(1. 華南理工大學(xué) 材料科學(xué)與工程學(xué)院，廣州 510640；2. 廣東安恒鐵塔鋼構(gòu)有限公司，佛山 528000)
摘 要: 將熱, 鍍鋅鋼板浸入含有25 g/L Ce(NO3)3·6H2O、4~6 g/L H2O2(30%)、15~20 g/L H3Cit的處理液中，在70 ℃下處理10 s~240 min，從而在其表面獲得鈰鹽轉(zhuǎn)化膜。采用中性鹽霧試驗(NSS)和電化學(xué)極化曲線來分析膜層耐蝕性能，確定最佳成膜時間范圍。采用掃描電鏡(SEM)觀察膜層的微觀形貌，利用能譜儀(EDS)、X射線光電子能譜儀(XPS)、紅外吸收光譜儀(IR)分析膜層的化學(xué)組成。結(jié)果表明：處理時間為10 min左右的鈰鹽轉(zhuǎn)化膜耐腐蝕性能最優(yōu)，最佳工藝條件下得到的鈰鹽轉(zhuǎn)化膜的耐蝕性能與鉻酸鹽轉(zhuǎn)化膜的相當(dāng)；隨著處理時間的延長，膜的厚度增加，膜層的裂紋變寬；處理時間超過10 min后膜層逐步產(chǎn)生脫落，耐腐蝕性能也隨之降低；轉(zhuǎn)化膜的生長過程中，前期以檸檬酸鈰吸附膜的沉積為主，后期以Ce(OH)3/Ce2O3及Ce(OH)4/CeO2的沉積占主導(dǎo)。
關(guān)鍵字: 熱鍍鋅；鈰鹽轉(zhuǎn)化膜；檸檬酸；生長過程
（1. School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640, China;
2. Guangdong Anthen Iron Tower and Steel Structure Co., Ltd., Foshan 528000, China）
Abstract:Cerium salt conversion coatings modified with citric acid were obtained on galvanized steel samples by immersing the samples into an aqueous solution containing 25 g/L Ce(NO3)3·6H2O, 4−6 g/L H2O2(30%) and 15−20 g/L H3Cit at 70 ℃ for 10 s−240 min. The corrosion resistance of the modified coatings was assessed by neutral salt spray tests (NSS) and electrochemical polarization curve. The micromor-structure of the coatings was observed by scanning electron microscopy (SEM). The chemical composition of the coatings was investigated by X-ray energy dispersive spectrometer (EDS), infrared spectroscopy (IR) and X-ray photoelectron spectroscopy (XPS). The results indicate that the optimum treatment time is about 10 min and the corrosion resistance of the modified coating is closed to that of chromate film. The thickness of the coating increases and the cracks in the coating is wider with the treatment time prolonging. When the treatment time is more than 10 min, the coatings are easy to fall off, and the corrosion resistance of the coating also decreases. The growth process of the coating can be divided into two stages: at the initial time the complexes ions of cerium citrate are adsorbed on the whole surface of galvanized steel, while cerium citrate is deposited on surface, then the Ce(OH)3/Ce2O3 and Ce(OH)4/CeO2 mixture are deposited on surface of the coatings.
Key words: galvanized steel; cerium salt conversion coating; citric acid; growth process
