材料
Online ISSN : 1880-7488
Print ISSN : 0514-5163
ISSN-L : 0514-5163
40 巻 , 455 号
選択された号の論文の26件中1~26を表示しています
  • 山中 和夫
    1991 年 40 巻 455 号 p. 967-977
    発行日: 1991/08/15
    公開日: 2009/06/03
    ジャーナル フリー
  • 腐食防食部門委員会TG『電子部品』
    1991 年 40 巻 455 号 p. 978-981
    発行日: 1991/08/15
    公開日: 2009/06/03
    ジャーナル フリー
    Corrosion and tarnishing are common troubles of all electric contacts. The Task Group has surveyed a number of reports, symposium volumes, and other informations published in 1980-87, and reviewed them from the viewpoints of corrosion mechanism, resistance to corrosive environment, performance, and test method.
  • 大塚 俊明
    1991 年 40 巻 455 号 p. 982-988
    発行日: 1991/08/15
    公開日: 2009/06/03
    ジャーナル フリー
    The ellipsometric investigation of passivation film on metal was demonstrated. The following topics were described.
    (1) The passive film on cobalt, to which the ellipsometry was applied for the study of its layered structure in combination with an electrochemical method.
    (2) The passive film on titanium, to which a multiple-angle-of-incidence “ex-situ” method was applied, combined with the conventional “in-situ” ellipsometry, for surveying the optical constants of titanium substrate as well as the passive film.
    (3) The thin oxide film formation during the dry corrosion of pure iron.
    (4) The spectroscopic measurement, from which the optical absorption coefficients of thin passive films on iron and titanium were estimated to be compared with the conventional absorption spectra of the oxides.
    (5) The recent application of the microscopic ellipsometry to a two-phase stainless steel, the results of which indicated that there was a significant scatter of the film thickness depending on the composition of grains.
  • 中平 宏, 原田 良夫, 三船 法行, 土井 哲也
    1991 年 40 巻 455 号 p. 989-995
    発行日: 1991/08/15
    公開日: 2009/06/03
    ジャーナル フリー
    Four kinds of stabilized zirconia coatings, 8Y2O3·ZrO2, 7.6MgO·ZrO2, 10CaO·ZrO2 and 15CeO2·ZrO2 undercoated with NiCrAlY were sprayed on Type 304 stainless steel substrate by plasma spraying. The hot corrosion resistance of these materials were evaluated by investigating the coatings after heating in furnace for 3 hours at 1273K with corrosive ashes, and by monitoring the Acoustic Emission (AE, hereafter) of coatings with corrosive ashes in the 1273K_??_RT thermal cycle test. Corrosive components such as V, Na and S penetrated through the porous sprayed coatings, and caused the coatings to peel off due to corrosion of the undercoat. Stabilizing elements, MgO and CaO readily reacted with V and S compounds, but Y2O3 and CeO2 were relatively resistant to hot corrosion.
    In the thermal cycle test, the AE signal counts were detected immediately at the beginning of the test for coatings with corrosive ashes, and the coatings were spalling or broken down. On the other hand, the sprayed coatings without corrosive ashes required a number of cycle repetitions before AE signal could be measured. AE analysis allows not only the beginning of coating damages but also corrosion progressing to be detected in satisfactory response. These results also show that the AE monitoring method is applicable to evaluate the hot corrosion resistance for the thermal barrier coatings.
  • 今川 博之, 松野 健三, 山岡 五雄
    1991 年 40 巻 455 号 p. 996-1002
    発行日: 1991/08/15
    公開日: 2009/06/03
    ジャーナル フリー
    The electrochemical Potentiokinetic Reactivation method (EPR) which evaluates the intergranular corrosion susceptibility of stainless steel was applied to the intergranular corrosion test of Type 316SS in saturated ammonium sulfate solutions with different pH at 80°C. The corrosion behavior was evaluated with the critical passivation current (Ia), the maximum reactivation current (Ir), and the reactivation ratio (Ia/Ir). The immersion test of the specimens, both solution-treated and sensitized, was conducted for 150hrs, and the surface was observed by a scanning electron microscope (SEM). Type 316SS was attacked by the test solution when the solution pH was lower than 2. The corrosion was stimulated by sensitization of heat treatment at 650°C, that is, the reactivation ratio was as high as 40%. It is concluded that the EPR method is feasible to evaluate the intergranular corrosion of austenitic stainless steel in corrosive chemicals.
  • 杉江 他曽宏, 本岡 隆文, 藤井 知
    1991 年 40 巻 455 号 p. 1003-1008
    発行日: 1991/08/15
    公開日: 2009/06/03
    ジャーナル フリー
    Monitoring of corrosion of metals and alloys is a time consuming work even though various techniques are now available. The random-pulse method developed by Ichise et al. for electrochemical analysis has been applied to the examination of corrosion behavior and its rate. The current response was obtained as a function of potential, and was transformed to the spectral data to compress the informed data from the system by fast Walsh transformation. The behavior and the rate of corrosion were well elucidated by using the transformed data. The average current density, or the corrosion rate, agreed with the result of the polarization measurement. Therefore, it is concluded that the random-pulse method combined with a pattern recognition technique is applicable to investigate the corrosion of metals and alloys within one minute.
  • 三谷 進
    1991 年 40 巻 455 号 p. 1009-1015
    発行日: 1991/08/15
    公開日: 2009/06/03
    ジャーナル フリー
    Metastable austenitic stainless steels, SUS 302, SUS 304 and SUS 304L, were cold-rolled with 20% to 80% reduction. Hydrogen evolution from these steels after electrolytical hydrogen-charging was investigated. The main results are as follows:
    (1) The amount of evolved hydrogen at room temperature increased with working degree and martensite content in SUS 302, but decreased in SUS 304 and SUS 304L.
    (2) During continuous heating of the specimens after aging at room temperature, hydrogen evolution began at about 373K (100°C) and had almost finished at about 623K (350°C). In SUS 304 and SUS 304L, the temperature of maximum hydrogen evolution was about 533K (260°C), but SUS 302 had the maximum at a lower temperature. The peaks of SUS 302 decreased as the working degree increased.
    (3) The amount of hydrogen evolved due to continuous heating fluctuated with working degree. At the same working degree, the order of the amounts was SUS 302<SUS 304<SUS 304L.
    (4) In 20% cold-rolled SUS 302, hydrogen charging caused lattice expansion, so the peaks of X-ray diffraction shifted to a lower angle. The peaks returned to the angles of uncharged specimens after aging at room temperature since hydrogen was released. In 20% cold-rolled SUS 304 and SUS 304L, a hydride was formed by hydrogen charging, in addition to lattice expansion. This caused a transformation due to aging at room temperature while hydrogen was released. The strain-induced martensite phase decreased hydrogen-induced transformation.
    (5) In SUS 302, blisters caused by hydrogen charging became more noticeable with increasing working degree. In SUS 304 and SUS 304L, surface cracks caused by hydrogen charging became pronounced as working degree decreased.
  • 西澤 英和, 金多 潔, 佐藤 修央, 平野 浩二
    1991 年 40 巻 455 号 p. 1016-1022
    発行日: 1991/08/15
    公開日: 2009/06/03
    ジャーナル フリー
    It is expected that the application of PSPC for X-ray stress analysis will realize high speed versatile measurement which is beyond the capacity of any conventional apparatus. But at present stage, the total time for the X-ray stress measurement is not improved so much, even if a PSPC detector is installed on a conventional goniometer. This is mainly due to the fact that the PSPC system is too sensitive to mis-setting for a consentional goniometer to obtain a diffraction profile with sufficient accuracy.
    In order to overcome this difficulty, the authors have developed a new goniometer without a fan-shaped X-ray tube guide. The features of the system are summarized as follows.
    (1) The movement of an X-ray tube is achieved by a X-Y-ψ table, each axis of which can be controlled independently.
    (2) The distance between a goniometer and specimen can be measured by means of a displacement tranceducer using lazer beam.
    For the purpose of determining a method for measuring the peak shift of diffraction profile obtained through PSPC, a series of Monte Carlo simulation has been performed. It was made clear that we can evaluate stress whose standard diviation is less than 20MPa, if the data is sampled at the condition that the S/N ratio is larger than 9. The X-ray stress constant obtained through bending tests on annealed and 2.5% strained low carbon steel plates was about -300MPa/deg.
  • 加賀谷 忠治, 加藤 政則, 八嶋 昭弘, 川口 幸宏, 江上 登
    1991 年 40 巻 455 号 p. 1023-1028
    発行日: 1991/08/15
    公開日: 2009/06/03
    ジャーナル フリー
    In order to make clear the absorption energy, transition temperature and fracture behavior of friction welded joint, the instrumented Charpy impact tests have been carried out at various temperatures from 173K to 473K, using 0.15%C carbon steel specimens with butt joint. The main results obtained are as follows:
    (1) The energy transition curve of the weld interface and the heat affected zone shifted to the lower temperature side than that of the parent material. The absorption energy at the transition region was the highest at the weld interface.
    (2) The energy transition temperature was about 250K in both the parent material and the heat affected zone, and apporoximately 230K in the weld interface. These temperatures and the fracture appearance transition temperatures agreed in most cases.
    (3) The crack propagation energy in the weld interface at the lower position of the transition region was extremely larger in comparison with that of the parent material and the heat affected zone.
    (4) The impact bending strength of the weld interface, the heat affected zone and the parent material became maximum around the lower position of the transition region, having no corresponding relationship with the absorbed energy.
  • 山田 常雄, 児島 慶亨, 大中 紀之, 近崎 充夫
    1991 年 40 巻 455 号 p. 1029-1034
    発行日: 1991/08/15
    公開日: 2009/06/03
    ジャーナル フリー
    Residual thermal stress in SiC/(C/C) (C/C: carbon-fiber-reinforced carbon matrix composite) laminates, which are cooled to 273K after interlayer and SiC layer formations on C/C at 1973K, has been analyzed by a finite element method using a plane-strain element model. It was assumed that the interlayer of the laminate has a controlled compositional gradient, and its thickness is twice that of the SiC layer. The analytical model was 10mm square shape with 1.3mm thick. In order to study the effects of thickness of the SiC layer tSiC and compositional gradient exponent P of the interlayer on normal residual thermal stress σx, tSiC and P were varied from 0.00429 to 0.394mm and from 0.1 to 6.5, respectively.
    In the laminate without the interlayer, as tSiC increases σx in the SiC layer decreases, finally reaching a constant value of 785MPa at tSiC above 0.12mm. It is confirmed that inserting the interlayer is an effective way to reduce σx in the SiC layer and the greatest reduction of σx in the laminate is obtained when P is 3. In the laminate with the interlayer of P=3, as tSiC increases σx in the SiC layer and the interlayer also decrease and σx in the SiC layer reaches a constant value of 138MPa at tSiC above 0.2mm. In the above analysis, if a plane-stress element model is used instead of the plane-strain element model, σx and displacement decrease by about 32 and 24%, respectively.
  • 桜井 茂雄, 梅沢 貞夫
    1991 年 40 巻 455 号 p. 1035-1041
    発行日: 1991/08/15
    公開日: 2009/06/03
    ジャーナル フリー
    Near-threshold fatigue crack growth behavior for distributed cracks in Hastelloy-X has been examined with reference to the effects of crack size and environment on the threshold stress intensity ΔK.
    The threshold stress intensity value for a large crack in air was lower than in vacuum. This result was same for a small crack in air and vacuum experiments. But the value for a small crack was about 50% lower than for a large crack in vacuum. In air, the small crack threshold was lower than the large one. These results were discussed in terms of fatigue crack closure. Observation of crystallographic fracture surface in vacuum suggested the roughness induced crack closure mechanisms.
    The distributed-small-cracks specimen was obtained by low cycle fatigue loading tests. The threshold stress intensity for the distibuted-fatigue-crack growth could be estimated by the maximum crack size of the distributed cracks. The coalescence of small cracks did not affect the near-threshold fatigue crack growth behavior.
  • 村田 雅人, 向井 喜彦
    1991 年 40 巻 455 号 p. 1042-1048
    発行日: 1991/08/15
    公開日: 2009/06/03
    ジャーナル フリー
    Intermetallic compounds in the Ti-Al system are expected to be used as a new material in high temperature environments, but it's still very difficult to fulfill the required performance characteristics.
    In the present paper, the strength, fracture toughness and hot corrosion resistance of TiAl intermetallic compounds were studied. As the results, it was made clear that the effect of heat treatment on fracture strength was well described by Larson-Miller Parameter, P. Furthermore, the susceptibilities of oxidization and hot corrosion were evaluated. TiAl intermetallic compound was oxidized at temperatures higher than 1073K and the susceptibility of hot corrosion became remarkable at temperatures higher than 1173K, which results from the selective corrosion of Ti3Al phase.
  • 宮原 健志, 力石 哲也, 木戸 光夫, 上野 学
    1991 年 40 巻 455 号 p. 1049-1055
    発行日: 1991/08/15
    公開日: 2009/06/03
    ジャーナル フリー
    The characteristics of static or cyclic fatigue crack growth initiation of two ceramics (alumina (Al2O3) and partially stabilized zirconia (PSZ)) under tensile loading have been investigated in high purity water at room temperature. The time to crack growth initiation. tg, at static and cyclic fatigue tests in water was shorter than that in air. In addition, it decreased markedly with increasing KI or ΔKI. From the observation of fracture surface for static and cyclic fatigue by SEM, it was shown that fracture surface was the mixed type of intergranular and transgranular cracking in alumina and intergranular cracking in PSZ. Fracture behavior under cyclic loading revealed the occurrence of time-dependent crack growth initiation in alumina and cyclic-dependent one in PSZ. The reason why the fracture time decreased by cyclic fatigue for PSZ is considered to result from the promotion of interaction between fatigue crack and microstructure, such as microcracking and phase transformation in the process zone, and the activation of hydration reaction at the crack tip.
  • 西村 新, 向井 喜彦
    1991 年 40 巻 455 号 p. 1056-1060
    発行日: 1991/08/15
    公開日: 2009/06/03
    ジャーナル フリー
    A glass fiber reinforcement plastic bolt (FRP bolt) has several good properties such as corrosion resistance or electrical insulation. Therefore, it exhibits an excellent performance in a suitable service environment or operation condition.
    In this study, the FRP bolt which has center roving and braid structure was fatigued under controlled load at 293K and 77K. And its deformation behavior during a fatigue process and its fatigue life were discussed based on the change of crack density in the FRP bolt.
    As the results, the following conclusions are obtained:
    (1) The fatigue strength of three types of FRP bolts tested became lower as its tensile strength became low. Especially, when the diameter of center roving in the FRP bolt decreased, the fatigue strength became below enormously.
    (2) No crack was observed in the center roving region. But it was clarified that the change of crack density observed in a braid region corresponded to the increment of displacement at a maximum or a minimum load, and that the cyclic range of displacement did not change so much.
    (3) There was a period in the fatigue process, in which the displacement at a maximum load increased linearly. By using the increment of displacement per cycle in this period, the fatigue lives were able to be expressed by only one curve regardless of bolt types, but it depended on test temperature.
  • 西田 友久, 武藤 睦治
    1991 年 40 巻 455 号 p. 1061-1065
    発行日: 1991/08/15
    公開日: 2009/06/03
    ジャーナル フリー
    Fracture toughness tests of sintered high speed steels with various contents of oxygen were carried out using specimens with fatigue precracks. Tensile tests of the sintered high speed steels were also carried out. No significant effect of oxygen content on tensile strength was found. The surface defect of a tensile specimen seems to be a more influential factor to control tensile strength. Fracture toughness of sintered high speed steel decreased with an increase in oxygen content. The reason for this may be that the extremely small size oxides, which are produced on the surface of powder and distributed in the grain during the material processing, reduce the fracture strength of the relevant quasi-cleavage plane and consequently result in the decrease in fracture resistance.
  • 津田 政明, 広瀬 幸雄, 黒瀬 雅詞, 松岡 三郎, 黒部 利次, 田中 啓介
    1991 年 40 巻 455 号 p. 1066-1072
    発行日: 1991/08/15
    公開日: 2009/06/03
    ジャーナル フリー
    Stress corrosion cracking tests were conducted in 3.5%NaCl solution by using SNCM439 steel specimens which have three different prior-austenite grain sizes, d=12, 78 and 172μm. The fracture surfaces obtained were analyzed from a viewpoint of fractal geometry.
    The results obtained are summarized as follows:
    (1) The crack growth rate, da/dt, increased with increasing the stress intensity factor, K, and with decreasing prior-austenite grain size, d.
    (2) The grain boundary fracture area, φ, decreased with increasing K. At a given K level, φ increased with increasing d.
    (3) The profiles of stress corrosion cracks had the character of fractal. The relevant fractal dimension, D, was about 1.05 in the region c where the intergranular cracking was predominant, while it was about 1.10 in the region b where the mixed feature of intergranular and transgranular cracking appeared.
    (4) The fractal analysis explained the dependence of da/dt on d.
  • 内田 仁, 井上 尚三, 小山 雅隆, 森井 美佳, 小寺澤 啓司
    1991 年 40 巻 455 号 p. 1073-1078
    発行日: 1991/08/15
    公開日: 2009/06/03
    ジャーナル フリー
    The stress corrosion cracking (SCC) of pure copper poly- and single crystals in NaNO2 solutions was investigated potentiostatically by the slow strain rate technique. The susceptibility to SCC has a maximum in 1kmol·m-3 NaNO2 solution of 7.3-7.5pH, at the strain rate below 1.67×10-5S-1. In this solution, a close correlation was found between the SCC and anodic polarization behavior of pure copper: The potential range for SCC occurrence was 0-100mV (SCE), nearly corresponding to that of passivity/transpassivity transition where the formation or rupture of black tarnish film (Cu2O) occurred. The fractographic results showed that many cracks nucleated from the specimen surfaces with frequent slip-steps, producing the tarnish film. The crack propagation was predominantly transgranular, along ‹110› direction on {110} plane. The evidence introduced here supports an anodic dissolution mechanism for the transgranular SCC of pure copper in NaNO2 solutions, including a tarnish rupture mechanism.
  • 板谷 雅雄, 三好 良夫, 小倉 敬二
    1991 年 40 巻 455 号 p. 1079-1085
    発行日: 1991/08/15
    公開日: 2009/06/03
    ジャーナル フリー
    Hydrogen assisted crack growth of austenitic stainless steel may be controlled by the content of hydrogen which diffuses to a crack tip fracture process zone. A numerical analysis was conducted to investigate the influence of temperature and stress levels on the hydrogen concentration at the crack tip. Since α' martensite is induced by the plastic strain around the crack tip in this steel, the variation of diffusion coefficient as a function of the plastic strain and temperature was taken into account for the analysis. According to the analysis, the maximum hydrogen concentration was found occur at 60°C in SUS301 and at 32°C in SUS304, respectively. Such a trend was observed for both the cases of internal and external hydrogen. It was found that hydrogen accumulated in the process zone ahead of the crack tip when the volume fraction of martensite was high in the process zone and it was low enough in the surrounding area of the process zone. The hydrogen concentration at the crack tip was found to decrease, when the process zone size increased over the diffusion distance of hydrogen. All the results were consistent with the experimental results of crack growth test under cyclic loading.
  • 岩永 弘之, 沖 猛雄
    1991 年 40 巻 455 号 p. 1086-1092
    発行日: 1991/08/15
    公開日: 2009/06/03
    ジャーナル フリー
    It is well known that the metallic materials show the environmental embrittlement phenomena which cause ruptures at short period when stress is applied in various corrosive environments. The hydrogen embrittlement accompanied with the cathodic reaction is also included in these phenomena. It is said that the austenitic stainless steel SUS304 employed in structural materials causes stress corrosion cracking, but hydrogen embrittlement may or may not occur.
    In this study, in order to examine the hydrogen embrittlement behavior of SUS304 stainless steel from the change of mechanical properties or the change of fracture surface morphology, slow strain rate tension tests were carried out under the environment of hydrogen evolution immediately after the specimens were held for various time periods at hydrogen evolution potentials on the cathodic polarization curve which was obtained in 3%NaCl solution. The main results obtained are summarized as follows.
    (1) The reduction in area, which indicates, usually a remarkable change in the embrittled materials, decreased continuously with increasing holding time in each setting potential. This tendency became more pronouned at lower setting potential of -2.0V (vs. S.C.E.), and an embrittlement phenomenon could be found. The same results were also obtained for the change of time to fracture.
    (2) The fracture surface morphology accompanied with the embrittlement was represented by the transgranular fracture. The region of transgranular fracture containing the cleavage fracture occupied a wide range of fracture surface when the specimen was held for longer time at lower setting potential.
  • 高橋 昌男, 泉 佐和子, 金丸 文一
    1991 年 40 巻 455 号 p. 1093-1099
    発行日: 1991/08/15
    公開日: 2009/06/03
    ジャーナル フリー
    Nitride thin films in the Cu3N-TiN system were prepared by a reactive sputtering method. Analyses of X-ray photoelectron spectra and X-ray absorption spectra for the films revealed the following.
    (1) The valence state of copper is nearly equal to unity in both Cu3N and the anti-rhenium trioxide-type solid solutions in the Cu3N-TiN system, and the charge transfer occurs from copper to nitrogen.
    (2) Copper has a peculiar electronic state in Cu3N compared to metal atoms in other metal nitrides, i.e., 3d electrons of copper are quite localized.
    (3) With the addition of TiN, the contribution of 3d electrons of metal to the levels consisting of metal 3d electrons and nitrogen 2p electrons increases, and the bonding state seems to become band-like one. These electronic states are considered to play an important role on the thermal stability of anti-rhenium trioxide-type Cu3N and nitride films in the Cu3N-TiN system.
  • 長島 伸夫, 升田 博之, 松岡 三郎
    1991 年 40 巻 455 号 p. 1100-1104
    発行日: 1991/08/15
    公開日: 2009/06/03
    ジャーナル フリー
    Photo-electron emission from bare surface of metals is influenced by oxidation. In this study, therefore, photo-electron emission from aluminium, titanium, lead and zinc surfaces were examined at elevated temperature (-25 to 200°C) in vacuum (760 to 10-6 Torr) and in dry (0.0003%RH) and humid air (80%RH) at 23°C. The behavior of photo-electron emission from aluminium was compared with the results of the micro oxidation of its surface examined by a quarts crystal microbalance. Based on these results, the dependence of fatigue crack growth of an aluminium alloy on humidity was considered.
  • 芳賀 裕, 渡辺 隆信, 四十宮 龍徳
    1991 年 40 巻 455 号 p. 1105-1110
    発行日: 1991/08/15
    公開日: 2009/06/03
    ジャーナル フリー
    Cadmium selenide (CdSe) was encapsulated in polymethylmethacrylate (PMMA) or polystyrene (PSt) by the encapsulating polymerization process. The behavior of CdSe in the encapsulating polymerization, and the photoconductivities and the photosensitive mechanism of the resulted composite materials were investigated. The polymerization was carried out by use of the initiators giving positive and negative charges to the molecular ends of the produced polymer. In both cases of the initiator, it was observed that a large part of the polymer existed in the form of stable latex polymer in the aqueous phase. The encapsulating polymer on the CdSe particles resisted to the Soxhlet extraction. The dark current, the photocurrent and the relative sensitivity of the CdSe encapsulated in PMMA were found to be enhanced as compared with CdSe and CdSe-dispersed PMMA. These values tended to increase with the increase of the encapsulating ratio. In addition, the voltage-current characteristics, temperature dependence of dark current, the light intensity dependence and the initial rising rate of photocurrent were investigated, it was concluded that the photoconductive mechanism of the CdSe encapsulated in PMMA was caused by the carrier trap.
  • 曽我部 雄次, 都築 正之, 阪井 克倫, 千田 豊満, 岸田 敬三
    1991 年 40 巻 455 号 p. 1111-1117
    発行日: 1991/08/15
    公開日: 2009/06/03
    ジャーナル フリー
    The effect of temperature on viscoelastic properties of CFRP (carbon fiber reinforced plastic) was examined by means of a wave propagation testing. Specimens used in the present study were two types of CFRP rods, which were made from the same prepreg but in different fiber orientation. Longitudinal impact tests were performed in the temperature range -40-80°C, and strain wave histories were resolved into Fourier components in order to determine the complex compliance as well as the viscoelastic model at each temperature. The experimental results revealed that the dynamic compliance (real part of complex compliance) increased with temperature, but change of the loss compliance (imaginary part of complex compliance) was not monotonous as it showed a maximum value at about -20°C and showed a minimum value at about 40°C. Furthermore, shear properties were evaluated from the longitudinal data on the two types of specimens based on the coordinate transformation law of viscoelastic functions (e.g. complex modulus, complex compliance) which were derived in the previous paper.
  • 野口 徹, 佐藤 信吾, 赤木 健一, 吉田 光則
    1991 年 40 巻 455 号 p. 1118-1124
    発行日: 1991/08/15
    公開日: 2009/06/03
    ジャーナル フリー
    Compact tension(CT) tests were performed at various test speeds on epoxy resin specimens with different hardness achieved by varying base compounds ratio. The calculated toughness, Kqi, for unstable crack initiation, was compared with Charpy impact values, and the correlation between the two was discussed with the characteristics of the load displacement curve and the fracture appearance.
    The experiments showed that the toughness value, Kqi, depended strongly on the test speed, and was not correlated with impact value, or with static strength. However, there was a linear relation between the toughness and impact values for the specimens where the load-deflection curve and fracture appearance indicated an initial small slow-stable crack followed by rapid-unstable fracture. This occurred in very slow CT tests, where appearance of the rapid fracture was similar to that in impact specimens.
    In other cases, where the fracture was slow-stable, stick slip type rapid-unstable or rapid stable, Kqi was independent of the impact value, and the fracture appearance was quite different. The Kqa values, for crack arrest, were not correlated with impact values. It must be noted that the toughness values of CT tests should only be compared when the fracture types are similar.
  • 井上 久弘, 田代 徹也, 弓削 毅, 川口 格
    1991 年 40 巻 455 号 p. 1125-1129
    発行日: 1991/08/15
    公開日: 2009/06/03
    ジャーナル フリー
    As the first step to clarify the grinding mechanism of FRP, the quality of ground surface finish of unidirectional glass fiber reinforced plastics was investigated. It was shown in the previous paper [1] that the aspects of the cut end of glass yarn near the ground surface were classified into two modes by the direction of glass yarn, such as, the hollow pit and the swollen proturberance (uncut glass yarn). The present paper describes the investigation on how to produce the same quality ground surface finish irrespective of the change of glass yarn direction in the specimen and how the grinding method affects the quality of ground surface finish.
    The following results were obtained.
    (1) It was difficult to achieve the same quality of ground surface finish when the glass yarn direction was changed.
    (2) On the spark-out grinding, the length of uncut glass yarn decreased with increasing the number of spark-out grinding.
    (3) On the orthogonal plunge cut grinding, the length of uncut glass yarn increased with increasing the number of plunge cut.
    (4) None of these grinding methods could reduced the depthe of hollow pits.
  • 松本 浩之
    1991 年 40 巻 455 号 p. 1130-1136
    発行日: 1991/08/15
    公開日: 2009/06/03
    ジャーナル フリー
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