Self-Lubricating
Our AD-Carb Carbon-Graphite, Graphite, and composites are all self-lubricating, non-galling materials which have very low coefficient of friction. The coefficient of friction can be as low as .05 depending on any introduced lubrication materials and the surface finish of the bearing and mating material. Surface finish plays a very important role in maintaining low coefficient of friction. All carbon bushings must have the bearing surface ground to an 8 rms to 16 rms finish. Our premium AD-Carb carbon bushing material is composed of carbon-graphite and typically has a secondary material impregnated into it (to be discussed later). When used as a bushing, the crystal structure of the graphitized carbon allows formation of a light lubricating film on the mating surface, such as the shaft. The crystal structure of the amorphous carbon provides a wiping action that prevents excessive build up of graphite film, which would otherwise become a high friction film and lead to excessive wear. This filming/wiping action helps maintain low friction between the mating surface and the bearing surface.

To service a wider range of application such as where extended service is desired, the process of metal or resin impregnation can be implemented. Depending on the application, certain metal or resin impregnation can extend a carbon-graphite bushing's life by two to three times, or even more under some conditions. A metal or resin that is impregnated into the porosity of a carbon-graphite bushing provides an additional non-carbon, low friction bearing surface that works in conjunction with the amorphous and graphitized carbon. Grinding the bearing surface to a 8 rms to 16 rms finish further reduces the coefficient of friction and overall wear of the bushing. Additionally, the impregnation increases the mechanical strength and hardness of the carbon-graphite and provides characteristics that play a role in extending the life of the bushing. The thermal conductivity of the impregnated carbon-graphite is also increased, which allows for faster transfer of frictional heat away from the bearing surface, and aids in extending the life of the bushing.

Temperature Compatibility
Our plain carbon-graphite materials maintain self-lubricating non-galling properties up to 750 degrees Fahrenheit without oxidizing. It may be used up to 1500 degrees Fahrenheit in a non-oxidizing atmosphere. With special treatment, the material can be made to operate successfully up to 1100 degrees Fahrenheit with inhibited oxidation. Additionally, the strength of our material increases with an increase in temperature. Often we can supply these high-temperature bearing pre-fit into a stainless steel sleeve or other suitable sleeve to ease maintenance and reduce downtime involved in replacing the bushing. Some of our metal and resin impregnated materials can be used successfully at temperatures below zero and even for cryogenic service, depending on other environmental factors. Materials often used for extremely cold or cryogenic service include bronze impregnated carbon-graphite, silver impregnated carbon-graphite, babbitt impregnated carbon-graphite, and resin impregnated carbon-graphite.

Chemical Resistance
Our materials are chemically stable and will not react with most chemicals. It is important that chemical reactivity is taken into consideration when considering what metal or resin impregnated material to use, and the impregnant can react with some chemicals. Please consult our engineering department on chemical compatibility, so a suitable material can be selected.