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Abstract

Articles are disclosed which bear a carbon coating layer, wherein carbon-carbon bonding within the coating layer is mostly of the sp2 form: wherein the coating has a specific wear rate under wet conditions of less than 10.sup.-6 m.sup.3 /Nm: wherein the coating has an adhesion critical load of at least 70N: wherein the coating has a hardness of at least 1000 VHN: wherein the coating has a coefficient of friction (dry) of not more than 01. The coating may be a multi-layer coating containing successive metal-containing and carbon layers. The article may be constituted as a medical prosthesis. Methods are disclosed of forming hard wear resistant carbon coatings by sputter ion plating with at least one carbon target in which an ion current density of for example above 0.5 mA/cm.sup.2 is applied at the substrate to be coated in order to deposit a carbon-containing coating layer and/or which comprise sputter ion plating with at least one carbon target and at least one metal target in order to deposit a carbon coating layer and a metal-containing coating layer. Coating apparatus suitably comprises magnetron sputter ion plating apparatus having at least one metal-donating target and at least one carbon-donating target. Such apparatus may include at least two magnetrons arranged to generate a magnetic field between them with field lines extending from one magnetron to the or an other, and the magnetrons, and field lines extending directly from one magnetron to the or an other, form a barrier which tends to prevent the escape of electrons from within a plasma-containing working space within which the substrate is coated.

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First Claim