Abstract: The present work investigated the effects of moisture absorption on the residual tensile strength of unnotched, notched and double-patch repaired carbon/epoxy composites. Patches were bonded to the parent plate using Araldite2015 adhesive. Specimens were aged in demineralised water at 70°C and tested at moisture content of 0% (dry), 3%, 6% and 7%. Results showed that upon ageing, a maximum of 11% and 17% of strength reduction was found in unnotched and repaired specimens, respectively. On the contrary, a maximum of 15% increment in strength was observed in notched specimens. In addition, good fits to the experimental data were found using the proposed residual strength model, with the maximum difference of less than 6%.
Abstract: This study aims to investigate failure mode response of woven natural kenaf/epoxy composite hexagonal tubes subjected to an axial and lateral quasi-static crushing test. The hexagonal composite tubes were prepared by the hand lay-up technique using a variety of hexagonal angles 40ο, 50 ο, and 60 ο. The result showed that hexagonal composite tubes under an axial compression test exhibited few failure modes such as, the transverse crack failure mode . Splaying failure mode and local buckling failure mode respectively, whereas the tubes under lateral test only exhibited longitudinal fracture.
Abstract: The electrical characteristics of insulating materials play a key role on the working performance and operation reliability of power equipment. With the rapid development of superconducting technology in recent years,the working temperature of high temperature superconducting power equipment can be controlled around the liquid nitrogen temperature. Due to its excellent dielectric performance and mechanical properties, polyimide have been widely used in power equipment at room temperature. However, polyimide, as a kind of cryogenic insulating materials, is rarely reported at present. Therefore, the study of the insulating characteristics of polyimide at the cryogenic temperatures is of great significance. The DC breakdown property and flashover performance of polyimide are tested around room temperature (300K) and liquid nitrogen temperature (78K). The results show that temperature has some effects on the DC breakdown property and flashover performance of polyimide.
Abstract: Effect of magnetic field strength on carbide precipitation behavior in W6Mo5Cr4V3 highspeed steel during medium temperature tempering was investigated. The applied magnetic field promoted the precipitation and refinement of M6C and MC carbides at boundaries and in the grain interior, but maximum spheroidization occurred for those M6C carbides precipitated at boundaries, the stronger the magnetic field strength, the stronger the spheroidization effect. The high magnetic field hinders the precipitation of M2C type carbides, and the M2C type carbides basically disappear when applying the magnetic field.
Abstract: In this paper, we present a model of gate tunneling current in cylindrical surrounding-gate MOSFETs through dual layer high-k dielectric/SiO2 stacks. The model was derived under a quantum perturbation theory by taking into account both structural and electrical confinement effects. The influences of high-k materials and SiO2 thickness on the gate tunneling current have been studied. The calculated results show that the HfO2 is the most effective high-k material to decrease the gate tunneling current. It is also shown that the gate tunneling current is reduced with the SiO2 thickness. In addition, the obtained tunneling currents are fitted well with those obtained under the self-consistent calculation.
Abstract: In this paper, Ti sheets were anodized to obtain TiO2 nanotube arrays electrodes. The impact of different oxidation conditions on photoelectric properties of TiO2 nanotube arrays were discussed by the photocurrent density, and the optimal oxidation conditions of TiO2 which had good photoelectric properties were found. Pigments were extracted from fresh spinach leaves, tomatoes and carrots, and to be used as plant dye to sensitize TiO2 electrodes. The photocurrent density and the Incident Photon to Current Efficiency (IPCE) of the plant dye sensitized TiO2 electrodes were examined.
Abstract: Glycidyl methacrylate (GMA) was grafted onto poly (lactic acid) (PLA) by internal mixer using dicumyl peroxide (DCP) as an initiator. The results from proton nuclear magnetic resonance (1H-NMR) and gel permeation chromatograph (GPC) indicated that the grafting reaction of GMA onto PLA took place successfully. In order to obtain the optimal GMA content used to graft onto PLA chain, the GMA content was varied into 5, 10 and 15 wt% of PLA. GMA content of 10 wt% was found to give the highest elongation at break of glycidyl methacrylate grafted poly (lactic acid) (PLA-g-GMA). The weight-average molecular weights, the number-average molecular weights and polydispersity index of PLA increased after grafting with GMA. After grafting, the brittle fracture behaviour of PLA was changed to ductile fracture behaviour of PLA-g-GMA. With its superior mechanical properties compared to those of pure PLA, PLA-g-GMA can be considered to be used as a new generation of biodegradable polymer, which can be applied in many industrial applications.
Abstract: In this study emulsification- chemical crosslinking method was employed. The principle of this method is that macromolecular chains linked together by chemical bonds forming polymers with a body or mesh structure. The sodium tripolyphosphate was used as crosslinking agents.Because sodium tripolyphosphate has many negative groups which can react with the amino of CS, thus they can form the crosslinking in intramolecular and intermolecular.
Abstract: The combustion of biomass for energy generation is practiced in an increasing scale in Indonesia as the country heads towards the long-term national energy mix targeted by 2025. However, biomass combustion is prone to operational problems caused by the generally low-melting nature of biomass ashes. This work discusses the effects of co-combusting coal with POEFB (palm oil empty fruit bunch) and bamboo with respect to the thermomechanical behavior of the produced ashes. Coal is observed to increase the ash fusion temperatures (AFT) of neat and combined POEFB and bamboo ashes by as much as 300 °C. Aluminosilicate minerals in the coal combine with potassium in the biomass during co-combustion, producing high-melting K-aluminosilicates. A linear correlation is identified between measured AFT and ash liquidus temperatures estimated by FactSage thermochemistry calculation software, enabling the prediction of AFT of coal-biomass co-combustion systems.