热镀锌板双硅烷无铬钝化膜性能的研究

目的为进一步提高热镀锌板无铬钝化膜的耐腐蚀性能。方法以偏钒酸铵和氟钛酸作为无机组分,添加主要成膜物质苯丙乳液,通过硅烷偶联剂KH-560和KH-570将两者紧密连接,在热镀锌板表面获得一层耐腐蚀性较强的双硅烷无铬钝化膜。采用中性盐雾试验、电化学试验、扫描电镜(SEM)、傅里叶红外光谱(FTIR)等表征钝化膜的耐腐蚀性能。结果热镀锌板-双硅烷无铬钝化膜经96 h中性盐雾试验,腐蚀面积在2%~4%,腐蚀电流密度比热镀锌板基体降低一个数量等级,这表明双硅烷无铬钝化膜能提供良好的耐腐蚀能力。SEM分析表明在热镀锌板表面生成了一层均匀、连续、致密的钝化薄膜,钝化膜的厚度大约在3μm。FTIR分析表明,双硅烷无铬钝化膜中存在—(CH_2)_n—、C=O、Si—O、Si—O—Si、Si—O—Zn键。结论在热镀锌板表面生成了一层均匀、致密的钝化膜,使热镀锌板呈现良好的耐腐蚀性能,且满足工业应用标准。

Properties of Bis-silane Chromium-free Passive Film on Hot-dip Galvanized Steel

The work aims to further improve corrosion resistance of chromium-free passive film on hot-dip galvanized steel. With H2TiF6 and NH4VO3 as proper inorganic constituents and styrene-acrylic emulsion as major film-forming material, a layer of corrosive bis-silane chromium-free passive film was obtained on hot-dip galvanized steel by binding the constituents tightly using silicon coupling agent (KH-560, KH-570). Corrosion resistance of the bis-silane chromium-free passive film was charac-terized by neutral salt spray test, electrochemical test, scanning electron microscopy and Fourier infrared spectroscopy. Corro-sion area of the film accounted for approximately 2%~4% after 96 h neutral salt spray test, and corrosion current density was one order of magnitude lower than that of untreated hot-dip galvanized steel, indicating that the bis-silane chromium-free pas-sive film could exhibit excellent corrosion resistance. SEM analysis showed that a nearly 3μm thick uniform, continuous and compact passive film took shape on the surface of hot-dip galvanized steel. FTIR analysis indicated that—(CH2) n—, C=O, Si—O, Si—O—Si and Si—O—Zn bonds were present in the passive film. The hot-dip galvanized steel exhibits excellent cor- rosion resistance and meets requirements of industrial application since a layer of uniform and compact passive film takes shape on the surface of hot-dip galvanized steel.