Lube it for life

Mechanical carbon machine parts excel where oil-grease lubricants won't work. Sometimes moving parts go into applications that just can’t risk exposure to petroleum lubricants. Nobody wants grease in their corn flakes, for example. Ditto for pharmaceuticals. Mechanical-carbon materials contain self-lubricating graphite and are sometimes the only way of handling such needs. Bonding fine graphite particles with a hard, strong, amorphous carbon binder produces a mechanical- carbon material that is called “carbon-graphite.” Further heat treating, to approximately 5,100°F (2,800°C), turns the amorphous carbon binder into graphite. This graphitized material is called “electrographite.” Electrographite materials are typically softer and weaker than carbongraphite, but have superior thermal conductivity and better resist chemicals and oxidation. Both carbon-graphite and electrographite are normally produced with about 15% porosity by volume. To boost mechanical properties the material is impregnated by vacuum pressure with thermal-setting resins, metals, or inorganic salts. All three boost lubricating properties but provide other qualities as well. The most common thermalsetting resins used are phenolics, polyesters, epoxies, and furan resins. Resin impregnation produces materials that are impermeable. The most common metal impregnations are babbitt, copper, antimony, bronze, nickel-chrome, and silver. Metal impregnation produces harder and stronger materials. In addition, they have better thermal and electrical conductivity. Inorganic salt impregnations are proprietary formulations that improve oxidation resistance of the carbon-graphite or electrographite base material. There are two categories to which mechanical-carbon applications are divided: dry running and submerged. As two metal parts rub together without oil-grease lubrication, oxide films on the metal surfaces quickly wear off. The two metals will have a strong atomic attraction. Atomic attraction results in high friction and wear, and — at higher speed or loads — galling and seizing. In contrast, no oil-grease lubricants are needed when carbon materials rub against metal. There is not strong atomic attraction between carbon and