Thin first layer, typically 75 to 150 micrometers, placed between substrate and functional coating. General-purpose bond coats such as nickel-aluminum, nickel-chromium and molybdenum bond well to blasted metal and give the top coat a rough base. Under thermal barriers the bond coat is usually an MCrAlY or aluminide that also resists oxidation and grows the protective oxide the ceramic sits on.
Bond coat's on, give it a minute to cool and go straight to the ceramic, don't let it sit.
Shoot the top coat soon after the bond coat; a bond coat left sitting for hours picks up moisture and dust and loses grip on the next layer.
Also heard as
- bond
- bondcoat
- prime coat
- undercoat
Do not mix it up with
- Bond line: The bond coat is a sprayed layer, while the bond line is the interface where a coating meets the substrate.
Related terms
Top coat
The outer, functional layer of a multilayer coating, sprayed over the bond coat.
MCrAlY
Family of oxidation-resistant alloys of nickel or cobalt with chromium, aluminum and yttrium.
Nickel aluminum
Nickel-aluminum composite that reacts in the flame to give a strongly bonded first layer.
TGO
Thermally grown oxide: the alumina layer that grows between bond coat and ceramic in hot service.