Composite thermal barrier coating

A component comprising:

• a substrate presenting a surface;
• and
• a composite thermal barrier coating including:
• a first layer bonded to the surface of the substrate;
• a second layer bonded to the first layer;
• wherein the second layer comprises a plurality of hollow microspheres defining a porous structure;
• and
• a third layer bonded to the second layer;
• wherein the third layer is non-permeable to combustion gases such that the third layer seals against the second layer.

An internal combustion engine comprising:

• a component configured to be subjected to combustion gasses, the component including:
• a substrate presenting a surface;
• and
• a composite thermal barrier coating including:
• a first layer bonded to the surface of the substrate;
• a second layer bonded to the first layer;
• wherein the second layer comprises a plurality of hollow microspheres defining a porous structure;
• and
• a third layer bonded to the second layer;
• wherein the third layer is non-permeable to combustion gases such that the third layer seals against the second layer.