中熵超級不鏽鋼磨耗腐蝕行為之研究

Abstract

中熵超級不鏽鋼(Medium-Entropy Super Austenitic Stainless Steel)具有良好的耐蝕性，且具有比一般不鏽鋼更為優良的機械性質，因此被期望能夠廣泛地應用在海洋工程領域中。然而，在真正的工程應用上，不是只有單純腐蝕的現象產生而已，當材料應用於海上構件時，尤其是在氧濃度高的飛濺區，腐蝕速率會大幅提升，若同時又受到波浪、風以及海水的衝擊，構件將會暴露在磨耗與腐蝕的作用下。磨耗和腐蝕分別是指藉由物理性質和電化學性質導致材料質量逐漸損失的過程，當這兩種現象同時發生時，即為磨耗腐蝕，磨耗腐蝕會使材料壽命大幅下降，因為磨耗發生會使腐蝕加速，而腐蝕發生也導致磨耗加劇，在兩者的交互作用下，磨耗腐蝕對材料造成的損失遠大於磨耗或腐蝕單獨出現。 本研究特別針對文獻中常見的304不鏽鋼及市面上的商用S31254鋼與新型的中熵超級不鏽鋼(MEASS)，以上三種不鏽鋼進行磨耗腐蝕行為之分析及比較。實驗過程中將透過動電位極化曲線來量測材料的抗蝕性質，並透過陰極磨耗試驗來評估三種不鏽鋼之耐磨耗性。磨耗腐蝕試驗後的試樣將利用光學顯微鏡、掃描式電子顯微鏡及表面輪廓儀進行表面分析，過程中也同時利用ASTM-G119標準計算材料重量損失率來進行驗證。實驗結果發現中熵超級不鏽鋼(MEASS)具有三種不鏽鋼中最佳的耐磨耗性及耐磨耗腐蝕性。

Medium-Entropy Super Austenitic Stainless Steel has great corrosion resistance, and it has superior mechanical properties than normal stainless steels. Therefore, it is expected to be widely used in marine engineering. However, it is not only the phenomenon of pure corrosion in real engineering applications. When the materials are applied to offshore components, especially in the splash zone with high oxygen concentration, the corrosion rate will be greatly increased. If it is simultaneously effected by waves, wind and seawater, the grain in the seawater generate frictional motion against the components, which will be effected by corrosion and wear. When this two degradation processes occur simultaneously, it is known as tribocorrosion. Tribocorrosion will greatly reduce the lifetime of the material, because wear accelerate corrosion, and corrosion also intensify wear. The synergistic effects can lead to total material loss far more than the sum of wear and corrosion alone. This study specifically analyzed and compared the tribocorrosion behaviors of three stainless steels, such as 304SS and S31254 and Medium-entropy austenitic stainless steel (MEASS). The corrosion resistance of the materials was measured by measuring the potentiodynamic polarization curve during the experiment procedure and the wear resistance of the materials was evaluated by using tribometer. The specimens after tribocorrosion would be analyzed by optical microscope, scanning electron microscope and surface profile. Moreover, the material loss rate was calculated during the experimental process for verification. The results indict that MEASS has the best corrosion resistance and tribocorrosion resistance than the others.