Adhesion measurement procedures for kinetic and thermal spray coatings using a stud-pull tester

This paper reports on the use of an epoxy-coated stud-pull device to perform adhesion measurements on kinetic and thermal spray coatings for metal/metal and metal/ceramic systems. Four different methods were used for testing. The first method used the stud-pull device without a retaining cylinder pushing against the coating. The second method used a retaining cylinder. In the third method the coating was machined by electric discharge machining (EDM) to form a disc-like structure with a diameter identical to that of the epoxy-coated stud. The fourth method replaced the EDM machining by controlled rotary-disc cutting using SiC slurry to machine a disc-like structure in the coating. The first two methods gave a relatively consistent measurement of adhesion, provided the coating thickness is less than 2.5% of the stud diameter. For thicker coatings, both the third and fourth methods are recommended.