Boundary where the coating meets the base metal, inspected in cross section for contamination, embedded grit, oxide films, gaps and cracks. A clean, tight bond line with full contact over the blasted profile indicates good preparation. Failures that run along it are adhesive failures, usually traced back to cleaning, blasting or time between blast and spray.
There's a dark film right along the bond line, something was on that surface before we sprayed.
Also heard as
- interface
- bondline
- coating interface
Related terms
Embedded grit
Abrasive particles left stuck in the substrate after blasting, visible at the bond line in a cross section.
Adhesive failure
A bond test break at the coating-substrate interface, meaning the coating let go of the base metal.
Bond coat
The first layer sprayed on a substrate to help the following coat stick and sometimes protect the metal.
Mount
A polished cross section of a coated coupon set in resin, used to check structure under the microscope.