Effect of TZVCC drying temperature on the adhesion performance of the epoxy coating on AA6063

ABSTRACT

A multi-metal Ti/Zr/V based conversion coating was employed to improve the adhesive strength of the epoxy coating on aluminum alloy 6063 (AA6063). The drying temperature of Ti/Zr/V conversion coating (TZVCC) was studied as a factor that could influence the adhesion performance of the epoxy coating on the substrate. The surface morphologies, cross-section micrograph and chemical compositions of different samples were fully characterized by scanning electron microscope (SEM), transmission electron microscopy (TEM) and energy disperse spectroscopy (EDS), respectively. The tape measurement and pull-off tests were used to investigate the adhesive strength of samples under three conditions (dry, wet and recovery). The TZVCC after conversion treatment for 50 s had a golden appearance and exhibited a smooth and compact structure. Drying the TZVCC at high temperature could reduce the sizes of the holes disposed on the TZVCC/epoxy coating interface, as well as improve the adhesive strength. The highest pull-off strength was obtained at drying temperatures of 80°C, 100°C and 100°C for dry, wet and recovery conditions. TEM results revealed that the epoxy resin powder would permeate into TZVCC during the curing process, which significantly improved the adhesive strength of the epoxy coating on the matrix.

KEYWORDS:

• Adhesion
• aluminum and alloys
• conversion coating
• drying temperature
• epoxy

Acknowledgements

This work is supported by the Fundamental Research Funds for the Central Universities (grant No. 2015ZZ069) and Funds from the Dongguan University of Technology (grant No. GC300502-45).