Plasma-enhanced chemical vapor deposition of carbon-based coatings on surfaces
AssigneeAGM Container Controls, Inc.
InventorsAndrew Tudhope, Salvatore Gennaro
Life of this patent
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Abstract
Systems and methods for producing carbon-based coatings featuring diamond-like carbon (DLC) structures on the internal surfaces of cylindrical or tube-like components is disclosed. The methods feature the use of plasma-enhanced chemical vapor deposition (PECVD) to provide a generally uniform coating on the surface. Longitudinally homogeneous plasma is ignited directly inside the tube-like component. A bipolar pulse with a reverse active plasma step is used. The pressure and bias voltage are selected so as to cause the deposition of a carbon-based coating on the inner surface.
Claims18
An apparatus for coating an inner surface of an electrically conductive hollow tube (6), herein referred to as a hollow tube, disposed within a vacuum chamber (1), the apparatus comprising:
- a. a first end cap (5), comprising a first electrically insulating material, having an opening for a gas supply (18);
- b. a second end cap (8), comprising a second electrically insulating material;
- c. a wire (7) passing through a center of the first end cap (5), wherein the hollow tube (6) is disposed between the first end cap (5) and the second end cap (8), wherein the wire (7) is electrically conductive, wherein the wire (7) spans from the first end cap (5) to the second end cap (8) and is disposed longitudinally through a center axis of the hollow tube (6);
- d. the gas supply (18) connected to the opening of the first end cap (5), wherein the gas supply (18) fills the hollow tube (6) with a gas, wherein the gas is contained within the hollow tube (6) by the first end cap (5) and the second end cap (8), wherein the gas, when ignited by an electrical pulse, reacts to create an electrically insulating carbon-based coating that is deposited on the inner surface of the hollow tube (6);
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- e. a pulse biasing system (13), capable of generating a series of electrical pulses, having a negative output connected to the hollow tube (6) and a positive output connected to the wire (7), wherein the hollow tube (6) acts as a cathode and the wire (7) acts as an anode;
- wherein the pulse biasing system (13) delivers a series of positive and negative electrical pulses to the wire (7) and the hollow tube (6), respectively, wherein an electrical field is generated between the hollow tube (6) and the wire (7) for igniting the gas to deposit the electrically insulating carbon-based coating on the inner surface of the hollow tube (6), and wherein the pulse biasing system periodically reverses the electrical pulses delivered to the wire (7) and the hollow (6) tube.
An apparatus for coating an inner surface of a plurality of electrically conductive hollow tubes (6) with an electrically insulating coating, herein referred to as hollow tubes, disposed within a vacuum chamber (1), the apparatus comprising:
- a. a plurality of top end caps (5), each top end cap (5) is capable of holding a hollow tube (6) of a plurality of hollow tubes (6);
- b. a plurality of bottom end caps (8), each bottom end cap (8) is disposed at an opposing end of the hollow tube (6) from the top end cap (5), wherein each of the bottom end caps (8) are capable of holding a weight of and centralizing a plurality of wires (7);
- c. the plurality of wires (7), each passing through a center of each top end cap (5), each wire is disposed longitudinally through the center axis of the hollow tube (6) and spans to each bottom end cap (8);
- d. a gas splitter (22), connected between the gas mixer (20) and the plurality of hollow tubes (6), capable of distributing an equal amount of gas to each hollow tube;
- e. a plurality of gas flow controllers (24,25), each connected between the gas splitter (22) and one of the plurality of top end caps (5);
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- f. a pulse biasing system (13), capable of generating a series of electrical pulses, having a negative output connected to the plurality of hollow tubes (6) and a positive output connected to the plurality of wires (7), wherein the plurality of hollow tubes (6) act as cathodes and the plurality of wires (7) act as anodes.
A method of coating an inner surface of at least one conductive hollow tube (6), the method comprising:
- a. extending a conductive wire (7) longitudinally through a center axis of the at least one conductive hollow tube (6), wherein the wire (7) is disposed from end to end of the hollow tube (6);
- b. filling the at least one conductive hollow tube (6) with a gas from a gas supply (18), wherein the gas comprises a mixture of chemical components which, when ignited, cause an electrically insulating carbon-based coating to be deposited on the inner surface of the at least one conductive hollow tube;
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- c. supplying a bipolar voltage pulse (50, 60) to the at least one conductive hollow tube (6) and the conductive wire (7) disposed therein, wherein the bipolar voltage pulse (50, 60) ignites the gas, thereby depositing the electrically insulating carbon-based coating on the inner surface of the at least one conductive hollow tube (6).
Dependencies are inferred from the claim text.