Materials Science Forum Vols. 544-545

Abstract: This study proposes a means to recycle waste tires as a material to reduce ground vibration. A series of field experiments was carried out to assess the reduction effect of railroad transport vibration by utilizing waste tire chips. The ground vibration during the railroad transport operation was measured in two railroad lines to investigate the vibration characteristics prior to field model tests. Test results showed that the frequency of vibration induced by railroad transport ranged from 5Hz to 100Hz, while the dominant frequency was within the range of 20Hz to 40Hz. A series of field model test was carried out by using tire chips (5cm×5cm in size) as a reduction material for railroad vibration. The field experiment results showed that the reduction effect of waste tires for railroad vibration increased with increasing thickness of the waste tire layer and increasing frequency of the vibration source. From these experimental results, it can be concluded that waste tires can be recycled effectively for reduction of railroad.

Abstract: Ice storage system that water is used as low temperature latent heat storage material, refrigerator capacity is increased and COP is decreased because refrigerator is operated at low temperature due to supercooling of water in the course of phase change from solid to liquid. This study is investigated the cooling characteristics of the TMA-water clathrate compound including TMA (Tri-methyl-amine, (CH3)3N) of 20~25 wt% as a low temperature latent heat storage material at -5°C, cooling source temperature. The results showed that the phase change temperature, the specific heat is increased and the supercooling degree is decreased as the weight concentration of TMA became higher. Especially, low temperature latent heat storage material containing TMA 25 wt% has the average of phase change temperature of 5.8°C, supercooling degree of 8.0°C and specific heat of 4.099kJ/kgK in the cooling process. Phase change temperature higher than that of water and inhibitory effect against supercooling can be confirmed through experimental study on cooling characteristics of TMA-water clathrate compound.

Abstract: TiO2 coatings on titanium alloy substrates were prepared by atmospheric plasma spraying using commercial nano-powders and followed by H2SO4 treatment. The bioactivity of coatings was evaluated by the simulated body fluid soaking test. Scanning electron microscopy and energy-dispersive X-ray spectrometry were used to characterize the surface morphologies and phase composition of the coating before and after soaking in simulated body fluid. The results obtained indicate that H2SO4-treated TiO2 coating can induce a bone-like apatite formation on its surface, however, no apatite appears on the surface of as-sprayed TiO2 coatings. The acid concentration and treated time affected the bioactivities of TiO2 coatings.

Abstract: In this study, CrZrN film was deposited on AISI 4130 cylinder barrel and valve plate using a unbalanced magnetron sputtering. The tribological properties between a coated steel cylinder barrel and coated steel valve plate were evaluated by a custom-built disk-to-disk tribometer and the results were compared with those between a coated steel cylinder barrel and a conventional bronze valve plate. The lowest friction coefficients were observed between a coated steel cylinder barrel and coated steel valve plate and they were approximately one half of those between a coated steel cylinder barrel and conventional bronze valve plate in the range of testing up to 1600rpm. Coated valve plate and bronze valve plate showed a steady state of friction coefficient at approximately 0.03 and 0.06, respectively after about 1000 rpm, but steel valve plate without coating showed a continuous decrease in friction coefficient, which suggested that active wear is continuously occurring. By applying CrZrN coating on the commercial cylinder barrel and steel valve plate, much improved tribological results could be obtained, by a factor of approximately 2 in terms of friction coefficient than those from bronze valve plate. Under a tap water environment CrZrN coating appeared to perform better than CrSiN coating. Although further work to reduce the friction coefficient below 0.13 in the steady state after initial drop is still needed, possibilities of applying CrZrN coating to realize a water hydraulic pump were demonstrated through the present work.

Abstract: Runoff from bridge impermeable surface is discharged directly into the receiving river or sewage pipe. However, generally, a bridge does not have sufficient space to place some treatment system. In this study, therefore, we investigated the down-flow filtration using expended polypropylene media (EPM) to treat runoff from bridge. Experiments were conducted employing down-flow filtration column (d
h, 50
600mm) to investigate the removal efficiency of pollutants. The EPM5, EPM10, EPM15 and f-EPM10 filters were developed from high molecular material, and were classified by different foaming rates and present of functional material. The experiment using f-EPM10 showed good hydraulic filtration performance without overflow for 1hr. But overflow, in the experiments using EPM5, EPM10 and EPM15, was observed within 1hr. Since f-EPM contains functional material, that can be improved water flow without clogging. The total SS removal efficiency of filtration equipment was rapidly decreased after overflow. In addition, a down-flow experiment, having slope of 15°, to avoid SS deposition at top of the column was carried out. Though SS deposition was found to be similar in two types flow, the flow of down-flow experiment, having slope of 15°, made progress without overflow for 3hr. This is because deposited SS didn’t intercept water inflow.

Abstract: PDMS(polydimethylsiloxane) is a flexible and biocompatible material and is widely used in bio- or medical-related fields. In this paper, we have developed the soft electrode to be stretchable bi-axially by using tissue-like soft material (PDMS). We have established the simple method to deposit the metal layer on the PDMS layer to be stretchable bi-axially and we have evaluated the electrical property according to the application of bi-directional stresses. This stretchable electrode can be extensively utilized in biomedical fields such as implantable electrode and wire at the flexion region or artificial skin.

Abstract: Aerogel has its advantages of light density of 0.003-0.35 g/cm3 and its high specific surface area, 600-1000m2/g, mean pore diameter ~20nm. However, aerogel has its disadvantages of fragility and high cost. To overcome the mechanical fragility, we synthesized aerogel composite blankets with glass wools by drying at ambient atmosphere. Colloidal silica sol was first prepared by ion exchanging sodium silicate through amberlite column. Then, glass wool was soaked into the pH-controlled silica aerogel and then gelated. Ageing of silica aerogel composite was conducted in purified water and solvent exchange/surface modification was simultaneously processed in hexane and TMCS solution. After drying at 60oC and heat-treatment at 230oC, we evaluated the properties of aerogel composite, its apparent density and specific surface area.