【作者】 谭德新；

【导师】 史铁钧；

【作者基本信息】 合肥工业大学 ， 材料学， 2011， 博士

【摘要】 论文的主要目标是：先制备高耐热、高碳率的热固性三苯乙炔基硅烷树脂，然后以它们为基体，利用木材的天然构造，结合Sol-Gel直接浸渍方法，经过热处理，制备SiC/C（TiN/C）复合木陶瓷；再研究树脂和复合木陶瓷的结构与性能，为SiC/C（TiN/C）复合木陶瓷的进一步工业化应用提供理论和实验依据。主要创新工作如下：1)用乙烯基三氯硅烷和苯基三氯硅烷为原料，苯乙炔基镁为格氏试剂，通过格氏反应制备了乙烯基三苯乙炔基硅烷（VTPES）和苯基三苯乙炔基硅烷（PTPES）。用FT-IR、1H-NMR、13C-NMR和²⁹Si-NMR等手段分析证实，合成的化合物为目标产物。用DSC分析显示，单体VTPES的熔点为85℃，聚合起始温度为289℃；单体PTPES的熔点在115℃，聚合起始温度为336℃，它们的加工窗口都在200℃以上。用kissinger方法处理DSC曲线，经过计算得到两种单体的活化能分别为114.25kJ/mol和153.89kJ/mol，反应级数为0.92和0.93，符合一级动力学方程。用TGA分析显示，两种单体的聚合物的热分解温度在550℃左右，经过800℃处理后聚合物的残炭量可达75%。2)分别用氧化铁和金属镍为催化剂，研究了不同温度和催化剂对聚乙烯基三苯乙炔基硅烷树脂（PVTPES）石墨化程度的影响。用XRD分析表明，当热处理温度增加到1590℃时，聚合物的石墨化度超过86%，随着催化剂含量的增加，晶面间距d002从0.3439nm降低到0.3361nm，接近理想石墨的晶面间距。热处理温度大大低于无催化剂情况下石墨化所要求的温度。用电镜分析显示，石墨化产物结晶度高，形态多样，呈环状、棒状或胶囊状。比较氧化铁和镍在1590℃下的催化效果：当镍含量从3%增加到15%时，晶面间距d002在0.3372nm左右变化，而氧化铁催化体系其晶面间距d002逐渐降低到0.3361nm；拉曼图谱分析显示镍催化硅烷树脂的R值为1.03，而氧化铁催化其R值为0.51，氧化铁在1590℃下显示更好的催化石墨化效果。3)系统研究了溶剂极性、热处理温度和木粉粒子尺寸对木粉自身相对结晶度和热稳定性的影响。研究发现：随着溶剂极性的增加，木粉的被抽提物从3.75%增加到7.22%，相对结晶度从46.5%增加到52.9%，热分解温度从319℃降低到304.7℃，其原因是弱极性溶剂有助于木粉中热稳定性较高的木质素的去除；同样当热处理温度处于低于170℃的范围时，随着温度的增加，木粉的相对结晶度略有升高，从46.9%增加到50%；温度超过200℃，木粉中纤维素的结晶区被破坏，木粉的热稳定性降低。当木粉尺寸从35μm增加到250μm时，木粉的相对结晶度从42.6%增加到45.8%，受传热滞后影响，木粉的热分解温度从293.4℃增加到329.5℃。4)以氧化铁和镍为催化剂，研究了不同含量和温度对杉木粉催化石墨化的影响，探讨了催化机理。用XRD分析显示，当热处理温度从900℃增加到1590℃时，杉木粉的石墨化度可达95%；当催化剂含量增加到15%时，d002接近于0.3354nm，石墨化度几乎达到100%。并且随着温度的增加，氧化铁与碳反应生成碳化铁，催化石墨化过程遵循碳化物形成-分解机理进行；而镍在升温过程中保持稳定，催化石墨化过程遵循溶解-析出机理。对比氧化铁和镍的XRD和拉曼图谱分析表明，在1400℃下镍对木粉具有更好的催化石墨化效果，而在1590℃下炭化6小时，两种催化体系的R值均为0.6，显示相同的催化效果。5)用Sol-Gel方法，成功将正硅酸四乙酯（TEOS）溶胶浸渍到炭化杉木的管胞和纹孔中。当反复浸渍次数到9次时，炭化杉木增加量可达145.2%。将浸渍物分别在800℃和1590℃下炭化，经SEM分析显示，较高温度下，杉木炭的管胞和纹孔结构同时收缩，管胞壁变薄，从2-4nm减少到小于2nm，同时SiO₂粒子逐渐由无定形向晶态转换，并发生SiO₂粒子与碳源之间的固-固和液-固反应，从而生物质C逐渐向SiC转化，最终形成SiC木陶瓷。将钛酸四丁酯（TNBT）直接浸渍到杉木炭中。在温度达800℃时，TNBT分解生成的无定形TiO₂完全变成晶态，然后逐渐与保护气氛氮气反应，到1200℃时完全生成TiN晶粒，这些TiN粒子逐渐沉积到炭的表面形成TiN木陶瓷。随着温度升到1590℃，由于TiN状态稳定，体系仅发生炭的石墨化转化。经过N2等温吸附脱附测试显示：TiN木陶瓷孔结构的一部分为杉木炭原有的孔，孔径约在4nm左右；另一部分为TiN晶粒生成所产生的新孔，孔径约12nm左右。将单体VTPES常温下分别浸渍到SiC木陶瓷和TiN木陶瓷中，热处理后制得SiC/C复合木陶瓷和TiN/C复合木陶瓷。经过摩擦性能测试：两种复合木陶瓷均具有很好的耐磨性，随着浸渍次数和热处理温度的增加，两种陶瓷材料的磨耗量逐渐降低并趋于定值。更多还原

【Abstract】 The purpose of our investigation is to prepare polytri（phenylethynyl）]silane resin with highthermal stability and char yield, then using this resin as matrix to synthesize SiC/C（TiN/C）composite woodceramics, which was prepared in virtue of nature structure of fir by Sol-Gelimpregnation method via thermal treatment. Furthermore, the studies of structure and properties ofresin and ceramics provide theoretical and experimental foundation for the industrialization of SiC/C（TiN/C） composite woodceramics.The major creative works are listed as following:1) Using vinyltrichlorosilane and phenyltrichlorosilane as raw materials, phenylethynylmagnesium as Grignard reagent, vinyl tri（phenylethynyl）silane〔（ph-C≡C）3-Si-C=CH2〕（VTPES） andphenyl tri（phenylethynyl）silane〔（ph-C≡C）3-Si-ph〕（PTPES） were synthesized by Grignard reaction.Their molecular structures were characterized by means of nuclear magnetic resonance (1H-NMR,13C-NMR,²⁹Si-NMR), Fournier transform infrared （FT-IR）. The corresponding kinetic parameters,such as activation energy （Ea）, pre-exponential factor （A） and the order of the reaction （n）, were alsoobtained according to the Kissinger method by differential scanning calorimetry （DSC）. The resultsshow that their melting points of VTPES and PTPES were84℃and116℃, and their curing peaktemperatures were285℃and336℃, respectively, which indicated that the two monomers had botha wide processing window over200℃. The activation energy was114.25kJ/mol and153.89kJ/mol,and the order of the reaction （n） was0.92and0.93. The curing reaction rates were consistent with afirst-order kinetic equation. TGA showed that the decomposed temperature of the two polymers wasabout550℃and the char yield was beyond75%at800℃.2) Catalytic graphitization of poly [vinyl tri（phenylethynyl）]silane resin （PVTPES） with ironoxide and nickel between900℃and1590℃under nitrogen atmosphere was investigated. Theeffects of the catalyst content and the heat treatment temperature （HTT） on the graphitization werestudied. The structural change in the graphitization process was also characterized by X-raydiffraction （XRD）, High-resolution transmission electron microscopy （HRTEM） and laser Raman（LR）. The XRD results show that the （002） diffraction angle increased from25.95°to26.50°, andthe graphitization degree was also beyond86%when the HTT increased from900℃to1590℃,which indicated that the two catalysts had excellent catalytic effect at low temperature. The （002）diffraction angle closed to26.50°and the graphitization degree closed to86%when the catalystcontent increased from3%to15%. HRTEM images indicate that the graphitic carbon materialspossessed a high graphitization with coil, rod and capsule morphology.Comparative analysis of catalytic effect of Ni and Fe2O3was investigated at1590℃. The （002）diffraction angle changed between26.40°and26.42°with increasing the catalyst content, and thecorresponding R （ID/IG） value was1.03. While the diffraction angle closed to the26.56°using ironoxide as catalyst and the corresponding R value was0.51, which indicated that iron oxide was moreeffective than nickel at1590℃.3) The effects of solvent polarity, HTT and particle size on relative crystallinity index （Ic） andthermal stability of fir powder were investigated by XRD, thermal gravity analysis （TGA）,derivative thermogravimetry （DTG） and FT-IR. The results show that the percentage of extractionincreased from3.75%to7.22%when the solubility parameter varied from7.3to12.1, and the Icalso increased from46.5%to52.9%. On the contrary, the decomposed temperature decreased from319℃to304.7℃. When the HTT was at below170℃, the Ic was increased from46.9%to50%as the increase of temperature. Beyond200℃, the crystalized cellulose began to melt, resulting in adecrease of thermal stability. The Ic slightly decreased from46.8%to42.6%and the thermalstability decreased from329.5℃to293.4℃as the particle sizes decreased from400μm to35μm.4) Catalytic graphitization of fir powder with iron oxide and nickel between900℃and1590℃under nitrogen atmosphere was investigated. The effects of the catalyst content, the HTT andholding time on the graphitization were analyzed, and the structural change was also studied byXRD, HRTEM and LR. XRD results show that the （002） diffraction angle increased from26.04°to26.50°, and the graphitization degree was also beyond95%when the HTT increased from900℃to1590℃. Noticeably, the iron oxide reacted with carbon to form metal carbide and the graphiticcarbon was formed by carbide formation-decomposition mechanism. While the nickel waschemically stable in the experiments and the catalytic graphitic mechanism were carbondissolution-precipitation mechanism. The （002） diffraction angle closed to26.56°and thegraphitization degree was also increased from50%to100%when the catalyst content increasedfrom3%to15%. Comparative analysis of catalytic effect of Ni and Fe2O3showed that nickel wasmore effective than iron oxide at1400℃. But the R values were both0.6when the holding timewas6h at1590℃, which indicated that the two catalysts had the same catalytic effect when the heattreated time was long enough.5) Using tetraethylorthosilicate （TEOS） as precursor, SiO₂/charcoal hybrid materials withinterpenetrating network were fabricated by Sol-Gel method. The results show that the weight addedto145.2%when the impregnation times repeated nine times. In the course of carbonization of hybridmaterials from800℃to1590℃, SiO₂particles transformed from amorphous into crystalline and theSiO₂reacted with carbon to form SiC particles or whiskers by solid-solid or solid-liquid reaction,resulting in the formation of SiC woodceramics.The direct impregnation of Titanium n-butoxide （TNBT） show that the TiO₂particles obtainedby condensation of TNBT transformed from amorphous to crystalline at low800℃accompany withthe reaction with N2which acted as protection atmosphere to form TiN particles. When thetemperature arrived at1200℃, the reaction finished and the TiN woodceramics was composed ofamorphous carbon, graphitic carbon and TiN crystal. While the TiN crystal was chemical stabilityand the ceramics only transformed from amorphous carbon to graphitic carbon when HTT increasedto1590℃. The N2adsorption and desorption isotherm showed that the pore of the TiNwoodceramics consisted of two parts: one was the original pore structure of fir charcoal with4nm,although the impregnation of TNBT decreased the pore volume, the effect of TNBT on porediameter was slight; another was the pore of TiN crystal with12nm.The SiC/C （TiN/C） composite woodceramics were prepared by impregnating the VTPESmonomer in Si （Ti） woodceramics at ambient temperature, then cured and carbonized at designedtemperature. Experimental investigation was conducted on the friction and wear properties of SiC/C（TiN/C） composite woodceramics. The results showed that the wear percentage closed to a certainvalue with increasing the impregnation times and carbonized temperature due to the lubrication ofgraphitic carbon grain.更多还原