本文選題：碳化硅 + 灰分含量��； 參考：《寧夏大學(xué)》2017年碩士論文

【摘要】：碳化硅具有優(yōu)良的化學(xué)穩(wěn)定性、高的載流子遷移率、介電常數(shù)低及硬度高等特點(diǎn),成為最有應(yīng)用前景的半導(dǎo)體材料之一,而納米級(jí)碳化硅粉體更因純度高、粒徑分布范圍小、高比表面積等優(yōu)異特點(diǎn)備受人們的青睞。寧夏是碳化硅生產(chǎn)大省,但所生產(chǎn)的碳化硅大多數(shù)為塊狀的,所以?xún)r(jià)格相對(duì)較低,而塊狀的碳化硅則需要通過(guò)氣流粉碎才可以得到碳化硅粉體,從而增加了生產(chǎn)成本。本論文在本課題組前期的研究基礎(chǔ)上,主要以寧夏石嘴山市汝箕溝的太西煤為碳源,采用不同的方法合成了納米級(jí)β-SiC顆粒,并對(duì)其物相、形貌等進(jìn)行了表征,為寧夏納米級(jí)碳化硅粉體的制備工藝提供理論依據(jù)。主要實(shí)驗(yàn)研究?jī)?nèi)容及結(jié)果概括如下:1、碳源灰分含量對(duì)碳化硅粉體的影響1)以硅酸鈉為硅源,灰分含量不同的太西煤(6%、10%、20%)經(jīng)不同酸處理劑脫灰后為碳源,在1450 ℃下采用碳熱還原法制備出不規(guī)則顆粒狀和線狀的β-SiC,粒徑大小集中分布在300～500 nm。此外,灰分含量的多少以及酸處理劑種類(lèi)的不同對(duì)樣品的形貌、尺寸都有較大的影響。2)以硅酸鈉為硅源,脫灰與未脫灰蘭炭為碳源,硝酸鐵為催化劑,制備出碳化硅。反應(yīng)物蘭炭顆粒大小一定的情況下,脫灰和未脫灰所得到的β-SiC的形貌和尺寸不同,脫灰后所得產(chǎn)物結(jié)晶度更高、顆粒尺寸更小,且有棒狀形貌的碳化硅產(chǎn)生。由HR-TEM表征可得,產(chǎn)物的晶格條紋清晰可見(jiàn),進(jìn)一步說(shuō)明產(chǎn)物的結(jié)晶度較高,此外,兩相鄰條紋的間距為0.25 nm,與3C-SiC的(111)晶面間距相吻合。3)當(dāng)以100目脫灰蘭炭為碳源時(shí),所得產(chǎn)物的粒徑分布在0.6-1.2 μm,以200目脫灰蘭炭為碳源時(shí),所得產(chǎn)物的粒徑分布在0.3～1.0 μm,這說(shuō)明反應(yīng)原料尺寸的大小在一定程度上可以控制產(chǎn)物的大小。2、微波燒結(jié)制備β-SiC的影響因素1)以太西煤和硅酸鈉為原料,Fe(N03)3·9H20為催化劑,在1600。C x60min采用微波燒結(jié)制備出了結(jié)晶度高、純度較高的單一相納米級(jí)β-SiC顆粒,比表面積為16.606 m2/g,產(chǎn)率達(dá)到75.7%,顆粒尺寸主要分布在70-300 nm。2)FT-IR和XPS譜圖分析進(jìn)一步說(shuō)明了目標(biāo)產(chǎn)物的存在,高分辨透射電鏡顯示出相鄰的晶格條紋間距為0.25 nm,與β-SiC的(111)面間距相一致且生長(zhǎng)方向?yàn)閇111],TGA測(cè)試結(jié)果說(shuō)明產(chǎn)物在800℃以下具有極好的熱穩(wěn)定性和強(qiáng)的抗氧化性。3)在反應(yīng)過(guò)程中,當(dāng)遵循氣-液-固(VLS)機(jī)理時(shí),合成了納米β-SiC顆粒,遵循氣-固(VS)機(jī)理時(shí),合成了納米β-SiC晶須,β-SiC的整個(gè)生長(zhǎng)過(guò)程機(jī)理解釋示意圖和反應(yīng)方程式可以清楚地解釋其生長(zhǎng)機(jī)理。3、前驅(qū)體的構(gòu)筑對(duì)β-SiC的影響1)以太西煤和硅酸鈉為原料,Fe(N03)3·9H2O為催化劑。硅酸鈉和太西煤的混合物加HCl除去Na2O形成的凝膠經(jīng)過(guò)紅外干燥和冷凍干燥后得到前驅(qū)體,前驅(qū)體在1450℃、氬氣保護(hù)下,反應(yīng)5 h,得到綠色的、粒徑均勻的碳化硅粉末。經(jīng)紅外干燥的前驅(qū)體最終得到的產(chǎn)物的比表面積為13.597m2/g,粒徑分布在200～300nm,經(jīng)冷凍干燥的前驅(qū)體最終得到的產(chǎn)物的比表面積為14.878 m2/g,粒徑分布在100～200 nm。2)當(dāng)硅酸鈉和太西煤的混合物不加HC1除Na2O,加表面活性劑時(shí),形成的凝膠經(jīng)紅外干燥后得到前驅(qū)體,前驅(qū)體在1450℃下經(jīng)碳熱還原反應(yīng)后得到的SiC為松散的骨架狀,粒徑大小在200-300 nm,比表面積為11.927 m2/g。4、企業(yè)次級(jí)SiC的提純1)超聲提純比傳統(tǒng)提純節(jié)省時(shí)間,大大減少了混合酸的使用量,且酸可以循環(huán)使用,進(jìn)而減少了純水的使用和廢水的排放量,降低了成本。2)由于篩選出來(lái)的粉末樣品和顆粒樣品所含雜質(zhì)的多少和種類(lèi)不同,所以應(yīng)分開(kāi)提純。與粉末樣品相比,顆粒狀樣品除了要粉碎,還需要經(jīng)過(guò)二次酸洗等步驟。粉末樣品提純工藝較簡(jiǎn)單,費(fèi)用較低,而顆粒狀的樣品,工藝復(fù)雜,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.

【學(xué)位授予單位】：寧夏大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類(lèi)號(hào)】：TN304.24

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