Method for forming a protective coating with enhanced adhesion between layers

Abstract

A method for forming a protective coating on a substrate comprising, applying a bond coating to the substrate, the bond coating having a first surface roughness, ionizing an inert gas which flows into the surface of the bond coating so as to impart a second surface roughness to the bond coating greater than the first surface roughness, wherein the inert gas is ionized and caused to flow into the surface of the bond coating by a reverse polarity current supplied to an electrode which removes at least one electron from the inert gas, and applying a top coating to the bond coating. Additionally, a method for preparing a surface to receive and adhere to a coating comprising roughening the surface to create a micro-roughening network on the surface. In addition, a method of improving strain tolerance and cyclic spallation life of a protective coating.

We claim: 
     
         1 . A substrate having a protective coating comprising:
 a bond coating attached to the substrate, the bond coating having a first surface roughness;   a micro-roughening network on a surface of the bond coating;   a top coating adhered to the micro-roughening network;   wherein the micro-roughening network has a second surface roughness greater than the first surface roughness and is obtained when an inert gas is ionized and caused to flow into the surface of the bond coating by a reverse polarity current supplied by an electrode that removes at least one electron from the inert gas.   
     
     
         2 . The substrate of  claim 1 , wherein the protective coating further comprises a thermal barrier coating. 
     
     
         3 . The substrate of  claim 1 , wherein the inert gas is ionized using a reverse transfer arc welding torch. 
     
     
         4 . The substrate of  claim 1 , wherein the first surface roughness is less than about 60 microinches Ra. 
     
     
         5 . The substrate of  claim 1 , wherein the second surface roughness is between about 75 microinches Ra to about 750 microinches Ra. 
     
     
         6 . The substrate of  claim 1 , wherein the second surface roughness is between about 100 microinches Ra to about 600 microinches Ra. 
     
     
         7 . The substrate of  claim 1 , wherein the electrode and the bond coating are devoid of an electric arc between each other. 
     
     
         8 . The substrate of  claim 1 , wherein the bond coating is an aluminide diffusion bond coating. 
     
     
         9 . The substrate of  claim 8 , wherein the aluminide diffusion bond coating comprises a bond coating material selected from the group consisting of modified or alloyed aluminides, CrAl, PdAl, PtAl, simple aluminide, silicon modified aluminides, and over aluminized MCrAlY. 
     
     
         10 . The substrate of  claim 1 , wherein the top coating comprises a ceramic material. 
     
     
         11 . The substrate of  claim 10 , wherein the ceramic material is selected from the group consisting of yttria, magnesia, ceria, scandia, and rare earth oxide partially stabilized zirconia. 
     
     
         12 . The substrate of  claim 1 , wherein the top coating is a dense vertically cracked coating. 
     
     
         13 . A substrate having a protective coating with improved strain tolerance and cyclic spallation life comprising:
 a bond coating attached to the substrate;   a micro-roughening network on a surface of the bond coating; and   a top coating adhered to the micro-roughening network;   wherein the micro-roughening network is obtained when an inert gas is ionized and caused to flow into the surface of the bond coating by a reverse polarity current supplied by an electrode that removes at least one electron from the inert gas.   
     
     
         14 . The substrate of  claim 13 , wherein the ionized inert gas that flows into the surface of the bond coating roughens the surface of the bond coating. 
     
     
         15 . The substrate of  claim 14 , wherein the surface of the bond coating has a roughness that is between about 75 microinches Ra to about 750 microinches Ra. 
     
     
         16 . A protective coating comprising:
 a bond coating having a first surface roughness; and   a top coating adhered to the bond coating; and   a micro-roughening network surface at an interface of the bond coating and the top coating, wherein the micro-roughening network surface has a second surface roughness greater than the first surface roughness;   wherein the micro-roughening network surface is obtained when an inert gas is ionized and caused to flow into a surface of the bond coating by a reverse polarity current supplied by an electrode that removes at least one electron from the inert gas.   
     
     
         17 . The protective coating of  claim 16 , wherein the bond coating comprises a bond coating material selected from the group consisting of modified or alloyed aluminides, CrAl, PdAl, PtAl, simple aluminide, silicon modified aluminides, and over aluminized MCrAlY. 
     
     
         18 . The protective coating of  claim 16 , wherein the top coating comprises a ceramic material selected from the group consisting of yttria, magnesia, ceria, scandia, and rare earth oxide partially stabilized zirconia. 
     
     
         19 . The protective coating of  claim 16 , wherein the second surface roughness is between about 75 microinches Ra to about 750 microinches Ra. 
     
     
         20 . The protective coating of  claim 19 , wherein the second surface roughness is between about 150 microinches Ra to about 450 microinches Ra.