Abstract: A fluid device includes a displacement assembly and a balance plate assembly disposed adjacent to the displacement assembly. The displacement assembly includes a ring and a rotor disposed in a bore of the ring. The ring and rotor cooperatively define a plurality of volume chambers. The balance plate assembly includes a housing that defines a cavity. A balance plate is disposed in the cavity. The balance plate includes a first end surface and an oppositely disposed second end surface. The balance plate is adapted to move axially between a first position in which the second end surface of balance plate abuts a first end face of the ring to a second position in which the second surface of the balance plate is recessed in the cavity.

Abstract: A device configured for converting energy includes a first surface, a second surface configured for moving with respect to the first surface during operation of the device, and a coating disposed on at least one of the first surface and the second surface. The coating includes a first layer of a ceramic alloy represented by the general formula AlMgB14—X, wherein X is present in an amount of from 0 to 70 parts by weight based on 100 parts by weight of the ceramic alloy and is a doping agent selected from the group of Group IV elements and borides and nitrides thereof, and a second layer disposed on the first layer and including carbon in a gradient concentration. The coating has a hardness of from 10 to 20 GPa and a coefficient of friction of less than or equal to 0.12.

Abstract: A fluid device includes a displacement assembly and a balance plate assembly disposed adjacent to the displacement assembly. The displacement assembly includes a ring and a rotor disposed in a bore of the ring. The ring and rotor cooperatively define a plurality of volume chambers. The balance plate assembly includes a housing that defines a cavity. A balance plate is disposed in the cavity. The balance plate includes a first end surface and an oppositely disposed second end surface. The balance plate is adapted to move axially between a first position in which the second end surface of balance plate abuts a first end face of the ring to a second position in which the second surface of the balance plate is recessed in the cavity.

Abstract: A device configured for converting energy includes a first surface, a second surface configured for moving with respect to the first surface during operation of the device, and a coating disposed on at least one of the first surface and the second surface. The coating includes a first layer of a ceramic alloy represented by the general formula AlMgB14—X, wherein X is present in an amount of from 0 to 70 parts by weight based on 100 parts by weight of the ceramic alloy and is a doping agent selected from the group of Group IV elements and borides and nitrides thereof, and a second layer disposed on the first layer and including carbon in a gradient concentration. The coating has a hardness of from 10 to 20 GPa and a coefficient of friction of less than or equal to 0.12.