Key Engineering Materials Vol. 841

Abstract: Plastic injection moulding is widely used for manufacturing due to variety of plastic product. In this study, plastic part defects such as air bubble and gas mark defect are commonly occurs in thermoplastic part, specifically acrylonitrile butadiene styrene (ABS). In order to optimize the process parameters of injection moulding, design of experiment (DOE) with Response Surface Methodology (RSM) model was used. Process parameters such as melt temperature, mould temperature and injection pressure were selected for the DOE development. The experiments were conducted with melt temperature range from 200 °C to 240 °C, mould temperature from 60 °C to 80 °C and injection pressure from 90 to 99%. The result indicates that, all the selected parameters were significantly influence the rejection rate of the automotive ABS part. The optimum melt temperature, mould temperature and injection pressure were 220 °C, 70 °C and 98% respectively, in obtaining minimum rejection rate.

Abstract: Electric Discharge Machining (EDM) working fluid as a medium can control electrical discharges occur, carry away the heat, compress discharge channel and help remove the corrosion products out of the gap. The main working fluids used in EDM are oil-based working fluid, gas-based working fluid, powder mixed working fluid, gas mixed working fluid and water-based working fluid. In order to improve the green and safety of EDM working fluid, an oil-in-water working fluid is proposed. A gap flow field model of EDM is established by using external flushing fluid. The flow field distribution, pressure distribution and corrosion products distribution of the machining gap are analyzed by using computational fluid dynamics. The effects of inlet pressure, processing depth and electrode size on the flow field are studied. The simulated results show that within a certain range, removal effect of the corrosion products will increase with inlet velocity and the size of electrode and decrease with processing depth.

Abstract: Bacterial cellulose (BC) was synthesized using Gluconacetobacter xylinus (BCRC 14182). Synthesized BC was powdered and dissolved in Bis(ethylenediamine) copper (II) hydroxide (Cuen) solution to introduce the amine (NH₂) group onto the BC network to yield modified BC (mBC) which was then blended with poly (vinyl alcohol) (PVA) and subsequently crosslinked with genipin (Gp). Pristine, modified and crosslinked hydrogels were studied using Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM) and swelling behavior in water. FTIR revealed a distortion on the BC network chain via a reduction in the absorption of OH peak of mBC and the emergence of peaks at 1587 and 1560 cm^-1 attributed to N-H stretching of the induced NH₂ group. SEM confirmed the 3-D fibril and porous structure of BC which became distorted after modification and crosslinking. The hydrogels showed equilibrium water content of 86.5%, 67.5%, 66.7% and 33.0 % for BC, PVA, mBC-PVA and mBC-PVA-Gp, respectively. The decreased swelling in mBC-PVA-Gp indicated that genipin was able to crosslink the modified BC.

Abstract: The surface characterization of MgO thin films was investigated by using surface analysis instruments such as X-ray photoelectron spectroscopy (XPS), reflection electron energy loss spectroscopy (REELS) and ultra-violet photoelectron spectroscopy (UPS). The MgO thin films was prepared on Si substrates by using electron beam evaporation deposited at room temperature (RT) and 300 °C in air. The XPS was used to investigate the effect substrate temperature on the chemical state in the thin films surface. The O1s spectra was showed that the hydrate MgO, Mg(OH)2, was detected in the surface of film at RT and it was decreasing at substrate temperature of 300 °C in air. The band gap obtained for MgO thin films using primary energy of 1500 eV were 6.57 and 7.41 eV for film deposited at RT and 300 °C in air, respectively. The work function of MgO thin films were 4.16 and 4.60 eV for films deposited at RT and 300 °C in air, respectively. Our results suggested that the electronic properties can be improved by the heating treatment during deposition.

Abstract: This paper deals with the development of button made from a hydroxyapatite (HA) and bioglass composite. The HA powder derived from the bovine bone were added 2.5 and 5 wt% of P₂O₅-CaO-Na₂O-bases glass and subsequently sintered at 1200 - 1350 °C to form the HA ceramics. It was observed that the densest HA ceramic could be achieved for the sample composed of hydroxyapatite with the addition of 5 wt% of bioglass and sintered at 1300°C, resulting in the maximum value of bending strength of about 77 MPa, which ensured the use in load bearing applications of this HA ceramic. The HA and 5 wt% bioglass composite is designed as a button for reattach the bone flap after a craniotomy procedure. Each device is comprised of an inner plate and an outer plate. The fabrication processing was used the powder compression and then sintering at 1300°C for 3 h. The button have fracture toughness (K_1C) values of 1.3±0.1 MPa.m^1/2 and bending strength of 65.7±3.8 MPa. The liquid phase sintering of this sample contributed to the high mechanical properties that can be use as craniotomy flap fixation.

Abstract: Buckets are the most important component in backhoe construction, the bucket functions as a digger and carrier component in an excavator. Due to the heavy working media of the excavator so that this component is the most easily damaged part, damage that often occurs is wear caused by friction arising so that the thickness of the bucket is reduced which can eventually cause cracks in the bucket and in continuous use can cause the bucket to crack and broken. Cladding method is done to shorten the time or simplify the repair process is to directly patch the damaged part with a welding layer and then do the grading using a grinding. This study aims to determine the physical and mechanical properties of the material from the cladding process when compared with the raw material, the variations used are raw material, cladding with filler welding, and cladding with plates. The welding process is carried out with GMAW (Gas Metal Arc Welding) and low carbon steel. Welding results will be tested tensile strength, bending strength , impact test, hardness test, chemical composition, and corrosion rate. From the hardness test results showed that the weld metal from plate variation has the highest hardness value of 443 VHN. From the results of tensile testing the basic material has the highest value with 359.08 MPa. From the bending test results the highest value obtained from filler verification with 494.01 Mpa and the highest impact price obtained from the plate variation cladding method with a value of 1.49 J / mm2

Abstract: The aim of this research was to study the feasibility for applications related to powder metallurgy in EDM electrode fabrication by combination of the percentage Cu-C-Ni element. The experiment was performed by comparing preliminary distribution results of particle size before and after the grinding of metal powders. The work-piece was pressed at a pressure of 200 Psi using a uniaxial press machine. The pressed green compact work-piece was then baked in a furnace. The gas inside the furnace that was used to control the temperature during the cold press procedure had a mixture gas ratio between argon and hydrogen of 95:5 (common grade) at 1030 ^oC and a soaking time of one hour. The results were examined by comparing the electric resistivity property, apparent density, bulk density as well as the porosity percentage inside the work piece material. The results revealed that the optimum combination of percentage Cu-C-Ni element was Cu92-C3-Ni5 (%wt), leading to the satisfactory Copper distribution in most of the structure. The size of sub sieve powder after grinding was found to be 22-31 micron with an electric resistivity of 1.45829E-05 k-ohm*cm. The minimum porosity percentage was found to be 2.19 %. Therefore, the element properties were found to be suitable for using as an electrode in EDM work when compared to that of the electrode prototype (EDM C3).

Abstract: Consumer’s preference towards organic material enriched nature based green products in the cosmetics and personal care industry have intensified over the years. This paper shares the synthesis and characterization of an active organic biocarbon material derived from carbonized powdered coconut shell by bicarbonate cured activation for use in charcoal-based cosmetic and personal care products. The optimum conditions for activation was observed at 800 °C, run for 180 min, with a bicarbonate impregnation ratio of 1:3. Experimental design followed Box-Behnken approach. The increase in iodine (757.30 mg/g) and methylene blue number (111.00 mg/g) are indicative of a highly porous biocarbon material that reflects its excellent adsorption capability. Suitability of the biocarbon material for application in charcoal-based cosmetic formulation mixture was supported through proximate, texture, and color analysis. Overall material characteristics are beneficial for effective adsorbent and exfoliant functions in cleansing, detoxifying, and scrubbing.

Abstract: In this study, two types of adsorbent including activated carbon and bio-sorbent were produced from Palm fiber wastes (PFW), which were activated by phosphoric acid. The influence of adsorbent type and phosphoric acid concentration on methylene blue adsorption was investigated. The most optimum adsorbent was determined based on adsorption capacity and removal percentage of each adsorbent. The result shows that 9.984 mg/g of adsorption capacity and 99.84% of removal percentage were achieved in 90 minutes’ adsorption, which demonstrates the huge potential of bio-sorbent and was chosen to be the most optimum adsorbent based on methylene blue removal. The characterization of bio-sorbent was then investigated using FTIR and SEM. FTIR result shows that bio-sorbent contains cellulose which affected the adsorption process while SEM result shows the cleaner pores and surface compared to bio-sorbent before activation.

Abstract: The Co-Processing Model consist of the hydrodeoxygenation (HDO) of guaiacol compound was represented of bio-oil model and the hydrodenitrogenation (HDN) of quinolone compound was represented petroleum model, were investigated in tetralin at 300 °C under pressure of hydrogen 50 bar with the CoMoP sulfided supported on Al₂O₃-TiO₂ catalyst and without phosphorus (P), the potential activity evaluation was compared with commercial catalysts. The liquid products after reaction were characterized by GC/MS. The CMAT, 0.5PCMAT and 1PCMAT catalysts proved to be effective for hydrodeoxygenation of guaiacol leading to significantly increased percentage of HDO, there are presence the %HDO as 57.93, 58.33 and 58.94 respectively, whereas the commercial catalysts showed the % HDO in range as 28-30%, while 2PCMAT catalysts showed the activity was less in HDO of guaiacol than other synthesized catalysts but showed high activity more than the commercial catalysts. Additionally, the HDN activity of CMAT catalyst showed that were improved, especially the phosphorus adding to CMAT present were high activity, due to the effects of the phosphorus as the catalyst promoter result to change of their morphologies and increase in Mo dispersion and increase in stacking of MoS₂ crystallites, involve the formation of new acid sites on the catalyst surface.