Improving groove contact

摘要

Carbon is one of the most common and versatile elements found on Earth. In its purest form it has the odd characteristic of being what chemists call allotropic. That is to say, it can appear in more than one distinct form of the same state. Carbon's two main allotropic forms are diamond and graphite, each of which has unique properties of great value. Graphite can be used for pencils when moulded into thin rods with clay, it is valuable as electrodes in various chemical processes, it can be used to make crucibles, or as a lubricant. The diamond, however, is completely different in its mechanical properties and is noted not only for the great beauty of its cut crystals when used by a jeweller, but also for being the hardest substance known to man.