Development and Characterization of Pre-treatment Process to Enhance Dye Affinity and Corrosion Resistance for Metal Surfaces
Project no. 20305 · Status: Kapanmış (Yayın bekleniyor) · 2018
Summary
It is aimed to develop a chromate-free, environmentally friendly and industrially practicable pre-treatment process to advance the corrosion resistance and paintability of galvanized steel and aluminum surfaces where coil coatings are widely applied. In accordance with this purpose, the silane coating solution containing three different silane sources ?-glycidoxypropyltrimethoxysilane (?-GPS), 3- Aminopropyltriethoxysilane (APTES) and tetraethyl orthosilicate (TEOS) was prepared by following sol-gel hybrid inorganic-organic method. Galvanized steel and aluminum surfaces, which have been removed from oil and dirt, were coated with the prepared silane solution and then cured. A melamine-based primer and topcoat were also applied to the pre-treated surfaces after completion of the pre-treatment step. Additionally, metal surfaces coated with both commercial phosphate and sol-gel pretreatment materials were evaluated in comparison with our existing silane pretreatment study. As parameters, effect of the pH and silane content on film forming properties were chosen . Chemical structures of the silane sol-gel pretreatment mixture was characterized by FTIR (Fourier transform infrared spectroscopy) while the thermal behaviours of the pretreatment material was investigated by using TGA-DSC (Thermal gravimetric and differential thermal analyzer) were investigated. The metal-paint adhesion was determined by mechanical tests such as impact, tensile and t-bending tests. On the other hand, corrosion evaluations were carried out in the salt spray and condensing humidity chambers. As a result of these tests, it can be concluded that the surfaces which were hydrolyzed for 24 hours and containing 4 v.% silane (?- GPS,APTES,TEOS) had a performance similar to the conventional phosphate pretreatment.