Study on the double-layrs structure of electnodeposits on the marine steel structures catbodicay probed in seawater

海水探测海洋钢结构阴极沉积层双层结构研究

基本信息

批准号：
15360457
负责人：
KASHIKI Isamu
金额：
$ 8.26万
依托单位：
Hokkaido University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2004
项目状态：
已结题

项目摘要

Recently, there is an increasing trend of utilizing oceanic space for some activities of human being. This trend makes various kinds of structures be necessary to be constructed in seawater. In accordance with this, the maintenance of these marine structures has become important, particularly because oceanic environments are far more severe in maintaining structures than terrestrial ones. A method of maintaining ferrous marine structures is a cathodic protection (CP) accompanied with calcareous deposits. Previously, we revealed that the calcareous film deposited on a marine structure is composed of double layers of Mg(OH)_2 and CaCO_3 with a clear boundary between the two. The objective of this study is to propose a simple method of analyzing the respective structures of the double layers, i.e., Mg-and Ca-rich layers, separately, and to examine the validity of the method. Needless to say, it is very important to know the structure of calcareous deposits, because the calcareous deposits play a main part in the cathodic protection of a marine structure accompanied with a deposit.In this study, a new method was proposed of analyzing the double layrs structures of calcareous deposit films formed on the surface of steel cathodically polarized in seawater. The method was based on the assumption that pore-water in the deposits should be distributed between the layrs according to the difference of their water-affinities. From the assumption, various structural factors concerning the double layers in the deposits were derived. In order to examine the validity of the theoretical model for analyzing the double layers structures, calcareous deposit films with various Ca/Mg compositions was prepared through either varying hydrodynamic state of seawater around the cathode or diluting seawater under a constant cathodic current density and temperature. The application of the above model to these deposits proved the validity of the model to analyze the double layrs structures.

最近，将海洋空间用于人类某些活动的趋势越来越多。这种趋势使得在海水中建造各种结构。基于此，这些海洋结构的维护变得重要，尤其是因为海洋环境在维持结构方面比陆地更为严重。维持亚铁船体结构的一种方法是伴有钙质沉积物的阴极保护（CP）。以前，我们揭示了沉积在海洋结构上的钙质膜由Mg（OH）_2和Caco_3的双层组成，两者之间具有清晰的边界。这项研究的目的是提出一种简单的方法来分析双层的各个结构，即分别分别毫克和富含CA的层，并检查该方法的有效性。不用说，知道钙质沉积物的结构非常重要，因为钙质沉积物在伴有沉积物的海洋结构的阴极保护中起主要作用。在这项研究中，提出了一种新方法，分析了在海水中钢天主教层面的钢层面部形成的钙质沉积物的双层结构。该方法是基于这样的假设：沉积物中的孔隙水应根据其水的差异分布在Layrs之间。从假设中，得出了有关沉积物中双层的各种结构因素。为了检查理论模型分析双层结构的有效性，通过在阴极周围的海水的水动力学状态或在恒定的阴极电流密度和温度下稀释海水，制备了具有各种CA/mg组成的钙质沉积膜。上述模型在这些沉积物中的应用证明了该模型分析双层结构的有效性。