【摘要】：碳鋼是一種被廣泛應(yīng)用的金屬材料,但由于它的化學(xué)特性較為活潑,使得其在應(yīng)用中容易發(fā)生腐蝕。因此,腐蝕領(lǐng)域?qū)W者們對(duì)碳鋼的腐蝕防護(hù)問(wèn)題一直都很關(guān)注。合理添加緩蝕劑被認(rèn)為是一種經(jīng)濟(jì)、高效的防護(hù)手段。本論文合成了兩個(gè)具有表面活性的噻二唑類緩蝕劑,主要研究成果如下:以三聚氯氰、正己胺、正辛胺、2-巰基-5-甲基-1,3,4-噻二唑(MMTD)、N,N-二甲基-1,3-丙二胺作為反應(yīng)原料,合成了兩個(gè)噻二唑衍生物:MTC_6T和MTC_8T,并通過(guò)ESI-MS、~1H NMR、FT-IR對(duì)其進(jìn)行結(jié)構(gòu)表征。MTC_6T和MTC_8T降低0.5 M H_2SO_4溶液表面張力的能力明顯優(yōu)于MMTD。當(dāng)MTC_6T和MTC_8T的添加量分別達(dá)到0.2 mM、0.1 mM后,隨濃度的進(jìn)一步增加表面張力改變較小,此時(shí)的濃度為臨界膠束濃度。失重法、電化學(xué)測(cè)試、量子化學(xué)計(jì)算及掃描電鏡測(cè)試結(jié)果表明:MMTD、MTC_6T和MTC_8T的緩蝕效率隨著緩蝕劑濃度的增大而逐漸提高;隨溫度的升高而逐漸降低。三個(gè)噻二唑衍生物在硫酸溶液中均屬于混合型緩蝕劑,緩蝕劑的加入降低了碳鋼表面的雙電層電容,腐蝕反應(yīng)阻力增大。最高占據(jù)軌道能量(EHOMO)為MTC_8T高于MTC_6T,最低空軌道能量(ELUMO)為MTC_8T低于MTC_6T,因此在腐蝕介質(zhì)中較MTC_6T活潑。掃描電鏡測(cè)試中,MTC_6T和MTC_8T保護(hù)下的金屬表面平整,顯著抑制了坑蝕的發(fā)生。吸附熱力學(xué)及動(dòng)力學(xué)研究結(jié)果表明:硫酸溶液中MMTD在碳鋼表面的吸附符合Fr eundlich等溫吸附;而MTC_6T及MTC_8T在碳鋼表面的吸附符合Langmuir等溫吸附,該過(guò)程是自發(fā)進(jìn)行的,溫度升高阻礙吸附過(guò)程;MTC_6T和MTC_8T在碳鋼表面的吸附是以化學(xué)吸附為主的混合型吸附。溫度一定的條件下,緩蝕劑濃度增加,使得指前因子Ar和表觀活化能Ea都增大。Ea值滿足Ea(MTC_8T)Ea(MTC_6T)Ea(MMTD),這進(jìn)一步證實(shí)了MTC_8T的緩蝕效果最優(yōu)。
[Abstract]:Carbon steel is a kind of widely used metal material, but it is easy to corrode because of its active chemical properties. Therefore, the corrosion protection of carbon steel has always been concerned by scholars in the field of corrosion. The reasonable addition of corrosion inhibitor is considered to be an economical and efficient means of protection. In this paper, two surface-active thiadiazole corrosion inhibitors were synthesized. The main research results are as follows: cyanuric chloride, n-hexylamine, n-octylamine 2-mercapto -5-methyl-1-thiadiazole (MMTD) were used as raw materials for the reaction. Two derivatives of thiadiazole, MTC6T and MTCIM _ 8T, were synthesized, and their structures were characterized by ESI-MSI ~ 1H NMR-FT-IR. The ability of MTC_8T to reduce the surface tension of 0.5 M H_2SO_4 solution was obviously better than that of MMTD. When the addition of MTC_6T and MTC_8T reached 0.2mmM and 0.1mm respectively, the surface tension changed slightly with the further increase of concentration, and the concentration was critical micelle concentration. The results of weightlessness method, electrochemical test, quantum chemistry calculation and scanning electron microscopy showed that the corrosion inhibition efficiency of MTC_8T and MTC6T increased with the increase of the concentration of inhibitor, and decreased with the increase of temperature. The three thiadiazole derivatives are all mixed corrosion inhibitors in sulfuric acid solution. The addition of corrosion inhibitor reduces the double layer capacitance of carbon steel surface and increases the corrosion reaction resistance. The highest occupied orbital energy (EHOMO) is higher than that of MTC _ s _ (6) T, and the lowest empty orbit energy (ELUMO) is lower than that of MTC _ s _ (6) T, so it is more active than MTC_6T in corrosive medium. The metal surface under the protection of MTC6T and MTC_8T was smooth in scanning electron microscopy (SEM), which significantly inhibited the occurrence of pit erosion. The results of thermodynamics and kinetics show that the adsorption of MMTD on carbon steel in sulfuric acid solution conforms to the Fr eundlich isotherm adsorption, while the adsorption of MTC_6T and MTC_8T on the surface of carbon steel conforms to Langmuir isotherm adsorption. The adsorption of MTCST6T and MTC_8T on carbon steel surface is a mixture of chemisorption and chemisorption. With the increase of the concentration of the inhibitor at a certain temperature, both the pre-exponential factor ar and the apparent activation energy EA are increased. The value of EA (MTC_8T) Ea (MTC_6T) Ea (MMTD),) further proves that the inhibition effect of MTC_8T is optimal.
【學(xué)位授予單位】：中北大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TG174.42

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