用失重法和电化学方法测定了Cr13和Cr26两种高铬铸铁在热 强碱介质中的腐蚀.电位-时间曲线显示两种材料在介质中的电位均出现高-低-高的变化，表 明材料腐蚀趋势在不同的浸泡时间发生变化；不同材料各电位段历时不同，Cr13第一个高电 位段仅数分钟，而Cr26约10 h；由极化曲线法所获得的仅是测试瞬时(对Cr13是低电位段的 某瞬时，对Cr26是第一高电位段某瞬时)的腐蚀速度，与失重法获得的浸泡时间的平均腐蚀 率有差别；用局部阴极极化曲线和电位-时间曲线相结合的方法估计的腐蚀率在远离析氢区 域测试时与失重法测定的结果有一定比例关系，前者约大一倍，可加修正系数后尝试代替失 重测量，但在析氢区域附近，由于Au电极的氢超电势比铸铁材料低，两种方法测试的结果差别较大.
The corrosion behavior of two types of cast iron,Cr 13 and Cr26 in hot alkaline solution was measured by weight loss and electrochem ical methods.Potential-time curves showed that potential changes from higher to lower then to higher in the medium while potentials of the two materials were di fferent in each period.In the first period,high potential lasted several minutes for Cr13 and about 10 hours for Cr26.The corrosion rates deduced by polarizatio n curves were instantaneous(at some point for Cr13 in lower potential period and for Cr26 in the first higher potential period)and were quite diff erent from the results by weight loss method.In the range far from potential of evolving hydrogen the rates deduced by combination of cathode polarization curve of Au and potential-time curves were twice as great as those deduced by weight loss method.So the former could take place of the latter with a coefficient of a bout 2.Near the potential of evolving hydrogen the difference of resul ts by two methods was remarkable,which may be considered as the result of the hydrogen overpotential on Au lower than that on the cast irons.
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