible outflow of the resin, the resin should be converted to the irreversible solid state. Even cured at high temperature and add the appropriate catalyst. The duration of this process takes roughly 10 hours, eight hours before the internal gauge pressure of 0.4-0.5 MPa and a temperature of heat treatment is performed at 50-SOT conditions, 1.0 ^ / h speed gradually warming; After two hours at atmospheric pressure heat treatment is performed under 1401 - 130.

　　When using other resins, process parameters can be changed.