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繊維含有量44vol%の三次元炭素繊維強化フラン樹脂 (3D-CFRFR) を作製し, 1000℃以下の種々の温度で加熱した. 1000℃の加熱による体積収縮は, フラン樹脂単体で50%であったが, 3D-CFRFRでは数%であった. 曲げ強さは加熱処理温度 (HTT) の上昇に伴って減少した. フラン樹脂に対する繊維強化効果はHTT500℃以下で認められた. 加熱に伴う曲げ強さの低下は, マトリックスと炭素繊維境界面のはく離と炭素繊維の損傷による. はく離や損傷はマトリックスのフラン樹脂の熱分解を通して起こる. 炭素繊維積層表面直角方向 (σs, Es) の曲げ強さと曲げ弾性率は, 厚さ直角方向 (σt, Et) のそれらより小さかった. 両方向の曲げ強さおよび両方向の曲げ弾性率には直線関係があり, それぞれσt=2.7σs, Et=1.7Esで表される.

フェノール樹脂による人造黒鉛の接合を試み, 曲げ強さ, 引張強さ, 電気抵抗率の測定から接合状態を調べた. 250℃以下での熱処理では, 接合は完全であったが, 樹脂層は絶縁層を形成した. 500℃以上の熱処理によって樹脂層は炭素化してガラス状炭素となった. 曲げ強さと引張強さは, 500℃と1500℃で処理した接合試料で一時的に減少したが, より高い温度で処理することによって増加した. 1000℃以上で熱処理した接合試料の電気抵抗率は未接合試料のそれと変わらなかった. フェノール樹脂を人造黒鉛の接合剤として利用できる.

アラミド (テクノーラ) とフェノール樹脂またはフラン樹脂を成分として, 自然積層で繊維が一方向に揃った繊維含有量18vol%の繊維強化プラスチック (FRP) を作製した. 熱処理に伴う曲げ強度変化からこれらのFRPの特性評価を行った. マトリックス樹脂の耐熱温度は200℃で, テクノーラの耐熱温度は400℃であった. したがって, 200～400℃の範囲で繊維効果が期待できた. フェノール樹脂は500℃以上の熱処理により多くのひび割れが発生した. しかしFRPにするとひび割れは抑制された. 繊維の短軸方向からの付加荷重に対しては, FRPの曲げ強度は樹脂単体のほぼ2倍であった. テクノーラとフラン樹脂から作製したFRPはテクノーラとフェノール樹脂から作製したFRPより強度は大きかった. 実験データは, フェノール樹脂よりもフラン樹脂の方がマトリックスとして適性があることを示す. 炭素化前では強度と減量には比例関係が見られた. また, 曲げ強度 (σ) と密度 (ρ) には指数則, σ∝ρnの関係が認められた.

ケブラークロスとフルフリルアルコール樹脂(フラン樹脂)から作製した積層複合材料の熱処理に伴う強度変化を，600 °C以下の温度で熱処理した試料片の曲げ試験から明らかにした．積層複合材料の繊維含有量は39 vol%で，マトリックスのフラン樹脂とほぼ同等の曲げ強度を示した．熱処理温度200–500 °Cの間で繊維強化効果が認められた．クロス積層複合材料の特徴は，荷重 vs. たわみ曲線に現れた．すなわち，Fig. 8cに示したように，ある荷重下で突然の曲げ破壊は起こらなかった．しかし，炭素化が進行する500 °C以上の熱処理試料ではこの特性は消失した．熱処理試料の曲げ強度(σ)とかさ密度(ρ)には，σ ∝ ρn の関係が認められた．さらに，クロス積層面に平行方向について，曲げ弾性率対曲げ強度のプロットをとると直線関係となったが，垂直方向では直線関係とならなかった．

Changes of the bending strength σ and the lattice strain e of a glassy carbon manufactured by the carbonization of phenol-formaldehyde resin at 1000°C were examined in connection with the bulk density p and the crystallite size Lc in the heat treatment temperatures (HTT) ranging from 1000 to 2800°C for the heat treatment times (HTt) of 1h and 9h. The values of σ and p attained the maximum at cα. 1250°C, and the relationship of σ∝ρn was recognized. The exponent n has different values below and above 2000°C. The lattice strain e estimated from the (002) and (004) reflections by using the equation, cosθ/λ=K/Lc+2e·sinθ/λ, showed negative values, and decreased with the increase in Lc. The relationship, Lc·e=constant, was recognized. A significant effect of HTt on the values of Lc and e was confirmed at the HTTs above 1750°C but it is insignificant for the values of σ.

Boron and titanium carbides were synthesized by the carbothermic reduction of boron or titanium oxides dispersed in a cure resin. On raising heat treatment temperature (HTT), the metal oxides were reduced and reacted with the resin carbon produced from resin, and also the resin carbon was graphitized partly by the presence of metal oxides. When the cure resin containing 65 or 70wt% TiO2 was fired at 2000 and 2250°C, a porous sintered TiC was produced. The sintering bodies with addition of 70 wt% TiO2 showed specific surface area of 240 m2/g (HTT: 2250 °C), the bending strength of 70MPa (HTT: 2000°C), and the specific resistance of 2×10-4Ωcm (HTT: 2250°C).

The relationship, σ=aρn was recognized between bending strength (σ) and bulk density (ρ) of the heat-treated charcoals at various heat treatment temperatures (HTT) below 2500°C, and the exponent (n) was almost constant (n=1.3). Usually, the bending strength of carbon materials decreases by the proceeding of graphitization with temperature heat treatment. On the other hand, the bending strength of the bincho-tan manufactured by carbonization of oak (ubamegashi) ncreased with increasing HTT. The specific surface area of the powdered samples decreased with increasing HTT and converged to a value near 80m2/g at HTT 2500°C regardress of the different texture of charcoals. The small angle X-ray scattering (SAXS) data of the heat-treated charcoals showed that the micropores of R=10-50 nm (R Guinier radius) almost disappeared with high temperature treatment.

Carbonization behavior and density dependence of bending strength were observed onwoods and resin-impregnated woods through heat treament. Soft and hard woods were selected as the samples to which furfuryl alcohol resin was applied. The bending strength of woods were the lowest at heat treatment temperature (HTT) of around 400·Z, which was the same tendency as that for furfuryl alcohol resin. The resin impregnation did not make bending strength increase but volume shrinkage reduce. The relationship, σ=apn was recognized between the bending strength (σ) and the bulk density (p) at each HTT for all the woods examined. Also, the relationship, σ =bpm existed for each wood heat-treated at various HTTs. The exponents n and m were estimated 1.3 and 8.5, respectively. The factors a and b were dependent on HTT.

Boehmite samples were prepared from aluminium isopropoxide which was hydrolyzed in hot water under different conditions, and heat-treated at various temperatures below 1200°C. Amount of adsorbed moisture and specific surface area of the samples were measured. The amount of adsorbed moisture was maximum when the boehmite was in the dried gel state, which was almost the same as that of silica gel. The amount of adsorbed moisture slightly decreased up to the heat treatment temperature of 600°C. The adsorption feature was scarcely improved even when ultrasonic irradiation and freeze drying technique were applied. A quantitative analysis by differential scanning calorimetry (DSC) was attempted, and the following equation was derived to estimate the activation energy E of desorption of moisture; E≅nRT1T2/S0⋅ΔS/ΔT Where n is the order of reaction, R the gas constant, S0 the total area of endothermic curve fitting in desorption of moisture, T1 and T2 are the start and end temperatures of the reaction, and ΔS shows the area against the temperature change ΔS on the DSC curve. By the application of the above equation to the DSC data of samples heat-treated at 600°C, an activation energy of 1.7-2.7kJ/mol was obtained.

An electron spin resonance (ESR) study in combination with X-ray diffraction has been made on carbons prepared from a coal-tar pitch through heat treatments in the range of 1100–2000 °C. ESR spectra were observed for specimens heat-treated at 1100 °C or less and 1500 °C or higher, but hardly detected for those treated ca 1250 °C unless a high amplification technique was employed. The heat treatment time dependence measurement supports that carbon layer segments formed by the carbonization reaction are combined each other in a large scale at near 1250 °C so as to remove the structural defects carrying unpaired electrons.

The effects of additives on the densification and color quality of TiN ceramics were studied. Some oxides (Al2O3, CaCO3, TiO2, Y2O3, ZrO2) as additives were prechecked by sintering, and we selected TiO2 as an addition. TiN was densified by pressureless sintering at 1550° to 1850°C in N2. Samples with addition of 8wt% TiO2 sintered at 1550°, 1700°, and 1850°C showed the relative densities of 97.7, 99.8, and 99.7%, respectively. The optical reflectivity of polished samples was similar to that of gold. Vicker's hardness of some sintered bodies reached about 16GPa. Therefore, polished sintered bodies can be used for ornament.

Al2O3-ZrO2複合粉末を原料として複合セラミックスを作製して,曲げ強度,ビッカース硬度の密度依存性を検討した.その結果,複合セラミックスの密度(p)と曲げ強度(σ),ビッカース硬度(Hv)の間には,σ ∝ pn,Hv∝ pmの関係が認められた.All2O3含量20-50wt%でnの値は大きく変化した.mの値の変化は小さかった.これらの値の変化はフラクタル次元〓に関係し,Al2O3含量20-50wt%の間で構造がZrO2型からAl2O3型に変化することを示す.ZrO2成分の正方晶は複合焼結体中で安定化された.正方晶含量と曲げ強度の問にははっきりした対応関係はなかった.

Dried boehmite gel was preheated at various temperatures below 800°C and they were pressed and formed into bars. Then they were sintered in the temperature range of 1500-1650°C. The porosity and the bending strength of these sintered bodies were affected by the preheat-treatment temperature of the boehmite gel. There was no change in the structure of the sintered bodies which were preheated at temperatures below 200°C. A sintered body at 1650°C gave a porosity of 40% and a high bending strength of 80MPa. The relation, σ=aρn was established between the bending strength (σ) and the density (ρ) of the sintered bodies. The exponent n in the above relation is the same and the factor a is different between these two starting samples, boehmite and intermediate alumina. The factor a is affected by the fractal structure of sintering body.

Fired bodies were prepared from the clay mineral (kaolin and pyrophyllite) and Y2O3-stabilized zirconia powders. The bulk density (ρ) dependence of the bending strength (σ) and Vickers hardness (HV) were studied. The relation, σ∝HVn/m was obtained from the power law of σ∝ρn and HV∝ρm. Also, the relation, KIc∝σt, was proved. The fracture toughness (KIc) can be estimated easily from the measurement of σ. Moreover, an empirical equation χ=χ0exp(-nP) was derived theoretically using the power law, where χ is a physical quantity related to the mechanical properties and P is the porosity.

The particle feature and the graphitization behavior were studied for the soot produced by burning of the cure mixture of NH4ClO4 and hydroxyterminated polybutadiene (HTPB) under N2 gas pressure of 0.49 and 6.9 MPa. The soot particles appeared cluster including chain-like structure. The size of particles and the distribution of carbon layer segments of the soot depended on the HTPB content and the burning pressure. The pattern of gathering of carbon layer segments was irregular very much when the large content of resin and low burning pres-sure were applied. The structural change and shape change from spherical to polygonal were remarkable when the soot was heat-treated at the temperature above 1500°C. At a heat treat-ment temperature (HTT) of 2800°C, the value of interlayer specing, d002, was more than 0.3425nm, and that of the crystallite size, Lc, was below 11nm. Moreover, many structural defects could be seen in stacking layers of polygonal particles. On plotting of log Lc vs d002 for the soots heat treated at various temperatures, a straight relationship was observed at the region of d002>0.3425nm.

The cure mixtures of NH 4 ClO 4 /resin in various ratios were burned under N 2 gas pressure up to 70 kgf/cm 2 . The burning rate, yield of soot, and morphology were studied by transmission electron microscopy. A relation of r = aP n was seen between the burning rate, r , and the burning pressure, P . The soot was an aggregate of the spherical units. The diameter of soot particles depended on the mixture ratio but scarcely under burning pressure up to 70 kgf/cm 2 . The concentric orientation of carbon layer segments around multiple nuclei was developed, and the length of segments became larger by burning at high temperature under high pressure. The distribution pattern of carbon layer segments in soot particles was similar to that from quenched structure of polymer mixtures that appeared in the phase separation process.

アルミニウムアルコキシドを熱水中で加水分解してベーマイトゾルを調製し,ゾルに対する水熱処理効果を調べた。水熱処理によってベーマイト粒子は大きくなった。粒子径の増大は高温で加熱処理してα-アルミナ化した場合,同一加熱処理温度(HTT)では未処理のべーマイトからのα-アルミナに比べて結晶粒は小さかった。ゾルの解こう剤にはカルボン酸を使用したが,ゾルーゲル変換を考慮した場合,解こう効果は酢酸及びプロピオン酸に適性があるように思われた。乾燥ゲルをHTT1100～1150℃の範囲で加熱処理することによってθ-アルミナからα-アルミナに変換した。この範囲のHTTでの組織変化は注目に値する。すなわち,均一組織に成長核が多数発生し,それらが成長して直径約10～20μmの球晶組織を形成した。各球晶内でアルミナ粒子は放射状に配向しており,アルミナ化後の結晶成長はこの配向に沿って発達した。球晶組織の発達は水熱処理したベーマイトでより明瞭であった。

Green sheets were made from polycarbosilane (PCS), phenol-formaldehyde resin or furfuryl alcohol resin by adding binder with the weight ratio of PCS to resin equal to 2/1 or 1/1. The two types of green sheets were heat-treated at 1200° to 1400°C under N2 gas to form SiC/C composite sheets 0.4-0.6mm thick. The SiC/C composite sheets were highly amorphous, that is, the crystallite sizes of L111 and LC of SiC and C components in the SiC/C composites were below 34A and 25A, respectively. As another feature, it was recognized that amorphous SiO2 was formed as a secondary product by the reaction of silicon in PCS and oxygen in resin during pyrolysis. Little difference was observed in bending strength and oxidation resistance between two SiC/C composite sheets. These features depend on the content of SiC in the composite sheet. The effective mixing ratio is PCS/resin≥2/1.

Coal-tar pitch was heat-treated at various temperatures up to 1000°C and the weight loss (Δw/w) measurement, CHN analysis, polarized-light microscopic observation, IR and ESR spectra, and X-ray diffraction study were done. These data gave us the feature of structural change of coal-tar pitch through carbonization reaction, especially the change which occurred in the temperature range of pitch solidifying was remarkable. The behavior of structural change varied with the heat-treatment temperature (HTT) 500-600°C as a border. At HTT 600°C the bulk mesophase was formed completely and absorption bands except aromatic rings disappeared in IR spectrum, and the value of interlayer spacing showed for a typical disoriented carbon, that was 3.44A. The radical concentration (N) was the maximum at this HTT 600°C.By plotting log N against Δw/w, a linear relationship was observed. This relationship suggests that the amount of released components is in proportion to the amount of breaking hydrocarbon chains, and it brings the radical formation.

The porous and crosslinked polycarbosilane with a powerful affinity for oxygen was obtained by the pyrolysis of polydimethylsilane in N2 gas atmosphere. This polycarbosilane was converted to silicon carbide by heat-treating at the temperatures from 1200 to 1400°C in N2 gas atmosphere, and quartz was formed as a by-product. The addition of polyvinyl butyral as a carbon source to polycarbosilane prevented quartz formation. The chemical analysis of silicon carbide showed that the ratio of Si to C was not theoretical but C content was larger than Si. As the temperature rose, the ratio of Si to C approached theoretical value, and free carbon content increased.

A slurry was made from zirconia powder (yttria-stabilized zirconia powder), aluminium hydroxide sol (boehmite sol), binder and plasticizer, and was formed to green sheet by the doctor blade method. The green sheet was sintered in the temperature range of 1300° and 1500°C in air. The optimum alumina content to obtain a good ZrO2/Al2O3 thin sheet was 10-15wt%. The thin sheet sintered at 1400°C was characterized by the thickness of 100μm, density of 4.9g/cm3, bending strength of 486MPa, modulus of elasticity of 167GPa, and resistivity of 2-4×1012Ω⋅cm.

A fine powder SiC was formed into SiC specimens of 5×5×30mm under 1500 kgf/cm2 and heated at temperatures from 1000 to 1500°C in air. At the heat treatment temperature (HTT) 1100°C, it was found that the weight of SiC specimens increased to a maximum but the density decreased to a minimum because of oxidation reaction occurred during heating. The SiC specimens heat-treated at 1300°C showed a bending strength of 200 MPa at density of 2.05 g/cm3. This high strength was caused by the development of a thin SiO2 phase formed by the oxidation of the surface of SiC specimens.By the use of X-ray diffraction measurement, it was seen that SiO2 in the oxidationphase was amorphous below HTT 1300°C and gradually crystallized with increasing HTT. Above HTT 1500°C, the oxidation phase came off from inside of SiC specimens accompanying self disintegration caused by the structural difference between surface and inside of SiC specimens.

Silicon carbide coating was applied to a thin high purity of alumina film which was produced from aluminum alkoxide sol by the sol-gel method. This alumina film was treated with a polycarbosilane solution and heattreated at 1200°C. The bending strength of the coated alumina film was improved, and no electrical resistivity change was observed in the thickness direction.

A SiC/Al2O3 composite sheet was prepared from a green sheet composed of polycarbosilane (PCS) and Al2O3 powder with the weight ratio of 2:1. The green sheet was fired in the temperature range of 1200° to 1400°C under N2 gas atmosphere, and three point bending strength of the composite was examined. The strength in room temperature increased with firing temperature and showed the maximum value of 333MPa at 1300°C. Dispersion of Al2O3 particles in the SiC matrix was effective to increase the strength of monolithic SiC sheet derived from PCS. When the composite was fired at 1400°C, however, the bending strength dropped rapidly in a similar manner as PCS-derived SiC fiber.

The morphological feature of carbon residues obtained by the detonation reaction of the compressed TNT, 40% PETN/60% DNN and 40% PETN/60% DNT mixtures was examined by spin concentration and X-ray parameters measurements, and also by electron microscopic observation.The carbon residues did not give a spherical appearance.From the morphology of the carbon residues before and after heat treatment it is supported that they are formed directly from atomic carbon vapour species without forming hydrocarbon droplets on their process.

ESR studies were carried out on a variety of glass-like carbons made from different precursors heat-treated in the range 300–2500 °C. It was found that the behaviors of unpaired electrons were nearly identical. The temperature dependence of ESR spectrum showed that the behavior of localized unpaired electrons in the glass-like carbons changed to that of delocalized ones at HTT about 2500 °C. The ESR spectrum of the glass-like carbons heat-treated at 800 °C consisted of a single line under a pressure of above 10−4 Torr but split into two components when air was admitted. This strong interaction with unpaired electrons and air (oxygen molecules) is caused by the active structure related to micropores in the glass-like carbons. We suppose that the polyene type radicals are the most suitable as the active structure to interpret the behavior of unpaired electrons in glass-like carbons heat-treated at 800 °C. As another major point in this study, it was found that there is a correlation between unpaired electro...

The coal-tar pitch was fractionated by the difference in solubility to organic solvents.Microstructures of carbons derived from fractionated pitchs themselves and those in CF/C Composites were investigated by optical microscopy. The microstructures of the carbon derived from BS pitch, BI/PS pitch, and PI pitch are flow, fine mosaic, and isotropic, respectively. The effect of carbon fiber on reduction of the anisotropic region of the matrix carbon apprears in some fractionated pitchs.This is related to the viscosity.Microstructure of the composite can be controlled by the mixture of fractionated pitches.

Radicals formed spontaneously during the cure reaction of epoxy resins with 2,4,6-trinitrophenol (TNP) or 2,4,6-trinitroresorcinol (TNR) have been investigated using electron spin resonance (ESR) technique. The ESR spectrum of the radicals stabilized in the epoxy resins cured with TNP was a triplet and the other spectrum of the radicals in the epoxy resins cured with TNR was a triplet with high anisotropy. The triplet splittings and g-values were attributed to radicals of the type (Remark: Graphics omitted.). The asymmetric line shapes of the triplet splittings caused by the 14N coupling constant are induced by the slow motion of the radicals in the polymer. The presence of radicals of this type suggests the transfer of an oxygen of a nitro group of TNP or TNR during the cure reaction.

Carbon fiber/coal-tar pitch composite (51wt%carbon fiber) and a coal-tar pitch were carbonized up to 650°C in argon atmosphere at300kg/cm2.The carbonization under pressure was carried out in sealed gold tube, which was set in a stellite bomb.The composite and the pitch thus carbonized were re-heated under normal pressure to investigate the effect of carbon fiber on the mesophase formation at the initial stage of carbonization, coke yield and graphitization of the pitch.The mesophase formation in the pitch matrix of the composite was delayed under pressure.At the appearance of the mesophase spheres it was found to coalesce with each other, which seemed to accelerate by the presence of carbon fiber.Under pressure and with the presence of carbon fiber the coke yield from pitch increased.The stacking of lammelar molecules was oriented concentrically around the carbon fibers, when the bulk mesophase formed at 650°C.The composite obtained at 650°C under pressure was re-heated from 1000°C to2500°C under normal pressure, formation of crack was observed in the coke matrix and also at the boundary of coke matrix and carbon fiber.The graphitizability of the coke matrix in the composite measured from the crystallite size and the interlayer spacing showed similar behaviour as the coke obtained from the pitch alone.

Explosive shock compression of about 8.52×104 atom was given to acetylene black packed into a mild steel container by a low density of 0.094g/cm3. The acetylene black was graphitized by this shock compression and variety of shapes could be seen in it by the observation of electron microscope. It is the most interesting morphologycal change that the spherule of graphite produced in the shocked acetylene black. The spherule might be formed from droplet. The formation of droplet suggests that the temperature rises above 4000°C.

Damages on acetylene black (AB) and natural graphite (GP) exposed to the detonation reaction of PETN were examined by X-ray measurement and electron microscopic observation. Their surfaces were covered by amorphous carbons but they could be removed by treatment of hydrochloric acid. On AB the carbon structure disappeared but the graphitization proceeded inside. On the other hand, GP was reduced in size and damaged in structure.