Gas turbine rotor bimetallic ring seal and method therefor

A method for forming a ring seal for sealing between two structures comprising the steps of:

• a) providing a ring made from a material selected from a group consisting of cobalt and nickel;
• b) coating said ring with a first layer of platinum to form a dense platinum layer;
• c) applying a second layer of porous platinum having a thickness between about 0.002 inches to about 0.006 inches over said first layer by electroless plating said coated ring in a platinum bath comprising 1.0 gram/liter platinum as diammine dinitrite salt Pt(NH3)2(NO2)2, 50 milliliter/liter of 25% ammonium hydroxide NH4OH, and 1.5 gram/liter hydrazine hydrate N2H4—H2O, with the temperature at 85° C. and a plating rate of 0.5 micron/hour at the beginning of the process and gradually increasing to 3.0 micron/hour as the surface area increases;
• d) heating said twice coated ring in an inert atmosphere until the included hydrogen escapes;
• e) cooling said twice coated ring and mounting said ring between said structures;
• and
• f) plastically deforming the ring between said structures to form said ring seal.

A method for forming a ring seal for sealing between two structures comprising the steps of:

• a) providing a ring made from a material selected from a group consisting of cobalt and nickel;
• b) mechanically cleaning the ring such that the surface is substantially free from an oxide layer;
• c) coating said ring with a first layer of platinum to form a dense platinum layer;
• d) heating the coated ring in an inert atmosphere at temperature between about 900 to about 1000 degrees Celsius until the platinum and nickel diffuse together;
• e) applying a second layer of porous platinum having a thickness between about 0.002 inches to about 0.006 inches over said first layer by electroless plating said coated ring in a platinum bath comprising 1.0 gram/liter platinum as diammine dinitrite salt Pt(NH3)2(NO2)2, 50 milliliter/liter of 25% ammonium hydroxide NH4OH, and 1.5 gram/liter hydrazine hydrate N2H4—H2O, with the temperature at 85° C. and a plating rate of 0.5 micron/hour at the beginning of the process and gradually increasing to 3.0 micron/hour as the surface area increases;
• f) heating said twice coated ring in an inert atmosphere until the included hydrogen escapes;
• g) cooling said twice coated ring and mounting said ring between said structures;
• and
• h) plastically deforming the ring between said structures to form said ring seal.