Abstract: Vacuum annealing was carried out for the SMAT treated CP-Ti sample at different temperatures. The structure and the properties of the SMAT sample before and after the annealing were analyzed by means of the optical microscope, hardness and polarization curve testing. The results show that, when the annealing temperature of surface nanocrystallized CP-Ti treated CP-Ti (SMAT) was below 350°C, the microstructure and hardness of nanostructured surface was stability, and its corrosion resistance was improved compared to non-annealing one. In particular, the corrosion resistance at 150°C was better than that of the original CP-Ti.
Abstract: Bismuth potassium titanate – strontium titanate (1-x)Bi0.5K0.5TiO3-(x)SrTiO3 (BKT-ST) lead-free ceramics when x = 0-0.20 were synthesized by the solid state reaction method with normal sintering. The ferroelectric phase transition was studied by X-ray diffraction (XRD). All compositions showed a single phase perovskite structure with tetragonal symmetry at room temperature and the phase structure transformed from ferroelectric tetragonal – paraelectric cubic in the range of x ³ 0.10 . Dielectric study revealed that the dielectric relaxor behavior was induced with increasing ST and transition temperature (Tm@εr max) of ST-doped BKT had a tendency to decrease with increasing ST. The Bi0.5K0.5TiO3 – SrTiO3 system was expected to be a new and promising candidate for lead-free capacitors.
Abstract: This work focused on the preparation of the biocomposite films of polylactic acid (PLA) reinforced with microcrystalline cellulose (MCC) prepared from agricultural waste, banana stem fiber, and commercial microcrystalline cellulose, Avicel PH 101. Banana stem microcrystalline cellulose (BS MCC) was prepared by three steps, delignification, bleaching, and acid hydrolysis. PLA and two types of MCC were processed using twin screw extruder and fabricated into film by a compression molding. The mechanical and crystalline behaviors of the biocomopsite films were investigated as a function of type and amount of MCC. The tensile strength and Young’s modulus of PLA composites were increased when concentration of MCC increased. Particularly, banana stem (BS MCC) can enhance tensile strength and Young’s modulus of PLA composites than the commercial MCC (Avicel PH 101) because BS MCC had better dispersion in PLA matrix than Avicel PH 101. This result was confirmed by SEM image of fractured surface of PLA composites. In addition, XRD patterns of BS MCC/PLA composites exhibited higher crystalline peak than that of Avicel PH 101/PLA composites
Abstract: Gold nanoparticles (Au NPs) were prepared by using pulsed laser ablation with and without cover slide. The cover slide was used to confine atoms/ions in order to reach supersaturation condition. The obtained Au NPs were investigated by UV-vis spectroscopy, transmission electron microscopy (TEM), and zeta potential measurement. The absorbance spectra exhibited its absorption peak at around 520 nm for both Au NPs ablating with and without cover slide. It was found that Au NPs ablating with cover slide exhibited smaller size and size distribution (10.6 ± 5.9 nm) than those of without cover slide (34.1 ± 21.5 nm) at laser power of 5.00 mJ/pulse. This is due to supersaturation effect and re-irradiation effect caused by cover slide that trapped atoms/ions of gold and trapped Au NPs, respectively. Also, the zeta potential of Au NPs had a negative value suggesting negative surface charge. The lowest zeta potential was observed for Au NPs ablating with cover slide at 5.00 mJ/pulse and it was in consistent with an observation of the highest pH value. In addition, the Au NPs ablating with cover slide at 5.00 mJ/pulse showed the least change with time indicating the most stable Au NPs which was in consistent with the lowest zeta potential results. Thus, pulsed laser re-irradiation could be used for size reduction of Au NPs prepared by pulsed laser ablation in water media.
Abstract: Biodegradable blend films of polylactide (PLA), thermoplastic starch (TPS), and poly(butylene adipate-co-terephthalate) (PBAT) were prepared through reactive modification. Three types of compatibilizers, methylenediphenyl diisocyanate (MDI), maleic anhydride (MA), and MA-g-PE, were studied. PLA and PBAT were blended in the presence of the compatibilizer to improve and evaluate the interfacial interaction. PBAT content was varied from 0 to 20 wt%, while compatibilizer content was differed from 0 to 5 wt% based on PBAT amount. For ternary blending, PLA, TPS, and PBAT were melt-blended with and without compatibilizer in a twin screw extruder using glycerol and tapioca starch as plasticizer and filler, respectively. The effects of type and content of compatibilizer and blend compositions on the physical, thermal, morphological, and tensile properties of the films were investigated. The results showed that the blend films with MDI had appropriate physical, thermal, and tensile properties. The presence of small amount of MDI enhanced the thermal and tensile properties of the films compared to the uncompatibilized films. This can be explained by a uniform morphology of the dispersed phase in the PLA matrix.
Abstract: A magnetron sputtering system was used to deposit AlCrN thin films. Chemical compositions of the films were determined by both EDXS and RBS, while structures analyses were conducted by XRD in a Seifert XRD3000 diffractometer. Macroscopic residual stresses of films were determined by curvature measurements using DEKTAK IIA profilometer, while in-grain stresses were extracted by the “sin²Y method” from XRD measurements. A nanoindenter from CSM (Switzerland) was used to determine the hardness of the films. A CrN type FCC structure was obtained with a strong (200) fiber texture for the range of compositions Al1-xCrxNy (0.56 < x< 0.89) of interest here. The global stresses were compressive for all FCC films resulting from the high energetic deposition conditions used. In-grain compressive stresses were determined for the films with thickness < 500nm, while thicker films (> 500nm) showed tensile in-grain stresses. Stress-free lattice parameter a0 strongly decreased from 4.13 to 3.97 A°. Hardness values were obtained in a range extending from 17 to 27 GPa with an increase obtained as Cr content increases and correlated to the residual-stress level.
Abstract: Magnesium alloys are the lightest known structural material and have been very attractive for usage in marine and transportation industry (for its weight savings and payload increase), and also for its portability in hand-held devices. It is recyclable and one of the most abundant metal. Lately, it has gained attention for its biocompatibility, and also its biodegradable properties depending on the alloying elements. They can be used as a biomaterial in various applications from heart stents to implant screws and fixtures. In this work, amorphous magnesium alloys have been processed, based on its glass forming ability, by various techniques in order to obtain its amorphous state, and the microstructure are characterized by thermal analysis, X-ray diffraction and electron microscopy. Their mechanical properties are also presented. High temperature tensile tests show similar strength to room temperature strength, while the total failure strain is significantly increased from around 0.5% to 10%.
Abstract: The heat-treatable, precipitation-hardening, aluminum alloys are of special interest for automobile where high strength and dent resistance are required, and for bumpers, where good strength and shock absorption are needed. In both cases, good formability is also an important requirement. The heat-treatable 6000-series Al-Mg-Si alloys have been the material of choice for automobile. Despite the high strengthening potential of Al-Mg-Si alloys, processing factors such as the artificial aging processes, as well as the duration of artificial aging, can seriously impede the strengthening process. The highest tensile strength of A6082 alloy was obtained when Mg/Si atomic ratio is set to 1.1 due to the biggest volume fraction of intermetallic compound containing Mg and Si. It was to determine how aging process affected the microstructure and mechanical properties of the A6082 alloy as different ratio between Mg and Si.
Abstract: In our study of organic molecules for OLED, we have paid attention to 4,4'-bis(N-carbazolyl)biphenyl (CBP), an arylamine commonly used as phosphorescent host or hole transport material in OLED, and performed photochemical and photocatalytic experiments. For the photocatalytic experiment, heterogeneous mixture of CBP and TiO2 powder (Degussa P25) in tetrahydrofuran solution has been placed under UV radiation. Both photochemical and photocatalytic experiments have resulted in degradation of CBP, however, with widely different rates and degradation products. With ever increasing demand for high performance OLEDs, higher stability and longer lifetime of their organic components are essential. In this respect, current informations are sure to be valuable in the design and operation of OLEDs as well as arylamine-based OLED.
Abstract: The extrusion property of the paste has a significant effect on the production of terracotta panel. The influence of sodium carbonate addition on the exchange ability of ions, thickened hydrate film with the sodium cations and the plasticity of mud pie was investigated. When the addition of sodium carbonate is 0.015%wt, the plasticity and yield strength of paste are excellent. The best performance specimen with 0.015% sodium carbonate has a few fluctuation of effective strain and the ratio of the maximum with the minimum velocity of paste is the least while extruding from meatus of discharging.