Journal of the Ceramic Society of Japan (日本セラミックス協会学術論文誌)
Online ISSN : 1882-1022
Print ISSN : 0914-5400
ISSN-L : 0914-5400
100 巻, 1160 号
選択された号の論文の58件中1~50を表示しています
  • 平田 好洋, 竹島 久美子, 石原 義巳
    1992 年 100 巻 1160 号 p. 353-361
    発行日: 1992/04/01
    公開日: 2010/08/06
    ジャーナル フリー
    CVD-processed ultrafine mullite powder (<0.1μm)-micrometer size Si3N4-whisker or mullite-whisker were dispersed in H2O-C2H5OH-C3H8O3 with a low surface tension at pH 4.0 to prevent cracking during drying of wet green compacts consolidated by filtration. The rheological behavior of suspensions, consolidation process of the solids by filtration, and the pore structures of green compacts were studied to understand the formation of crack-free dense powder compacts with uniformly dispersed whiskers in the nanometer size matrix mullite. The crack-free powder compacts were hot-pressed at 1500°C for 1h at 10 to 39MPa in N2 atmosphere or pressureless-sintered at 1600° to 1650°C for 4 or 10h in air or vacuum. The monolithic mullite (99.9% T.D.) and 10% mullite-whisker-added mullite (91.2% T.D.) with the average strengths of 468MPa and 242MPa, respectively, showed little degradation of strength at 1300°C. The composite with 10vol% Si3N4-whisker (99.8% T.D.) showed a high average strength (632MPa) at room temperature, while the strength decreased to 341MPa at 1300°C. The fracture toughness (1.68MPa⋅m0.5) of the monolithic mullite was increased to 2.94MPa⋅m0.5 by the addition of 10% Si3N4-whisker.
  • 丸野 重雄, 伴 清治, 王 允夫, 岩田 久, 伊藤 晴夫
    1992 年 100 巻 1160 号 p. 362-367
    発行日: 1992/04/01
    公開日: 2010/08/06
    ジャーナル フリー
    Composites comprising hydroxyapatite (HA) containing glass layer and pure titanium or Ti-6Al-4V alloy, so called HA-G-Ti functionally gradient materials, have been shown to be useful for bioactive artificial joints and dental implants. In the present study, the mechanical and thermal properties of the HA containing glasses were examined. The compressive strength of HA containing glasses less than 70wt% HA content was sufficiently larger than that of bone. The hardness of about 70wt% HA containing glass corresponded to that of natural teeth. It has been found from DSC analysis that the glass little reacts with HA at firing temperature (950°C). Thermal expansion coefficients of HA containing glasses with relatively low HA content were suitable values for the coating on Ti and Ti-6Al-4V. The bonding strength of the glass to Ti substrate reached the maximum value of 28MPa under the condition of 2.3μm in surface roughness (center line average). The HA-G-Ti composites with bioactive surface, etched in a mixture of HF and HNO3, showed a good apposition to the bone in vivo.
  • 鳥居 一雄, 岩崎 孝志, 小野寺 嘉郎, 西山 〓行
    1992 年 100 巻 1160 号 p. 368-372
    発行日: 1992/04/01
    公開日: 2010/08/06
    ジャーナル フリー
    Novel trioctahedral Ni-smectites were synthesized hydrothermally from Ni-Si hydrous oxide at 125°-300°C under autogeneous water vapour pressure for 2h. With increasing temperature of hydrothermal reaction, adsorption of methylene blue (MB) increased from 0.20meq⋅g-1 to 0.76meq⋅g-1 between 125° and 175°C, but gradually decreased from 0.76meq⋅g-1 to 0.48meq⋅g-1 between 175° and 300°C. On heating, the specimen NS-04 synthesized at 200°C formed a porous material with mesopores and micropores indicating a maximum specific surface area (SSA) of 222m2g-1. Addition of fluorine decreased the MB adsorption and increased SSA. The mesoporous material from a precursory Ni-smectite NS-04 has a total SSA of 537m2g-1, a pore volume of 0.79 cm3⋅g-1 and an average pore diameter of 59Å, which are significantly higher than those of conventional pillared clays.
  • 門間 英毅, 西川 治光
    1992 年 100 巻 1160 号 p. 373-376
    発行日: 1992/04/01
    公開日: 2010/08/06
    ジャーナル フリー
    Apatitic layered octacalcium phosphate (Ca8(HPO4)2 (PO4)4⋅5H2O; OCP) was intercalated with β-dihydromuconate ions (-OOC(R)COO-, R; CH2-CH=CH-CH2). The basal spacing of the OCP structure was expanded to 23.7Å by the intercalation (OCP: 18.7Å). The spacing was contracted by heating (dehydration), and reverted by exposure to H2O vapor (rehydration). Such zeolite-like behavior toward H2O was observed below 350°C. A remarkable contraction in the basal spacing by dehydration suggested the bending of zig-zag R chains supporting the layer structure. Improvement of the thermal stability of the OCP layer structure was judged from increases in starting temperatures for the following processes: 2HPO42-→P2O74-, formation of apatitic OH-, disappearance of OCP phase and appearance of apatitic phase. No significant differences were observed in thermal behavior between the intercalates of the doubly unsaturated R and saturated R, i.e., CH2-CH2-CH2-CH2, were a little. The intercalation decreased the catalytic activity for the dehydration of 2-propanol.
  • 長谷川 明宏, 亀山 哲也, 本江 秋弘, 植田 稔, 明石 和夫, 福田 健三
    1992 年 100 巻 1160 号 p. 377-381
    発行日: 1992/04/01
    公開日: 2010/08/06
    ジャーナル フリー
    Many coating methods of hydroxyapatite (HAp) on mechanically strong materials as substrates have been studied for increasing the mechanical strength of bioactive HAp. In this paper, coating of HAp on 3mol% Y2O3 partially stabilized zirconia (PSZ) substrate, a bioinert and highly strong and fracture-resistant material was studied utilizing a new plasma spraying method of a radio-frequency (r. -f.) thermal plasma. High contents of HAp in the coated layer were obtained by using larger HAp powders at smaller plasma powers and at lower substrate temperatures. The decomposition of the HAp phase was suppressed below the substrate temperature of about 1500°C. Adhesive strength of the coated HAp layer to the substrate was measured to be 5-14MPa. The surface of the coated layer had many pores. Thus, a possibility of coating HAp on the PSZ utilizing a r. -f. thermal plasma process was indicated. The HAp coated layer on the PSZ can be used as a mechanically strengthened and biocompatible material.
  • 岡田 一樹, 佐久間 健人
    1992 年 100 巻 1160 号 p. 382-386
    発行日: 1992/04/01
    公開日: 2010/08/06
    ジャーナル フリー
    Grain growth behavior in Al2O3-ZrO2(2.5mol%Y2O3) during high-temperature annealing was examined. In alumina-rich alloys, the growth of coarse alumina grains was effectively retarded by fine zirconia grains. The retarding effect could satisfactorily be explained by the prediction of Zener's pinning effect. In zirconia-rich alloys, the size of alumina grains was almost the same as that of zirconia grains, and they influenced little growth of zirconia grains. The results on zirconia-rich alloys were related to the sluggish grain growth of zirconia containing 2.5mol%Y2O3.
  • 武部 博倫, 手島 卓也, 中島 真澄, 森永 健次
    1992 年 100 巻 1160 号 p. 387-391
    発行日: 1992/04/01
    公開日: 2010/08/06
    ジャーナル フリー
    A powder processing technique is developed for the fabrication of tetragonal zirconia-nickel functionally gradient materials. The powder volume fraction, the linear shrinkage during drying, and the pore radius of monolithic zirconia-nickel green compacts with various zirconia/nickel volume ratios were measured. A multilayer zirconia-nickel green compact with a step-wise compositional gradient was formed by slip casting and then pressureless-sintered. The key to successful fabrication is to avoid the fracture of green compact during drying process in an ambient atmosphere. In conclusion, it is desirable to minimize differences in permeability and pore radius between neighboring layers in a multilayer green compact.
  • 鳥塚 史郎, 佐藤 馨, 原田 淳, 山本 秀治, 西尾 浩明
    1992 年 100 巻 1160 号 p. 392-397
    発行日: 1992/04/01
    公開日: 2010/08/06
    ジャーナル フリー
    A ceramic TiB2-20wt% (2mol% Y2O3-ZrO2) composite has a high three-point bending strength of 1200MPa. However, this composite lacks sinterability, so that glass encapsulation HIP'ing is required to obtain a full dense sintered compact. However, addition of 2.5-5.0wt% SiC improved the sinterability drastically. TiB2-19.5wt% (2mol% Y2O3-ZrO2)-2.5wt%SiC was densified to 96% of its theoretical density by vacuum sintering at 1700°C for 14.4ks, and this sintered compact was hot isostatically pressed (HIP'ed) without glass encapsulation. In this work, the microstructure and sintering mechanism of TiB2-19-19.5wt% (2mol% Y2O3-ZrO2)-2.5-5.0wt% SiC were investigated. TiB2-19-19.5wt% (2mol% Y2O3-ZrO2)-2.5-5.0wt% SiC was densified drastically above 1600°C. TiB2-1.0-10.0wt% SiC had the same sinterability as TiB2-19-19.5wt% (2mol%Y2O3-ZrO2)-2.5-5.0wt% SiC. Therefore, SiC improved the sinterability of TiB2, regardless of the presence of ZrO2. The microstructure of HIP'ed compacts was observed with a SEM and a TEM. Enriched areas of SiC were not observed with the SEM. However, TEM observation showed that thin strip-like grain boundary phases consisting of Ti, Si and Zr exist between grain boundaries of TiB2 and ZrO2, and that (Ti, Zr)5Si3 exists at the triple points of grain boundaries. These grain boundary phases were formed by the reaction among SiC, Ti, and Zr. These were entirely or partially liquid phase at the sintering temperature of 1700°C. As a result, TiB2-19-19.5wt% (2mol% Y2O3-ZrO2)-2.5-5.0wt% SiC was densified by liquid phases sintering, which was the main mechanism in which sinterability was improved by the addition of SiC.
  • 小林 和夫, 佐野 秀明, 前田 和敏, 内山 休男
    1992 年 100 巻 1160 号 p. 398-403
    発行日: 1992/04/01
    公開日: 2010/08/06
    ジャーナル フリー
    High temperature oxidation tests from 600 to 1400°C were carried out for graphite/B4C/SiC/ZrB2 composite in different atmospheres such as dry air, dry oxygen and moist air with different moisture contents. From weight change, SEM observation, change of surface roughness and X-ray diffraction of the sample before and after the oxidation, it was found that the oxidation behaviour depends strongly on the nature of oxide layer formed on the surface by oxidation, and that the nature of the oxide layer depends on the temperature and time of oxidation, the oxygen partial pressure, and moisture content. The oxide layer was found to consist of mainly a B2O3-SiO2 glass phase, rich in B2O3 at low temperatures and rich in SiO2 at high temperatures. Active oxidation was observed at about 1100°C in dry air, at about 900°C in dry oxygen and moist air. Particularly, in the presence of moisture, oxidation proceeded extensively and sample was oxidized deeply from the surface to the inside through the less protective layer. An excellent protective layer formed at 1200°C oxidation and it protected the sample from further oxidation under all conditions examined.
  • 今井 久雄, 関口 淳之輔, 村上 泰
    1992 年 100 巻 1160 号 p. 404-407
    発行日: 1992/04/01
    公開日: 2010/08/06
    ジャーナル フリー
    Fine particles of ruthenium-alumina composites were prepared by three different methods, i.e., direct synthesis, reduction of mixed oxide and impregnation methods. In the direct synthesis method, the sample was prepared by hydrogenolysis of a mist of a mixed solution of ruthenium chloride and aluminium nitrate. Transmission electron microscopy as well as electron and X-ray diffraction measurements showed that amorphous ruthenium clusters (<2nm) dispersed in an amorphous alumina particle were prepared by this method. Reduction of the mixed oxide prepared in the same way in a stream of air produced the particles undistinguishable from the above sample by X-ray diffraction and transmission electron microscopy, whereas the conventional impregnation method gave crystalline ruthenium clusters dispersed on the alumina surface. The infrared spectrum of adsorbed carbon monoxide showed three characteristic absorption bands at about 2000, 2070 and 2140cm-1 in all samples, but their frequencies and relative intensities were different, depending upon the method of preparation. In the sample prepared by the direct synthesis method, the frequencies and relative intensities of these bands changed during crystallization of the ruthenium clusters by firing at high temperatures. It is concluded that the most highly dispersed metal-ceramics composite was prepared by the direct synthesis method.
  • 金丸 守賀, 立野 常男, 日下 貞司
    1992 年 100 巻 1160 号 p. 408-412
    発行日: 1992/04/01
    公開日: 2010/08/06
    ジャーナル フリー
    The influence of addition of fine TiC particles on the mechanical properties of Al2O3 matrix composites with 20wt% SiC whisker fabricated by hot-pressing was studied. With increasing TiC content up to 4wt%, the flexural strength and the fracture toughness at room temperature increased. The maximum values of 1200MPa and 7.5MPa⋅m1/2, respectively, were obtained at a TiC content of 4wt%. Transmission electron microscopic observations indicated that the TiC particles were dispersed not only at the grain boundaries but also within Al2O3 grains, and SiC whiskers were located at the grain boundaries. SEM observations showed that the abnormal grain growth of Al2O3 was inhibited by TiC particles.
  • カオリナイト-ポリビニルピロリドン層間化合物の合成
    菅原 義之, 杉山 智英, 長山 哲治, 黒田 一幸, 加藤 忠蔵
    1992 年 100 巻 1160 号 p. 413-416
    発行日: 1992/04/01
    公開日: 2010/08/06
    ジャーナル フリー
    A kaolinite-poly (vinylpyrrolidone) intercalation compound has been prepared by the intercalation of an N-vinyl-2-pyrrolidone monomer (VP) and subsequent heat treatment. The intercalation of VP was achieved by treating a kaolinite-ammonium acetate intercalation compound with a VP aqueous solution. The basal spacing decreased from 14.2 to 12.6Å, and infra-red spectroscopy (IR) and solid-state 13C nuclear magnetic resonance with cross polarization and magic angle spinning techniques (13C CP/MAS NMR) showed the displacement of ammonium acetate by VP. When the kaolinite-VP intercalation compound was heated at 200°C for 1h, the basal spacing did not vary. The IR and 13C CP/MAS NMR spectra showed the disappearance of vinyl groups and became similar to those of poly (vinylpyrrolidone) (PVP). These results clearly indicate the polymerization of VP between the layers of kaolinite.
  • 千田 中哉, 藤沼 明子, 松浦 正道, 塚原 園子
    1992 年 100 巻 1160 号 p. 417-421
    発行日: 1992/04/01
    公開日: 2010/08/06
    ジャーナル フリー
    Copper metallization of AlN substrate and Molybdenum metallization of Si3N4, SiC and Al2O3 substrates were performed using an ion beam dynamic mixing method. In this method, a high energy ion beam of 50keV (Ti+, Ar+ or N+) and a co-evaporated metal vapor (Cu or Mo) were irradiated onto a ceramic substrate to deposit the metal film. This method, especially with Ti+ ion beam, was found to be quite useful to obtain adhesive metal films. A Cu film coated on an AlN substrate showed an adhesion strength of>70MPa, and a high soldering strength of>40MPa for a soft solder. The adhesion strength of a Mo film coated on a ceramic substrate did not decrease when heated up to 973K: a Mo-coated ceramic was bonded to a Cu rod using an amorphous brazing metal at 973K, resulting in a strong joint of >120MPa for each type of ceramics. The ceramics-metal interface region of the Mo-coated Si3N4 and SiC were observed by TEM and XPS, and an interface layer well-mixed by an energetic Ti+ ion beam was confirmed. Amorphous compounds and fine precipitated crystals such as TiN, composed of the implanted Ti, the evaporated Mo and some constituent elements of the ceramics, were identified in the interface layers.
  • 柳 炳換, 高橋 実, 鈴木 傑
    1992 年 100 巻 1160 号 p. 422-425
    発行日: 1992/04/01
    公開日: 2010/08/06
    ジャーナル フリー
    The mechanical properties of the green sheet prepared by a doctor blade method were investigated, such as fracture stress, Young's modulus, elongational viscosity, and strain to fracture. The mechanical properties of green sheet depend largely on the added organics. The results on the green sheets are summarized as follows:
    (1) The mechanical properties of the green sheet increase with increasing total amount of added organics.
    (2) The green sheet has low strength and brittleness less than 1 of the binder to plasticizer ratio, and has high strength and stiffness greater than 1.5. The green sheet exhibits the optimum flexibility at the binder to plasticizer ratio of 1-1.5.
    (3) The mechanical properties of the green sheet depend little on the degree of polymerization of PVB by adding the same weight.
  • 宇尾 基弘, 山下 恭子, 鈴木 正康, 民谷 栄一, 軽部 征夫, 牧島 亮男
    1992 年 100 巻 1160 号 p. 426-429
    発行日: 1992/04/01
    公開日: 2010/08/06
    ジャーナル フリー
    The porous silica gels were prepared from tetramethoxysilane (TMOS)-polyethyleneglycol (PEG)-H2O-methanol solution by the sol-gel process. Microstructure of gel was affected by the composition of starting solutions. The pore diameter of porous gels ranged from 0.1μm to 10μm. The pore diameter increased with increasing H2O and H2SO4 contents and with increasing molecular weight of PEG, whilst it decreased with increasing PEG concentration. Yeast cells were immobilized in porous silica gels prepared from TMOS-PEG solutions by the sol-gel process. Yeast cells were immobilized as spores. After incubation, yeast spores germed and growth of the yeasts were comfirmed.
  • 宇尾 基弘, 沼田 雅彦, 鈴木 正康, 民谷 栄一, 軽部 征夫, 牧島 亮男
    1992 年 100 巻 1160 号 p. 430-433
    発行日: 1992/04/01
    公開日: 2010/08/06
    ジャーナル フリー
    The immobilized mercuric reductase covalently coupled to porous glass was prepared and its properties were investigated. Mercuric reductase immobilized on arylamino and carboxyl derivatives exhibited high relative activities about 20-30% compared with soluble enzymes. The optimum pH of mercuric reductase immobilized on these derivatives was 7.5, slightly higher than that of soluble state (7.0-7.2). The stability of mercuric reductase increased with immobilization onto arylamino derivative and the immobilized enzyme maintained at 30°C for 29 days showed 80-90% of initial activity. As the application of immobilized enzyme, mercuric ion sensor was prepared and it was found that mercuric ion higher than 0.5μM was detectable with this sensor.
  • 淡野 正信, 可児 圭子, 高尾 泰正, 高木 弘義
    1992 年 100 巻 1160 号 p. 434-438
    発行日: 1992/04/01
    公開日: 2010/08/06
    ジャーナル フリー
    The synthetic process for the composite polycrystalline Ba2YCu3O7-y (abbreviated to BYCO) superconductor by the sol-gel method was discussed. The solution containing Ba2+-, Y3+-, Cu2+- and Si-alkoxide was changed to gel by very slow drying. The dried gels were converted to superconductor by heat treatment under low pressure of air and subsequent oxidizing in O2 atmosphere. The sintered BYCO body had a nano-composite structure consisting of BYCO and Ba2SiO4 and other phases. This sintered body showed an enhanced magnetic property in the superconducting state because of introduction of pinning centers. On the other hand, composition control to avoid the segregation of a secondary phase at grain boundaries was effective in increasing the conductivity of superconducting transport current.
  • 村上 泰, 今井 久雄
    1992 年 100 巻 1160 号 p. 439-443
    発行日: 1992/04/01
    公開日: 2010/08/06
    ジャーナル フリー
    Layered calcium phenylphosphate, Ca2(OH)(O2.5POC6H5)3, and calcium phenylphosphonate, CaO0.5{(HO)2OPC6H5}2⋅2H2O, were prepared by combining aqueous ammonia solutions of sodium phenylphosphate and phenylphosphonic acid and of calcium nitrate, respectively. Thermal changes of calcium phenylphosphate and calcium phenylphosphonate were systematically investigated by thermal analysis, X-ray diffraction and IR spectra. Calcium phenylphosphate decomposed with the two step liberation of phenyl groups at 150°-300°C. In calcium phenylphosphonate, phenyl groups were completely released at 500°C following the dehydration in the two steps at 50°-150°C.
  • 佐藤 清, 鈴木 直, 舟山 徹, 礒田 武志
    1992 年 100 巻 1160 号 p. 444-447
    発行日: 1992/04/01
    公開日: 2010/08/06
    ジャーナル フリー
    A low viscosity perhydropolysilazane which is converted to Si-N ceramics with a 70-90wt% yield by pyrolyzing at temperatures above 800°C, was used as a matrix precursor. The preform of SiCw/Si-N composites was prepared by slip casting, and impregnated with the polysilazane. The impregnated specimen was cured at 100°-300°C in a N2 gas under the pressure of 0.05-0.1MPa, and fired to 1200°C. To obtain dense composites, impregnation, curing and firing processes were repeated. The preforms of Cf/Si-N and Cf/SiCw/Si-N with unidirectional aligned fiber were prepared by filament winding. The prepregs were cured and fired, and the densifying processes were repeated. The densities of the Cf/Si-N and Cf/SiCw/Si-N were increased to 90-96% of the theoretical values. Such extensive densification resulted from the excellent infiltrativity and the high ceramic yield of the polysilazane. Owing to the high density of the matrix and the adequate shear strength of the fiber/matrix interface, the three-point flexural strength of the Cf/SiCw/Si-N was substantially high, 695MPa.
  • 中平 敦, 新原 晧一
    1992 年 100 巻 1160 号 p. 448-453
    発行日: 1992/04/01
    公開日: 2010/08/06
    ジャーナル フリー
    Al2O3/SiC nanocomposites exhibited the high fracture toughness and strength at room temperature and good high-temperature mechanical properties. These significant improvements of mechanical properties were contributed to the dispersion of nanometer-size SiC particle within Al2O3 matrix grains. In this paper, the sinterability of Al2O3/SiC nanocomposites containing 5vol%SiC particles was compared to the sinterability of monolithic Al2O3. Especially, the densification and grain growth behaviors of Al2O3 with nanometer-size SiC particles were investigated in a temperature range of 1000° to 1800°C during hot-pressing to clarify the role of nanometer-size SiC particle for Al2O3/5vol% SiC nanocomposites. The addition of SiC particle remarkably delayed the densification rate and grain growth of Al2O3 matrix grain. In addition, TEM observation showed that SiC particles were dispersed within Al2O3 matrix grains for Al2O3/SiC nanocomposite hot-pressed above 1200°C. The consolidation process will be discussed in detail for these Al2O3/SiC nanocomposites.
  • 吉田 秀人, 宮田 昇, 佐川 雅昭, 石川 繁樹, 内藤 一成, 榎本 尚也, 山岸 千丈
    1992 年 100 巻 1160 号 p. 454-458
    発行日: 1992/04/01
    公開日: 2010/08/06
    ジャーナル フリー
    SiC composites (C/SiC) reinforced with unidirectionally oriented carbon fibers were fabricated by the pressureless sintering method completed with infiltration of polycarbosilane (PC). This method is effective for increasing density and strength of the composite.The open porosity of C/SiC of 10% was achieved after 10 times infiltration of PC and the strength reached 380MPa. Fracture behavior of C/SiC changed from delamination parallel to the fibers to fiber failure after the infiltration.
  • M. Isabel NIETO, Pilar MIRANZO, Salvador de AZA, José S. MOYA
    1992 年 100 巻 1160 号 p. 459-462
    発行日: 1992/04/01
    公開日: 2010/08/06
    ジャーナル フリー
    The effect of processing parameters, such as sintering atmosphere, SiC content, temperature and time of heat treatment, on densification and microstructural evolution of Al2O3/SiC composites has been investigated. Samples containing 5, 10, 20 and 30vol% of SiC were treated at temperatures ranging from 1400° to 1750°C using Ar and N2 as sintering atmospheres. When sintering atmosphere is N2, carbothermal reduction was always observed. In Ar, partial oxidation of SiC was detected. In both atmospheres the extent of the reaction depended on the open porosity, which was controlled by the SiC content and heat treatment conditions.
  • 秋宗 淑雄, 小笠原 俊夫, 広崎 尚登
    1992 年 100 巻 1160 号 p. 463-467
    発行日: 1992/04/01
    公開日: 2010/08/06
    ジャーナル フリー
    Mechanical properties of SiC-particle/Si3N4 composites produced from two types of starting powders were investigated. Composites fabricated from the Si3N4 powder prepared by nitridation of Si showed a 40% increase in bending strength resulting from greater fracture toughness. In contrast, composites made from Si3N4 powder obtained by thermal decomposition of Si(NH)2 exhibited increase in only bending strength. The latter composites contained SiC particles, which inhibited grain growth of β-Si3N4. These differences are attributed to the effect of carbon and oxygen in the starting powders on the sinterability of β-Si3N4. The SiC additive and impurities in the starting powders are responsible for the difference in the sintering behavior of β-Si3N4, and thereby resulting in different mechanical properties.
  • 高坂 祥二, 中西 政仁, 古賀 和憲
    1992 年 100 巻 1160 号 p. 468-471
    発行日: 1992/04/01
    公開日: 2010/08/06
    ジャーナル フリー
    Fracture toughness of Si3N4 ceramics with and without addition of TaSi2 particles, prepared by hot-pressing at 1750°C and 1650°-1750°C, respectively, was determined. The fracture toughness increased significantly with increasing TaSi2 content. The enhanced toughness by the addition of TaSi2 particles was interpreted to be due to the residual compressive stress resulting from the larger thermal expansion coefficient of TaSi2 than that of Si3N4.
  • 中野 喜久男, 神谷 晶, 小川 裕之, 西野 洋一
    1992 年 100 巻 1160 号 p. 472-475
    発行日: 1992/04/01
    公開日: 2010/08/06
    ジャーナル フリー
    Silicon carbide composites reinforced with unidirectionally oriented carbon fibers have been fabricated by slurry impregnation followed by hot pressing. Identification of crystalline phases, observation of the metallographic structure, and measurement of flexural strength and fracture toughness at room and high temperatures in vacuum were carried out. The flexural strength and fracture toughness were 420MPa and 13MPa√m at room temperature and were about 600MPa and 20MPa√m at 1400° to 1600°C. The improvement of the mechanical properties at high temperatures was explained by the suppression of crack propagation and by the increment of fiber pull-out due to softening of boundaries.
  • 伊藤 義康, 柏谷 英夫
    1992 年 100 巻 1160 号 p. 476-481
    発行日: 1992/04/01
    公開日: 2010/08/06
    ジャーナル フリー
    The residual stresses of functionally gradient materials induced during the fabrication process were analyzed by comparing with two-layer composites prepared by direct bonding. Functionally gradient materials can be grouped into three classes, structurally gradation plates from the surface to the back, gradation coatings formed on the substrate, and gradation joints formed between base metals. In this paper, firstly, these three types of functionally gradient materials of stabilized zirconia/nickel-based alloy composites were chosen for finite element method analysis of residual stress distributions. It was verified that the residual stresses induced by uniform heating process could be decreased by use of the gradation techniques. Especially, the stress singularities at the edge of the interface of direct bonding composites were eliminated in case of the functionally gradient materials. Secondly, the effects of gradation size and material constants, such as Young's modulus and thermal expansion coefficients on the residual stress of the functionally gradient materials were investigated by the thermo-elastic analysis using the finite element method. It was found that the residual stresses could be effectively analyzed by application of a dimensionless parameter, which is σ(1-μ1)/[E112)ΔT] (σ: residual stress, μ12: Poisson's ratio, E1: Young's modulus of material 1, (α12): difference in thermal expansion coefficient between materials 1 and 2, ΔT: temperature difference) in case of the functionally gradient materials. Thus, the analytical results indicated that the fabrication of large functionally gradient materials was difficult because of the increasing of the residual stresses for the same gradation thickness.
  • チタン酸アルミニウム粒径の影響
    矢野 豊彦, 清原 正勝, 大津賀 望
    1992 年 100 巻 1160 号 p. 482-487
    発行日: 1992/04/01
    公開日: 2010/08/06
    ジャーナル フリー
    The effects of aluminumtitanate (AT) particle size on the sinterability, bending strength, thermal expansion, thermal stability and thermal shock resistance of aluminumtitanate-mullite composites with various mixing ratios were studied. The results were summarized as follows. (1) The sintered density slightly increased with decreasing AT particle size. (2) The grain size of AT in sintered bodies was nearly equal to the particle size in raw mixtures, except for <1μm powder. (3) The bending strength of the composites was not influenced significantly by the particle size of AT. It was the highest at 26wt%AT composites and decreased with increasing amount of AT. (4) The degree of thermal expansion hysteresis increased with increasing amount of AT regardless the particle size. (5) The thermal expansion coefficients in heating stage of the composites were highest at 48wt%AT except the largest particle size composites, and decreased in higher AT content. These coefficients slightly increased with decrease in particle size of AT in raw mixtures. (6) The critical temperature difference of the composites raised with increase in particle size in the same AT composition.
  • 北 英紀
    1992 年 100 巻 1160 号 p. 488-493
    発行日: 1992/04/01
    公開日: 2010/08/06
    ジャーナル フリー
    The study was conducted about dimensional change and the microstructure of material (RBSTN) produced by using Si and Ti mixture as staring powders. And also adiabatic piston head was fabricated as a trial using the material. The results were summarized as follows.
    (1) The dimensional change ratio increased as a function of the amount of Ti powder with a change from shrinkage to expansion at about 12wt% of Ti. And it was clearly shown that expansion of 1.3% occurred during sintering for compacts of Si(70wt%) and Ti(30wt%) mixture powders. On the contrary, shrinkage of 0.08% occurred when only Si was used as a starting powder.
    (2) The dimensional change ratio during dewaxing and sintering were plus and constant, almost independent of the packing density in green body.
    (3) In sintered body, TiN0.9 and small amount of TiO2 in a and β-Si3N4 as matrix, were formed.
    (4) Almost no gap was found at the boundary of SSN frame and porous ceramics (RBSTN) inside due to the small expansion of it during sintering. And partially they were bonded.
    (5) Al, originally one of the elements of SSN, diffused into porous ceramics, which suggested that it might work for bonding SSN and RBSTN.
  • 馬渕 守, 今井 恒道, 久保 勝司, 東 健司, 岡田 義浩, 谷村 眞治
    1992 年 100 巻 1160 号 p. 494-498
    発行日: 1992/04/01
    公開日: 2010/08/06
    ジャーナル フリー
    Aluminum matrix (6061) composites reinforced with either whiskers or particulates of Si3N4 were processed under the same hot extrusion conditions, and their superplastic properties have been compared in constant strain rate tension tests at a constant temperature of 818K. Large elongations from 400 to 450% were observed at a high strain rate range from 10-1 to 1s-1 in the Si3N4p/6061Al composite. For the Si3N4w/6061Al composite, on the other hand, a similar value of about 450% elongation was obtained at a lower strain rate of 4×10-2s-1 than that for the Si3N4p/6061Al composite. Grain sizes were about 2μm for the Si3N4p/6061Al composite and about 3μm for the Si3N4w/6061Al composite. High strain rate superplasticity of both composite may be attributed to fine grained structures. On the true stress-true strain curves of the Si3N4w/6061Al composite, strain hardening was observed over almost entire part of elongation during superplastic flow. For the Si3N4p/6061Al composite, on the other hand, the near steady state of flow stress or strain softening was found, suggesting a difference in microstructural evolution during superplastic flow between these composites.
  • 李 建興, 松尾 陽太郎, 木村 脩七
    1992 年 100 巻 1160 号 p. 499-503
    発行日: 1992/04/01
    公開日: 2010/08/06
    ジャーナル フリー
    The effect of fiber coating on the residual thermal stresses, interface, and mechanical properties of CVD-(C, SiC) coated Nicalon fiber-reinforced alumina matrix composite were studied. Using a tri-cylindrical model, the residual thermal stresses caused by the mismatch of their thermal expansion coefficients and the mechanical behavior were calculated. The results indicated that when the fibers coated with carbon, which has lower Young's modulus, the residual thermal stresses at fiber-coating interface and coating-matrix interface were reduced compared with uncoated fiber reinforced composite materials, and these stresses decrease with increase in the thickness of carbon coating. In the CVD-(C, SiC) coated fiber-reinforced alumina composite, the reduction of the residual interfacial stress decreased the shear strength required for fiber pullout, so that the work of fracture was increased compared with that of uncoated Nicalon fiber-reinforced alumina composite.
  • 新保 章弘, 井出 秀夫, 植木 正憲
    1992 年 100 巻 1160 号 p. 504-508
    発行日: 1992/04/01
    公開日: 2010/08/06
    ジャーナル フリー
    ALON was successfully consolidated by pressureless sintering of a powder mixture of 70mol% Al2O3 and 30mol% AlN, a composition in the single ALON phase region in the Al2O3-AlN system. BN was incorporated (0-50vol%) into the ALON, and ALON-BN composites were also consolidated by the pressureless sintering. In both cases, Y2O3 was added (4-8vol%) as a sintering aid. The relative density of the sintered bodies was higher than 90%. Reduction of the density due to BN addition was compensated by adjusting the amount of Y2O3. In the bending tests, ALON and its composite ceramics exhibited excellent high temperature properties. The strength of these ceramics did not decrease until 1400°C (1673K), and then decreased gradually to about 100MPa at 1600°C (1873K). ALON-BN composite exhibited the lowest erosion rate (<2μm/min) in molten steel (low carbon Al-killed) in comparison with sialon, Al2O3, ZrB2 and AlN. The thermal shock durability was also improved by the incorporation of BN. Microstructural analysis showed that the high temperature integrity of the ALON and its composite ceramics are attributed to the existence of the grain boundary crystalline yttrium aluminium garnet (YAG) phase.
  • 林 博文, 矢野 豊彦, 井関 孝善
    1992 年 100 巻 1160 号 p. 509-513
    発行日: 1992/04/01
    公開日: 2010/08/06
    ジャーナル フリー
    The characteristic low brittle-ductile transition temperature of TiC was utilized to toughen SiC matrix composites at high temperatures. AlN, Ti and C powders were used as a dopant to alter the intrinsic properties of SiC matrix or dispersed TiC particles. The fracture toughness of the SiC matrix was improved in the temperature from room temperature to 1600°C by the incorporation of dispersed TiC particles. At low temperatures, the toughening mechanism in SiC/TiC composites was crack deflection or crack bridging while above 1200°C, it was plastic deformation of TiC particles.
  • 安田 榮一, 包 勤立, 新原 晧一
    1992 年 100 巻 1160 号 p. 514-519
    発行日: 1992/04/01
    公開日: 2010/08/06
    ジャーナル フリー
    Compressive creep experiments have been conducted with SiC/MgO nano-composites to understand the effects of SiC particles on the creep behaviors of MgO at high temperatures. The ranges of temperature and stress employed for the deformation studies were 1300°-1500°C and 5.8-40MPa, respectively. TEM and SEM observations were carried out to characterize the microstructures of crept specimens. Analyses of the stress exponents, activation energies and microstructures indicate that specimens with more than 10vol% SiC crept through grain boundary sliding which was accommodated by dislocations moving at the regions of grain boundaries. For the specimens with less than 5vol% SiC, the creep was controlled by dislocations moving between SiC particles. The obvious decrease in creep rate for nano-composites were mainly due to the retarded dislocation movement and the restrained diffusion flows by fine SiC particles dispersed uniformly within MgO matrix.
  • 小山 孝, 内田 晋, 西山 昭雄
    1992 年 100 巻 1160 号 p. 520-524
    発行日: 1992/04/01
    公開日: 2010/08/06
    ジャーナル フリー
    The effect of the microstructure on the mechanical properties and the cutting performance of Al2O3-30wt%Ti(C, N) ceramics was studied. Three Al2O3-Ti(C, N) ceramics with average Al2O3 grain size of 1.6-1.9μm, 1.0-1.2μm and 0.7-1.0μm were obtained by presintering and HIPing. Large Ti(C, N) grains were mainly distributed at the grain boundaries and prevented the grain growth of Al2O3 grains. But in the ceramics with large Al2O3 grains, some fine Ti(C, N) particles were dispersed within Al2O3 grains. As microstructure became finer, the bending strength increased and the fracture toughness KIC decreased. In the cutting test of tool steel (SKD11), the flank wear became less and the tool life became longer as the grain size decreased and N/(C+N) ratio in Al2O3-Ti(C, N) increased.
  • 上野 和夫, 袖岡 賢, 廣岡 淳
    1992 年 100 巻 1160 号 p. 525-529
    発行日: 1992/04/01
    公開日: 2010/08/06
    ジャーナル フリー
    The influence of sintering temperature and time on mechanical properties was studied for a 20wt% SiC whisker/Si3N4 composite. α to β phase transformation of Si3N4 was retarded by the whisker incorporation compared to monolithic Si3N4, but the delay became smaller with increasing sintering temperature. The bending strength and the fracture toughness increased with increasing sintering temperature from 1700° to 1900°C when sintered for 30min. On the other hand, when the sintering time was extended from 30min to 90min at 1800°C, both the bending strength and the toughness decreased significantly. The behavior of the composite properties can be explained on the basis of the contribution of the matrix microstructure including the content and the size of elongated β grain and the bonding strength between the Si3N4 grains and SiC whiskers.
  • 津田 浩, 榎 学, 岸 輝雄
    1992 年 100 巻 1160 号 p. 530-535
    発行日: 1992/04/01
    公開日: 2010/08/06
    ジャーナル フリー
    The interfacial properties such as interfacial shear strength, residual clamping stress and coefficient of friction of SiC fiber-reinforced borosilicate glass composites were evaluated using a single-fiber pull-out test. Maximum interfacial shear stress was adopted as an interfacial debond criterion and Poisson's effect of the fiber due to the applied stress was considered in the present evaluation. During the single-fiber pull-out test, AE signal was measured to understand the relationship between load-time curve and interfacial debonding behavior. Interfacial debonding behavior was classified into two types that are with and without stress transfer at the debonded interface. When the shrinkage of the fiber induced by the applied tensile stress overcomes the clamp due to interfacial residual radial stress, abrupt interfacial fracture occurs. Critical condition for these behavior was derived and influence of interfacial debonding behavior on the fiber bridging mechanism was discussed.
  • 佐々木 元, 中瀬 裕文, 菅沼 克昭, 藤田 輝昭, 新原 晧一
    1992 年 100 巻 1160 号 p. 536-540
    発行日: 1992/04/01
    公開日: 2010/08/06
    ジャーナル フリー
    Si3N4 matrix composites with dispersed SiC particles were prepared by hot-pressing compacts of powder mixtures of sub-micron size SiC and Si3N4 particles. SiC particles in nano-meter scale were dispersed uniformly inside Si3N4 grains. After adding SiC particles, the configuration of β-Si3N4 grains changed from equiaxed/platelet-like to rod-like structure. At 20vol% SiC, grains were fine and equiaxed. With increasing SiC content, the α- to β-phase transformation was suppressed, and relative density was decreased. On the other hand, the bending strength reached a maximum value at 10vol% SiC and fracture toughness was maximum at 5vol% SiC. These changes are related closely to the shape of Si3N4 grains and relative density. Young's modulus was minimum at 5vol% SiC. This seems to be caused by the disorder of the interface structure between SiC and Si3N4. Vickers hardness was constant up to 10vol% SiC and increased beyond it.
  • ウイスカー径及びウイスカーへのカーボン被覆の影響
    芦塚 正博, 上吉川 誠
    1992 年 100 巻 1160 号 p. 541-546
    発行日: 1992/04/01
    公開日: 2010/08/06
    ジャーナル フリー
    The effects of whisker diameter and carbon-coating to whisker on the mechanical properties of 20vol% SiC whisker-reinforced diopside and cordierite glass ceramic composites were studied. The flexural strength of the diopside reinforced with the whisker of 0.5μm diameter was 385MPa and that with the whisker of 1.1μm diameter was 355MPa. The flexural strengths of the diopside reinforced with the carbon-coated whisker were 358MPa for 0.5μm diameter and 334MPa for 1.2μm diameter. On the other hand, the flexural strength of the cordierite glass ceramic composite reinforced with carbon-coated whisker was almost the same as that reinforced with the noncoated whisker. The fracture toughness of diopside glass ceramic composites was increased with increasing whisker diameter and by coating whiskers with carbon. On the other hand, the fracture toughness of the cordierite glass ceramic composites was little affected by increasing whisker diameter nor by coating whiskers with carbon. It is concluded that the strengthening mechanism of the SiC whisker-reinforced glass ceramic composites is in load transfer phenomenon. While, it is confirmed that the toughening of the diopside glass ceramic composites is mainly due to whisker pullout, crack deflection and load transfer to whisker, and that of the cordierite glass ceramic composites is due to load transfer to whisker.
  • 矢野 義彦, 白川 幸彦, 師岡 久雄
    1992 年 100 巻 1160 号 p. 547-550
    発行日: 1992/04/01
    公開日: 2010/08/06
    ジャーナル フリー
    Multilayered composites having the structure of Ni/ZnO/PrCoOxide/Au were fabricated by the sputtering technique and their electrical properties were examined. It was found that a multilayered composite is an excellent low voltage varistor (α=30, breakdown voltage=6.5V). The results of the voltage-current (V-I) and the capacitance-voltage (C-V) measurements revealed that a depletion region was formed in the ZnO thin film close to the ZnO/PrCoOxide interface. The potential barrier in the ZnO/PrCoOxide multilayered composite was discussed in comparison with a single grain boundary model in ZnO ceramic varistors.
  • 坂野 久夫, 小倉 幸治
    1992 年 100 巻 1160 号 p. 551-554
    発行日: 1992/04/01
    公開日: 2010/08/06
    ジャーナル フリー
    Hydrostatic piezoelectric constant dh of 0-3 composite of polymer and ceramic powder mixture of PZT and PbTiO3 were investigated in order to obtain “d31-zero” constant by applying appropriate reverse poling field to prepoled ones. The composite composition was of chloroprene rubber (25vol% polymer) and PbTiO3 (PT) ceramic powder mixture of three kinds of the powder having different average particle sizes (3.3(X), 7.3(Y), and 31.8(Z)μm) with equivolumed X, Y and Z (X=Y=Z=1/3), in which the 7.3μm PbTiO3 ceramic powder (Y) was partially or fully replaced by a PZT ceramic powder with 7.5μm average particle size (75vol% ceramic powder). An improved dh-value of 18×10-12C/N was obtained at the composite in which 80 percent of the 7.3μm PbTiO3 powder was replaced by the 7.5μm PZT powder.
  • 江本 秀幸, 北條 純一
    1992 年 100 巻 1160 号 p. 555-559
    発行日: 1992/04/01
    公開日: 2010/08/06
    ジャーナル フリー
    BaTiO3-Ni mixed powders were sintered at 1300°C in Ar or air, and the sintering behavior and dielectric properties were investigated. The bulk density of sintered bodies was 95-99% of theoretical. BaTiO3-Ni composites were produced in Ar. When coarse Ni powder (4-7μm) and ultrafine BaTiO3 powder (0.02μm) were used, a large number of Ni particles were isolatedly dispersed in the BaTiO3 matrix. The dielectric constant increased remarkably with an increase in Ni content up to εr′=11000 at 40vol% Ni according to the modified Maxwell formula. Although monolithic BaTiO3 sintered in Ar had a high dielectric loss owing to the formation of oxygen vacancies working as electron donor, BaTiO3-Ni composite had a low dielectric loss. This is because of the fact that a small amount of NiO dissolved into BaTiO3 and Ni ions worked as electron acceptor to compensate the charge of oxygen vacancies. Firing in air resulted in the oxidation of Ni to form BaTiO3-NiO composites with low dielectric constants and high dielectric losses.
  • 今中 佳彦, 亀原 伸男
    1992 年 100 巻 1160 号 p. 560-564
    発行日: 1992/04/01
    公開日: 2010/08/06
    ジャーナル フリー
    The shrinking behavior of Cu/ceramic circuit boards as it applies to controlling dimensional tolerances was studied. This report includes the shrinking behavior of ceramics and copper and of the Cu/ceramic interface. It also includes the relationship between the shrinkage of the Cu/ceramic circuit board during firing and the copper content of the laminated body (which is decided before firing). Results show that the mismatch in the onset of the components' sintering temperatures affects the microstructure of the Cu/ceramic interface. The total shrinkage mismatch causes compression stress in copper wiring. The firing shrinkage of the circuit board depends on its copper content and, as copper content increases, its shrinkage approaches that of copper paste.
  • 中原 浩彦, 裴 哲薫, 河本 邦仁, 柳田 博明
    1992 年 100 巻 1160 号 p. 565-569
    発行日: 1992/04/01
    公開日: 2010/08/06
    ジャーナル フリー
    The results of the present investigation on the MIM model structure would support our suggestion that the non-linear I-V characteristics generated from the TiN/TiO2 composite is attributed basically to TiN/TiO2/TiN structure with an appropriate thickness of the insulating intergranular TiO2 phase. Even though an aimed microstructure as shown in Fig. 1 has not been satisfactorily obtained in the present study, proper insertion of thin insulating layers into intergranular regions in metallic non-oxide ceramics was verified to give rise to non-linear current-voltage characteristics which can be further furnished to be used for electronic applications.
  • 方 慶一郎, 嶋田 勇三
    1992 年 100 巻 1160 号 p. 570-576
    発行日: 1992/04/01
    公開日: 2010/08/06
    ジャーナル フリー
    Low dielectric constant glass-ceramic composite for high speed LSI packaging substrates has been developed by introducing isolated pores. Pore structure control can be achieved through the addition of polymer spheres to ceramic powders followed by subsequent thermal decomposition. The dielectric constant of the glass-ceramic composite, composed of quartz glass, cordierite and borosilicate glass having thermal expansion coefficient matching with that for Si chips, can be reduced to 2.9 by the introduction of 26% porosity. When applying such porous materials to multilayer substrates, it is important to consider how pores are isolated and whether or not they are sphere shaped, small and uniformly distributed, in order to prevent degradation in dielectric and mechanical reliabilities. However, the isolated porosity limit is about 13% and the dielectric constant can be reduced to 3.4. Besides, application to glass-ceramic composites composed of quartz glass and borosilicate glass has resulted in reduction in the dielectric constant (3.2). In addition, by using of a green sheet lamination technique, low dielectric constant multilayer glass-ceramic substrate with wiring was developed. The propagation delay can be reduced to 6.5ns/m.
  • 安田 公一, 大沢 栄也, 松尾 陽太郎, 木村 脩七
    1992 年 100 巻 1160 号 p. 577-580
    発行日: 1992/04/01
    公開日: 2010/08/06
    ジャーナル フリー
    The fracture surface area of the chevron-notched carbon fiber reinforced silicon nitride composite was measured by the Kr-BET adsorption technique. The energy-absorbing mechanism of the composite was discussed on the basis of the actual fracture energy. The average actual fracture energy of the composite is nearly the same as the fracture energies of polycrystalline ceramics. This fact suggests that the large energy-absorbing capacity of the composite depends on how the fracture surface area can increase. Furthermore, application of the loading/unloading technique reveals that the actual fracture energy of the composite increases to a maximum at an initial stage of the failure, and then decreases to a constant value at a final stage. This indicates that the energy-absorbing mechanism changes from the formation of the fracture surface to the pullout of fibers.
  • 神谷 信雄, 和田 重孝
    1992 年 100 巻 1160 号 p. 581-584
    発行日: 1992/04/01
    公開日: 2010/08/06
    ジャーナル フリー
    (1) Izod impact test was proposed to evaluate the fracture energy of mode I failure of fiber-reinforced ceramics.
    (2) By selecting the notch geometry of a specimen and the loading condition, the fracture of carbon fiber-reinforced silicon nitride resulted from mode I crack.
    (3) The fracture energy of carbon fiber-reinforced silicon nitride measured by Izod impact test was about 62kJ/m2 which 20 times as large as that of monolithic silicon nitride.
  • 武藤 範雄, 柳田 博明, 宮山 勝, 中辻 照幸, 杉田 稔, 大塚 靖
    1992 年 100 巻 1160 号 p. 585-588
    発行日: 1992/04/01
    公開日: 2010/08/06
    ジャーナル フリー
    To measure residual electrical resistance during and after straining was found to be a promising method for foreseeing the fracture of the CFGFRP (carbon fiberglass fiber reinforced plastics) composites containing carbon fiber bundles. On loading, the electrical resistance of the CFGFRP composites increased nonlinearly with increasing strain. Permanent, residual electrical resistance was reproducibly observed even after the removal of load, and the change was dependent on the maximum strain applied. Two kinds of PAN-based high strength carbon fiber and PAN-based high modulus carbon fiber were evaluated for their suitability for foreseeing the fracture of the CFGFRP composites. The former showed a larger residual electrical resistance than the latter.
  • 渡辺 秀美, 木村 修
    1992 年 100 巻 1160 号 p. 589-592
    発行日: 1992/04/01
    公開日: 2010/08/06
    ジャーナル フリー
    Two-layered hybrid composites, the Al2O3 layers containing different amounts of SiC whisker, were prepared by hot-pressing the two layers simultaneously. Outstanding improvement was observed in the strength and fracture toughness of composites when one of the layers is reinforced by 10vol% whisker addition. The difference of the fracture toughness between the layers in the composite is also observed. The effects of residual stresses resulting from the thermal expansion mismatch between two layers were discussed.
  • 松下 純一, 佐野 省
    1992 年 100 巻 1160 号 p. 593-595
    発行日: 1992/04/01
    公開日: 2010/08/06
    ジャーナル フリー
    The effect of Cr and C addition on the sintering process of TiB2 ceramics was investigated and discussed from microstructural and compositional viewpoints. Simultaneous addition of 6.2wt% Cr and 1.3wt% C resulted in high density, high bending strength and high hardness. Results of X-ray diffraction of the TiB2 composite fired at 900°-1900°C showed that Cr and C reacted with TiB2 to form CrB and TiC during the sintering process.
  • 谷 英治, 菖蒲 一久, 渡辺 忠彦
    1992 年 100 巻 1160 号 p. 596-598
    発行日: 1992/04/01
    公開日: 2010/08/06
    ジャーナル フリー
    Carbon fiber-reinforced SiC composites were prepared by reaction-bonding. The formation of SiC (3C type) took place by a reaction between carbon from phenol resin and silicon powder above 1320°C and completed at 1420°C. This reaction did not damage the carbon fiber, and fiber pull-out was observed on the fracture surface. The bulk density and the flexural strength of these composites were 1.7-1.8g/cm3 and -130MPa, respectively. Impregnation with molten silicon at 1600°C increased the bulk density but decreased the flexural strength, due to the reaction of carbon fiber with silicon.
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