超音速火焰喷涂及封孔处理对低合金钢抗中性盐雾腐蚀性能的影响

通过电化学极化测试和中性盐雾试验,研究了300 M低合金钢上空气助燃的超音速火焰喷涂(HVAF)WC/17Co、WC/10Co4Cr涂层及硅氟树脂封孔处理后的抗腐蚀性能,并和电镀硬铬(EHC)的性能进行对比.中性NaCl溶液电化学极化测试结果表明,涂层处理明显提高了低合金钢的腐蚀电位.400h中性盐雾腐蚀结果表明,基体和涂层处理后抗腐蚀顺序依次为:WC/10Co4Cr 封孔＞WC/10Co4Cr＞EHC＞WC/17Co 封孔＞WC/17Co＞基体.腐蚀后的SEM观察发现,腐蚀介质先腐蚀涂层中的粘结相,当其扩散到基材表面则优先腐蚀基体.

Effect of High - Velocity - Air- Flame Spraying and Sealing with Silicon-Fluorine Resin on Corrosion Resistance of Low Alloyed Steel in Neutral Salt Fog

Electrochemical polarization measurement and neutral salt fog test were carried out to investigate the corrosion resistance of high-velocity-air-flame (HVAF) sprayed WC/17Co and WC/10Co4Cr coatings before and after sealing with silicon-fluorine resin on low alloyed 300M steel substrate. The corrosion resistance of the HVAF coatings was also compared to that of electroplated hard chromium coating (EHC). The morphologies of the corroded surfaces of the coatings were observed using a scanning electron microscope. It was found that the HVAF coatings had much better corrosion resistance than the steel substrate. The corrosion resistance determined by neutral salt fog test was ranked as WC/10Co4Cr+sealing treatment>WC/10Co4Cr>EHC>WC/17Co+sealing treatment>WC/17Co>300M steel. The adhesive phase in the coatings experienced preferential micro-electrochemical corrosion at the early stage of corrosion test. However, when the corrosive medium started to attack the coating-substrate interface, the substrate would experience preferential corrosion.