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.

　　In graphite field, impregnation is a kind of technology ,via dipping graphite product into certain kind of melted material, which can change physical or chemical condition of graphite product.

　　In general, increasing in porosity of graphite product can not only lead to decling in gravity (density),rising in resistance, decreacing in mechanical strength, but also make product become more easier to be oxidated, to be corrosion and to be immersed. To avoid those circumstance, you can use impregnation technology to control porosity of graphite product.

　　Usually, when you face following condition, you should apply impregnation .

　　1. Producing little scale graphitized electrode and Joint stock.

　　Those product are required high strength, low density and resistivity, so semi-finished products should be impregnated by coal tar pitch previously.

　　2. Producing high quality graphite anode used in diaphragm electrolyzer.

　　Normal graphite anode can only work for 5-6 months,but impregrated graphite anode can work 8-9 months, because ,after impregration,there is less porosity existing in graphite anode. Less porosity means less corrosion and less immersion. In order to improve service life of graphite anodes , drying oils (such as Tung oil, linseed oil, etc) should be used during the curse of producing, which can prolong 1/3 service life.

　　3. Producing impermeable graphite chemical .

　　Graphite products are porous materials, whose porosity can reduce by impregnating into organic resins (such as phenolic resins, Furfuryl ketone resin). At the same time,while mechanical trength was improved by this technology, thermal condition can also stay at it’s good condition.

　　4. Producing wear-resistant carbon and graphite products.

　　When the working temperature and the working media don’t allow to use lubricating oil and other liquid lubricants, using graphite and carbon materials,such as sealing rings, bearings or redirect loop is the only way to ensure the machine runs at high temperatures for long periods. This graphite or carbon wear-resisting material needs high density and hardness and wear-resistance, so this product usually impregnated by synthetic resins or low melting point metals (such as aluminum, Tin alloy, lead-bronze and babbit).

　　That is all what I want to introduce.After reading this article, you must have a superficial impression on impregnation technology.If want to learn more knowledge about graphite product, welcome to our web site:www.bjgreatwall.com. If you have any question, don’t hesitate to contact me:This email address is being protected from spambots. You need JavaScript enabled to view it..