Cathodic arc deposition apparatus and method
A cathodic arc coating apparatus includes a vessel, a cathode disposed in the vessel, and a stinger assembly. The stinger assembly includes a first magnetic field generator disposed in a first stinger cup in selective contact with the cathode. The first stinger cup has at least a first electrically conductive cup portion spaced from a second electrically conductive cup portion by a thermally insulating layer therebetween.
1. A cathodic arc coating apparatus comprising:
a vessel;
an anode spaced apart from a cathode disposed in the vessel, the cathode having at least one evaporative surface;
a first power supply configured to bias the cathode with a positive potential;
means for retaining at least one workpiece in the vessel so that the at least one workpiece is exposed to the at least one evaporative surface;
means for initiating an electrical arc between the anode and the cathode for vaporizing a portion of the evaporative surface to form a metallic plasma;
a second power supply configured to bias the at least one workpiece with a negative potential equal to or less than a negative potential of the anode, thereby directing the metallic plasma toward the at least one workpiece; and
a stinger assembly for steering the electric arc over the evaporative surface of the cathode, the stinger assembly including at least a first magnetic field generator disposed in a first electrically conductive cup portion joined to a second electrically conductive cup portion in selective contact with the cathode, defining a first stinger cup having a thermally insulating layer between the first electrically conductive cup portion and the second electrically conductive cup portion such that the thermally insulating layer is disposed directly between the first magnetic field generator and the cathode when the first stinger cup is in contact with the cathode.
2. The apparatus of claim 1 , wherein the cathode includes a puck comprising an evaporative surface formed of a metallic material.
3. The apparatus of claim 2 , wherein the metallic material comprises a metal selected from the group consisting of: nickel, cobalt, chromium, aluminum, titanium, yttrium, zirconium, and alloys thereof.
4. The apparatus of claim 1 , wherein the vessel contains an inert atmosphere.
5. The apparatus of claim 1 , wherein the vessel contains a gas under partial pressure, the gas selected from the group consisting of: oxygen, nitrogen, carbon dioxide, and combinations thereof.
6. The apparatus of claim 1 , further comprising:
a platter supporting a plurality of workpiece holders, including the first workpiece holder, about an axis of the cathode.
7. The apparatus of claim 6 , wherein at least one of the plurality of workpiece holders is adapted to retain at least one airfoil.
8. The apparatus of claim 1 , wherein at least one of the first cup portion and the second cup portion comprises copper.
9. The apparatus of claim 1 , wherein the thermally insulating layer is non-metallic.
10. The apparatus of claim 9 , wherein the thermally insulating layer comprises air.
11. The apparatus of claim 9 , wherein the thermally insulating layer is maintained under partial vacuum.
12. The apparatus of claim 1 , further comprising a cathode support base secured to, and electrically insulated from the vessel.
13. The apparatus of claim 12 , further comprising: a second magnetic field generator disposed within the cathode support base.
14. The apparatus of claim 13 , wherein the cathode support base comprises a second multi-part stinger cup, the second multi-part stinger cup having at least a first electrically conductive cup portion spaced from a second electrically conductive cup portion by a thermally insulating layer therebetween.
15. The apparatus of claim 1 , wherein the first electrically conductive cup portion is joined to the second electrically conductive cup portion via respective first and second radial flanges.