A seal assembly includes a carbon seal that has a sealing surface. A seal seat has a sealing surface and is positioned for rotation relative to the carbon seal. A diamond-like carbon coating at least partially forms the sealing surface on the seal seat.

A seal assembly includes a carbon seal that has a sealing surface. A seal seat has a sealing surface and is positioned for rotation relative to the carbon seal. A diamond-like carbon coating at least partially forms the sealing surface on the seal seat.

An apparatus has: a first member; a shaft rotatable relative to the first member about an axis; and a seal system. The seal system has: a seal carried by the first member and having a seal face; a seal housing; a seat carried by the shaft and having a seat face in sliding sealing engagement with the seal face; and a plurality of coil springs biasing the seal face against the seat face, each coil spring having a first end and a second end. The seal has a plurality of spring compartments. Each of the plurality of coil springs is partially within a respective associated compartment of the plurality of spring compartments.

Apparatus and associated methods relate to a segmented radial seal assembly that includes at least two segments, each segment having a first end and a second end at opposite ends. A first segment first end has a protruding feature and defines a tangential vector from a circumferential ring that is formed by the segmented radial seal. The protruding feature defines a curved face having at least a first axis of curvature that is parallel to the tangential vector. The second segment second end has a recessed feature that is matingly engageable to the first segment first end, thereby forming a first radial seal segment joint. The segmented radial seal assembly is configured to surround a shaft.

Apparatus and associated methods relate to a segmented radial seal assembly that includes at least two segments, each segment having a first end and a second end at opposite ends. A first segment first end has a protruding feature and defines a tangential vector from a circumferential ring that is formed by the segmented radial seal. The protruding feature defines a curved face having at least a first axis of curvature that is parallel to the tangential vector. The second segment second end has a recessed feature that is matingly engageable to the first segment first end, thereby forming a first radial seal segment joint. The segmented radial seal assembly is configured to surround a shaft.

A bearing compartment seal for a gas turbine engine includes at least one seal ring defining an axis and having a radially inward facing sealing surface and a seal runner having a support constructed of a first material and an interface portion constructed of a second material. The interface portion includes a radially outward facing surface. A first coefficient of thermal expansion of the second material is at most approximately equal to a second coefficient of thermal expansion of the at least one seal ring.

A circumferential sealing assembly for use between a lower-pressure side with a lubricant oil therein and a higher-pressure side with a hot gas therein is presented. The assembly includes a sealing ring interposed between either a rotatable runner and a housing or a sleeve and a housing within a turbine engine. Ducts communicate the hot gas into grooves to form a thin film between the ring and the runner or the ring and the sleeve. First embodiments include grooves on the runner, ducts through the runner, and both grooves and ducts rotating with the runner. Second embodiments include grooves on the ring, ducts through the runner, and ducts rotating with the runner. Third embodiments include grooves on the ring and ducts through the ring adjacent to a runner. Fourth embodiments include grooves on the runner, ducts through the ring, and grooves rotating with the runner. Fifth embodiments include grooves on the sleeve, ducts through the sleeve, and both grooves and ducts rotating with the sleeve. Sixth embodiments include grooves on the ring, ducts through the sleeve, and ducts rotating with the sleeve. Seventh embodiments include grooves on the ring and ducts through the ring adjacent to a sleeve. Eighth embodiments include grooves on the sleeve, ducts through the ring, and grooves rotating with the sleeve.

A circumferential sealing assembly for use between a lower-pressure side with a lubricant oil therein and a higher-pressure side with a hot gas therein is presented. The assembly includes a sealing ring interposed between either a rotatable runner and a housing or a sleeve and a housing within a turbine engine. Ducts communicate the hot gas into grooves to form a thin film between the ring and the runner or the ring and the sleeve. First embodiments include grooves on the runner, ducts through the runner, and both grooves and ducts rotating with the runner. Second embodiments include grooves on the ring, ducts through the runner, and ducts rotating with the runner. Third embodiments include grooves on the ring and ducts through the ring adjacent to a runner. Fourth embodiments include grooves on the runner, ducts through the ring, and grooves rotating with the runner. Fifth embodiments include grooves on the sleeve, ducts through the sleeve, and both grooves and ducts rotating with the sleeve. Sixth embodiments include grooves on the ring, ducts through the sleeve, and ducts rotating with the sleeve. Seventh embodiments include grooves on the ring and ducts through the ring adjacent to a sleeve. Eighth embodiments include grooves on the sleeve, ducts through the ring, and grooves rotating with the sleeve.

A seal system for a gas turbine engine includes a seal runner manufactured of a Molybdenum alloy material that provides a first coefficient of thermal expansion and a seal ring manufactured of a graphitic material that provides a second coefficient of thermal expansion greater than the first coefficient of thermal expansion.

A seal assembly adapted for use with a gas turbine engine includes a runner, a seal, and a compliant holder. The runner extends circumferentially about an axis and the compliant holder. The compliant holder engages the runner and is configured to support the runner radially relative to the axis. The seal extends circumferentially around the runner to block fluid flow through the seal assembly.