Abstract: Enhanced corrosion resistance is achieved in a coating by using a germanium-containing precursor and hollow cathode techniques to form a first layer directly on the surface of a workpiece, prior to forming an outer layer, such as a layer of diamond-like carbon (DLC). The use of a germanium or germanium-carbide precursor reduces film stress and enables an increase in the thickness of the subsequently formed DLC. Germanium incorporation also reduces the porosity of the layer. In one embodiment, a cap layer containing germanium is added after the DLC in order to further reduce the susceptibility of the coating to chemical penetration from the top.

Abstract: A method of forming a diamond-like carbon coating by plasma enhanced chemical vapor deposition on an internal surface of a hollow component having an inner surface. A reduced atmospheric pressure is created within a pipe or other hollow component to be treated. A diamondoid precursor gas is introduced to the interior of the component. A bias voltage is established between a first electrode and one or more second electrodes. The first electrode is or is attached to the component. The second electrode is externally offset from an opening of the component, by a hollow insulator. A plasma region is established adjacent an inner surface of the component and extends through the hollow insulator. The precursor gas comprises at least one diamondoid. The pressure and bias voltage are selected such as to cause the deposition of diamond-like carbon on the inner surface.

Abstract: The invention relates to a method for forming high sp3 content amorphous carbon coatings deposited by plasma enhanced chemical vapor deposition on internal surfaces and employing the “hollow-cathode” technique. This method allows adjustment of tribological properties, such as hardness, Young's modulus, wear resistance and coefficient of friction as well as optical properties, such as refractive index. In addition the resulting coatings are uniform and have high corrosion resistance. By controlling pressure, type of diamondoid precursor and bias voltage, the new method prevents the diamondoid precursor from fully breaking upon impact with the substrate. The diamondoid retains sp3 bonds which yields a high sp3 content film at higher pressure. This enables a faster deposition rate than would be possible without the use of a diamondoid precursor.

Abstract: The invention relates to a method for forming high sp3 content amorphous carbon coatings deposited by plasma enhanced chemical vapor deposition on external surfaces. This method allows adjustment of tribological properties, such as hardness, Young's modulus, wear resistance and coefficient of friction as well as optical properties, such as refractive index. In addition the resulting coatings are uniform and have high corrosion resistance. By controlling pressure, type of diamondoid precursor and bias voltage, the new method prevents the diamondoid precursor from fully breaking upon impact with the substrate. The diamondoid retains sp3 bonds which yields a high sp3 content film at higher pressure. This enables a faster deposition rate than would be possible without the use of a diamondoid precursor.

Abstract: Enhanced corrosion resistance is achieved in a coating by using a germanium-containing precursor and hollow cathode techniques to form a first layer directly on the surface of a workpiece, prior to forming an outer layer, such as a layer of diamond-like carbon (DLC). The use of a germanium or germanium-carbide precursor reduces film stress and enables an increase in the thickness of the subsequently formed DLC. Germanium incorporation also reduces the porosity of the layer. In one embodiment, a cap layer containing germanium is added after the DLC in order to further reduce the susceptibility of the coating to chemical penetration from the top.