超细煤基β-SiC粉体的构筑及其结构特性的研究

发布时间：2018-05-14 08:38

本文选题：碳化硅 + 灰分含量　；参考：《宁夏大学》2017年硕士论文

【摘要】：碳化硅具有优良的化学稳定性、高的载流子迁移率、介电常数低及硬度高等特点,成为最有应用前景的半导体材料之一,而纳米级碳化硅粉体更因纯度高、粒径分布范围小、高比表面积等优异特点备受人们的青睐。宁夏是碳化硅生产大省,但所生产的碳化硅大多数为块状的,所以价格相对较低,而块状的碳化硅则需要通过气流粉碎才可以得到碳化硅粉体,从而增加了生产成本。本论文在本课题组前期的研究基础上,主要以宁夏石嘴山市汝箕沟的太西煤为碳源,采用不同的方法合成了纳米级β-SiC颗粒,并对其物相、形貌等进行了表征,为宁夏纳米级碳化硅粉体的制备工艺提供理论依据。主要实验研究内容及结果概括如下:1、碳源灰分含量对碳化硅粉体的影响1)以硅酸钠为硅源,灰分含量不同的太西煤(6%、10%、20%)经不同酸处理剂脱灰后为碳源,在1450 ℃下采用碳热还原法制备出不规则颗粒状和线状的β-SiC,粒径大小集中分布在300～500 nm。此外,灰分含量的多少以及酸处理剂种类的不同对样品的形貌、尺寸都有较大的影响。2)以硅酸钠为硅源,脱灰与未脱灰兰炭为碳源,硝酸铁为催化剂,制备出碳化硅。反应物兰炭颗粒大小一定的情况下,脱灰和未脱灰所得到的β-SiC的形貌和尺寸不同,脱灰后所得产物结晶度更高、颗粒尺寸更小,且有棒状形貌的碳化硅产生。由HR-TEM表征可得,产物的晶格条纹清晰可见,进一步说明产物的结晶度较高,此外,两相邻条纹的间距为0.25 nm,与3C-SiC的(111)晶面间距相吻合。3)当以100目脱灰兰炭为碳源时,所得产物的粒径分布在0.6-1.2 μm,以200目脱灰兰炭为碳源时,所得产物的粒径分布在0.3～1.0 μm,这说明反应原料尺寸的大小在一定程度上可以控制产物的大小。2、微波烧结制备β-SiC的影响因素1)以太西煤和硅酸钠为原料,Fe(N03)3·9H20为催化剂,在1600。C x60min采用微波烧结制备出了结晶度高、纯度较高的单一相纳米级β-SiC颗粒,比表面积为16.606 m2/g,产率达到75.7%,颗粒尺寸主要分布在70-300 nm。2)FT-IR和XPS谱图分析进一步说明了目标产物的存在,高分辨透射电镜显示出相邻的晶格条纹间距为0.25 nm,与β-SiC的(111)面间距相一致且生长方向为[111],TGA测试结果说明产物在800℃以下具有极好的热稳定性和强的抗氧化性。3)在反应过程中,当遵循气-液-固(VLS)机理时,合成了纳米β-SiC颗粒,遵循气-固(VS)机理时,合成了纳米β-SiC晶须,β-SiC的整个生长过程机理解释示意图和反应方程式可以清楚地解释其生长机理。3、前驱体的构筑对β-SiC的影响1)以太西煤和硅酸钠为原料,Fe(N03)3·9H2O为催化剂。硅酸钠和太西煤的混合物加HCl除去Na2O形成的凝胶经过红外干燥和冷冻干燥后得到前驱体,前驱体在1450℃、氩气保护下,反应5 h,得到绿色的、粒径均匀的碳化硅粉末。经红外干燥的前驱体最终得到的产物的比表面积为13.597m2/g,粒径分布在200～300nm,经冷冻干燥的前驱体最终得到的产物的比表面积为14.878 m2/g,粒径分布在100～200 nm。2)当硅酸钠和太西煤的混合物不加HC1除Na2O,加表面活性剂时,形成的凝胶经红外干燥后得到前驱体,前驱体在1450℃下经碳热还原反应后得到的SiC为松散的骨架状,粒径大小在200-300 nm,比表面积为11.927 m2/g。4、企业次级SiC的提纯1)超声提纯比传统提纯节省时间,大大减少了混合酸的使用量,且酸可以循环使用,进而减少了纯水的使用和废水的排放量,降低了成本。2)由于筛选出来的粉末样品和颗粒样品所含杂质的多少和种类不同,所以应分开提纯。与粉末样品相比,颗粒状样品除了要粉碎,还需要经过二次酸洗等步骤。粉末样品提纯工艺较简单,费用较低,而颗粒状的样品,工艺复杂,耗材耗能。
[Abstract]:Silicon carbide has excellent chemical stability, high carrier mobility, low dielectric constant and high hardness. It has become one of the most promising semiconductor materials. The nanoscale silicon carbide powder is more and more popular because of its high purity, small size distribution, high specific surface area and so on. Ningxia is a major province of silicon carbide production, But most of the silicon carbide produced is massive, so the price is relatively low, and the massive silicon carbide needs to be smashed by air to get the silicon carbide powder, thus increasing the production cost. On the basis of the previous research, this paper mainly takes the western coal of Ru ski in Shizuishan City, Ningxia as the carbon source, and uses different kinds of carbon sources. Nanoscale beta -SiC particles were synthesized, and their phase and morphology were characterized. The theoretical basis for the preparation of Ningxia nanoscale silicon carbide powders was provided. The main experimental research contents and results are summarized as follows: 1, the effect of the ash content of carbon source on the silicon carbide powder is 1, and the sodium silicate is the silicon source and the ash content is different (6%, 10%, 20%) after deashing with different acid treatment agents as carbon source, the irregular granular and linear beta -SiC was prepared by carbon thermal reduction at 1450 C. The size of particle size was concentrated in 300~500 nm.. The amount of ash content and the different kinds of acid treatment agent had a greater influence on the shape and size of the sample.2) with sodium silicate as silicon. The morphology and size of the beta -SiC obtained by deashing and non deashing are different. The crystallinity of the product is higher, the size of the particles is smaller, and the silicon carbide is produced with the rod shape. It is characterized by HR-TEM. The lattice stripe of the product is clearly visible, further indicating that the crystallinity of the products is higher, in addition, the distance between the two adjacent stripes is 0.25 nm, and the spacing of the 3C-SiC (111) is in anastomosing.3). When the 100 mesh de ash carbon is the carbon source, the particle size of the product is distributed in the 0.6-1.2 mu m, and the particle size of the obtained product with 200 mesh de ash carbon as the carbon source. The cloth is 0.3 ~ 1 m, which shows that the size of the reaction material can control the size of the product to a certain extent.2, the influence factor of the preparation of the beta -SiC by microwave sintering is 1). The catalyst of Tai Xi coal and sodium silicate, Fe (N03) 3. 9H20 as the catalyst, the single phase nanometer grade with high crystallinity and high purity is prepared by microwave sintering in 1600.C x60min. The specific surface area is 16.606 m2/g, the specific surface area is 16.606 m2/g, the yield reaches 75.7%, the particle size is mainly distributed in 70-300 nm.2. The FT-IR and XPS spectrum analysis further illustrate the existence of the target products. The high resolution transmission electron microscopy shows that the spacing of the adjacent lattice stripe is 0.25 NM, and the distance between the (111) surface of the beta -SiC is the same and the growth direction is [111] and TGA test junction. The result shows that the product has excellent thermal stability and strong antioxidant.3 below 800 C) during the reaction process, when the mechanism of gas liquid solid (VLS) is followed, nano beta -SiC particles are synthesized. When the mechanism of gas solid (VS) is followed, the nano beta -SiC whisker is synthesized. The mechanism interpretation and reaction equation of the whole growth process of beta -SiC can be clearly explained and the reaction equation can be clearly explained. Explain its growth mechanism.3, the influence of the construction of precursors on beta -SiC 1) taking the coal and sodium silicate as the raw material, Fe (N03) 3. 9H2O as the catalyst. The gel formed by the mixture of sodium silicate and Tai West coal and HCl removal of Na2O has been obtained by infrared drying and freeze-drying, and the front drive is protected by 5 h under the protection of argon at 1450. The specific surface area of the final product obtained by the infrared drying precursor is 13.597m2/g, the particle size distribution is 200 to 300nm, the specific surface area of the products obtained by the freeze-dried precursor is 14.878 m2/g, the particle size is 100~200 nm.2, when the mixture of sodium silicate and the coal of the west coal is not HC1 Na2O When the surface active agent is added, the precursor formed by infrared drying is obtained by infrared drying. The precursor obtained by carbon thermo reduction at 1450 C is loose skeleton, the size of the particle is 200-300 nm, the specific surface area is 11.927 m2/g.4, and the purification of the enterprise secondary SiC is 1). The ultrasonic purification is less time than the traditional purification, and the mixed acid is greatly reduced. The amount of use, and the acid can be recycled, reduces the use of pure water and the discharge of waste water and reduces the cost of.2). It should be purified separately because of the number and variety of the impurities contained in the selected powder samples and particle samples. Compared with the powder samples, the granular samples need to be washed two times in addition to the crushing. The purification process of powder sample is simple and the cost is low, while the granular sample is complex and consumables consume energy.

【学位授予单位】：宁夏大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN304.24

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