炔醇類有機物對碳鋼高溫酸洗腐蝕抑制作用; Inhibition of steel corrosion in 2M HCl at 85℃ by acetylenic alcohols

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Title:	炔醇類有機物對碳鋼高溫酸洗腐蝕抑制作用;Inhibition of steel corrosion in 2M HCl at 85℃ by acetylenic alcohols
Authors:	王俊堯;Jyun-yao Wang
Contributors:	機械工程研究所
Keywords:	炔醇類抑制劑;高溫酸洗;低碳鋼;電化學分析;Chemical cleaning;Electrochemical analysis;Corrosion inhibitor
Date:	2007-06-21
Issue Date:	2009-09-21 11:58:10 (UTC+8)
Publisher:	國立中央大學圖書館
Abstract:	本論文在研究含有-OH基及C≡C三鍵之炔醇類有機抑制劑，在2M鹽酸85℃環境下對鋼鐵酸洗之腐蝕抑制作用。研究方法採用重量損失法、直流極化法、交流頻譜法，鋼鐵表面使用FTIR及XPS分析。研究結果顯示影響炔醇類抑制效率之因素有三：(1)鄰接C≡C之碳鍊長度增加，其抑制效率增加。(2) C≡C三鍵位結構末端具有較高抑制效率。(3) C≡C三鍵所鍵結之官能基，以氫氧基（2-Butyne-1,4-diol）與苯環(3-Phenyl-2-propyn-1-ol)皆比單純接一碳鍊(2-Butyn-1-ol)抑制效率好。由電化學研究得知炔醇類抑制劑屬於陰極型抑制劑，其在鋼鐵上的吸附屬於Langmuir等溫吸附。由活化能之計算得知，添加炔醇類抑制劑活化能下降（Addition free105.9kJmol-1> 2-Butyn-1-ol 90.4 kJmol-1）推測抑制劑之吸附屬於化學吸附。長鏈型炔醇類（2-Nonyn-1-ol）在腐蝕環境中之抑制效率隨時間增長而大幅下降，且在三價鐵離子存在下抑制效率更差。 FTIR表面分析之結果顯示，2-Nonyn-1-ol 在鋼材表面形成C＝C、C＝O鍵結。XPS表面分析之C1s結果顯示，抑制劑能在鋼材表面吸附形成C-H、C-C、C-O的化學鍵結；偵測Fe2p2/3訊號時，可以得到試片表面呈現相同的鍵結，但經Ar+離子濺渡蝕刻30秒後，在高抑制效率系統中(2-Propyn-1-ol與2-Nonyn-1-ol)鋼鐵表面偵測到0價鐵的訊號，推測抑制劑分子保護鋼材表面使其較不易被氧化，生成氧化物也較薄。 The inhibiting effect of some acetylenic alcohols has been investigated on the corrosion of low carbon steel (iron in 2M HCl at 85℃. Coupon test (weight loss measurement) and electrochemical techniques (including linear polarization resistance, Tafel extrapolation and electrochemical impedance spectroscopy) were applied to estimate the corrosion rate of steel and the inhibition efficiency of the inhibitors. The inhibition efficiency (Ef%) was defined as Ef% =100 (i-io)/io where I and io are the corrosion rate of steel in the presence of and in absence of inhibitors. The inhibition efficiency of the acetylenic alcohols was found to depend on their chemical formulae: (1) The Ef% increases with increasing the number of carbon chain linked to the C≡C triple bond. (2) The Ef% is higher for the alcohols with a terminal C≡C triple bond than that in the internal. (3) Substitution the —CH3 in 2-Butyn-1-ol by －CH2OH group (i.e., 2-Butyn-1,4-diol) by benzene ring (—C6H5) (i.e., 3-Penyl-2-propyn-1-ol) increases the Ef%. Resulting from Tafel extrapolation, almost all the alcohols cause a negative shift of the corrosion potential and reduced the corrosion current. This surmises that the inhibitors belonged to cathodic type. The activation energies were estimated to be 105.9 and 90.4 kJmol-1 in the absence of inhibitors and in the presence of 2-butyn-1-ol, respectively, using Arrhenius plot. It suggests that the lower activation energy caused by 2-butyn-1-ol is resultant from its chemisorption on steel. The adsorption of acetylenic alcohols on the steel surface in 2M HCl solution obeyed the Langmuir adsorption isotherm. The inhibition efficiency decreases with time for the inhibitors with long carbon chain (e.g., 2-Nonyn-1-ol). More vigorous is the tendency for in the addition of ferric ions (Fe3+). Analysis through FTIR spectra showed that there are adsorption bands of C＝C、C＝O present on steel surface caused by the addition of 2-Nonyn-1-ol as an inhibitor. XPS spectra of the inhibited steel display the existence of C-C and C-H species adsorbed on the steel surface. XPS analysis on Fe2p 3/2 depicted a similar chemical state on the steel surface whether or not present an inhibitor. After etching by sputtering Ar+ for 30 s, the steel surface effectively inhibited exposed their metallic peak. In comparison, the exposed surface was still in the oxide forms of iron for the inefficient inhibition.
Appears in Collections:	[Graduate Institute of Mechanical Engineering] Electronic Thesis & Dissertation

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