The viscosities of mixed-alkali lead silicate glasses were measured by the penetration viscometer in the softening range approximately from the flow point to the softening point. The densities of glasses at room temperature were also determined by the buoyancy method. The results obtained are summarized as follows: (1) The minimum of viscosity appears at the molar concentration ratio of about 0.5 for the Na-K glasses and at the Na2O-rich side for the Li-Na glasses. For the K-Li glasses, on the other hand, the viscosity decreases with increasing Li2O content. (2) The apparent molar volume-composition curve indicates a negative deviation from linearity for all the Li-Na, Na-K, and K-Li glasses. (3) The compositional dependency of viscosity and that of the apparent activation energy of viscous flow show the same tendency for all the mixed-alkali glasses. (4) The correlation between the minimum of viscosity and the largest negative deviation of molar volume in the Na-K glasses was interpreted in terms of the assumption of the increase in alkali-oxygen bond strengths based on the interaction between dissimilar alkali ions.
In order to establish a proper method of testing the hardness of plastic pipes, which is the objective of our study, various kinds of experiments were performed on plastic pipes most commonly used in industries and other fields for transporting fluids. The hardness measurement of plastic pipes depends on the following factors: (1) shape of measuring face, (2) testing conditions and measuring method, (3) conditions of pipe samples, and (4) deflection of pipes. Since the results of hardness tests are useful not only for the quality control of plastic pipes but also for the convenience of commercial transactions, the machines to be used for testing their hardness must be those acceptable in a wide area. The principal characteristics required for the hardness testing of plastic pipes are: (1) reduction of uncertainty in the measured values, which is particularly important for maker-commercial transactions, and (2) simplicity of determining mechanical properties at high or low temperatures over a long period of time, which is important for the user.
Tensile test pieces of aluminium bi-crystal were obtained by the strain annealing method from commercial aluminium plate. Orthogonal grids of 20lines/mm were printed on the surfaces of the specimens. The plastic deformation of these specimens were measured by the usual moiré technique. The amount of deformation obtained experimentally almost agrees with that calculated on the basis of slip of crystal plane, but it becomes small near the grain boundary. That is, the grain boundaries tend to restrict deformation of crystals. The distribution of elongation in the neighborhood of grain boundaries is similar to the result obtained by Urie and Wain4). The effect of grain bondaries reaches to 2∼5mm from grain boundary. It seems that the extent of such region is related to the Schmidt's factors of bi-crystals and their slip direction. Next, to examine the rotation of crystal lattice induced by plastic deformation, Laue photographs were taken. For this purpose, about ten slits of 4cm in length and 0.45mm in diameter were set in a row. This slits system makes it possible to take Laue patterns around the grain boundary on a X-ray film. It was observed that the amount of rotation of crystal lattice and the direction of its rotation axis are abnormal in the neighborhood of grain boundary.
Owing to the thermal and viscoelastic natures, the mechanical properties of thermoplastics closely depend on the various factors such as testing temperature, test speed and so on. In fatigue under repeated stresses, the materials are more sensitive to such factors and sometimes show the considerable temperature rise which generally causes the reduction of fatigue strength. Two kinds of thermoplastic materials were prepared, namely Polymethylmethacrylate (PMMA) sheet of 4mm in thickness and Polycarbonate (PC) sheet of 3mm in thickness. Their glass transition temperatures are 120°C and 150°C respectively, and the elastic modulus of PMMA is 1.5 times larger than that of PC. They were fatigued in plane bending with the test speed of 1800rpm to obtain the dependencies of their fatigue strengths on the testing temperature and pause periods during fatigue test and to examine the relations between the fatigue behavior and the temperature rise of specimen itself, deflection change during fatigue test and fracture surface. At high stress levels PMMA failed in cyclic thermal softening by extraordinary temperature rise resulting from the internal damping, but at low levels it fractured by fatigue crack propagation. As for PC, the temperature rise was relatively so small that all the failures took place by fatigue crack propagation over the wide range of stress levels. Moreover, the fatigue behavior of PMMA was strongly affected by the test conditions, especially thermal conditions. The fatigue life decreased as the testing temperature rised but it was prolonged by the pause during fatigue. On the other hand, the fatigue behavior of PC was not so much influenced by the above conditions as PMMA. These differencies in fatigue behavior correspond to that in temperature dependency of mechanical properties of these materials.
The elastic constants and Vickers hardness of B2O3-PbO glasses have been determined. The data obtained for Vickers hardness, isotropic wave velocities, bulk modulus, shear modulus and Young's modulus are listed in Table I and II together with the density and molar volume. The variation of these data with composition of the glasses are shown in Fig. 1∼3. It can be seen that both the elastic constants and Vickers hardness increase with increasing PbO content up to its maximum value at about 42 mole percent PbO and then decrease; that is, beyond this further addition of PbO produces a softer glass. The increase of the elastic constants and hardness in the composition range of approximately 20∼42 mole percent PbO is interpreted based on the evidences that the four-co-ordinated borons are present and the type of lead-oxygen association becomes more covalent bonding.
Thermal conductivities and specific heats of vitreous materials in the system As-S-Te (composition: 12.7-38.8 at % As, 39.8-87.3 at % S and 0-30.6 at % Te) were measured in the temperature range from 25 to 80°C by a comparative method and an adiabatic calorimeter. Thermal conductivity at 40°C, λ40, decreased with increasing Te content introduced into As-S parent glasses. The values of λ40 of As-S glasses, which have been reported previously, as well as those of As-S-Te glasses increased with covalent bond concentration, [v]. The bond concentration is defined as the total moles of all kinds of covalent bonds in unit volume of the glasses. Comparison of λ40 for the glasses with same [v] and the same amount of cross-linking indicated that the value for As-S-Te glass was lower than that for As-S glass. The heat capacity at 40°C per gram formular weight of AsSxTey, C(AsSxTey), can be estimated by the following bond additivity relation, C(AsSxTey)=5.1[A]+5.9[B] where[A]is the total moles of As-S and As-Te bonds and [B] the moles of Te-S, Te-Te and S-S bonds per gram formular weight of AsSxTey. The agreement of the values of heat capacities estimated by the above relation with the observed values for As-S-Te glasses was slightly worse than that in the case of As-S glasses. The present result suggests that the bond contribution by each bond species should be determined to improve the accuracy of the additivity relation.
Organic cations were substituted for some of alkali cations on the surface of metaphosphates by immersion in aqueous solutions of hydrochlorides of ethylamine, hexamethylenediamine and aniline. The heats of immersion of the surface-treated phosphates in benzene and methanol were measured with a twin microcalorimeter, and the following results were obtained. (1) When the phosphates were treated with ethylamine, little change of their surface properties was observed. (2) The specific surface area of surface-treated phosphate increased with the amount of organic cation substituted. (3) The heat of immersion of the phosphates treated with hexamethylenediamine increased, especially in benzene, with increasing surface concentration of the organic cation. (4) In benzene the heat of immersion of the phosphates treated with aniline decreased with increasing surface concentration of the anilinium cation, while the immersional heat in methanol increased with the concentration. This dependence in methanol can be interpreted in terms of the OH-π interaction between the anilinium cations on the surface of the phosphate and the methanol molecules.
In this paper, an elastic constant and Poisson's ratio of the grain or the fiber reinforced composite materials are analyzed by applying the probabilistic technique. The analytical model used is composed of two kinds of elements: the one is made of matrix only and the other contains a grain or fibers. These elements are disposed to make a composite model by using two-dimensional random vectors in order to simulate the condition of an actual material. The finite element method is applied to analyze the deformation behavior of this model. The numerical calculations to examine the above mentioned technique are performed for the spheroidal graphite cast iron and the glass fiber reinforced plastic. The former is one of the grain reinforced composite materials and the latter one of the fiber reinforced materials. The results on these models coincide with the experimental ones fairly well.
In the stress analysis of the brittle lacquer coating applied on engineering structures, it is postulated that the coating completely adheres to their surface. The coating often peels off from the surface, however, even at lower strain than that corresponding to the yield point of mild steels, when the surface is polished to be mirror-like. If the adhesion between the two boundaries fails prior to cracking in the coating, it is too difficult to estimate acculately the applied strain on the structures, since the strain can not be properly transmitted from the surface to the coating. As is well known, adhesion is dominated by several factors which are completely interrelated. From the practical point of view, the author has firstly investigated the influence of surface roughness, which is important in the surface preparation of specimens. Several testing methods are proposed to evaluate the adhesion force, but they can not be applied to brittle lacquer coating, as the coating shows predominantly high brittlenss and cracks in the direction normal to principal tensile strain. To detect the delamination point under compressive load, which corresponds to the strain when the coating begins to peel off from the surface, a new experimental apparatus has been prepared by using composite beams. From the experiments by means of this device, the influence of surface roughness on adhesion has been clarified and the practical range of surface roughness which provides stable adhesion has been determined.