HU Tingting, CHEN Guoqing, LI Minghao, FU Xuesong

(Dalian University of Technology, Dalian 116085, Liaoning, China)

Abstract: Using sodium silicate (Na₂SiO₃) as a binder and SiO₂, MgO, Al₂O₃, Na₂O, CaO powders as the ceramic aggregate, an enamel-coating was deposited on 316L stainless steel substrate by using a slurry method. The effect of sintering temperature ranging from 600 ℃ to 800 ℃ on microhardness, thermal shock resistance and the corrosion resistance of the ceramic coating were studied. When the sintering temperature was 750 ℃, four chemically stable and corrosion-resistant phases, including Al₂SiO₅, 3Al₂O₃·2SiO₂, Ca₂SiO₄ and Mg₂Al₂O₅, were formed in the coating. As the sintering temperature was increased from 600 ℃ to 800 ℃, the microhardness was increased from 65 HV to 371 HV. When the sintering temperature was increased from 600 °C to 750 °C, the self-corrosion potential of the ceramic coating was increased from -0.530 V to -0.379 V, while the self-corrosion current density was reduced from 26 μA to 5.6 μA, which indicated that the corrosion resistance of the ceramic coating was enhanced. After thermal shock resistance experiments at 700 ℃ for 20 times, the ceramic coating sintered at 750 ℃ did not fall off, which ensured a good thermal shock resistance and good combination with the matrix.
Key words: slurry method; stainless steel; enamel coating; thermal shock resistance; the corrosion resistance