Microstructural study of carbonized wood after cell wall sectioning

Wooden blocks of Japanese cedar (Cryptomeria japonica) were carbonized at 700 and 1,800 degrees C. The microstructure was analyzed by transmission electron microscopy (TEM) and mu-Raman spectroscopy of the inner planes of wood cell walls. The predominant structure was of a turbostratic nature and no heterogeneity was observed originating from the original cell walls. TEM observations of samples carbonized at 1,800 degrees C showed ordered regions in the surface layer of cell walls. This result was supported by polarized mu-Raman analysis. It may be caused by the deposition of carbon compounds volatilized from the cell walls during pulse current heating

Development of SiC/C Composite Materials from Wood Charcoal by a Pulse Current Sintering Method and Their Properties

この論文は国立情報学研究所の学術雑誌公開支援事業により電子化されました

Spectroscopic analysis of carbonization behavior of wood, cellulose and lignin

The surface and bulk chemistry of Japanese cedar (Cryptomeria Japonica), cotton cellulose and lignin samples carbonized at 500-1,000 degrees C was investigated by elemental analysis, Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and micro-Raman spectrometry. The objective was to link the original wood components to the final carbonized wood microstructures. The carbonized samples show increasing degrees of order from cellulose to wood to lignin. The cellulose component in the wood strongly affects the ordering of polyaromatic carbons in carbonized wood; this ordering is attributed primarily to the difference in ratio between aromatic and aliphatic carbons and to the amount of cross-linking by ether and carboxylic groups up to 500 degrees C

Characterization of sp(2)- and sp(3)-bonded carbon in wood charcoal

Japanese cedar (Cryptomeria japonica) preheated at 700 degrees C was subsequently heated to 1800 degrees C and characterized by electron microscopy, X-ray diffraction, and micro-Raman spectroscopy. The degree of disorder of carbon crystallites and the amount of amorphous phase decreased considerably with an increase in heat treatment temperature to 1400 degrees C, while carbon crystallites clearly developed above this temperature, showing that the microstructure of carbonized wood undergoes drastic changes around 1400 degrees C. Besides showing the bands for sp(2-)bonded carbon, the Raman spectra showed a shoulder near 1100 cm(-1) assigned to sp3-bonded carbon. With an increase of heat treatment temperature, the peak position of the Raman sp(3) band shifted to a lower frequency from 1190 to 1120 cm(-1), which is due to the transformation of sp3-bonded carbon from an amorphous phase to a nanocrystalline phase. These data showed that the microstructure of carbonized wood from 700 degrees to 1800 degrees C consisted of the combination of sp(2-) and sp(3-)bonded carbon, which is probably due to the disordered microstructure of carbonized wood. It is suggested that the sp(3-)bonded carbon is transformed from an amorphous structure to a nanocrystalline structure with the growth of polyaromatic stacks at temperatures above 1400 degrees C

Electrical and thermal conductivities of porous SiC/SiO2/C composites with different morphology from carbonized wood

Porous SiC/SiO2/C composites exhibiting a wide range of high thermal and electrical conductivities were developed from carbonized wood infiltrated with SiO2. As a pre-treatment, the samples were either heated at 100 A degrees C or kept at room temperature followed by sintering in the temperature range 1200-1800 A degrees C. The microstructure, the morphology, and the electrical and thermal conductivities of the composites were investigated. Pre-treatment at room temperature followed by sintering up to 1800 A degrees C produced composites exhibiting a greater size of carbon crystallites, a higher ordering of the microstructure of carbon and beta-SiC and a smaller amount of SiO2, resulting in electrical and thermal conductivities of 1.17 x 10(4) Omega(-1) m(-1) and 25 W/mK, respectively. The thermal conductivity could be further improved to 101 W/mK by increasing the density of the composite to 1.82 g/cm(3). In contrast, the pre-treatment at 100 A degrees C produced composites possessing a lower thermal conductivity of 2 W/mK

Comparison between carbonization of wood charcoal with Al-triisopropoxide and alumina

A comparison was made between the catalytic carbonization of biomass carbon suspended in Al-triisopropoxide and in biomass carbon mixed with 40 µm sized Al2O3 particles. Both types of samples were plasma sintered during 5 min under an argon pressure of 50 MPa at temperatures up to 2200 °C. Plate-like catalytic graphitization develops by formation and dissociation of plate-like Al4C3. Plasma sintering under the proper CO partial pressure and heat treatment temperature is instrumental in forcing the Al2O3 to react with the carbon, forming first Al4C3 and subsequently graphite. The difference between Al-triisopropoxide and Al2O3 is a matter of intensity of the graphite reaction versus the size of the graphite patches.

Electron Microscopic Study on Catalytic Carbonization of Biomass Carbon: I. Carbonization of Wood Charcoal at High Temperature by Al-Triisopropoxide

Currently, carbonized materials from wood or waste have been focused upon as raw materials for carbons. These carbons are important for the production of artificial graphite. First hand observation was done on the growth of long parallel graphite structures in wood charcoal. A comparison is made between graphitization in pure biomass carbon and catalytic graphitization in biomass carbon suspended in Al-triisopropoxide. Both types of samples were carbonized during 5 min under an argon pressure of 50 MPa at temperatures up to 2500 Kelvin. Catalytic graphitization was developed by formation and dissociation of plate like Al4C3, but only at temperatures higher than 2000 K.