A coating (20) for a component of a power transmission system (10) and a method of coating a substrate is provided. The coating is substantially metal-free with a low hydrogen to carbon ratio. The method includes placing a graphite carbon target and the substrate in a magnetron sputtering chamber. The magnetron sputtering chamber is evacuated and filled with gas. The graphite carbon target is sputtered by the ionized inert and/or hydrogen gas so that the substrate is coated with a metal-free diamond-like-carbon coating.