Abstract: Powder feed cylinder assemblies and powder feeders are provided. A powder feed cylinder assembly includes a cylinder, a bit, and bushings. The cylinder has a main passage, a first feed channel, and a second feed channel, each feed channel at two axial locations between the cylinder's two ends. The bit extends through the main passage and has an outer surface including a helical channel formed thereon. A center bushing is disposed in the main passage between the two axial locations and has a first axially-extending passage through which the bit extends. The first end bushing is disposed in the main passage on one side of the center bushing and has a second axially-extending passage through which the bit extends. The second end bushing is disposed in the cylinder on the other side of the center bushing and has a third axially-extending passage through which the bit extends.

Abstract: Methods are provided for cleaning a component having internal passages. A method includes contacting the component with an aqueous hydrogen fluoride solution without agitating the solution for a time period in a range of about 20 minutes to about an hour to dissolve a solid piece of blockage material blocking at least a portion of the internal passages, the aqueous hydrogen fluoride solution comprising, by volume, about 40 percent to about 60 percent hydrogen fluoride and optionally, a corrosion inhibitor, and the blockage material comprising a silicate and rinsing the component with water to remove at least a portion of the aqueous hydrogen fluoride solution from surfaces of the component defining at least a portion of the internal passages.

Abstract: Powder feed cylinder assemblies and powder feeders are provided. A powder feed cylinder assembly includes a cylinder, a bit, and bushings. The cylinder has a main passage, a first feed channel, and a second feed channel, each feed channel at two axial locations between the cylinder's two ends. The bit extends through the main passage and has an outer surface including a helical channel formed thereon. A center bushing is disposed in the main passage between the two axial locations and has a first axially-extending passage through which the bit extends. The first end bushing is disposed in the main passage on one side of the center bushing and has a second axially-extending passage through which the bit extends. The second end bushing is disposed in the cylinder on the other side of the center bushing and has a third axially-extending passage through which the bit extends.