本文選題：陽極氧化 + 晶須��； 參考：《太原理工大學》2011年碩士論文

【摘要】：一維材料是本世紀高新技術領域的一種新型功能材料,是材料領域中非常重要的部分。其中鎂鹽晶須有優(yōu)良的耐高溫、耐腐蝕性能、電絕緣、高強度、高硬度等特性,作為塑料、金屬、陶瓷等材料的增強劑時顯示出極佳的物理、化學性能和優(yōu)異的機械性能,在生產(chǎn)和技術領域有著廣闊的應用前景。因此,晶須的制備具有重要的學術意義和應用價值。 本文采用常溫常壓的電化學方法成功制備了硼酸鎂晶須和硅酸鎂晶須,克服了傳統(tǒng)制備方法存在的高溫高壓高能耗的不足,主要研究內(nèi)容為：①采用電化學陽極直接氧化法制備硼酸鎂晶須,首先利用SEM、XRD、EDS、IR和TG-DTA等手段對晶須的表面形貌、結構以及元素組成等進行了表征,其次采用三電極體系測定了反應的循環(huán)伏安曲線,研究了其電化學過程,同時考察了溫度、毒化劑和電流密度等因素的影響,并探討了其毒化機理；②采用電化學陽極直接氧化法制備硅酸鎂晶須,利用SEM、XRD、EDS、IR和TG-DTA等手段對其表面形貌、結構和元素組成等進行了分析；③采用基于密度泛函理論的第一性原理對晶須微觀結構進行了計算。結果表明： 1、通過SEM觀察可得,硼酸鎂晶須長為6～8μm,直徑約為500 nm,長徑比為12:1～16:1;XRD、EDS和IR分析可知其為硼酸鎂(Mg2B2O5)晶須；由TG-DTA分析可得硼酸鎂晶須中不含有結晶水；從循環(huán)伏安圖看出,陽極在2.0 V附近發(fā)生氧化反應,Mg2+在陰極沒有發(fā)生還原反應；制備硼酸鎂晶須的最佳條件為：0.20mol/L毒化劑,電流密度為0.06A/cm2,溫度為20℃左右,乙醇和水體積比為1:3,通電時間1h,硼酸的濃度為0.44mol/L,氯化鈉的濃度為0.20mol/L,平均電流效率約為35%。 2、通過SEM分析可知硅酸鎂晶須長度為5-6μm,直徑約為500 nm,長徑比為10:1～12:1,符合晶須的定義；其XRD譜分析表明出現(xiàn)正交晶系結構的硅酸鎂的特征峰,還含有少量的氧化鎂,其衍射峰強度大,說明結晶良好；EDS和IR分析可得其構成為Mg2SiO4;由TG可知該產(chǎn)品不含結晶水；制備硅酸晶須的最佳電流密度為0.6A/cm2。 3、通過第一性原理計算可得,Mg2B2O5和Mg2SiO4原胞的帶隙寬度分別為4.9eV和5.0eV,均接近于絕緣體。Mg2B2O5晶胞價帶主要為氧的2p、鎂的3s和硼的2s、2p態(tài)的貢獻,導帶主要是硼的2p態(tài)的貢獻。Mg2SiO4原胞價帶主要由氧的2p、鎂的3s態(tài)和硅的3s、3p態(tài)的貢獻,導帶主要由硅的3p和少量鎂的3s態(tài)的貢獻。Mg2B2O5和Mg2SiO4原胞結合能分別為-1444.1990eV和-1646.0148eV,其中Mg2SiO4原胞穩(wěn)定性較大。 總之,本文采用電化學陽極直接氧化法成功地制備出了硼酸鎂晶須和硅酸鎂晶須,該方法在國內(nèi)外還未見報道(已申請兩項發(fā)明專利)。該研究將為其它晶須的制備提供一條新的途徑。
[Abstract]:One-dimensional material is a new functional material in the field of high-tech in this century, and it is a very important part in the field of material. Magnesium salt whiskers have excellent properties of high temperature resistance, corrosion resistance, electrical insulation, high strength, high hardness and so on. As reinforcements for plastics, metals and ceramics, magnesium whiskers show excellent physical and chemical properties and excellent mechanical properties. It has a broad application prospect in the field of production and technology. Therefore, the preparation of whiskers has important academic significance and application value. In this paper, magnesium borate whisker and magnesium silicate whisker were successfully prepared by electrochemical method at room temperature and atmospheric pressure. The main content of this study is to prepare magnesium borate whiskers by electrochemical anodic direct oxidation. Firstly, the surface morphology, structure and elemental composition of the whiskers were characterized by SEM-XRDX EDSI-IR and TG-DTA. Secondly, the cyclic voltammetry curve of the reaction was measured by three-electrode system, the electrochemical process was studied, and the effects of temperature, toxicant and current density were investigated, and the toxic mechanism was discussed. (2) magnesium silicate whiskers were prepared by electrochemical anodic direct oxidation method. The surface morphology, structure and elemental composition of the whiskers were analyzed by means of SEMXRDX EDS-IR and TG-DTA. (3) the microstructure of whisker was calculated by using the first principle based on density functional theory (DFT). The results show that: 1. By SEM observation, magnesium borate whisker is 6 8 渭 m in length, 500 nm in diameter, and aspect ratio is 12: 1 1: 1 X RDX DS and IR analysis shows that it is magnesium borate mg 2B 2O 5) whisker; magnesium borate whisker does not contain crystal water by TG-DTA analysis; the cyclic voltammetry shows that there is no crystal water in magnesium borate whisker. The anodic oxidation reaction happened near 2.0 V and Mg2 did not deoxidize at the cathode, the optimum conditions for preparing magnesium borate whisker were as follows: 0.20mol / L toxic agent, current density 0.06A / cm ~ 2 and temperature about 20 鈩，

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