棕榈藤基碳化硅复相陶瓷的制备研究

发布时间：2018-05-10 17:28

  本文选题：棕榈藤 + SiC复相陶瓷　； 参考：《中国林业科学研究院》2017年硕士论文

【摘要】：本研究根据C-Si反应机理从黄藤(Daemonorops margaritae(Hance)Beccari)材中制备SiC复相陶瓷。所制备的棕榈藤基Si C复相陶瓷(R-SiC)包含SiC、未反应的生物质炭和SiO_2,是一种具高附加值的藤基陶瓷,对拓宽棕榈藤材的应用领域具有重要意义。通过X射线衍射(XRD)、傅里叶变换红外光谱(FT-IR)、X射线荧光光谱(XRF)、氮气物理吸附、场发射环境扫描电子显微镜(FESEM)和透射电子显微镜(TEM)以及X射线能谱分析(EDAX)等手段分析了不同制备方法、溶胶制备及浸渍工艺、热解参数对SiC复相陶瓷物相、化学组成、微观形貌和元素分布的影响,优化制备工艺。论文主要研究内容和结果如下:(1)以单质硅粉和SiO_2溶胶为硅源,棕榈藤粉为碳源,分别采用液相熔融硅渗透法(LSI)、溶胶-凝胶法(Sol-Gel)制备SiC复相陶瓷。结果表明:Sol-Gel制备的SiC复相陶瓷(R-SiCSiO_2)中SiC含量为24.57%,比表面积为21.99 m2/g;LSI制备的SiC复相陶瓷(R-SiCSi)中SiC含量为23.28%,比表面积为6.25 m2/g;Sol-Gel能将藤材的孔隙结构较好的保留在R-SiCSi O_2中,而LSI很难将藤材孔隙结构保留在R-SiCSi中。相对于LSI,Sol-Gel制备的R-SiC具有较完整的孔隙结构、较高的SiC产率和比表面积,在制备多孔SiC复相陶瓷上更具优势。(2)以正硅酸乙酯(TEOS)、无水乙醇(EtOH)、去离子水(H2O)为原料,盐酸或氨水为催化剂制备SiO_2溶胶。结果表明:以盐酸为催化剂制备酸性Si O_2溶胶的稳定性、固含量、粘度和浸渍性能分别为24.33 h、15.90%、7.14 mPa·s和8.75%,相对于碱性SiO_2溶胶,其粘度低,固含量高,浸渍性能好;采用正交实验系统研究原料配比和pH值对酸性溶胶稳定性、固含量、粘度和浸渍性能的影响,优选出的溶胶制备参数为原料配比n(TEOS):n(EtOH):n(H2O)=1:4:6、p H=2.5;通过对酸性溶胶辅助超声波处理,研究处理时间对溶胶性能的影响,优选的处理时间为10 min。(3)通过调节热解温度和保温时间,采用溶胶-凝胶法一步热解制备R-SiC。结果表明:不同热解参数制备的R-SiC均能保留棕榈藤材的孔隙结构;随着温度的升高、保温时间的延长,R-SiC的密度减小、比表面积增大且SiC产率升高;温度为1500℃、保温时间为120 min的热解参数下制备的R-SiC具有最高的比表面积(43.38 m2/g)、最低的密度(0.25 g/cm3)和最高的SiC产率(44.24%);R-SiC横切面上的SiC主要以晶须的形式存在。
[Abstract]:Based on the mechanism of C-Si reaction, SiC multiphase ceramics were prepared from Daemonorops margaritae Hancea Beccarii. The prepared palm based sic multiphase ceramics (R-SiC) contain sic, unreacted biomass carbon and SiO2. it is a kind of rattan based ceramics with high added value, which is of great significance to broaden the application field of rattan wood. Different preparation methods were analyzed by means of X-ray diffraction, Fourier transform infrared spectroscopy (FT-IR), X-ray fluorescence spectroscopy (XRF), physical adsorption of nitrogen, field emission environment scanning electron microscope (FESEM) and transmission electron microscope (TEM), as well as X-ray energy spectrum analysis (EDAX). The preparation and impregnation process of sols, the effects of pyrolysis parameters on the phase, chemical composition, micromorphology and element distribution of SiC multiphase ceramics were optimized. The main contents and results of this paper are as follows: (1) SiC multiphase ceramics were prepared by liquid-phase melt silicon permeation method and sol-gel method using SiO_2 sol as silicon source and palm rattan powder as carbon source. The results showed that the content of SiC and specific surface area of SiC multiphase ceramics prepared by SiC / Sol-Gel were 24.57 and 23.28 respectively. The specific surface area was 21.99 m2 / g / g LSI, and the specific surface area was 6.25 m2 / g / g Sol-Gel, which could keep the pore structure of vine in R-SiCSi O _ 2, and the specific surface area was 6.25 m ~ (2) 路g ~ (-1) 路L ~ (-1) 路L ~ (-1) 路L ~ (-1) 路L ~ (-1) 路L ~ (-1) 路L ~ (-1) 路L ~ (-1) 路L ~ (-1). However, it is difficult for LSI to retain the pore structure in R-SiCSi. Compared with the R-SiC prepared by LSI-Sol-Gel, R-SiC has relatively complete pore structure, higher yield and specific surface area of SiC, and it has an advantage in the preparation of porous SiC composite ceramics. It uses tetraethyl orthosilicate (TEOS), anhydrous ethanol (EtOHH) and deionized water (H _ 2O) as raw materials. SiO_2 sol was prepared with hydrochloric acid or ammonia as catalyst. The results showed that the stability, solid content, viscosity and impregnation performance of acidic Sio _ 2 sol prepared with hydrochloric acid as catalyst were 24.33 h ~ 15.90 mPa / s and 8.75%, respectively. Compared with alkaline SiO_2 sol, its viscosity was low, solid content was high, and impregnation performance was good. The effects of raw material ratio and pH value on stability, solid content, viscosity and impregnation properties of acidic sol were studied by orthogonal experiment system. The influence of treatment time on the properties of sol was studied. The optimal treatment time was 10 min. 3) R-SiC was prepared by one step pyrolysis with sol-gel method by adjusting the pyrolysis temperature and holding time. The results show that R-SiC prepared with different pyrolysis parameters can retain the pore structure of rattan wood, and with the increase of temperature, the density of R-SiC decreases, the specific surface area increases and the yield of SiC increases with the increase of temperature, and the temperature is 1500 鈩，

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