Patent ID: 7178584

Claim:
Copper tubing for heat exchanger, wherein the copper tubing has an inner wall with grooves coated with a plasma polymerized polymeric coating of a polymer resulting from plasma polymerization of an unsaturated aliphatic hydrocarbon monomer gas or a fluorine-containing monomer gas at a predetermined pressure and a non-polymerizable gas, said coating being formed by a method including the steps of: providing a plasma polymerization chamber which contains the copper inner wall surface as an anode electrically connected to a negative terminal of a DC power supply, and a cathode electrically connected to a positive terminal of the DC power supply; maintaining a pressure in the chamber at a predetermined level; blowing an unsaturated aliphatic hydrocarbon monomer gas or a fluorine-containing monomer gas at a predetermined pressure and a non-polymerizable gas at a predetermined pressure into the chamber; and applying a voltage to the anode and cathode in order to obtain a DC plasma consisting of positive and negative ions and radicals generated from the unsaturated aliphatic hydrocarbon monomer gas or fluorine-containing monomer gas and non-polymerizable gas so as to form a polymeric coating on the copper inner wall surface by plasma deposition, wherein the unsaturated aliphatic hydrocarbon monomer gas includes acetylene and the non-polymerizable gas includes nitrogen and, wherein the polymerized polymeric coating results from a ratio of acetylene to nitrogen in the plasma discharge of about 1:1.