伽凡尼效應之應用研究

A Study on the Application of Galvanic Effect

金屬塗裝的耐蝕性檢測極為耗時，以一般習用的鹽霧試驗或鹽水浸泡試驗而言，試驗周期往往需要數十天。本文針對鋁合金之聚酯粉體塗裝，探討利用伽凡尼效應以快速篩選不良塗裝的可行性。研究結果顯示，利用石墨與鋁合金塗裝在鹽水中偶合而產生的伽凡尼效應，能夠快速的使鋁合金不良塗裝在4天內產生明顯的劣化現象。在塗裝的劣化過程中，交流阻抗指標與偶合電位指標皆同步出現明顯變化，因此，上述兩項指標皆可作為金屬塗裝劣化監測技術的重要依據。兩相比較，偶合電位量測方法具備即時監測及簡易可行的優點。

Conventional Corrosion testing, either the salt spray test or the salt water immersion test , is a very time consuming process and often taking dozens of days. The aim of this study is to quickly screen for poor corrosion resistance of polyester powder coating on aluminum alloy. It was found that the coating with poor corrosion resistance quickly degraded in 4 days by the galvanic effect produced by the graphite coupling with the coated specimen in the salt water. In the process of coating degradation, the indicators of AC impedance as well as the coupling potential obviously changed in the synchronization, so these two indicators can be used as an important basis for coating degradation monitoring technique. By comparison, the coupling potential measurement is more convenient for real time corrosion monitoring of coating.