Characterization of acid-base properties of the hydrated oxides on iron and titanium metal surfaces
Characterization of acid-base properties of the hydrated oxides on iron and titanium metal surfaces
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DOI：
10.1021/j100289a025
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发表时间：
1987-02
期刊：
影响因子：
--
通讯作者：
G. Simmons;B. Beard
中科院分区：
文献类型：
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作者：
G. Simmons;B. Beard
铁和钛金属氧化产生羟基化氧化物表面的能量和角分辨X射线光电子能谱显示，铁和钛的羟基浓度分别为2.6/nm/sup 2/和4.3/nm/sup 2/。作为pH值的函数的羟基氢与钾离子的交换被用来确定这些表面羟基的酸强度。铁和钛表面表现为酸，其pK值分别为11.5和10.0。钛的酸性更强的性质与相应金属氧化物中Ti/sup 4 +/比Fe/sup 3 +/更高的电荷/半径比一致。有机涂层和金属表面之间最强的化学相互作用被认为是通过涂层中的极性基团与表面羟基的氢键。在此基础上，在这项研究中测量的铁和钛表面的酸强度和碱强度从报告的磷酸盐交换铁被用来预测含有不同官能团的有机涂层的相对稳定性。
Energy and angular resolved X-ray photoelectron spectroscopy of iron and titanium metals oxidized to produce hydroxylated oxide surfaces showed the concentration of hydroxyl to be 2.6/nm/sup 2/ for iron and 4.3/nm/sup 2/ for titanium. Exchange of the hydroxyl hydrogens with potassium ions as a function of pH was used to determine the acid strength of these surface hydroxyls. The iron and titanium surfaces, behaving as acids, were found to have pK values of 11.5 and 10.0, respectively. The more acidic nature of titanium is consistent with the higher charge/radius ratio of Ti/sup 4 +/ compared to Fe/sup 3 +/ in the respective metal oxides. The strongest chemical interaction between organic coatings and metal surfaces is considered to be via hydrogen bonding of polar groups in the coating with surface hydroxyls. On this basis, the acid strengths of the iron and titanium surfaces measured in this study and the base strength from reported phosphate exchange on iron were used to predict the relative stabilities of organic coatings containing different functional groups.