Mechanical Carbon In Chemical Processing Equipment
By Glenn H. Phelps, Metallized Carbon Corp. |
Frequently, in chemical processing equipment it is possible to place the shaft support bearings in the chemical that is being processed. In some cases, this precludes the use of oil- or grease-lubricated bearings because the operating conditions are not conducive to the use of such materials. For example, bearings that are lubricated with oil or grease can be problematic when submerged in liquids such as water or other solvents, liquefied gases, heat transfer oils and corrosive chemicals. For these operating conditions, self-lubricating, mechanical carbon bearings are often the best solution.
This article takes a close look at mechanical carbons, describing what they are and how they function when running submerged in chemical processing equipment.
Mechanical carbons contain graphite, which they rely on for their self-lubricating characteristics. To make mechanical carbons, fine graphite particles are bonded with a hard, strong, amorphous-carbon binder to produce a mechanical carbon material that is called carbon-graphite. Further heat treating, to approximately 5,100°F (2,800°C), causes the amorphous-carbon binder to become graphitized, resulting in a material known as electrographite.
The electrographite is…