Advanced Materials Research Vol. 845

Abstract: An approach has been made in developing hybrid heat treatment process for improvement of surface properties of duplex stainless steel (DSS). The process was performed using horizontal tube furnace at temperature of 450° C at holding time of 4, 8, 16 and 30 hours. Carbon and nitrogen elements were simultaneously introduced onto the surface of DSS with a ratio of 5% CH₄ + 25% NH₃ + 70% N₂. The microstructure, phase analysis, surface hardness and hardness profile were systematically assessed. Hybrid heat treatment process managed to produce diffusional layer, where longer holding time had increased the thickness of the layer and improved the surface hardness. Expanded austenite phase has been formed at specimens 8, 16 and 30 hours. Longer holding time however gradually diffused Cr₂N at the ferrite grains at the substrates. From the process, it can be concluded that low temperature hybrid heat treatment be able to improve the surface hardness of DSS however concern on holding time must be highly considered.

Abstract: One of the most important phenomena in rubber science is the reinforcement by rigid entities, such as carbon black, clays, silicates and calcium carbonate. Thus, these fillers are added to rubber formulations to optimise properties that meet a given service application or set of performance parameters. Fillers can be divided into three categories reinforcing, semi-reinforcing and non-reinforcing. For a given elastomer and state of mix, bound rubber can be considered as a measurement of a surface activity of a filler and is considered as one of major factors in reinforcement. A strong rubber: filler interaction results in a large bound rubber content. Good dispersions and distribution of filler aggregates is also important for the full reinforcing potential of fillers to be reached. In this study, the influence of fillers on bound rubber content of Natural Rubber compounds were determined and compared. Results showed that the bound rubber content followed the trend of Carbon Black>Silica>Carbon Black>Starch. The two main filler characteristics that affect the bound rubber properties are the filler particle size and surface activity. The specific activity of the filler is determined by the physical and chemical nature of the filler surface in relation to that of elastomer. Keywords: reinforcement, surface energy

Abstract: Understanding of racket parameters is important for players to gain the best racket which could improve their games performances. This present study was aimed to investigate the effect of string tension toward performance of coefficient of restitution (COR) by neglecting the effect of racket frame stiffness. A finite element simulation of collision between ball and string-bed was performed in Abaqus explicit. The ball was dropped onto the centre of mass (CM) of the string-bed area with different values of string tension. From the results, the increasing values of string tension lead to increase values of COR. This finding will contribute to the enlargement of sweet spot in badminton racket as well as improving the player performances.

Abstract: Titania nanoparticles, TiO₂ were synthesized via microemulsion method prior to monometallic (Fe, Cu) or bimetallic (CuFe) incorporation using wet impregnation method. The prepared photocatalysts were characterized using X-ray diffraction, field emission scanning electron microscopy, diffuse reflectance UV-Vis spectroscopy and point of zero charge. The addition of metals, especially Cu enhanced the absorbance in the visible region. The lowest band gap was observed for the bimetallic Cu-Fe/TiO₂ (2.77 eV) compared to bare TiO₂ (3.05 eV). The performance of the photocatalysts for photodegradation of diisopropanolamine (DIPA) at pH 8 was determined using a batch glass reactor under simulated sunlight (980 W/m²). The best performance was displayed by Cu-Fe/TiO₂ with the highest DIPA removal of 92%.

Abstract: This article discusses the fundamentals and benefits of microwave hybrid heating. High dielectric loss materials can be processed using direct microwave heating, whereas low dielectric loss materials can only be process using microwave through microwave hybrid heating. It was shown that it is possible to virtually process any type of materials via microwave hybrid heating. Microwave hybrid heating offers faster heating rate than direct microwave heating. It reduces the problem of thermal runaway experience in direct microwave heating of high dielectric loss materials. The two basic types of microwave hybrid heating techniques were discussed with emphasis on the use of susceptor. Microwave hybrid heating using susceptor offers the advantage of using single energy source.

Abstract: With recent development in automotive industries, aluminium alloys have great demand in sheet metal fabrication industries. Sheet metal forming at slightly elevated temperatures is more acceptable in forming operations. The mechanical properties such as yield strength, ultimate tensile strength and percentage of elongation are very influential in determining the formability of sheet metals in various applications. In this paper, tensile property of Al5052 alloy is investigated at constant strain rate under different annealing conditions from room to 350°C. Servo controlled universal testing machine was used for tensile testing. The results of tensile testing indicate that the tensile properties including yield strength, ultimate tensile strength decreases and elongation percentage increases with the increase in annealing temperature. The analysis shows that the formability parameters, strain hardening index and strength coefficient increase with increase in annealing temperatures.

Abstract: Recently, Composite Sandwich Panel (CSP) technology considerably influenced the design and fabrication of high performance structures. Although using CSP increases the reliability of structure, the important concern is to understand the complex deformation and damage evolution process. This study is focused on the flexural and indentation behavior of CSP made of chopped strand mat glass fiber and polyester matrix as face sheets and polyurethane foam as foam core subject to flexural and indentation loading condition. A setup of three-point bending and indentation test is prepared using different strain rates of 1mm/min, 10mm/min, 100mm/min and 500mm/min to determine the effects of strain rate on flexural and indentation behavior of CSP material. The load-extension, stress-extension response and energy absorption of the panel show the relation between the flexural and indentation behavior of panels to strain rate as by increasing the strain rate, the flexural properties and the energy absorption of panel are increased.

Abstract: In this project, laser induced breakdown spectroscopy (LIBS) has been utilized to determine the heavy element (Copper) in soil sample. LIBS was used in this work to measure the detection limit of Cu in soil sample, on the basis of spectral features, many parameters to improve the sensitivity of LIBS detection of copper are proposed. Q-switch Nd:YAG laser pulse was carried out at 90 mJ and wavelength of 1064 nm to excite the soil samples in purpose of produce a fluorescence emission (plasma), which were analyzed via spectrum analyzer. The important experimental conditions such as the energy of laser source, integration time, the distance and angle of optical fiber from the sparks were optimized for obtain a best LIBS signal. Calibration curve of the Cu peak found to be 236.81 nm as the best peak to calculate the limit of detection (LOD) and found in this study about 2 ppm. From the results the concentrations of Cu is realized to be lower than the allowance limits of 1500 ppm according to the United States Environmental Protection Agency USEPA.

Abstract: The effect of CaO on microstructure and dielectric properties of Ba (Zn_1/3Ta_2/3)O₃ (BZT) ceramics was investigated. The addition of CaO disturbed the 1:2 ordering to 1:1 ordering structure of BZT ceramic. The average grain size significantly increased with the addition of CaO and formed a more compacted structure. The relative density increased with the addition of a small amount of CaO, but it decreased when the CaO content was increased. The dielectric constant (ɛ_r) value of the BZT significantly improved with the addition of the CaO for the specimens sintered at 1250°C and it could be explained by the increased of the relative density. However, for the specimens sintered at 1300°C, the dielectric constant value decreased with the addition of CaO which is attributed to the decrease of the relative density. The tan δ of the CaO doped with BZT ceramics is lower than pure BZT ceramics, and decreases as the CaO content increases. Meanwhile, for the percentage of bandwidth (%BW) it is shown that the best result is when it is doped with 0.5 mol% CaO and sintered at 1250°C. The best microwave dielectric properties obtained are ɛ_r =70.44, tan δ = 0.025 which occur for the 0.5 mol% doped CaO and when sintered at 1250°C/4 h.

Abstract: The main objective of this study was to enhance functional packaging properties of pectin film by using zinc oxide nanoparticles (ZnO-NPs) as nanoreinforcing agent. Pectin/ZnO bio-nanocomposite films were fabricated at 4 levels of ZnO-NPs, i.e., 0.5, 1.0, 2.0 and 5.0% (w/w). The effects of ZnO-NPs incorporation on improving the mechanical properties and water resistance of the films were investigated. ZnO-NPs were successfully incorporated into pectin films by nanodispersion technique followed by casting method. The presence of ZnO-NPs inside pectin films was observed clearly by SEM. The improvement in tensile strength could be achieved with ZnO-NPs incorporation without obvious loss in elasticity. Potential antimicrobial activity of pectin-ZnO nanocomposite films was proved in the absence of mold after exposing them at 97% RH and room temperature for 14 days, whereas the growth of mold had been observed in pure pectin film after 3 days of exposure. In terms of film transparency, the significant change in film opacity was only found in the film prepared with 5% of ZnO. Results suggested that it would be favorable to prepare pectin/ZnO nanocomposite film by using ZnO-NPs at the amount of 2% (w/w) in the future work.