發(fā)布時(shí)間：2018-03-30 00:14

  本文選題：鈦金屬　切入點(diǎn)：溶解度　出處：《華北理工大學(xué)》2017年碩士論文

【摘要】：傳統(tǒng)的電化學(xué)法制備鈦金屬主要以純氯化物為電解介質(zhì),制取鈦金屬粉末。而在NaCl-KCl-NaF熔鹽體系中,以碳鋼為工作電極,可以在其表面制備鈦金屬防腐涂層。鈦鍍層不僅提高了碳鋼基體的耐腐蝕性能,而且提供了一種更加簡便的獲得鈦金屬的工藝,該工藝的提出將碳鋼基體的力學(xué)性能與鈦金屬的耐腐蝕性能結(jié)合在了一起。利用等溫飽和法分析TiO_2在NaCl-KCl-Na F熔鹽體系中的熔融和溶解特性,確定了TiO_2在熔鹽體系內(nèi)的飽和溶解時(shí)間為4.0h,并且熔鹽組分中,隨著NaF摩爾分?jǐn)?shù)的增加,TiO_2在熔鹽體系中的溶解量升高;對(duì)不同配比的熔鹽進(jìn)行差熱分析,可以確定當(dāng)NaF含量較少時(shí),TiO_2影響著整個(gè)熔鹽體系的初晶溫度,而當(dāng)NaF含量較高時(shí),改變TiO_2的質(zhì)量分?jǐn)?shù)初晶溫度基本保持不變。采用循環(huán)伏安法和方波伏安法對(duì)NaCl-KCl-NaF-TiO_2熔鹽體系中的Ti(IV)離子的電化學(xué)還原機(jī)理進(jìn)行了分析。由實(shí)驗(yàn)結(jié)果可以確定Ti(IV)離子經(jīng)三步還原為鈦金屬,即Ti(IV)→Ti(III)→Ti(II)→Ti,并且該還原過程為不可逆反應(yīng);采用計(jì)時(shí)電流確定了鈦離子在陰極表面的形核機(jī)理為三維半球型瞬時(shí)形核過程。通過碳鋼表面電沉積鈦的實(shí)驗(yàn)研究可以確定,當(dāng)沉積溫度為800℃,電沉積電流為1.5A,沉積時(shí)間為1.0h情況下,獲得的沉積層質(zhì)量最好;通過對(duì)比直流電沉積和脈沖電沉積試樣的表面形貌,可以確定脈沖電沉積獲得的沉積層中晶粒尺寸更小,且沉積層更加致密、均勻、表面平整。在3.5%的NaCl水溶液中,采用極化曲線和交流阻抗測試方法研究了沉積試樣的耐腐蝕性能。測試結(jié)果表明,當(dāng)沉積電流為1.5A,沉積時(shí)間為1.0h時(shí)所得的試樣的耐腐蝕性最為優(yōu)異。與碳鋼基體相比,即使碳鋼表面只沉積少量的鈦,也能顯著提升其耐腐蝕性能。并且脈沖沉積試樣的防腐特性明顯優(yōu)于直流沉積試樣。
[Abstract]:Titanium powder was prepared by traditional electrochemical method using pure chloride as electrolytic medium, while carbon steel was used as working electrode in NaCl-KCl-NaF molten salt system. Titanium coating not only improves the corrosion resistance of carbon steel substrate, but also provides a more convenient process for obtaining titanium metal. This process combines the mechanical properties of carbon steel substrate with the corrosion resistance of titanium metal. The melting and dissolution characteristics of TiO_2 in NaCl-KCl-Na F molten salt system are analyzed by isothermal saturation method. The saturated dissolution time of TiO_2 in molten salt system is 4.0 h, and the dissolved amount of TiO-2 in molten salt system increases with the increase of NaF molar fraction. It can be ascertained that TiO2 affects the initial crystal temperature of the whole molten salt system when the content of NaF is low, and when the content of NaF is high, The electrochemical reduction mechanism of TiO_2 in molten salt system was analyzed by cyclic voltammetry and square wave voltammetry. Three steps of reduction to titanium, Tijiv). 鈫扵ijii). 鈫扵iII). 鈫扵he nucleation mechanism of titanium ions on the cathode surface is determined to be a three-dimensional hemispherical instantaneous nucleation process, and the experimental study on the electrodeposition of titanium on the surface of carbon steel can be confirmed. When the deposition temperature is 800 鈩，

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