Colloidal graphite was first obtained by Acheson in nineteenth Century. Raw materials for natural graphite or artificial graphite.
There are two methods for producing colloidal graphite: (1) mechanical method. Natural graphite crushed by hydrochloric acid and hydrofluoric acid to remove impurities. Added to the tannic acid in aqueous solution by repeated decantation into paste. Adding a certain proportion of water and ammonia, and then by ultrasonic treatment to further reduce the particle size, you can get colloidal graphite. (2) chemical method. After purification and crushing of natural graphite, adding concentrated nitric acid and concentrated sulfuric acid and water at 90 degrees Celsius, and then cleaning, drying, adding water, ethanol, acetone and other dispersing agent that is colloidal graphite. Addition of stabilizers such as sodium, sulfate and so on to make the graphite particles do not agglomerate. Ammonia causes the graphite colloid to transition to the colloidal solution, and the pH value is adjusted.
Generally, the content of colloidal graphite particles is 25% to 3% of the whole colloid. The content of graphite is high, and the colloid is large.
Properties and applications of colloidal graphite: (1) lubrication. Colloidal graphite has good lubricating performance, so it is widely used in casting, glass molding and demolding agent and high temperature bolt, high-speed rotating parts, internal combustion engine lubrication, difficult molten metal such as tungsten, molybdenum wire drawing die lubricant. (2) thermal insulation. The vertical direction of the surface of the colloidal graphite has heat insulation. Therefore it can be used as a high temperature thermal insulation film in the superheated steam cylinder and turbine propeller aspects of the application. (3) the film is uniform and has excellent conductivity and thermal conductivity. In the electronic industry to be applied, for the elimination of static electricity, inhibit the two reflection of the electron, to prevent reflection, increase the use of radiation cooling. (4) other. Due to the high dispersion of colloidal graphite, rubber and plastic industry as additive, wear resistance and improve product, compressive strength and conductivity, electrolysis industry preparation conductive liquid.