Ceramic turbine blade attachment having high temperature, high stress compliant layers and method of fabrication thereof

Abstract

A nickel base single crystal compliant layer on a ceramic blade has the capability to sustain high stresses and high operating temperature. Layers of nickel and platinum bonded on a single crystal superalloy over a sputtered gold-chromium layer support the high stress levels at elevated temperature without extrusion of the soft platinum or nickel layer and without destruction of an NiO compliant surface. The compliant layers have survived stress and temperature conditions without failure to the ceramic blade and the system can be stressed/heated and unloaded/cooled repeatedly without damage to the ceramic blades. A single crystal nickel base superalloy (i.e., SC180) has high strength properties at elevated temperature. Thin layers of chromium followed by gold are e-beam evaporated on one side of a polished surface of the alloy. Pure nickel is electroplated over this e-beam gold-chromium layer. Platinum is either electroplated or plated electrolessly over the nickel layer. The structure is annealed in vacuum or inert atmosphere to allow the diffusion of gold-chromium alloy into the superalloy and permit the nickel layer and diffusion of nickel into platinum to form a multilayer structure which is metallurgically bonded. The sheet is oxidized in air to allow diffusion of the nickel layer through the platinum to come to the surface and oxidize forming nickel oxide. This nickel oxide layer acts as the load distribution layer which does not extrude and the structural integrity of the compliant layer is maintained by the high-strength single crystal superalloy.

Dependencies are inferred from the claim text.