Thermal Spraying - Determination of Tensile Adhesive Strength
|Publication Date:||1 March 2017|
|ICS Code (Surface treatment):||25.220.20|
This document specifies the procedure to determine the tensile adhesive strength of thermally sprayed coatings under tension in the direction normal to the surface of the coating by applying a tensile test. By using this procedure, comparability of the test results is ensured.
The test is intended to determine the tensile adhesive strength between the thermally sprayed coating and the substrate material or between the bond and top coat and/or of the cohesive strength of the related coat of the coating system. In some cases, thermally sprayed coatings might have more than two layers. The method specified in this document applies also to determine the tensile adhesive strength between the interfaces of different layers in a coating system which consists of more than two layers.
This test is sufficient to compare coatings manufactured using same or similar feedstock materials and thermal spray processes with each other. The tensile adhesive strength test is not intended to provide absolute values for evaluation of the durability of coatings under operational use.
The test is used to assess the influence of substrate preparation, the spraying conditions and the process parameter on the tensile adhesive strength of thermally sprayed coatings. It can also be employed in order to monitor the consistency of the manufacturing and spraying processes.
NOTE This tensile test can also be applied to very thin coatings. Moreover, the infiltration of bonding agent into the thermally sprayed coatings containing a required level of porosity can be minimized using an appropriate bonding agent (foil rather than liquid). For further instructions, please refer to 6.5.3. This tensile test is inappropriate for determining the adhesive strength of fused spray coatings deposited using self-fluxing alloys due to their inherent high adhesion strength values.