An investigation was made on the method of removing water vapour from humid air under the gauge pressure of 0∼3kg/cm2 at a normal temperature by using Itaya-zeolite composed mainly of clinoptilolite. Approximately -50°C dew point air could be obtained by a two-cylinder small-sized pressure swing device. Itaya-zeolite showed an excellent pressure swing adsorption property compared with the commercial adsorbents, such as synthetic zeolites and silica gel. Thus it is useful for the development of a small-sized water vapour removing apparatus.
The precipitation conditions for obtaining spherical particles of one-phase vaterite have been determined, and the effects of additives during precipitation and transition on the transition isotherms have been studied with the spherical powders obtained with different precipitants such as Na2CO3 and (NH4)2CO3. The transition from vaterite to calcite in water media is characterized by abrupt appearance of calcite particles having well-developed crystal habits. Summarizing the experimental data, it is proposed that the dissolution-precipitation mechanism is operative in the transition, in which dissolution process is probably a rate-determining step.
The pore size distribution and pore structure of the original silica gel used for the present surface-treatment experiments were found to be invariant through the determination of argon adsorption isotherm at 77K and the surface area, as long as it was activated at lower temperatures than 450°C. The silica gel was treated with alicyclic alcohols, e. g., cyclopentanol, cyclohexanol, cycloheptanol, cyclohexane methanol and cyclohexane ethanol in an autoclave. The adsorbed amount of argon at 77K on these surface-treated silica gels showed an appreciable decrease in the whole range of relative pressure in comparison with that of the original silica gel and the surface area of these silica gels also decreased. The surface groups of these surface-treated silica gels except the ones treated with cyclohexane methanol or cyclohexane ethanol were driven off from the substrate almost perfectly by pyrolysis of these silica gels at 450°C. The argon adsorption isotherm at 77K and the surface area of these silica gels after pyrolysis at 450°C showed a fairly good agreement with those of the original silica gel.
Powdered polystyrene was treated with concentrated sulfuric acid at various temperatures and then compacted into specimens having various void fractions. The dynamic mechanical properties of the compacts were measured by the vibratory method in the same manner as shown in our previous papers. The mechanical loss factor Q-1 of the compacts increased with increases in treating temperature, void fraction and strain amplitude of vibration. The dynamic modulus σ0/ε0 which was defined as the ratio of a stress amplitude σ0 to a strain amplitude ε0 decreased with increases in treating temperature and void fraction, but varied quite little with increasing strain amplitude. The relation between the mechanical loss factor and the value, which was defined by the cohesive force between particles, the static compressive force superimposed on vibration force and the frictional coefficient between polystyrene itself, was united into a function independent of the treating temperature and the void fraction. This fact can be interpreted by Mindlin's model with respect to the inelastic behavior of a pair of particles in contact subjected to a cyclic force: The increase in the mechanical loss factor of powder compacts is attributed to the friction at weak junctions between particles.
The tensiling process curves for powders with various moisture contents have been experimentally obtained in order to correlate the mixing torque with the tensile strength. From the trend between the breakup displacement and the moisture content, the powders were able to be classified into three states, according to the region of moisture content: the pendular state (region I), the funicular state (region II) and the transition state from the funicular to the capillary state (region III). For the powders in the region I or II, the tensile strength increased with increasing moisture content. In the region III, however, the tensile strength was nearly constant or reached a maximum value and then reduced with increasing the moisture. The mixing torque for moist powders was excellently correlated with the tensile strength obtained by the tensile tests for the powders with the void fraction identical to that for the torque measurement.
The adhesive force between powder particles was measured in the heated state and the effect of adhesive force on fluidity was studied. The samples mainly used here were glass beads and alkali halide NaCl. Calcium carbonate and coal were also used. The adhesive force was determined by the tensile strength to cause layer-fracture of the packed powder. Since the sintering occurred at initial contact points between particles when the powder was heated in the packing state, the variation of adhesive force with temperature could not be measured accurately. In order to overcome this difficulty and obtain reproducible data, a new device (hereafter called a cell) was made. The sample powder in the cell can be heated in the fluid state so as that individual particles remain mobile. After keeping the sample powder at a certain temperature for a fixed time, the powder was closepacked at the same temperature and immediately the fracture force was measured. The fluidity of powder under heating was measured by the device reported previously. The following results were obtained from the above experiments. (1) Above 100°C, the adhesive force increased with increasing temperature. (2) Even in the state of fluidity, the apparent size of particles increased as a result of aggregation due to an increase in adhesive force. (3) Since the apparent size of the aggregated particles measured by a sieve increased rapidly from T/Tm≅0.7, the magnitude of adhesive force between the particles became small. Therefore, the fluidity of the powder increased in this region. Tm quoted above is the melting point or softening point of powder samples. (4) At higher temperatures, the powder itself begins to aggregate and solidify, resulting in rapid decrease of fluidity.
Measurements of dielectric constant and conductivity have been made on various ceramic powders using a two-phase mixture system. BaTiO3, TiO2 and ZnO powders were examined in the present study. The dielectric constant and conductivity of two-phase mixtures, which consisted of the powders and paraffine wax chosen as a dispersion medium, were both found to be described by a logarithmic mixture rule. By extrapolation in logarithmic rule plots of the mixtures to the end members, the dielectric constants and the conductivities of the powders used here were obtained as follows: Dielectric constant (at 500kHz); BaTiO3(1000-2000), TiO2(∼100), ZnO(∼10). Conductivity (ohm-1 cm-1); BaTiO3(∼3x10-10), TiO2(∼1x10-10), ZnO(∼1x10-4).
In order to investigate the capillary siphoning effect of a capillary bundle immersed in a slurry tank, the draining rate of clear water through a bundle of sterilized gauze, Qs, was measured, after suspended solids adhered to the bundle and settled in a CaCO3-slurry tank. Then, Qs was compared with the draining rate of distilled water through the bundle of clear gauze, Qo. The experimental results were discussed on the basis of a couple of models for adhesion of suspended solids to the bundle; (a) adhesion to the surface of the bundle and (b) to the inside of the bundle. The conclusions obtained are: (1) Model (a) gave a fairly good agreement with the experimental relationship between the draining ratio Q*(=Qs/Qo) and the amount of CaCO3 solids adhering to the bundle ΣWp. (2) This fact indicates that the suspended CaCO3 solids adhere to the surface of the bundle immersed in the slurry. (3) By vibrating the bundle, CaCO3 layer on the bundle surface could be shaken off, and the draining ratio Q* increased to about 0.8.
The mechanochemical reactions of polymethyl methacrylate and polystyrene were investigated at room temperature up to 15kbar static pressure by using a self-made high pressure apparatus capable of simultaneous shear deformation. Determinations of molecular weight and shearing stress of sheared sample confirmed that mechanochemical reactions proceed markedly in both polymer materials and the higher the static pressure, the more reactions proceed. The mechanochemical reaction rate and limiting molecular weight were evaluated by fitting the rate equation to experimental measurements on viscosity average molecular weight. We conclude that the mechanochemical reaction mechanism in deformed polymethyl methacrylate is somewhat different from that in deformed polystyrene. ESR data were also discussed.
Creep tests were performed on Kobe layer tuff under seven uniaxial compressive stress states. It was found that the creep strain varied in proportion to stress up to the 50% point of unconfined compressive strength (σs), and that the creep Poisson's ratio did not vary with time at low stress levels. These results indicate that the time dependent behavior of ground structure consisting of this rock may be analyzed by the linear viscoelastic theory if the design stress is below 0.5σs. It is convenient to use a rheology model when the linear viscoelastic theory is applied. For this purpose, the evaluation technique of rheology model constants must be considered. In this paper, the generalized Voigt model was introduced and the determination method of its constants was discussed. As the first step of this method, the approximate retardation spectrum was obtained by numerical differentiation of the experimental creep curve. Second, the number (n) of Voigt elements in the generalized Voigt model and the retardation times (Ti, i=1, 2, ……, n) were determined from the number of peak and the peak position in spectrum. Finally, the overall creep process was divided into several time ranges and the compliance Ji in each time range was determined by the method of least squares. It was proved that the experimental results could be interpreted reasonably by the creep function determined by applying the present method.
A method of probabilistic design for the fiber reinforced composite laminate under a plane stress state has been established by applying the second moment method to the maximum work theory proposed by Tsai and Wu. This theory was adopted as the failure criterion because of being applicable to the material with different tensile and compressive strengths. The fiber reinforced composite laminate was treated as an orthotropic material, and the design for the composite laminate in on-axis and off-axis states was made. The proposed method requires only the mean values and the coefficients of variation of both principle strength components and applied stress. Thus, it is considered to be simple and effective enough for practical use.
A noncontinuum crack tip deformation model in fatigue of metals was proposed and used to study some properties of surface microcrack propagation. It was shown that the model explained well the characteristics found in experiments of fatigue lives and fatigue crack growth rates.
The hold-time effect on notch sensitivity in low-cycle fatigue life was studied at 600°C in air by using austenitic stainless steel SUS 316. The total strain controlled tests with the hold-time tH from 10min. to 60min. were performed by use of the round notched specimens with the stress concentration factor Kt of 2.6, 4.2 and 6.0. From the tests, the following conclusions were obtained. The number of cycles to failure of the notched specimen decreased with an increase of tH. But the rate of decrease in fatigue life with an increase of tH was the most at tH of 10min. and at a longer hold-time the life was almost constant. Particularly, for the case of Kt of 2.6 the fatigue life increased slightly with an increase of tH in connection with notch-strengthening of the metal tested. Also, the life prediction method of“Modified both frequency ν and Kt fatigue life rule” of Nf=Nf0Ktmνl was applicable in order to predict accurately the life of a notched specimen at any condition of Kt and tH. The life prediction rule which corresponds to ASME Biler & Pressure Vessel Code Case N-47 was evaluated and the prediction was found inaccurate in comparison with that mentioned above. Furthermore, Neuber's rule was examined from the elasto-plastic solution for a semi-infinite plate with a semi-elliptic notch under anti-plane shear and the modified rule of Ktb=KσKε was found applicable to the prediction in creep-fatigue interaction, where b takes the numerical value from 1 to 2.
Low-cycle fatigue tests were carried out on precipitation hardening, heat resisting steel, JIS SUH 660, at room temperature, 450, 600 and 700°C under a triangular strain waveform for which the strain rate was 40, 4 or 0.4%/min. The results obtained are summarized as follows: (1) The stress range decreased or increased first and then decreased with increasing strain cycles depending on the test condition. The strain rate dependence of the cyclic stress-strain relation was scarcely observed at temperatures up to 600°C. At 700°C stress was smaller for the strain rate of 0.4%/min than that for 40%/min. (2) For the relation between the plastic strain range and the number of cycles to failure, the strain rate dependence was scarcely observed at room temperature and 450°C, but the number of cycles to failure decreased with decreasing strain rate at 600 and 700°C. The temperature dependence of the relation was clearly found at temperatures from room temperature to 600°C, but there was no difference between the relations at 600 and 700°C. (3) Transgranular fracture surface covered with striations and small dimples were observed for the specimens tested at room temperature and 450°C. Intergranular fracture occurred at 600 and 700°C. (4) For the temperature range at which transgranular fracture occurs, the temperature dependence of the Δεp-Nf relation could be explained by the mechanical parameter Δεp(Δσ/σu)2 which was introduced by Tomkins. (5) For the temperature range at which intergranular fracture occurs, the relation α=1/(1+an) was obtained, where a is a constant value of 4∼6 and α and n are exponents of Δεp-Nf and Δεp-Δσ relations, respectively.
In this paper, the effect of the glass transition temperature (Tg) on the electrical properties of carbon black-polymer composite resistors has been investigated. The resistors were made by mixing the furnace black with poly-methylmethacrylate (PMMA) or Poly-laurylmethacrylate (PLMA) and coating the mixture on porcelain plates. The resistance was measured in the heat cycle between 40 and 140°C. For the resistors containing PMMA with higher Tg than 80°C, the resistance increased rapidly at about Tg on the first heating half cycle and became unchanged at 40°C after the subsequent cooling half cycle. On the second temperature cycle, the resistance change was comparably small and the resistance change at 140°C was about 17% at the most, while the reproducibility on the temperature cycle was better. From the dilatometric measurement, it was found that Tg of PMMA mixed with carbon black shifted to a higher temperature and became obscure. This change in Tg was considered to be a reason why the resistance change became smaller on the second heating cycle. The composite resistor containing PLMA with Tg of -65°C shows no anomaly against the temperature cycle between 40 and 140°C. It was shown that the specific volume of the composition changed irreversibly against the temperature cycles. From this result, it is estimated that the rearrangement of carbon black network in the polymer matrix may occur. However, the resistors obtained from the copolymer of laurylmethacrylate with glycygylmethacrylate, which can be crosslinked with ethylene diamine, showed an anomaly even in the absence of Tg, when resistors were cured with ethylene diamine.
Many kinds of flame retardant, copper-clad paper base phenol laminate are now commercially available. But flame retardant, paper base phenol laminates have generally poor resistance against solder. The main cause for such poor solder resistance of the flame retardant (FR) laminates is considered to be the usage of additive type flame retardant agents. Authors investigated a method to improve the solder resistance and flammability of laminates by using reactive type flame retardant agents (P-Bromophenol), TCP and water soluble phenol. The results of the experiments were as follows. 1. For the cotton linter paper base FR phenol laminate containing 5% wt of Sb2O3 and 20% wt p-bromophenol, (1) Flammability UL 94V-1 (2) Solder resistance 26sec 2. For the kraft paper base FR phenol laminate containing 40% wt of p-bromophenol, (1) Flammability 94V-0 (2) Solder resistance 18sec