氮化硅掺杂环氧树脂复合涂层的制备及耐腐蚀性能研究

Preparation of Silicon Nitride Doped Epoxy-based Composite Coatings and Their Corrosion Resistance

目的将氮化硅作为填料加入环氧树脂,提高碳钢Q235有机涂层的耐腐蚀性能。方法利用球磨法将氮化硅填料均匀分散在环氧树脂中,探究了不同氮化硅含量涂层对Q235碳钢基体的保护,利用电化学阻抗谱(EIS)、吸水率实验、附着力实验及盐雾实验表征不同氮化硅含量涂层在3.5%NaCl溶液中的耐腐蚀性能。结果添加氮化硅后,涂层的低频阻抗模值及干湿态附着力均有不同程度提高。同时,氮化硅的加入降低了涂层的吸水率,增加了涂层的耐盐雾时间。浸泡初期(0.5 h),环氧树脂涂层(不含氮化硅)的低频阻抗模值为7.7×10~8?·cm^2,添加氮化硅的涂层的低频阻抗模值均增加了两个数量级,氮化硅含量为5%涂层的低频阻抗模值最大,为8.6×10^(10)?·cm^2。随着浸泡时间的增加,不同氮化硅含量的涂层低频阻抗模值均有不同程度的降低。其中,氮化硅含量(占环氧树脂质量的百分比,后文同)为5%的涂层的低频阻抗模值降低程度最小。浸泡2400 h之后,氮化硅含量为5%的涂层的低频阻抗模值最高,仍然能够达到3.3×10~8?·cm^2。结论氮化硅填料的加入提高了涂层的耐腐蚀性能,一定程度上可以保护金属基体免受腐蚀破坏。并且,当氮化硅含量为5%时,涂层的耐腐蚀性能最好。

The work aims to improve corrosion resistance of carbon steel Q235 organic coatings by adding silicon nitride （Si3N4） to epoxy resin as a kind of filler. Silicon nitride was uniformly distributed in epoxy resin in the method of ball milling. The protective effect of coatings with different silicon nitride content （on the basis of mass fraction） on Q235 carbon steel sub-strate was studied. Corrosion resistance of coatings with different silicon nitride content in 3.5% NaC1 solution was characte- rized based upon electrochemical impedance spectroscopy （EIS）, water absorption experiment, adhesion experiment and salt spray test. Low frequency impedance modulus and pull-off adhesion in dry-wet state of the coatings were improved by adding silicon nitride. At the same time, the addition of silicon nitride reduced water absorption of and improved salt spray resisting time of the coatings. Initially （0.5 h）, low frequency impedance modulus of the epoxy resin coating （0% silicon nitride） was 7.7× 10 8 Ω·cm2. The low frequency impedance modulus increased by two orders of rnagnitude after the addition of silicon ni- tride, but that of 5% coating was the maximum, 8.6× 1010·cm2. With the extension of immersion time, low frequency im- pedance modulus of the coatings decreased inordinately, and that of the 5% coating was the minimum. After 2400 h immersion, low-frequency impedance modulus of the 5% coating was the maximum, 3.3 ×10 8 ·cm2. In conclusion, the addition of silicon nitride filler can improve corrosion resistance of the coatings, and protect the metallic substrate against corrosion to certain extent. When the silicon nitride content is 5%, the coatings exhibit the best corrosion resistance.