Developments on Standard Cross-Cut/Tape Adhesion Test

Regarding the qualitative nature of the Cross-Cut/Scotch Tape standard test, and its limitation within classifying the modes of coating separation, this project was proposed to: 1- extend the qualitative limits in the reference table of the test standards by decreasing the lattice angles of cuttings and therefore, to introduce new coating separation mode classifications, 2- investigate about any possible relations could exist between the failure modes and the above angles, i.e. to modify the test to a semi-quantitative level and 3- present any empirical relationships might exist between the coating adhesion strength and the developed references table of failure modes. For this a large number of samples of different coatings and substrates were obtained. Specimens were prepared by creating cut lattices of angles: 90o, 60o, 45o, 30o and less. The Pull off standard tensile tests, near the crosscut locations was preformed. The corresponding results with the aim to attain the above aims were compared and studied. Results showed that by decreasing cross cut or lattice angles, the area of failures in the region of lattice tips increased. But the failure area along the cut lines did not change notably. It was also observed that as adhesion strength decreased, the coating separation area increased. In general, the coating and substrate mechanical properties had considerable effects on evaluating adhesion failure modes. It was concluded that, if lower cross cut angles were introduced into the cross cut test, intermediate failure classes and new grades, such as: 6, 7 and above, might be added to the test classification table. The other achievement in this research, which could be proposed, was the possible assessments of the adhesion strength of layers existing in the coated surfaces. This still require more work to be done

Developments on Standard Cross-Cut/Tape Adhesion Test Keywords:

Coss-cut , Ahdesion , Test