采用单因素实验和正交实验,以腐蚀深度量为评价指标,研究了污泥的p H值和含水率,以及腐蚀温度、腐蚀时间和污泥种类对干燥器用两种金属腐蚀行为的影响规律。采用极差和方差分析,给出了各因素影响的主次顺序和不同因素对金属腐蚀影响的显著性,最后通过SEM和EDX对腐蚀产物进行表征。结果表明:Q235碳钢的腐蚀深度量随着温度、污泥含水率和污泥酸度的增加而逐渐增加;各因素对金属腐蚀深度量的影响主次顺序为:钢材种类、温度、污泥p H值、时间t、污泥种类;最大腐蚀条件为:腐蚀温度为100℃、腐蚀时间为288 h、污泥p H值为4.9、污泥种类为市政污泥、金属材料为Q235碳钢;污泥p H值和温度引起的腐蚀为非均匀腐蚀,而污泥含水率引起的腐蚀为均匀腐蚀。
Taking the corrosion depth as the evaluation index, the influence of different factors such as p H value and moisture content of sludges, as well as corrosion temperature and time on corrosion behavior of two candidate material for dryers: Q235 carbon steel and 304 stainless steel is studied by single factor experiment and orthogonal experiment. The corrosion product is characterized by SEM and EDX at last. The results show that the corrosion depth of Q235 carbon steel increases with the increase of temperature, moisture content and acidity of the sludge. The effect of the influence of factors on the corrosion depth of steels may be ranked as a decreasing sequence as following: steel type, temperature, p H of sludge, time, and sludge type. The maximum corrosion of Q235 occurred in a metropolitan sludge with p H 4.9 at 100 ℃ for 288 h. The corrosion product on Q235 carbon steel is mainly brown loose substance, while that on 304 stainless steel is mainly light color strain- like one. The corrosion extent and the penetration of the aggressive elements for carbon steel is much deeper than those for stainless steel. The variation of temperature and p H value of the sludge may induce non- uniform corrosion of the steels, while the variation of the moisture content of the sludge may be responsible to uniform corrosion.
Corrosion Science and Protection Technology