Process for Applying a Heat Shielding Coating System on a Metallic Substrate

Abstract

A process is disclosed for applying a heat shielding coating system on a metallic substrate. The coating system comprises at least three individual layers selected from the group of barrier layer, hot gas corrosion protection layer, protection layer, heat barrier layer, and smoothing layer. The coating system is applied to the metallic substrate by low pressure plasma spraying in a single operation cycle. This process enables the layers to be applied in an arbitrary sequence. The process is preferably used in applying a coating system to a turbine blade, particularly a stator or a rotor blade of a stationary gas turbine or of an aircraft engine, or to another component in a stationary or aircraft turbine that is subjected to hot gas.

1 . A metallic component made of a Ni- or Co-alloy, having a heat shielding coating system comprising the following layers in sequence:
 a metallic barrier layer consisting of a metal alloy;   a hot gas corrosion protection layer consisting of a MCrAlY-alloy, M being a member of the group consisting of Fe, Co and Ni, or of a metal aluminide;   a protection layer for protection of the hot gas corrosion protection layer, said protection layer having a thickness of 1 to 20 μm;   a heat barrier layer; and   a smoothing layer;   wherein all of the layers are applied to said metallic component by low pressure plasma spraying in a single coating method without changing the coating technology or equipment.   
     
     
         2 . The metallic component of  claim 1  in which said protection layer has a thickness of 8 to 12 μm. 
     
     
         3 . A metallic component made of a Ni- or Co-alloy, having a heat shielding coating system comprising the following layers in sequence:
 a metallic barrier layer consisting of a metal alloy;   a hot gas corrosion protection layer consisting of a MCrAlY-alloy, M being a member of the group consisting of Fe, Co and Ni, or of a metal aluminide;   a protection layer for protection of the hot gas corrosion protection layer, said protection layer consisting of an aluminum oxide or terniary Al—Zr—O compound;   a heat barrier layer; and   a smoothing layer;   wherein all of the layers are applied to said metallic component by low pressure plasma spraying in a single coating method without changing the coating technology or equipment.   
     
     
         4 . The metallic component of  claim 3 , wherein said component is a turbine blade, a stator blade or a rotor blade of a stationary gas turbine or of an aircraft jet engine. 
     
     
         5 . The metallic component of  claim 3 , in which said metallic barrier layer has a thickness of 1 to 20 μm. 
     
     
         6 . The metallic component of  claim 5 , in which said metallic barrier layer has a thickness of 8 to 12 μm. 
     
     
         7 . The metallic component of  claim 3 , in which said metallic barrier layer comprises a NiAl-alloy or a NiCr-alloy. 
     
     
         8 . The metallic component of  claim 3 , in which said hot gas corrosion protection layer has a thickness of 50 to 500 μm. 
     
     
         9 . The metallic component of  claim 3 , in which said heat barrier layer has a thickness of 100 to 2000 μm. 
     
     
         10 . The metallic component of  claim 9  in which said heat barrier layer has a thickness of 150 to 500 μm. 
     
     
         11 . The metallic component of  claim 3  in which said heat barrier layer consists of an oxide ceramic substance and a stabilizer. 
     
     
         12 . The metallic component of  claim 11  in which said oxide ceramic substance is a zirconium oxide containing substance. 
     
     
         13 . The metallic component of  claim 11  in which said stabilizer comprises rare earth oxides. 
     
     
         14 . The metallic component of  claim 13  in which said rare earth oxides are selected from the group consisting of yttrium oxide or cerium oxide. 
     
     
         15 . The metallic component of  claim 3  in which said smoothing layer has a thickness of 1 to 50 μm. 
     
     
         16 . The metallic component of  claim 15  in which said smoothing layer has a thickness of 10 to 30 μm. 
     
     
         17 . The metallic component of  claim 3  in which said smoothing layer consists of an oxide ceramic substance and a stabilizer. 
     
     
         18 . The metallic component of  claim 17  in which said oxide ceramic substance is a zirconium oxide containing substance. 
     
     
         19 . The metallic component of  claim 17  in which said stabilizer comprises rare earth oxides. 
     
     
         20 . The metallic component of  claim 19  in which said rare earth oxides are selected from the groups consisting of Yttrium oxide or cerium oxide.