An apparatus for sputter coating the inner walls of tubes

A device for coating the inner walls of tubes by physical vapor deposition is described. An ion beam enters the tube parallel to the axis and impinges on a conical sputter target which is pushed through the tube. Material from the sputter target is thereby deposited onto the tube walls. With this device, the inner walls of steel tubes were coated with silver, and tantalum tubes were coated with platinum. The latter is effective in preventing tantalum tubes from becoming embrittled in contact with acid. (C) 1996 American Institute of Physics.