AC/DC/AC法을 利用한 重防蝕 塗膜의 防蝕性能 評價 硏究

Abstract

가혹한 부식 환경으로부터 금속 구조물을 보호하는 도막의 방식성능을 신속하게 평가하기 위해 목적으로 연구한 AD/DC/AC 시험법과 기존 가속노화 시험을 이용한 방식성능 평가법을 교류 임피던스 및 정전용량의 측정으로 비교·분석한 결과, 다음과 같은 결론을 얻었다. 1. AC/DC/AC 시험법의 타당성은 시험이 거듭되면서 도막이 가속 노화되어 cathodic delamination 현상이 발생하는 것을 교류 임피던스 값의 감소 및 정전 용량에 의한 물 흡수량이 증가하는 결과로부터 추론할 수 있었으며, 도막의 부착력 감소 및 외관 변화 결과에서 확인할 수 있었다. 2. 기존의 가속노화 시험법인 Artificial seawater immersion test, Salt spray test, Modified Cyclic salt fog/UV exposure test를 10주간 진행했으나 중방식 도막을 충분히 가속노화 시키지 못하여 방식성능을 평가하는데 변별력이 부족하는 것을 알 수 있었다. 3. 향후 기존의 가속노화 시험법으로 방식 도막을 충분히 노화시켰을 때의 결과와 AC/DC/AC 시험법과의 상관관계를 도출할 수 있을 것으로 판단된다. 따라서 AC/DC/AC 시험법을 이용하여 도막의 방식성능을 신속하게 평가할 수 있었으며, 작업의 신속성을 요구되는 산업현장에서 적용 가능성이 매우 높을 것으로 생각된다.

Due to the industry developing on, huge steel structures have been constructed recently on the industrial and coastal area such as industrial plants, power plants, ships and various storage tanks that are protected by high performance coatings against severe corrosive environment. Because of this demand, many kinds of paint are developed by several manufacturers and applied for the steel structures. Therefore, the investigation on ageing of organic coatings and the assessment protective properties of organic coatings is very important to protect metal structures appropriately. There are so many accelerated ageing tests for the evaluation of anticorrosive properties of organic coatings. However, those classic tests need long time to evaluate and classify high performance coatings. The main purpose of this study is to introduce an efficient and rapid assessment of performance of high performance coatings. The specimens were produced by applying different four kinds of coating system (Alkyd primer/top, Chlorinated rubber primer/top, epoxy primer/top, epoxy/urethane), respectively. In this study, AC/DC/AC technique was carried out as a rapid assessment coupled with accelerated ageing test to evaluate anticorrosive properties of specimens that was applied by high performance coating. The pull-off adhesion test and the observation of specimens were conducted to verify the degradation due to a formation of cathodic delamination. Other three accelerated ageing tests (Artificial seawater immersion test, Salt spray test, Modified Cyclic salt fog/UV exposure test) were also carried out for 10 weeks as a control group. Then, the electrochemical properties were measured by means of Electrochemical Impedance Spectroscopy(EIS). The results of AC/DC/AC technique showed that the impedance was steadily decreased and the water uptake was increased of all systems as a function of AC/DC/AC cycle. It means that the high performance coatings were degraded in a short time by means of AC/DC/AC technique. On the other hand, the electrochemical results of other classic test were not changed enough to evaluate anticorrosive properties. Consequently, AC/DC/AC technique has been proved to be an efficient and rapid method on the assessment of performance and lifetime prediction of high performance coatings.