Key Engineering Materials Vol. 851

Abstract: Prussian Blue Like (PBL) compounds that are potentially used as K-Ion Battery (KIB) electrodes have been synthesized from zinc(II) chloride and quinoline (Qn) precursors combining melting and direct reaction method. The formed K₂[Zn(Qn)₂][Co(SCN)₆] compounds melt in range 179-181°C with conductivity value reaches 468 μS/cm. Thiocyanate and quinoline ligands were characterized using FT-IR and UV-Vis spectrometry. The cyclic voltammetry of the formed compounds showed the reduction potential up to -0.34 V (versus AgCl/Ag).

Abstract: In this work, Fe₃O₄ nanoparticles (NPs) were synthesized using coprecipitation method and TiO₂ NPs were synthesized using sonication method. Fe₃O₄/polyaniline and TiO₂/polyaniline nanocomposites (NCs) were synthesized using polymerization methods. The samples were characterized by X-ray diffractometer, Fourier-transform infrared spectroscopy, and ultraviolet-visible spectroscopy. The results of X-ray diffraction data analysis presented that polyaniline decreased the crystallinity of Fe₃O₄ and TiO₂ NPs. However, the crystal structure of Fe₃O₄ and TiO₂ NPs did not change, which successively formed the cubic spinel and the tetragonal anatase phases. Furthermore, the functional groups of Ti-O-Ti and Fe-O were detected in the wavenumber ranges of 620-580 cm^-1 and 410-520 cm^-1, respectively. The presence of polyaniline was also detected by the emergence of a functional group of polyaniline which also showed that there was an interaction of Fe₃O₄ and TiO₂ NPs with polyaniline. Meanwhile, the results of UV-Vis data analysis showed that the addition of polyaniline decreased the bandgap energy of Fe₃O₄ and TiO₂ NPs significantly from 2.186 to 2.174 eV and from 3.374 to 3.320 eV, respectively.

Abstract: Photosupercapacitor is an integrated device for harvesting and storing solar energy into electrical energy. Photosupercapacitor is constructed by solar cell and supercapacitor. In the solar cell with DSSC type, one of the influential variables is photoanode performance. The photoanode with ZnO layer plays a role in light absorption, charge mobility, and electrical properties, which are influenced by crystal structure and nanoscale morphology. One of nanoscale morphology of ZnO that widely used is nanorods. This work is focussed to investigate the effect of annealing temperature on seed layer ZnO to growth nanorods shape in photoanode of photosupercapacitor and its performance. The seed layer ZnO nanoparticle was deposited onto FTO substrate by a screen printing method. The ZnO nanorod was grown by dippin FTO/ZnO in solution (Zinc nitrate, HMT, and DI water) under 100 °C. The photosupercapacitor was constructed by DSSC and ZnO symmetric supercapacitor which integrated by using aluminum foil substrate. The annealing temperature on ZnO nanoparticles affected on increasing crystal size of ZnO seed. All of the samples show ZnO wurtzite phase with the highest peak located on the hkl plane (101), but ZnO nanorod growth to hkl plane (100). The DSSC part efficiency produced around 0.874%. The resulting efficiency of photosupercapacitor is around 0.549%. The annealing temperature causes the value of specific capacitance to decrease, because of decreasing DSSC performance.

Abstract: The development of energy storage devices encourages the sustainability of research on basic materials of supercapacitor technology. SrTiO₃ is one of metal oxide called as titanate alkali metal ATiO₃ (A = Ba, Sr, Ca). This material shows an excellent dielectric constant, thus expected to be potential as raw material of supercapacitor. In this work, boron was used as a dopant on the SrTiO₃ system to modify its local structure and enhance the electrical properties. Synthesis SrTi_1-xB_xO₃ was carried out using a solid-state reaction method followed by the sintering process in various molar ratio. The microstructure of SrTi_1-xB_xO₃ compound was identified by X-ray Diffraction with Cu-Kα. XRD pattern identified the presence of SrTi_1-xB_xO₃ phase with a slight change in the lattice parameters. I-V measurement confirmed that the electrical conductivity increased gradually up to 16.04 Ω^-1cm^-1. For investigating their application for electrode materials, CV was employed and it presents that the specific capacitance and energy density of x = 0.08 were 5.488 Fg^-1 and 0.110 Jg^-1.

Abstract: Hematite (Fe₂O₃) is one of the abundant magnetic materials in nature. Hematite has good absorption ability in the region visible light and good electrochemical stability, which make this material is potential as photoanode for photoelectrochemical (PEC) cells. However, Fe₂O₃ has some disadvantages such as short hole diffusion length and low hole mobility. Therfore, it is necessarily to combine Fe₂O₃ with photocatalyst material to improve photoelectrochemical performances. ZnO is ones of photocatalist material with good electron mobility, wide band gaps, cheap and are easily fabricated. The aim of this study is to investigate the performance of bilayer Fe₂O₃/ZnO as photoanode for photoelectrochemical cell. The bilayer Fe₂O₃/ZnO was prepared by spin-coating techniques and doctor blade methods. The samples were characterized by X-ray diffarction, and Scanning Electron Microscopy. The performance of photoelectrochemical cell was investigated by Cyclic Voltammetry (CV) under light illumination. The result indicate that bilayer Fe₂O₃/ZnO has good photoelectrochemical properties.

Abstract: Nanofluid is an efficient fluid when used in heat exchanger system because of its larger thermal conductivity compared to conventional fluids such as water, oil, and ethylene glycol (EG). This research used MnFe₂O₄ nanoparticle due to its higher magnetic sensitivity compared to other ferrite nanoparticles and larger thermal conductivity than TiO₂. This research used the MnFe₂O₄ nanoparticle with a combination of EG-Water base fluids in ratios of 40:60, 60:40, and 80:20. MnFe₂O₄ nanofluid mixed with EG-Water base fluids was made using the two-step method with 0.05% MnFe₂O₄ volume fraction in each base fluid ratio. This research used shell and tube type heat exchanger with heat temperature of 60°C and cold temperature of 26°C that were carried out at volumetric flowrate in each base fluid ratio for 0.22 l/m, 0.44 l/m, and 0.66 l/m. This research aimed to find the best combination ratio of EG-Water in thermophysical (thermal conductivity, specific heat, density, and viscosity) and to find the effect of volumetric flowrate variations on the heat exchange characteristics (the Reynold number, the Nusselt number, ∆T LMTD, convection coefficient, heat transfer, and overall heat transfer coefficient). The results of this research were that the sample of EG-Water with 40:60 ratio had the best heat transfer characteristics compared to samples with 60:40 and 80:20 ratios. Meanwhile, for the volumetric flow rate, a higher volumetric flow rate resulted in a larger result.

Abstract: This research aims to determine the effect of adding filler material in the form of waste material on Nitrile Butadiene Rubber (NBR) in making roller rubber to improve quality in terms of hardness and tensile strength. Each rubber roller compound is made from a mixture of NBR with rice husk, recycled rubber and wood charcoal. The process of making NBR and NBR with the addition of alloys is done with two roll open mixers at a certain temperature and time accompanied by the addition of certain additives. Furthermore, the compound is pressed using Hydrosan and then cut according to the standard test to be performed. The process ends by placing the material in an environment with a certain humidity level for 24 hours. Tests carried out include the test of hardness by using Shore A Durometer and Universal testing machines to test the strength of tensile strength. The test results show that the addition of recycled rubber can increase hardness by 30% when compared to NBR without the addition of filler. While the value of tensile strength for NBR and recycled rubber alloys is much higher.

Abstract: In this era, technological advances in the field of construction and industry cannot be separated from welding, while the welding of medium carbon steel is a material that is widely applied using electric arc shielded electrodes and to obtain good results a post weld heat treatment (PWHT) process can be carried out. One of the heat treatments that can be applied to the post weld heat treatment is stress relief annealing. So in this paper a test was conducted to determine the value of ST70 hardness and steel phase from welding with stress relief temperature variations of annealing 600°C, 650°C, and 700°C in the weld metal area and heat affected zone. To find out the results of testing of the post weld heat treatment process with annealing stress relief method at temperatures of 600°C, 650°C, and 700°C in the weld metal area and heat affected zone, the tests used were microstructure, micro vickers hardness and X-Ray Diffraction. The results of the hardness test show that without the post weld heat treatment process the hardness in the heat affected zone is 311.8 HV and in the weld metal area is 329 HV. Whereas from the results of the diffraction phase analysis in the heat affected zone the development of grain size rises regularly along with the increase in temperature in the stress relief annealing process.

Abstract: Conversion coating in metal material was a method to control the corrosion. It applied in parts of car, aircraft, factory installation, and other appliances. There were three types of conversion coating: phosphate conversion coating, chromate conversion coating, and oxalate conversion coating. There were several aspects to consider in controlling the corrosion fully. This research used phosphate because phosphate conversion coating had a low corrosion rate, affordable production cost, and environmentally friendly. This research aimed to find out the corrosion resistance of ST37 carbon steel using phosphate conversion coating in various immersion durations. Therefore, the result was a breakthrough in using phosphate conversion coating for the industries. This research used the weight loss method to calculate the corrosion rate and macro photos to obtain the corrosion form during the test. This research used ST37 carbon steel with 100 mm x 30 mm x 10 mm as the specimen and phosphate with various coating durations (10, 20, and 30 minutes). Each variation had three specimens, so this research had nine specimens in total. This research calculated the daily corrosion rate for seven days using 5% NaCl as the corrosion solution. The average corrosion rate in specimens with 10 minutes duration was 1.9599 mpy, specimens with 20 minutes immersion was 1.7647 mpy, whereas specimens with 30 minutes duration were 1.3287 mpy. Thus, the longer immersion duration created a smaller corrosion rate. Also, the corrosion formed during the test was pitting and uniform corrosion.