Mechanical properties and oxidation corrosion resistance of phosphate ceramic coating enhanced by SiO2-BNNSs material

A method of preparing SiO2-BNNSs hybrid material by surface modification of boron nitride nanosheets (BNNSs) with SiO2 was proposed to improve the dispersion of BNNSs in the coatings. Then, phosphate ceramic coatings with BNNSs and SiO2-BNNSs were prepared on stainless steel (304) by spraying. Characterization of BNNSs and SiO2-BNNSs by X-ray diffraction, Fourier transform-infrared, Raman, and scanning electron microscopy proved the success of hybridization. The surface morphology and mechanical properties were conducted to characterize the protective performance of the coating. Simultaneously, the phase composition and electrochemical properties of the coatings after high-temperature oxidation were studied. The results showed that ceramic coatings had low surface energy with a contact angle of 102.41 degrees when .4 wt.% SiO2-BNNSs was added. Compared with BNNSs coating, the mechanical properties of SiO2-BNNSs coating were significantly enhanced, the hardness of .4 wt.%SiO2-BNNSs coating was as high as 170 HV, and the interface bonding strength was 12.24 MPa. For the oxidation corrosion resistance, .4 wt.% SiO2-BNNSs coating under oxidation at 400 degrees C for 50 h had the minimum corrosion current density and maximum impedance, which were .864 mu A/cm(2) and 177 k Omega/cm(2), respectively, this indicated that SiO2-BNNSs coating could still maintain excellent oxidation corrosion resistance under high-temperature conditions for a long time.