Tape Casting and Characterization of h-BN/PU Composite Coatings for Corrosion Resistance Applications

Abstract

In the present work, a slurry of polyurethane (PU) was prepared by adding various contents (3 and 8 wt.%) of hexagonal boron nitride (h-BN). Ethanol was utilized as a solvent to reduce the viscosity and sticking effect of the PU. The mixture was then applied as polymer matrix composite (PMC) coating on steel substrates via tape casting. The prepared coatings were characterized for their structure, adhesion and thermal properties, and corrosion resistance characteristics. The structural and morphological features of the h-BN/PU composites were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Rockwell-C adhesion tests were conducted to examine the adhesion between the substrate and composite coating. The potentiodynamic polarization tests were utilized to assess the anti-corrosion performance of composite coatings when applied and steel substrates. The results exhibited that the inclusion of h-BN filler (3 wt.%) could effectively enhance the anti-corrosion performance of the h-BN/PU composite. The reason for the improvement in corrosion properties was attributed to lower surface roughness, uniform distribution and great adhesion strength of PU/3 wt.% h-BN composite. Furthermore, the PU/3 wt.% h-BN composites showed relatively improved thermal stability and higher glass transition temperature (Tg). However, further loading of h-BN contents (8 wt.%) deteriorates the thermal and corrosion resistance properties of the composite due to the clustering of h-BN, which creates localized areas of increased corrosive activity.