关于再利用硅切削液的研究

【作者】 顾云松；

【导师】 杨振国；

【作者基本信息】 复旦大学 ， 材料物理与化学， 2011， 硕士

【摘要】 近年来,随着光伏产业以及通信产业的发展,大量硅材料的使用,致使多晶硅需求量的飞速增长。虽然生产工艺不断地改进,但是在生产过程中的浪费量依然十分巨大。整个单晶硅的加工工艺当中,大约有50%的单晶硅形成废料。在可持续发展观的指导下,如何将生产过程中产生的硅废料加以利用,成为坚持“节能、减排、降耗、增效”的一个重要课题。本论文中使用的原料来自于单晶硅切片过程中产生的硅废料,因此为合理地再利用切削过程中浪费的单晶硅提供了一些启示和解决方案。本论文主要从以下几个方面来研究硅切削废料的回收方案：首先对回收的单晶硅切削废料进行可行性分析,然后采用化学除杂的方法对切削废料进行初步的清洗。根据分析不同的清洗过程所得到的产物,对整个清洗方案进行调整,直到得到最终的清洗方案。经过该方案处理的样品,硅的含量能够达到99%以上,原料中的主要杂质的含量下降非常明显。接下来对清洗后的样品进行熔炼后,发现在现有的实验条件下要制备太阳能用多晶硅有-定的困难。要制备纯度较高的多晶硅需要更加严苛的条件,因此本论文从另一个方向进行探索。最终利用清洗后的硅废料在氩气氛围保护的电炉中,在1550℃的高温条件下,使用碳热还原法成功地制备了纳米碳化硅晶须。制得的纳米碳化硅晶须直径约为30nm左右,而长度则超过1微米,达到几个微米。因为其长径比大,所以具有较大的应用价值。论文采用了许多先进的测试方法对原料、制备的产物等进行分析。例如：使用X荧光光谱分析(X Ray Fluorescence)、X射线衍射(X Ray Diffraction)和扫描电子显微镜(Scanning Electron Microscope)来分析制备碳化硅的原料。同时使用X荧光光谱分析(XRF)、X射线衍射(XRD)、扫描电子显微镜(SEM)和透射电子显微镜(Transmission Electron Microscope)来分析碳化硅样品等。并在最后根据纳米碳化硅产物的分析结果,探讨了本论文中的纳米碳化硅晶须的生成机理,为今后的研究提供了一定程度的理论指导。综上所述,本论文通过回收单晶硅切削废料,并成功地在较简单的实验条件下制备纳米碳化硅晶须,从而达到保护环境、减少工业废弃物、变废为宝的目的。制得的纳米碳化硅晶须,因为拥有优良的物理、化学性质,有希望被广泛地应用于国防、环保、能源、航空、交通等等各个领域,具有很高的商业应用价值。更多还原

【Abstract】 Nowadays, with the high-speed development of photovoltaic industry and communication industry, the demand quantities of monocrystalline silicon increased quickly because of a lot of silicon materials were used. In the whole technics, about 50% monocrystalline silicon becomes silicon wastes. How to recycle these silicon wastes which generated in silicon wafer production process is an important project for insisting on "energy saving, emission reduction, energy, increased efficiency". The raw materials in this paper come from monocrystalline silicon slicing process. This paper gives some suggestions on reuse silicon wastes which are mentioned before, and mainly analyzes silicon waste recycling programs from the following aspects:Firstly, monocrystalline silicon wastes were analyzed to confirm the recycling possibility, and chemical method was used as basic refine step to removing these impurities in silicon wastes. The whole washing project was adjusted according to the analysis result of washed silicon wastes until the final washing project have been determined. The content of silicon in washed silicon wastes can be achieved above 99%, and the main impurity’s content decreased very significantly.Then it is found that preparing polycrystalline silicon used in solar cells is very hard in this condition after smelting these washed samples. So this project should find another way to continue this research. Finally, carbon thermal reduction method was successfully used to preparing nano silicon carbide whisker at 1550℃and in the protection of argon. The diameter of nano SiC whisker is about 30nm, and the length is more than 1 micron, to a few microns. Because of its length-diameter ratio is very large, these nano SiC whiskers have a greater value. According to analysis results of nano SiC, the formation mechanism of nano SiC whiskers was discussed and provided a degree of theoretical guidance for future study.To sum up, this paper achieved the purpose of environment protection, decreasing industry wastes and turning wastes into treasure by recycling monocrystalline silicon wastes and preparing nano SiC whiskers successfully in a simple condition. Prepared nano silicon carbide whiskers have excellent physical and chemical properties, so it is hopeful to be widely used in national defense, environmental protection, energy, aviation and transport fields, with high value commercial applications.更多还原