本文選題：磷酸鎂水泥 + 電化學��； 參考：《西南交通大學》2017年碩士論文

【摘要】：磷酸鎂水泥(MPC)以早強快硬、環(huán)境適應性強、粘結強度高、耐久等優(yōu)異性能而被廣泛應用于快速修補、廢料封存領域�，F(xiàn)有研究已對磷酸鎂水泥的水化機理、緩凝機理、微觀結構、原料配比、摻雜改性力學性能、耐久性進行大量探究,但大多以其塊狀混凝土試樣為研究對象。國外學者嘗試將磷酸鎂水泥用于金屬基體表面防護,并取得了良好效果,而國內研究很少。因此,本文嘗試用電化學測量技術探究碳鋼表面磷酸鎂水泥涂層的耐腐蝕性能。本論文在45號鋼表面制備MPC水泥涂層,并評價其耐腐蝕性和耐腐機理。論文第二章,在噴砂、磷化后的45號鋼表面用不同手工涂刷方式,制備一層厚約500 μm不同鎂磷比(M/P)的磷酸鎂水泥涂層。再采用短期電化學阻抗譜和線性極化法,對比M/P分別為3/1、4/1、5/1的磷酸鎂水泥的電化學特性,實驗結果表明M/P為5/1時磷酸鎂水泥涂層阻礙電荷轉移的作用力最大。隨后對比單次涂刷和多次涂刷對涂層性能的影響,結果顯示多次涂刷更有利于涂層對金屬基體的防護。論文第三章選擇M/P為5/1的MPC多次涂刷于磷化后45號鋼表面,并用SEM、XRD、較長期的線性極化法、電化學阻抗譜,長期的鹽霧試驗和粘結實驗表征涂層的防腐蝕性。結果表明MPC涂層由致密棱柱狀晶堆積而成,內部有少量微裂紋,主要成分為MgKPO_4·6H_2O、MgO和Al_2O_3。試樣浸泡1 h至12 d的R_p基本維持在2.0×10~5 Ω·cm~2,Rc 始終保持在8×10~4 Ω·cm~2左右,表明涂層可能有長期有效的防腐作用。且試樣在鹽霧箱中放置150 d后表面也未現(xiàn)腐蝕產物,粘結實驗結果顯示其粘結強度為4.8±0.7 MPa,進一步證明MPC可作為45號鋼表面長期穩(wěn)定的耐腐蝕涂層。論文第四章通過浸泡試驗和動電位極化法分析了 MPC涂層的耐腐蝕機理。結果顯示,浸泡在3.5%NaCl+MPC溶液中的試樣腐蝕程度最低,開路電位最穩(wěn)定,且極化曲線自腐蝕電位向正方向移動,陽極分支明顯下降。表明MPC內未完全反應的MgO和微溶磷酸鹽對45號鋼有陽極緩蝕作用。因此,MPC涂層為45號鋼提供物理阻隔和化學緩蝕雙重防腐蝕作用。
[Abstract]:Magnesium phosphate cement (MPC) has been widely used in the field of rapid repair and storage for its excellent properties such as early strength and quick hardening, strong environmental adaptability, high bond strength and durability. The hydration mechanism, retarding mechanism, microstructure, ratio of raw materials, doping modified mechanical properties and durability of magnesium phosphate cement have been studied extensively, but most of them take its block concrete sample as the research object. Foreign scholars have tried to use magnesium phosphate cement as surface protection of metal matrix, and achieved good results, but there are few researches in China. Therefore, the corrosion resistance of magnesium phosphate cement coating on carbon steel was investigated by electrochemical measurement technique. In this paper, MPC cement coating was prepared on 45 # steel and its corrosion resistance and corrosion resistance mechanism were evaluated. In the second chapter, a layer of magnesium phosphate cement coating with thickness of about 500 渭 m and different ratio of magnesium to phosphorus is prepared on the surface of 45 steel after sand blasting and phosphating by different manual brushing methods, and the coating thickness is about 500 渭 m and the ratio of magnesium to phosphorus is about 500 渭 m. The electrochemical characteristics of magnesium phosphate cement with M / P = 3 / 1 / 4 / 1 / 5 / 1 were compared by short term electrochemical impedance spectroscopy and linear polarization method. The experimental results show that when M / P is 5 / 1, the interaction force of magnesium phosphate cement coating hinders charge transfer is the largest. Then, the effects of single and multiple brushes on the coating properties were compared. The results showed that the multiple brushing was more favorable to the protection of the coating on the metal substrate. In the third chapter, MPC with M / P = 5 / 1 was chosen to brush the surface of 45 steel after phosphating many times. The corrosion resistance of the coating was characterized by SEMX XRD, linear polarization method, electrochemical impedance spectroscopy, long term salt spray test and bonding experiment. The results show that the MPC coating is composed of dense prismatic crystals with a small number of microcracks, and the main components are MgKPO_4 6H _ 2O _ 2O _ (MgO) and Al _ 2O _ 3 _ 3. When the samples were soaked for 1 h to 12 days, the RSP remained at about 8 脳 10 ~ (4) 惟 cm~2, indicating that the coating may have a long-term and effective anticorrosion effect. Moreover, no corrosion products were found on the surface of the specimen after being placed in the salt spray box for 150 days. The bond strength of the specimen was 4.8 鹵0.7 MPA, which further proved that MPC can be used as a long-term stable corrosion resistant coating on 45 steel. In chapter 4, the corrosion resistance mechanism of MPC coating was analyzed by immersion test and potentiodynamic polarization method. The results show that the sample immersed in 3.5%NaCl MPC solution has the lowest corrosion degree, the most stable open circuit potential, and the polarization curve moves in the positive direction from the corrosion potential to the anode branch. It is shown that MgO and microsoluble phosphate in MPC have anodic inhibition on 45 steel. Therefore, MPC coating provides both physical barrier and chemical corrosion inhibition for 45 steel.
【學位授予單位】：西南交通大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TG174.4

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