All issues
Volume 1987 (1987)
- Issue 131 Pages 161-
- Issue 130 Pages 101-
- Issue 129 Pages 59-
- Issue 128 Pages 2-
Volume 1987, Issue 128
Displaying 1-8 of 8 articles from this issue
- |<
- <
- 1
- >
- >|
-
Kenji Miyazaki, Hisayoshi Yoshida, Kazuo Kobayashi1987 Volume 1987 Issue 128 Pages 2-6
Published: January 25, 1987
Released on J-STAGE: June 28, 2010
JOURNAL FREE ACCESSStructural change in natural graphite power heat-treated with boron carbide power under a pressure of 19.6 MPa was investigated as functions of heat-treatment temperature from 1400 to 2300°C and content of boron carbide from 0 to 50 wt%.
Above 2000°C, d (002) and d (110) remarkably changed, (006) peak remarkably broad-ened and the lattice strain (εc) increased with increasing temperature and with increasing boron carbide content.Raman band at 1360 cm-1 also appeared.
From these experimental results, it was concluded that the three dimensional ordered structure of graphite began to change into a disorderedstate above 2000°C when boron carbide coexisted with. The disordering was found to be caused by boron atom diffusion into substitutional or interstitial position in graphite structure.The amount of substitution-ally diffused boron was estimated to be about 1-2 atom% at 2000-2300°C and this diffusion was thought to induce the decrease of d (002) and increase of d (110). Interstitial diffusion of boron began to start after substitution when boron existed in excess of the solubility limit. Interstitial insertion of boron was thought to induce the increase of d (002) but had no effect on d (110).View full abstractDownload PDF (866K) -
Eiichi Yasuda, Yasuhiro Tanabe, Hiroshi Machino, Shiushich Kimura1987 Volume 1987 Issue 128 Pages 7-11
Published: January 25, 1987
Released on J-STAGE: June 28, 2010
JOURNAL FREE ACCESSFuran resin was hot-pressed at the temperature regions of curing, carbonization under the pressure of 2 to 82 MPa and further those were heat-treated at 3000°C.
The resin pressed during carbonization was easily graphitized even under the pressing stress of 2 MPa.
When the stress was supplied after carbonization at 1000°C, furan resin was also graphitized a little.However, the stress was much higher than that in the hot-pressing and was above 82MPa.
After the resin began to be hard in curing, pressing as 82MPa dose not act on the graphitization of furan.View full abstractDownload PDF (5438K) -
Growth of Condensed Aromatic Nuclei in Some Condensed Polynuclear Aromatic (COPNA) Resins by HeatingE. Ota, Yu Hongan, S. Otani1987 Volume 1987 Issue 128 Pages 12-17
Published: January 25, 1987
Released on J-STAGE: June 28, 2010
JOURNAL FREE ACCESSSize-increase of polynuclear aromatic nuclei in heated COPNA resins, due to ring closure between aromatic rings, was studied by following up the change of UV spectra and the results were discussed in relation to the composition of resins and to the properties of carbons derived from them.
The resins were prepared by heating a mixture of an aromatic raw material, 1, 4- benzenedomethanol (PXG) as the cross-linking agent, and a catalyst. As raw materials, naphthalene, pyrene, and phenanthrene were used. Tetrahydrofuran solutions of the resins were thinly spread out on quartz plates followed by curing at 120°C. The resulting film specimens on quartz were heated successively at temperatures of 200, 300, 400, 430, and 500°C each for 1 hour in nitrogen. After each 1-hour-heating the specimens were subjected to UV analysis. The results were as follows:
(1) Generally the ring closure starts at ca. 300°C and becomes markedly above 400°C.
(2) The larger the PXG content is, the more the ring closure occurs finally after 500°C heating;
(3) The size of condensed aromatic nuclei in the resins after heating to 500°C increases with the decreasing ratio of PXG/Aro when the same raw material is used, and with the increasing molecular size of the raw material when the ratio of PXG/Aro is kept constant.
(4) The graphitizability of carbons derived from heated resins is enhanced with the increasing size of aromatic nuclei in the resins.View full abstractDownload PDF (975K) -
Yoshihiro Hishiyama, Yutaka Kaburagi, Dennis F. Baker, Robert H. Bragg1987 Volume 1987 Issue 128 Pages 18-23
Published: January 25, 1987
Released on J-STAGE: June 28, 2010
JOURNAL FREE ACCESSAnalysis has been carried out for the temperature dependence of thermoelectric power (S) of glassy carbon heat-treated between 1200 and 2700°C measured by Kaburagi et al. The thermoelectric power can be written in the temperature range from 1.5 to 280K
S=aT+bT1/2+SB,
where the first term is due to metallic-like conduction, the second term is attributed to variable range hopping, and the third term is a peaked function of temperature with a peak at about 23 K.View full abstractDownload PDF (1041K) -
Takeshi Meguro, Mitsuhiro Okamoto, Naochika Torikai1987 Volume 1987 Issue 128 Pages 24-29
Published: January 25, 1987
Released on J-STAGE: June 28, 2010
JOURNAL FREE ACCESSIn order to investigate the influence of carbonization conditions on the formation of microstructure of chars, the adsorption of carbon dioxide by the char samples prepared from Yallourn brown coal was carried out at20°C. The parameter Wo (micropore volume) and n in the Dubinin-Astakhov's equation were estimated from the adsorption isotherms.
As a result, the micropore volume W0 of chars increased with increasing the heattreatment temperatures up to approximately 850°C. Above 850°C, however, the value of Wo decreased with increasing the heat-treatment temperatures. This seems to be caused by the thermal shrinkage of pores above850°C. The increasing tendency of W0 was observed with decreasing the heating rates, especially in the temperature range of about 400 to 600°C. Similarly, the char samples, prepared by heating rate of 1°C/min in the temperature range of 200 to 600°C, were obtained in the higher yield. As the conclusion of this study, it seems likely that heating rates is important factor to be required in carbonization, particularly in the temperature range of 200 to 600°C, to make the high W0 char in the high char yeild.View full abstractDownload PDF (989K) -
Shiushichi Kimura, Kouichi Yasuda, Eiichi Yasuda, Yasuhiro Tanabe1987 Volume 1987 Issue 128 Pages 30-37
Published: January 25, 1987
Released on J-STAGE: June 28, 2010
JOURNAL FREE ACCESSCarbon fiber/pitch based carbon composites were prepard, which of the matrices were of carbonized from fractionated pitchs (BS, BI/PS, PI), the mixtures of them and fractionated pitch with carbon blacks. Mechanical properties (strength, Young's modulus, fracture strain) of the compoistes were dependent on the microstructure of their matrices. Especially, it was revealed that the nature of matrix carbon has a significant role on the flexural strength of the composites. The composite with fine mosaic structure showed the largest fracture strength of all.View full abstractDownload PDF (4927K) -
Noboru Akuzawa, Tooru Mitsuhashi, Takeo Amemiya, Yoichi Takahashi1987 Volume 1987 Issue 128 Pages 38-40
Published: January 25, 1987
Released on J-STAGE: June 28, 2010
JOURNAL FREE ACCESSA simple preparation technique of Li-GICs was described. Graphite sample and lithium metal was placed separately in a steel tube, which was then encapsulated in a pyrex glass tube. Several days were needed to obtain Li-GICs under the condition of 400-450°C. The X-ray diffraction measurement and the chemical analysis were performed for the products. The compositions of the stage 1 and 2 Li-GICs were determined to be LiC6 and LiC18. It must be noted that Li-GICs had a remarkable stability against oxygen. The stage 1 LiC6 was found to be almost insnsitive again oxygen at 0°C, and at 35°C, LiC7.5 was also proved to be stable as compared with KC8 or KC24.View full abstractDownload PDF (412K) -
Akio Hiraki, Hiroshi Kawarada1987 Volume 1987 Issue 128 Pages 41-49
Published: January 25, 1987
Released on J-STAGE: June 28, 2010
JOURNAL FREE ACCESSThe properties of diamond are ascribed to C-C sp3 bondings from the point of chemical bonding. Diamond-like carbon (DLC) thin film is defined as a carbon film which is composed of chiefly C-C sp3 bondings. The characteristics of DLC films are approaching those of diamond crystals. DLC films have been formed in non-equilibrium states such as plasma processes, because sp2 bondings are stable under atomospheric pressure and ordinary temperature.
Among plasma processes, we have concentrated on reactive sputtering which is distinguished from usual physical sputtering. In reactive sputtering deposition, H radicals are thought to sputter graphite target chemically and deposit sp3 rich thin films selectively on substrates. We have also discussed characterization techniques which are applied to distinguish the chemical bondings and the micro structures in DLC thin films.View full abstractDownload PDF (1384K)
- |<
- <
- 1
- >
- >|