The Film Forming Mechanism of Chromium-free Passivation in the Tannic Acid System for Electrogalvanized Coating

[摘要] In this paper, tannic acid, fluorine titanate and silane coupling agent passivation solution were used to prepare hot dip 55% Al-Zn steel sheet passivation coating. And then the mechanism of film formation was studied. The microstructure, surface composition, layer by layer element distribution and molecular structure of 55% Al-Zn steel sheet passivation coating were revealed in scanning electron microscopy, X ray photoelectron spectroscopy, glow discharge atomic emission spectrometry and infrared spectrometry, respectively. The results show that: in one hand, using the silane coupling agent would generate many sol-gel particles in the passivation solution. On the other hand, tannic acid would produce spatial mesh structure. Therefore, passivation solution would generate a smooth, uniform and compact 55% Al-Zn steel sheet passivation coating or membrane.

[发布机构] College of Mechanical and Manufacturing Engineering, Southwest Forestry University, No. 300 Bailong temple, Panlong District Kunming, Yunnan, China^1;Faculty of Materials Science and Engineering, Kunming University of Science and Technology, No. 253, Xuefu Road, Wuhua District Kunming, Yunnan, China^2

[效力级别] 机械制造 [学科分类] 材料科学（综合）

[关键词] Atomic emission spectrometry;Electrogalvanized;Element distribution;Film formations;Film forming mechanism;Infrared spectrometry;Passivation coating;Silane coupling agent