Process for applying a thermal barrier coating to a ceramic matrix composite

A method of bonding an insulation layer to a CMC layer, comprising:

• forming a layer of CMC material;
• firing the CMC layer to an intermediate stage of curing effective to leave a known amount of sintering shrinkage for a final firing stage;
• wetting a front surface of the CMC layer with an oxide forming binder;
• applying a first primer coat to the front surface of the CMC layer that is effective to increase sintering activity of the front surface of the CMC layer;
• applying a joining material to the first primer coat on the front surface of the CMC layer;
• drying and firing the joining material to an intermediate stage effective to produce a joining layer that comprises a plurality of cracks oriented generally perpendicular to the front surface of the CMC layer;
• wetting a front surface of the joining layer with the oxide forming binder;
• applying a second primer coat to the front surface of the compliant joining layer that is effective to increase sintering activity of the front surface of the joining layer;
• applying an insulation material to the second primer coat on the front surface of the joining layer;
• and
• drying and final firing the CMC layer, the joining layer, and the insulation material together under controlled conditions effective to finally cure and bond them together forming a material system, the plurality of cracks in the joining layer effective to relieve differential shrinkage stress between the CMC layer and the insulation material.