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，阐明了与吸附、电或热性质有关的木炭新功能。从微观结构与吸附性能、电性能、热性能的关系探讨了其作为新功能材料的可能性。日本雪松烘干粉和杉木粉从不同类型汞化合物的水溶液中去除汞。木粉和碳化木材在200、600和1000 ℃下可去除浓度范围为1 - 10 ppm的汞。1000 ℃焙烧的木粉对汞的去除效果最好，甚至优于活性炭。以4 - 50 ℃/min的升温速率从20 ℃升温至1300 ℃，对日本柳杉进行热处理。木炭加热到400 ℃以上时会发生剧烈的收缩.在较高的加热速率下，变形较大。采用实验室规模的电炉在700 ℃下对杉进行焙烧，然后采用直接脉冲烧结进行石墨化。SEM和TEM分析了木炭和石墨化。包括石墨颗粒的区域围绕微纤丝中的随机微结构。在1700 ℃烧结5 min的木炭与在2300 ℃烧结3 h的木炭的层间距基本相同。本研究的重点是阐明以细胞结构和纤维素微纤丝为特征的“木材”的微观结构。因此，弄清结构与轻质、高模量、导电性的关系是十分重要的。间伐或废弃木材的潜力，为开发新的功能，保持细胞结构的碳材料。

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.