Metallographic specimen in which a sectioned coupon or part is embedded in epoxy or phenolic, ground and polished to show the coating in cross section. Under the microscope it reveals thickness, porosity, oxides, unmelts, cracks and bond line condition. Coatings are often vacuum impregnated with low-viscosity epoxy before cutting to support pores and stop pullout.
Mount on the bond coat coupon looks clean, porosity's low, no grit at the interface, start production.
Also heard as
- met mount
- cross section
- metallographic mount
- puck
Related terms
Porosity
The fraction of a coating's volume made of voids between and within splats, usually reported in percent.
Pullout
Particles torn out of a coating during polishing, leaving holes that look like porosity in the mount.
Coupon
A small test piece sprayed alongside production parts to stand in for them in destructive tests.
Unmelts
Lab shorthand for particles that hit the surface without fully melting and kept their round shape.
Embedded grit
Abrasive particles left stuck in the substrate after blasting, visible at the bond line in a cross section.