GB/T 8642-2025 Thermal spraying—Determination of tensile adhesive strength

Scope

This document describes the method of tensile testing and establishes the procedure for applying tensile force to the coating in a direction perpendicular to the coating surface to determine the tensile bond strength of thermal spray coatings. By using this procedure, the comparability of test results is ensured.
This test is designed to determine the tensile bond strength between the thermal spray coating and the substrate, or between the bonding layer and the surface layer, as well as the cohesive strength of the related coatings in the coating system. In some cases, thermal spray coatings contain two or more layers. The method specified in this document can also be used to determine the tensile bond strength of such two-layer or multi-layer coatings at different coating interfaces.
This test is sufficient to compare coatings prepared using the same or similar raw materials and thermal spray processes. The tensile bond strength test does not provide absolute values for evaluating the durability of coatings in use.
This document is applicable to assessing the impact of substrate pretreatment, spraying conditions, and process parameters on the tensile bond strength of thermal spray coatings, as well as monitoring the consistency of production and spraying processes.
Note: This tensile test can also be applied to very thin coatings. In addition, selecting appropriate adhesives (sheets rather than liquids) can minimize the penetration of adhesives into thermal spray coatings with specified porosity. For more details, see 6.5.3. Due to the high bond strength of self-fusing alloys, this tensile test is not suitable for determining the bond strength of thermal spray self-fusing alloy coatings after remelting treatment.

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