炭化温度对木质陶瓷性能和结构的影响

以烟杆和热固性酚醛树脂为原料制备了木质陶瓷,研究了炭化温度对木质陶瓷失重率、体积收缩率、表观密度、开口气孔率和体积电阻率的影响,并通过扫描电镜、激光喇曼光谱和X射线衍射技术对木质陶瓷的微观结构进行了表征与研究.结果表明,木质陶瓷是一种由烟杆生成的无定形炭和酚醛树脂生成的玻璃炭组成的多孔复合炭材料;炭化温度越高,失重率和体积收缩率越大,体积电阻率越小,表观密度和开口气孔率则在973K出现转折点;炭化温度的升高使木质陶瓷中石墨微晶平均层间距d002减小,堆积厚度Lc增加,微晶直径La在973K之后增加;而木质陶瓷的激光喇曼谱图中只出现表征无序结构的D线和表征石墨结构的G线,并且表征无序化度的R值随着炭化温度的升高以973K为分界点先增加后减小;试样在973K之前主要是进行热解反应,之后则是木质陶瓷结构的重排及有序化过程.

Effect of carbonization temperature on the properties and structure of woodceramics from carbonizing tobacco stems/phenolic resin composites

A new woodceramics from carbonizing tobacco stems impregnated with phenolic resin at different carbonization temperatures up to 1773K was prepared,and the effect of carbonization temperature on the weight loss,volume shrinkage,apparent density,open porosity and volume electrical resistivity was investigated.The evolution of microstructure of woodceramics was examined by scanning electron microscopy(SEM),X-ray diffraction(XRD),and laser Raman spectroscopy techniques.Experimental results show that the woodceramics is a porous carbon composite materials consisting of tobacco stems-originated amorphous carbon reinforced by glass-like carbon generated from phenolic resin.With increasing of carbonization temperature,the weight loss and volume shrinkage are increasing,the volume electrical resistivity is decreasing,and there is a turning point at 973K for apparent density and open porosity.The interlayer spacing of graphite sheets in microcrystal of the woodceramics,d_(002),is decreasing,but the dimension of the parallel sheet groups,L_c,is increasing with increasing of carbonization temperature.As the carbonization temperature increased above 973K,the layer dimension,L_a,is increasing too.The Raman spectra of woodceramics show the known D band,which is related to disorder carbon,and G band,which is corresponding to graphite with varying characteristics.The integrated intensity ratio R=I_D/I_G(R-value) which is the degree of disorder of woodceramics is increasing before 973K and decreasing after 973K.The obtained results indicate that carbonization reaction occurred below 973K and transformation of microstructure to woodceramics took place at 973-1773K.