Enhancement of interfacial corrosion resistance between aluminum powder–modified zinc silicate–potassium silicate coating and steel bars for sand-based autoclaved aerated concrete

Organic coatings cannot provide long-term corrosion protection to steel bars in sand-based autoclaved aerated concrete because they are prepared at high temperatures and pressures. Herein, potassium silicate, zinc silicate, and aluminum powder were used as the raw materials to prepare inorganic aluminum powder–modified zinc silicate–potassium silicate coatings with anticorrosive properties. The physical, mechanical, microscopic, and anticorrosion properties of the prepared inorganic coatings were investigated using X-ray diffraction, Fourier-transform infrared spectroscopy, Raman spectroscopy , thermogravimetry–differential scanning calorimetry, scanning electron microscopy, electrochemical impedance spectroscopy , and potentiodynamic polarization. The results showed that aluminum powder increased the density of the zinc silicate–potassium silicate coatings and significantly improved the corrosion resistance and mechanical properties of the coatings. The prepared coatings exhibited stable qualities with no heat absorption and release before 317°C. The adhesive strength and impact resistance of the coatings were as high as 1.65 MPa and 50 kg·cm, respectively. The electrochemical test results showed that the coating resistance ( R c ), charge-transfer resistance ( R ct ), and polarization resistance ( R p ) of the 5.5–50Zn 2 SiO 4 –40Al coating were 7835, 135,915, and 89,568 Ω·cm 2 , respectively, which exhibited the optimal corrosion resistance.