采用电化学试验、表面形貌观察、腐蚀产物分析等方法研究了磷酸氢二钠(DSP)和D-葡糖酸钠(GS)两种物质复配后对镁合金在50％(体积分数,下同)乙二醇型冷却液中的缓蚀作用.结果表明:DSP对AZ91D镁合金在50％乙二醇冷却液中是一种混合抑制型缓蚀剂,GS对AZ91D镁合金在50％乙二醇冷却液中没有缓蚀作用;DSP和GS之间存在缓蚀协同效应,复配后的缓蚀剂是一种以抑制阳极过程为主的混合型缓蚀剂;GS的添加量存在极值,而DSP和GS的质量浓度比达到4∶1时,即复配缓蚀剂E,其缓蚀率趋于稳定;随着复配缓蚀剂E加入量的增大,缓蚀率增大,其加入量为2.5 g/L时,缓蚀率高达90％以上;复配缓蚀剂E对AZ91D镁合金起到缓蚀作用主要表现为形成了MgHPO4沉淀物,通过GS络合在镁合金表面,从而抑制了镁合金在乙二醇冷却液中的腐蚀.
Electrochemical methods,surface morphology observation and corrosion product analysis were used to inverstigate the inhibition of combined inhibitors compound by dibasic sodium phosphate (DSP) and gluconate sodium (GS) on AZ91D magnesium alloy in 50％ (volume) ethylene glycol coolant.The results show that DSP is a mixed type corrosion inhibitor for AZ91D magnesium alloy in 50％ ethylene glycol coolant.GS has no corrosion inhibition.There exists synergistic effect between DSP and GS,it is a combined inhibitor with mainly controling the anodic process..It tended to be a stable inhibition ratio as the mass concentration ratio of DSP to GS was 4 ∶ 1 i.e.,combined inhibitior E.With the increase of the content of combined inhibitor E,inhibition efficiency increased,when 2.5 g/L was added,the inhibition efficiency reached above 90％.The corrosion effect of the mixed inhibitor for AZ91D was to form MgHPO4,which may form a complex on the AZ91D surface due to the action of GS,and then depressed the corrosion of AZ91D in ethylene glycol coolant.
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