Microstructural Investigation of Carbonized or Sintered Wood and Development of New Functions

通过分析木炭的晶体结构特征，改变炭化或烧结过程中的温度或压力，阐明了木炭在吸附、电学或热学性能方面的新功能。研究了木粉的微观结构与吸附、电、热性能的关系，探讨了其作为新功能材料的可能性。日本雪松炭化木粉去除不同类型汞化合物水溶液中的汞。木粉和碳化木材在200ppm、600ppm和1000ppm的浓度范围内去除汞。炭化温度为1000℃的木粉对溶液中汞的去除效果最好，甚至优于活性碳。在20~1300℃范围内，以4~50℃/min的升温速率对日本雪松进行碳化处理。加热400℃以上的木炭表现出剧烈的收缩。升温速率越高，变形越大。在实验室规模的电炉中，Sugi在700℃下碳化，然后用直接脉冲烧结进行石墨化。用扫描电子显微镜和电子显微镜对木炭和石墨化产物进行了分析。包括石墨化颗粒的区域包围着微纤丝中的随机微结构。在1700℃下烧结5min的木炭的层间距与2300℃下炭化3h的木炭的层间距基本相同。本研究的重点是澄清以细胞结构和纤维素微纤维为特征的木炭的微观结构。弄清结构与轻质、高模、导电性之间的关系是非常重要的。间伐或废弃木材的潜力被显示为具有维持细胞结构的新功能的碳材料的开发。

New functions of wood charcoal related to adsorption, electric or thermal properties were clarified by analyzing characteristics of crystal structures of wood charcoal, changing the temperature or pressure during carbonization or sintering. The possibility as the material with new functions was investigated on the microstructures in the relation to adsorption, electric, or thermal property.Japanese cedar ovendried and carbonized wood powder removed mercury from aqueous solution of different types of mercury compounds. Wood powder and carbonized wood at 200, 600, and 1000 ℃ removed mercury with in the concentration range 1 - 10 ppm. Wood powder carbonized at 1000 ℃ performed best, even better than activated carbon in removing mercury in the solution. Japanese Cedar was carbonized at heating rate of 4 - 50 ℃/min from 20 up to 1300 ℃. The charcoal heated over 400 ℃ showed drastic shrinkage. The deformation was greater at higher heating rate. Sugi was carbonized at 700 ℃ , using a laboratory-scale electric furnace, and then graphitized with direct pulse sintering. SEM and TEM analyzed the wood charcoal and graphitization. The area including the graphitic particles surrounds the random microstructure in the microfibrils. The interlayer spacing in the wood charcoal sintered at 1700 ℃ for 5 min is almost the same as that of the wood charcoal carbonized at 2300 ℃ for 3 hrs.The point of this study is the clarification of microstructures of "wood" characterized as cell structures and cellulose microfibrils. It is important to make clear the relation between the structures and lightness, high modulus, conductivity. Potentials of thinning or waste wood were shown for the development of carbon materials with new functions maintaining cell structures.