Shear testing for characterizing the adhesive and cohesive coating strength without theneed of adhesives

摘要

The characterization of the adhesive and cohesive strength of thermally sprayed coatings is often evaluatedaccording to given standardized testing procedures. These tests require the preparation of normally large couponswhich have to be fixed together using an appropriate adhesive. Additionally they need time for preparation (e.g.Annealing/curing of the adhesive) and require test equipments normally not available at job shops for coatingdevelopment. One of the largest limitations of these tests is the applicability only for non-porous coatings, and insome cases the limited strength of the adhesive.Within a European CRAFT research project on "standards, measurements and testing", a new shear test methodwas developed to characterize the mode and value of failure of thermally sprayed layers in a more reliable and lesslimited manner. This new shear test does not need any adhesive and yields more intrinsic information on coatingquality than conventional tensile tests.