【摘要】：隨著經(jīng)濟(jì)的發(fā)展，石油等傳統(tǒng)能源日益枯竭而且人們對(duì)環(huán)境問(wèn)題的日益重視，使得世界各國(guó)都極力開展新能源的開發(fā)和利用。太陽(yáng)能由于具有清潔安全、無(wú)污染、相對(duì)持續(xù)、穩(wěn)定以及能源取之不盡等優(yōu)點(diǎn)被認(rèn)為是最理想的可再生資源。 本文是以二氧化硅粉末為原料，以熔鹽電解法為技術(shù)核心結(jié)合傳統(tǒng)冶金法進(jìn)行技術(shù)集成，直接制備多晶硅，然后對(duì)其進(jìn)行了工藝研究。通過(guò)熱力學(xué)計(jì)算，得出二氧化硅的理論分解電壓為1.10 V(vs.Ca~(2+)/Ca)。在熔融CaCl_2體系中，進(jìn)行直接電解還原SiO_2制取Si的實(shí)驗(yàn)，對(duì)電解產(chǎn)物進(jìn)行了XRD、SEM、EDS分析，結(jié)果表明：在電解溫度850℃，，槽電壓2.6 V下電解12個(gè)小時(shí)可以得到晶體化程度高和純度高的硅，純度達(dá)到了96.95%。通過(guò)對(duì)不同電解電壓下產(chǎn)物的分析，表明在2.6 V下發(fā)生離子化反應(yīng)，在2.8 V下發(fā)生鈣熱還原反應(yīng)。研究了電解工藝條件的影響，表明電解電流隨著試樣的質(zhì)量的增加而增大；燒結(jié)溫度和電解溫度會(huì)對(duì)電流效率產(chǎn)生影響，在600℃的燒結(jié)溫度和850℃電解溫度時(shí)，電流效率最高；對(duì)電解產(chǎn)物表面分析結(jié)果表明：造成后期電流變大的主要原因是石墨脫落和副反應(yīng)的發(fā)生；在不同溫度下的CaCl_2 (50 mol%) NaCl混合熔鹽中，成功電解出硅，證明了低溫熔鹽電解的可行性。對(duì)熔鹽電解硅的反應(yīng)機(jī)理進(jìn)行了分析，其可能的還原過(guò)程為：首先二氧化硅發(fā)生電化學(xué)還原，脫離出氧原子而形成具有閑置鍵的硅反應(yīng)中間態(tài)，中間態(tài)硅原子與鄰近的硅原子以Si-Si鍵的形式結(jié)合，迅速生成非晶態(tài)硅，在850℃的溫度下，非晶硅將發(fā)生晶型的轉(zhuǎn)變，重排而生成晶體硅。
[Abstract]:With the development of economy, oil and other traditional energy are increasingly exhausted and people pay more and more attention to environmental problems, which makes the countries all over the world try their best to develop and utilize new energy. Solar energy is considered to be the most ideal renewable resource because of its advantages of clean, safe, pollution-free, relative sustainability, stability and inexhaustible energy. In this paper, polysilicon is synthesized directly from silicon dioxide powder with molten salt electrolysis as the core technology and traditional metallurgical process. By thermodynamic calculation, the theoretical decomposition voltage of silica is 1.10V (vs.Ca~ (2) / Ca). In the molten CaCl_2 system, the direct electrolytic reduction of SiO_2 to produce Si was carried out. The results of XRD,SEM,EDS analysis showed that the electrolysis temperature was 850 鈩

本文編號(hào)：2310342