摘要
采用金属型铸造了3种成分的梯形高电位Mg-Mn牺牲阳极。通过模拟土壤环境中[饱和CaSO4-Mg(OH)2溶液]的恒电流腐蚀试验,研究了Mg-Mn牺牲阳极的腐蚀行为。结果表明,Mg-Mn牺牲阳极中杂质元素存在较大的溶质偏析和明显的晶粒尺寸差异,导致距离模具表面不同距离处的电流效率不同。杂质元素在晶界上不均匀分布,使Mg-Mn阳极产生晶间腐蚀,第二相粒子不均匀程度越大,未腐蚀部分机械剥落越严重,从而加大阳极的质量损失,降低了阳极的电流效率。腐蚀形貌观察发现,当Mg阳极表面呈现出条状的蚀坑时,机械剥落现象严重,腐蚀很不均匀,电流效率较低,仅为41%;Mg阳极的表面蚀孔孔径越细小,分布越均匀,电流效率越高。
Three ladder Mg-Mn sacrificial anodes with different chemical compositions were poured by permanent mold.The corrosion behavior was investigated by galvanostatic corrosion test in saturated calcium sulfate-magnesium hydroxide solution.The results indicate that：the impurity elements are severe due to the solute segregation,and the grain sizes distributed heterogeneously result in the un-evern current efficiency at different distance to the surface of the metal mold.The impurity elements are formed into the intermetallic phases locally distributed at the grain boundaries,resulting in the intergranular corrosion of magnesium sacrificial anode.Furthermore,with the increase of heterogeneous degree of secondary phase size,the mechanical spalling at un-corrosion position is promoted,resulting in the increase of weight loss of the anode and decreasing the electric current efficiency.The corrosion morphology observation reveals that the more localized strip-shaped etch pits are formed on the surface of the magnesium anode with more serious mechanically spalling and heterogeneous corrosion,resulting in the lowest current efficiency of 41%.With the decrease of diameter of corrosion
出处
《特种铸造及有色合金》
CAS
CSCD
北大核心
2012年第10期886-889,共4页
Special Casting & Nonferrous Alloys
基金
陕西理工学院基金资助项目(SLGQD0745)
关键词
金属型铸造
高电位
牺牲阳极
含量
点蚀
Metal Mold Casting, High Open-Potential, Mg-Mn Sacrificial Anode, Silicon Content, PittingCorrosion
