Applied Mechanics and Materials Vol. 848

Abstract: Bottles made from poly (ethylene terephthalate) (PET) can be recycled and reused the material to reduce the amount of waste going into landfills. In this study, electrospun fibres from recycled PET were produced by a melt-electrospinning method. The effect of the melting temperature, applied voltage and distance between die and collector on the morphology of the electrospun fibres was investigated. Thermal properties of recycled PET were characterized by a differential scanning calorimetry (DSC) and a thermo gravimetric analysis (TGA). It was observed that recycled PET granules were melted at a temperature of 260, 290 and 310 °C, the melt polymer was electrospun at a high voltage of 38 kV and electrospinning was carried out at a distance of 12 cm. The Recycled PET electrospun had diameters ranging from 45 to 65 µm.

Abstract: The aim of this research is to study improvement of power conversion efficiency (PCE) of organic-inorganic hybrid bulk heterostructure solar cell prepared by rapid convective deposition as a function of concentration of zinc oxide additive. The structure of hybrid solar cell used in this research is ITO/ZnO/P3HT:PC₇₀BM:ZnO(nanoparticles)/MoO₃/Au. By adding 5 mg/ml of ZnO nanoparticles in the active layer (P3HT:PC₇₀BM), the PCE was increased from 0.46 to 1.09%. In order to reveal the origin of improving efficiency, surface morphology and optical properties of active layers were investigated by atomic force microscopy (AFM) and UV-Visible spectroscopy, respectively. The results clearly indicate that the enhancement of solar cell efficiency results from (i) the proper phase sepharation of electron donor and acceptor in the active layer and (ii) the better absorption of the active layer. This research work introduces an alternative way to improve solar cell efficiency by adding ZnO into active layer.

Abstract: The objective of this research is to investigate the appropriated Tandem Submerged Arc Welding (TSAW) by Punch through technique for high pressure steel tank in ship building industry. Electrode Type AWS A5.17 EM12K and powder flux type AWS A5.17 F7A6 have been applied with electric current at AC+ 550-700 Amp/DC 460-610 Amp. The welding travel speed is controlled between 515-590 mm/min with arc length between 25-30 mm which SM400 steel type is 25 mm thickness. The welding is in horizontal position without any bevel on the steel piece. Studying the suitable parameters from the experiment type 2⁴ of this procedure experiment, the result has been found that the most suitable parameter set up for this welding is DC460, AC550, ST515, AL25. The experiment follows AWS D1.1 standard with 100% full penetration, tensile value at 542.61 N/mm². Welding line supports impact test at 0°C with average value of 66 Joules, average hardness value at 156.4 HV, bending at 180°. With out any defected found. Moreover, this method can be reduced welding cost around18,482 baht/day and also increased the welding lenght around 168%.

Abstract: Thai sausage or Isan sausage is a type of north eastern Thai cuisine which is famous for being served as an appitizer. Recently, Thai sausage production depends solely on manual tasks on stuffing and belaying the product, and as a result, it is hardly that the production can be well managed in terms of quantity, quality, and time. In this paper, we propose a novel design of semi-automatic system to improve the traditional Thai sausage production. Particulary, the machine is developed with a set of 24-volt, 36-watt,100-rpm DC motors used in both stuffering and belaying the materials, and it is mainly controlled by a programmable logic controller (PLC). Our design can yeild the product with short size of 4.5 cm and long size of 9 cm in length and both have the same 4 cm in diameter. On average, the output rates for the short-size products and the long-size products are 57 cm per minute and 71 cm per minute, respectively. This machine can improve production time compared to the previous process using manpower which can make short-size sausage and long-size sauge at 40 cm and 60 cm in one minute, respectively.

Abstract: The deposition using cold gas dynamic spraying of silver-doped hydroxyapatite (HA-Ag) /Titanium (Ti) composite have been fabricated on Al 6061 substrate. The biocompatibility of the obtained HA-Ag/Ti coatings was studied. The ratios of HA-Ag to Ti in their composite powders were 20:80, 50:50 and 80:20 (weight %). The HA-Ag/Ti coatings were successfully deposited using cold spraying parameters of 13-15 bars under helium gas, temperature of between 300-400°C. The biocompatibility results showed that human osteoblast and RAW cells spread and adhered well on the coating surfaces especially at low concentration of HA-Ag contained.

Abstract: This research work describes the processing of antibacterial and hydrophobic feedstock suitable for marine antifouling coatings. A composition of agglomerated ZnO-Cu powder and respective produced coatings were evaluated for fouling properties via antimicrobial activity test. Wettability of coating was also determined by contact angle measurements. These new antifouling coatings aim to prevent the growth of biofilm, reduce biofouling and improve both maintenance cost and fuel efficiency of the maritime structures and vessels. It should be able to extend dry docking cycle by providing an alternative environmentally compliant coating that is long lasting compared to conventional paint coatings. The results showed that ZnO and copper composites inhibit the C. marina attachment on the coating surfaces.

Abstract: Hot gas welding has been used in the process of polypropylene (PP) welding in many applications. It was appropriate for various multipart productions such as plastic constructions, automotive parts, tanks and pipeline. However, the surface properties of welded areas were varied particularly at each zone and thus affected numerous scratch resistances. The microstructure of scratch trace, hardness and scratch wear rate were studied by scanning electron microscope, hardness tester and scratch tester, respectively. From the results, it was found that the deformation of PP was induced with welding process. The scratch trace was showed that it related with decreasing of hardness properties.

Abstract: Several machine components including a part of electrical circuit box, an electrical motor and an automotive part were common ferromagnetic materials used under the magnetic fields. In the general, their friction had occurred in the magnetized materials during operation. The friction coefficient of the sample under magnetic fields was different from the sample without magnetic field treatment. Its friction coefficient had correlation with wear behavior of specimens. The wear protection procedures for the ferromagnetic parts during operation are recognized different from others without magnetization. Its friction coefficient was thus used to measure the wear characteristics with a ball on disc friction tester. The microstructure of wear trace and debris was investigated by scanning electron microscope. From the results, the magnetic fields affected the change of friction coefficient. The friction coefficient was decreased with an increasing magnetic intensity. This was because the wear debris was induced and thus decreased the adhesive wear mode during friction test.

Abstract: The aim of this research is to study the effects of welding repair parameters on weld joint of tube 35Cr-45Ni-Nb alloy by using the Gas Tungsten Arc Welding (GTAW) process of two different base metals. One was a new tube material and other was a used tube treated with carburized condition. The 35Cr-45Ni filler metal was sellected for welding repair experiments. The SEM-EDS analysis was used to observe a segregation of atom in the used tube specimen. The non-destructive examination (NDE) tests were done to check the imperfected area of weldment and heat affect zone (HAZ). Data from this research can be used as the guideline suggestion for the welding procedure specificcation (WPS) and the procedure qualification record (PQR) for the welding repair in the peroid of maintenace.