In case of high aspect ratio plastic parts molding, the deterioration of parts accuracy will occur by various deformations such as warp due to molding shrinkage. In this research, the resin flow control molding method has been developed which can control the flow of resin during molding and improve the dimensional accuracy and the mechanical strength of the molded parts. In this paper, we applied the developed new molding method to high aspect ratio pipe shape molding and examined whether it is possible to realize the high-precision molding.
Gold nanoparticles were grown under various sodium citrate concentration and self-assembled gold nanoparticle films were formed on a glass substrate under various conditions to examine the effect of sodium citrate concentration on the particle size of gold nanoparticles and the effect of processing time and processing temperature on the optical properties and electrical resistivity of the self-assembled gold nanoparticle film. As a result, it was found that the ratio of tetrachloroauric (III) acid to sodium citrate is preferably 1:3 was appropriate to obtain fine gold nanoparticles. The self-assembled gold nanoparticle films showed a network structure formed by nano-wires for all assembled conditions. However the thickness or the assembled state of the gold nano-wires was sensitive to the processing temperature whereas the processing time hardly affected the properties of the nano-wires. In particular, higher processing temperature led to a break in the nano-wires and then the optical properties and electrical resistivity was degraded.
There is little research on the mechanical characteristics of rock under tensile stress compared with the research on compressive stress. In this study, firstly, direction, length and number of micro cracks were investigated using Inada granite. Secondly, the uniaxial tension test is carried out with the specimen produced in a different direction, an anisotropy of uniaxtial tensile strength, Young's modulus and Poisson's ratio are investigated. In addition, to focus on the effective sectional area of the specimen, considered results on anisotropy of Young's modulus and uniaxial tensile strength were described.
In this study, the diametrical compression test was carried out using Inada granite by attaching strain gages to the test specimen. Young's modulus under tensile stress was estimated from the value of the measurement of the strain. The results obtained through this study are as follows: 1) It is deemed that Young's modulus under tensile stress can be estimated from the diametrical compression test results by the method shown in this research. 2) The standard deviation of tensile strain was calculated. The results showed that standard deviation increases rapidly, once the tensile stress exceeds a certain value. It is considered that the stress of a tensile fracture area differs within a test specimen if the load increases. Therefore, if tensile strength estimates from St=-2P/πDL use maximum load, it is possible that tensile strength was overestimated.
With great corrosion resistance and mechanical property, ferrite-austenitic duplex stainless steels have been applied to many components in corrosive environments such as sea water pumps. Due to different coefficients of thermal expansion and elastic moduli between the two phases, phase stress and plastic deformation will occur during heat treatment history in material processing such as casting, forging or annealing, which may affect material properties such as fatigue strength, welding stability and so on. Therefore residual stress measurement is important for the application of this material. In this study, strain-free diffraction angle 2θ0 was measured from strain-free reference samples, which were carefully prepared as electropolished thin plates with thickness of lower than 90 micrometer, nearly equal to the grain size of austenitic phase. X-ray stress constants were measured and discussed. With those fundamental parameters, multiaxial phase stress analysis became available by X-ray diffraction method.
With great corrosion resistance and mechanical property, ferrite-austenitic duplex stainless steels have been applied to many components in corrosive environments such as sea water pumps. Due to different coefficients of thermal expansion and elastic moduli between the two phases, plastic deformation and phase stress will occur during heat treatment history in material processing such as casting, forging or annealing, which may affect material properties such as fatigue strength, welding stability and so on. In this study, strain-free lattice constants of both phases were measured from strain-free reference samples, which were carefully prepared as electropolished thin plates with thickness of lower than 90 micrometer, nearly equal to the grain size of austenitic phase. Phase stress distribution along the thickness direction of hollow cylinders fabricated by centrifugally cast duplex stainless steel was measured by pulsed neutron diffraction using time-of-flight (TOF) method at Japan Proton Accelerator Research Complex (J-PARC). Based on these results, the mechanism of stress development during centrifugal casting and the effect of stress relief heat treatment (SRHT) were discussed.
To clarify the mechanism of the heat-treatment for wood between 100℃ and 200℃, the behaviors of endothermic and exothermic of wood and wood components (cellulose, hemicellulose, lignin) between 100℃ and 200℃ under the dried air condition were measured using the temperature-modulated DSC. The measurement were carried out in the heating processes under stepwise heating and cooling cycles (100℃→140℃→100℃→160℃→100℃→180℃→100℃→200℃, ±5℃/min). The total heat flow (THF) and the nonreversing heat flow (NRHF) curves of wood, cellulose and hemicellulose in the 1st heating process (100℃→140℃) were found in the exothermic side compared with the curves in other heating processes. The reversing heat flow (RHF) curves of wood in the 4th heating process (100℃→200℃) were found in the exothermic side compared with the curves in other heating processes. However the RHF curves of cellulose and hemicellulose were observed on the almost same line. The THF and NRHF curves of lignin were shifted to the exothermic side with the stepwise heating and cooling cycles. On the other hand, the RHF curves of lignin were shifted to the endothermic side with the cycles. These results suggest that the effects of the heat-treatment for wood between 100℃ and 200℃ are based on the thermodynamic stabilization of the conformation of cellulose, hemicellulose and especially lignin due to the heating history.