Turbine engine, engine structure, and method of forming an engine structure with thermal barrier coating protection
A turbine engine, an engine structure, and a method of forming an engine structure are provided herein. In an embodiment, an engine structure includes a metal substrate, a thermal barrier coating layer, and a metal silicate protective layer. The thermal barrier coating layer overlies the metal substrate, and the thermal barrier coating layer has columnar grains with gaps defined between the columnar grains. The metal silicate protective layer is formed over the thermal barrier coating layer, and the metal silicate protective layer covers the columnar grains and the gaps between the columnar grains.
1. An engine structure comprising:
a metal substrate;
a thermal barrier coating layer overlying the metal substrate, wherein the thermal barrier coating layer has columnar grains with gaps defined therebetween; and
a metal silicate protective layer formed over the thermal barrier coating layer, wherein the metal silicate protective layer covers the columnar grains and the gaps between the columnar grains, wherein the metal silicate protective layer comprises metal silicate in an amount of at least 98 wt. % based on the total weight of the metal silicate protective layer, wherein a metal in the metal silicate is chosen from zirconium, hafnium, and combinations thereof, and wherein the metal silicate protective layer is in crystalline form.
2. The engine structure of claim 1 , wherein the thermal barrier coating layer is further defined as a zirconia-based layer comprising the columnar grains.
3. The engine structure of claim 2 , wherein the zirconia-based layer comprises yttrium-stabilized zirconia.
4. The engine structure of claim 2 , wherein a metal in the metal silicate protective layer is chosen from hafnium and a combination of hafnium and zirconium.
5. The engine structure of claim 2 , wherein the metal silicate protective layer is disposed directly upon the zirconia-based layer.
6. The engine structure of claim 1 , further comprising a bond coat disposed between the thermal barrier coating layer and the metal substrate.
7. The engine structure of claim 1 , wherein the metal substrate comprises at least 50 weight % of one or more elemental metals, based on the total weight of the metal substrate.
8. The engine structure of claim 1 , wherein the metal silicate protective layer has a thickness of from about 1 to about 25 microns.
9. The engine structure of claim 1 , wherein the metal silicate protective layer has an exposed surface free from additional layers overlying the exposed surface.
10. The engine structure of claim 1 , further defined as a rotating component of a turbine engine.
11. A method of forming an engine structure, the method comprising the steps of:
providing a metal substrate;
forming a thermal barrier coating layer overlying the metal substrate, wherein the thermal barrier coating layer comprises columnar grains with gaps defined therebetween;
forming a metal silicate protective layer over the thermal barrier coating layer, wherein the metal silicate protective layer covers the columnar grains and the gaps between the columnar grains in the thermal barrier coating layer, and wherein the metal silicate protective layer comprises metal silicate in an amount of at least 98 wt. % based on the total weight of the metal silicate protective layer, and wherein a metal in the metal silicate is chosen from zirconium, hafnium, and combinations thereof; and
converting the metal silicate protective layer into crystalline form through post-formation heat treatment.
12. The method of claim 11 , wherein forming the metal silicate protective layer comprises sputtering a metal silicate over the thermal barrier coating layer to form the metal silicate protective layer.
13. The method of claim 11 , wherein forming the thermal barrier coating layer comprises forming zirconia-based thermal barrier coating layer over the metal substrate.
14. The method of claim 13 , wherein forming the metal silicate protective layer comprises depositing a metal silicate chosen from hafnium and a combination of hafnium and zirconium.
15. The method of claim 11 , wherein forming the thermal barrier coating layer comprises physical vapor depositing a thermal barrier coating material over the metal substrate to produce the columnar grains with the gaps defined therebetween in the thermal barrier coating layer.
16. The method of claim 11 , wherein providing the metal substrate comprises forming the metal substrate into a shape of the engine structure for a turbine engine.