Colloid Chemistry of Meso Structures and Reactivity of Steel Rusts

1)合成锈蚀本研究项目的目的是阐明S对钢的腐蚀和耐蚀性的机理，如耐候钢。用各种技术对人工合成的铁锈的结构和形成进行了研究。包括从胶体化学的角度来看。为了阐明合金化金属在耐候钢耐蚀性中的作用，从含有各种金属离子的铁盐水溶液中合成了铁锈。金属离子的影响很大程度上依赖于金属离子和锈组分的种类。添加到耐候钢中的大多数金属都干扰了锈蚀的结晶和颗粒生长。结果表明，用两种以上的金属合金化是有效的。特别是Ti(IV)的加入有效地控制了在Cl2-环境中形成的β-FeOOH的形成，表明与Ti的合金化有效地减少了钢在海洋和沿海地区…中的腐蚀更多的垃圾。此外，还研究了氯离子、硫酸盐和磷酸盐等阴离子对锈层形成和结构的影响，以考察腐蚀环境的影响。阴离子的存在对β-FeOOH的形成有明显的影响。2)耐候钢的锈层不同情况下形成的锈层具有氮吸附的特征。用氮吸附法研究了耐候钢在不同环境中暴露17年后的锈蚀情况。氮吸附测定的铁锈比表面积随空气中盐度的降低而减小，即铁锈颗粒随环境中氯离子浓度的增加而增大，海洋和沿海地区钢材的耐蚀性降低。钢的腐蚀速率随着比表面积的减小，即颗粒尺寸的增大而增大。这一结果表明，锈层的致密性与钢的耐蚀性有关，锈层的颗粒长大降低了锈层的致密性。结果表明，随着腐蚀过程的进行，铁锈颗粒不断长大。在不同情况下对不同钢材的锈蚀试验也得到了相似的结果。3)镀锌钢的锈蚀锌合金镀锌钢是各行各业的重要材料。镀锌钢的耐蚀性还没有得到深入的研究。利用合成的锌合金锈层，研究了镀锌钢的高耐蚀性机理。广泛应用于镀锌钢的锌铝合金在氯化锌溶液中加入少量Al(III)后，其锈层为片状硅铝石颗粒。片状颗粒以择优取向形成致密的锈层。这一事实很好地符合了镀锌铝合金钢在氯离子环境中的高耐蚀性。研究表明，锌铝镁合金镀锌钢在含氯离子的存在下具有较高的耐蚀性。测定了锌铝镁盐溶液中的空气透过率，结果表明，锌铝镁合金的锈层为片状细小颗粒，形成了比锌铝合金更致密的锈层。较少

1)Synthesized rustsThe aim of this research project is to elucidate the mechanism s of corrosion and corrosion resistance of steels, such as weathering steels.. The structures and formation of the rusts artificially synthesized were irvestigated by various techniques. Including in a point of colloid chemistry. To clarify the role of alloying metals in corrosion resistance of weathering steels, the rusts are synthesized from aqueous Fe salt solutions containing various metal ions. The influences of metal ions strongly depend on the kinds of metal ions and rust components. Most of metals added to weathering steels interfered with the crystalization and particle growth of rusts. It was shown that alloying with more than two kinds of metals is shown to be effective. Especially, the addition of Ti(IV) effectively controlled the formation of β-FeOOH which is formed in Cl^- environment, indicating that the alloying with Ti effectively reduces the corrosion of steels in marine and coastal dist … More ricts. The influences of anions such as chloride, sulfate, and phosphate on the formation and structure of rusts were also studied to investigate the effects of corrosion environment. The formation of β-FeOOH was markedly influenced by the presence of the anions.2)Rusts of weathering steelsThe rusts formed in different situations were characterized by nitrogen adsorption. The rusts on weathering steels exposed in different environments for 17 years were examined by nitrogen adsorption. The specific surface area of the rusts determined by nitrogen adsorption decreased with decreasing the air-born salinity, which means that the rust particles grow with the increase of environmental Cl^- and the corrosion resistance of steels is lowered in marine and coastal districts. The corrosion rate of the steels was increased with decrease of specific surface area, that is, increase of particle size. This result reveals that the compactness of rust layers relating to corrosion resistance of steels is lowered by the particle growth of rusts. It was shown that the rust particles grow with the progress of corrosion. The similar results were obtained on t the rusts on various steels exposed to different situations. Consequently, the adsorption method is useful for characterization of rusts, expecially particle size of rusts which can not be estimated by the other techniques.3)Rusts of galvanized steelsThe steel galvanized by Zn-alloys is an important material in various industries. The corrosion resistance of the galvanized steels is still not thoroughly explored. The mechanism of high corrosion resistance of the galvanized steels was investigated by using the synthesized rusts of Zn-alloys. The rusts of Zn-Al alloys which are widely used for galvanizing steels were sheet particles of simonkoleite on adding a small amount of Al(III) in ZnCl_2 solution. The sheet particles form the compact rust layers by preferred orientation. This fact well accords to a high corrosion resistance of steels plated with Zn-Al alloy in Cl^- environment. It is known that the steels galvanized by Zn-Al-Mg alloys show a high corrosion resistance in the presence of Cl^-. The rusts of Zn-Al-Mg alloys prepared from solutions of Zn-Al-Mg salts were fine sheet particles and formed more compact layers than those of Zn-Al alloys as confirmed by measuring the permeability of air into the rust layers. Less