A bypass valve assembly for use in turbine generators includes a valve body defining a central bore and a plurality of passageways. Each passageway has a smaller area at an inlet portion and a larger area at an outlet portion to define a flared passageway. A plurality of bypass valves is disposed within the plurality of passageways within the valve body. Each bypass valve includes a base portion and a nose portion, with each nose portion defining a predefined contoured surface area. At least a portion of the contoured surface area includes a wear coating disposed thereon. Optionally, the wear coating includes a plasma enhanced magnetron sputtering nanocoating.

A method for coating a sealing fin (2) on a component of a turbomachine, in particular on a blade tip (6) of a blade (1) of a turbomachine, with armoring (3, 30, 300), and to a corresponding component, in which method a blade (1) having at least one sealing fin (2) and a slurry which comprises particles of MCrAlY or particles for forming an MCrAlY layer (31), where M is nickel and/or cobalt, are provided, the slurry is applied onto the sealing fin and dried, and the sealing fin with the applied slurry is subjected to an aluminizing process so that the MCrAlY layer comprises an Al-rich sublayer (32).

A sealing element for a rotating sealing system of a turbomachine is provided. The sealing element, if installed in the sealing system according to the intended use, can be rotated around a rotational axis of the turbomachine. The sealing element comprises a ring-shaped sealing lip that has a central point through which the rotational axis extends if the sealing element is installed in the sealing system according to the intended use, wherein the sealing lip has at least one recess, and at least one rubbing element that is arranged at the sealing lip, wherein the at least one rubbing element is arranged inside the at least one recess and projects at least partially beyond the outer contour of the sealing lip in the radial and/or the axial direction with respect to the rotational axis. The at least one rubbing element has a plurality of layers of a rubbing material.

Methods are provided for repairing a defect on a silicon-containing substrate. The method may include applying a powder mixture into the defect of an existing coating on a surface of the silicon-containing substrate, wherein the powder mixture comprises silicon and germanium at a Ge mole fraction of 0.01 to 0.3; and heat treating the powder mixture within the defect at a sintering temperature that is 1150 C. to 1400 C. to form a repaired bondcoat within the defect. Repaired components are also provided that include a repaired bondcoat formed within the defect on the silicon-containing substrate, wherein the repaired bondcoat comprises a silicon-germanium phase comprising a Ge mole fraction of germanium of 0.01 to 0.3 and a Si mole fraction of silicon of 0.7 to 0.99.