Effect of Temperature on the Morphology and Corrosion Resistance of Modified Boron Nitride Nanosheets Incorporated into Steel Phosphate Coating

In this study, the impact of various temperatures (25 °C, 45 °C, and 55 °C) on q235 steel specimens was studied to analyze the influence on the morphology and corrosion resistance of modified boron nitride nanosheets incorporated into the phosphate coating. The morphology and surface modification of the coating were characterized by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). SEM results showed that the S-45 steel sample produced a higher number of nucleation sites and reduced grain size with a denser, more robust, and more corrosion-resistant phosphate coating compared to the S-25 and S-55 samples, respectively. The potentiodynamic polarization results demonstrate that the S-45 steel sample exhibited the best corrosion resistance performance with an electric current density of 5.48 × 10−8 A/cm2, an order of magnitude lower than the S-25 and S-55 samples, respectively. The coating weight results showed that the S-45 steel specimen achieved the densest and most uniform coating (32.14 g/m2).