Mechanical and anti-corrosive properties of hybrid sol-gel coatings

 
The market for coatings is rapidly changing and growing due to regulations and new requirements.[1] Therefore, hybrid materials that can be utilized on nearly any surface without extensive pretreatment procedures are the focus of this work. Coatings were deposited and functionalized by varying conditions during the synthesis and drying. Different fillers, like zinc dust, micaceous iron ore and talcum powder were added to enhance the properties further.[2] The coatings provide a barrier that can reduce and prevent corrosion of metallic surfaces. To optimize mechanical stability, the DoE approach was used.[3,4] Coatings were synthesized via the sol-gel process, where factors such as temperature, pH, ratio of reactants, amount of water and many more influence the properties of the product.[5] Through DoE interaction between factors as well as nonlinear behavior could be observed. Various target variables were examined, including layer thickness, adhesion and cross-cut performance. Besides, the coatings were analyzed with IR and impedance spectroscopy, as well as potentiodynamic measurements. Scanning electron microscopy indicates how particles are embedded within the coating, how failure mechanisms and coating degradation might occur. An outdoor weathering test was performed and evaluated. The results indicate an outstanding performance for the hybrid materials for the first two month. Sol-gel coatings are a promising alternative for chromate-free protection of metallic substrates and can compete with purely organic coatings. The inorganic network is not decomposed by sunlight and is more temperature stable. This, along with further functionalization and optimization, will lead to improved hybrid coatings suitable for challenging applications.