ABOVE-SHROUD LABYRINTH SEAL FOR STEAM TURBINE Russian patent published in 2014 - IPC F01D11/08 F16J15/447 

FIELD: machine building.

SUBSTANCE: comb is made or installed on a shroud of blades of a turbine rotor stage. Sealing units are installed with a sealing radial gap relative to an annular comb of the shroud of blades of the rotor stage and fixed by soldering in holders of the sealing units. Holders are made in a turbine stator case, each of which has an annular sector of a T-shaped shank in a turbine longitudinal section. The shank is installed in an annular slot of the turbine stator case, which is T-shaped in the longitudinal turbine section. The sealing units are made from particles of worn-in powder material in the form of a prism, which are adhesively connected to each other into solid material, with a trapezoidal or rectangular cross section with side support projections contacting the side walls of holders of sealing units. Each side of the sealing unit is provided at least with one symmetrically located side support projection. As worn-in powder material, material of the following composition, wt %, is used: Cr - 12.0 to 14.0%, Mo - 1.0 to 3.0%, Fe - is the rest, with powder particles with size of 10 mcm to 160 mcm in mechanical mixture with powder, with power particles with size of less than 1 mcm, hexagonal boron nitride - BN in the quantity (wt %) of 5.0% to 6.5% of total volume of the mixture and zinc stearate - Zi(C₁₈H₃₅O₂)₂ with powder particles with size of 1 to 75 mcm, wt %: 0.9% to 1.1% of total volume of seal material; with that, the sealing unit is made by cold pressing with further sintering in vacuum or in shielding atmosphere at temperature of 1050°C to 1150°C, and as shielding atmosphere, gas mixture containing the following components (vol %) is used: argon 6% to 50%, and ammonium is the rest.

EFFECT: invention allows improving strength and wear resistance of a seal.

2 dwg