——潮差區(qū)
(1. 中國科學院 海洋研究所，青島266071；
2. 東北大學 材料與冶金學院，沈陽 110004)
摘 要: 測試了熱浸鍍鋅(GI)、鋅-5%鋁-稀土(GF)和鋅-55%鋁-1.6%硅(GL)鍍層鋼板在青島站的潮差區(qū)海水腐蝕行為，并利用腐蝕質(zhì)量損失測試和顯微結(jié)構(gòu)分析，首次研究了3種鍍層鋼板的海水潮差區(qū)腐蝕行為。結(jié)果表明：3種鍍層在潮差區(qū)均出現(xiàn)不同程度的生物污損，與全浸區(qū)相比其腐蝕速度明顯降低；GI鍍層溶解速度最快，氧化膜保護效果不佳，耐腐蝕性能最差；GF鍍層的耐蝕性明顯提高，潮差區(qū)的充氣條件又促進了鍍層的鈍化，表現(xiàn)出較為優(yōu)異的耐腐蝕性能；由于保護性的鋅的腐蝕產(chǎn)物被滯留在富鋁的枝晶網(wǎng)絡(luò)中，比較充分的充氣條件又促進了鍍層富鋁相的鈍化，GL鍍層在海水潮差區(qū)表現(xiàn)出最佳的腐蝕性能。對位于海水潮差區(qū)的鋼材基體提供1 a保護期所需的鍍層最小厚度分別為：GI鍍層 25 μm；GF鍍層 12 μm；GL鍍層 3 μm；GF和GL鍍層在潮差區(qū)的耐蝕性分別是厚度相當?shù)腉I的3倍和5倍。
關(guān)鍵字: 熱浸鍍；熱浸鍍層；海水腐蝕；耐蝕性；潮差區(qū)
（1. Institute of Oceanology, Chinese Academy of Sciences,Qingdao 266071, China;
2. School of Materials and Metallurgy, Northeastern University,Shenyang 110004, China）
Abstract:The corrosion behavior of hot dip Galvanized (GI), Galfan (GF) and Galvalume (GL) coated steels exposed to seawater tidal zone of Qingdao site was investigated with seawater corrosion test and microscopy morphology analysis. Biofouling takes place on the coupons in this zone to some extend and may result in partial protection of coating surface and lower corrosion rate. The poor performance of GI coating is mainly attributed to its largest dissolution rate and less protective oxidation product layer. The better performance of GF coating is ascribed to its lower dissolution rate and more resistant oxidation film formed on the coating surface in contact with well-aerated seawater. The protective zinc corrosion products retained in the Al-rich dendritic network slows down further attack, and well-aerated condition promotes passivity of Al-rich phase, GL coating thus shows the best performance in tidal zone. The minimum coating thickness requirement for one year protection afforded to steel structures that is exposed to tidal zone is then calculated as: GI, 25 μm; GF, 12 μm; GL, 3 μm. The corrosion resistance of GL and GF are five and three fold as that of GI exposed to tidal zone.
Key words: hot dip by galvanization; hot dip coating; seawater corrosion; corrosion resistance; tidal zone
