Advanced Materials Research Vol. 576

Abstract: This paper describes the results of gaseous thermochemical treatment of nitriding duplex stainless steel using tube furnace. The nitriding was performed in temperature range between 400°C and 500°C for 6 hours, forming a dual layer structure with hard nitrogen layer. The nitriding gas composition used for this process is 50% NH4 + 50% N2 and 25% NH4 + 75% N2. The structural development was characterised using hardness tester, X-ray diffraction (XRD) and scanning electron microscopy (SEM). Based on the experimental results, it was found that nitrided layer produced maximum thickness nitrided layer about 13.96µm and hardness 666.3 HV0.025 at 450°C with 50% NH4. The formation of expanded austenite was observed in temperature range between 400°C and 500°C. However, the cromium nitride has been developed at temperature 500°C which decreased the corrosion properties of duplex stainless steel.

Abstract: In the recent development of a new process of electro-carburisation of mild steel in 800 °C molten carbonate based salts, further investigation has been carried out to study the effects of the cooling rate after the electro-carburisation process. In the process, the mild steel to be carburised was made the cathode and an inert SnO2 as anode. Salt mixture of Na2CO3-NaCl (mole ratio 4:1) was used as the electrolyte, and the process was carried out at voltage range of 1.0 to 2.5 V for 60 minutes, and thereafter cooled at certain rate. As revealed by the optical microscopy, the microstructural changes in samples that have been electro-carburised and thereafter cooled either rapidly or naturally in air, were featured by the increase of the carbon rich in the martensite structure at the expense of the original ferrite phase near the surface of the samples. Micro-hardness profiles measured from the surface to the centre of the electro-carburised sample presented clear evidence of carbon penetration as a function of the electrolysis voltage, and significant effects of cooling rate after the electro-carburisation process.

Abstract: Kenaf is categorized as one of the natural fibre which is used as replacement to man-made fibre due to its various advantages. It is a natural fibre of low density, low cost, recyclable and biodegradable. This paper presents the surface modification of kenaf biomass in terms of its morphology, chemical properties and crystallinity, as observed under scanning electron microscope (SEM), Fourier transform infrared (FTIR) and X-ray diffraction (XRD), respectively. Peak at 1600 cm-1 to 1200 cm-1 FTIR shows the disappearance of lignin in the treated kenaf. On the other hand, crystallinity indexes (CI) for untreated and treated kenaf are determined by XRD that show 83.3 % and 67.7 % accordingly.

Abstract: We report an application of silver colloid on cotton textile using a one- step method. Cotton fabric was treated with silver colloid and antimicrobial activity against Staphylococcus Aurous (gram positive) and Escherichia coli (gram negative) bacteria were evaluated. The treated fabric was evaluated in terms of physical properties such as tensile strength and stiffness, wrinkle recovery angle and degree of whiteness was evaluated. The change in chemical structure and morphology were evaluated using FTIR and SEM respectively. The study revealed that the maximum antimicrobial activity was obtained at 2.5 % of silver colloid while the 3 minutes cure of the treated cotton provided a better overall performance in terms of antimicrobial activity and physical properties.

Abstract: Metal/polymer/metal laminate composite is of great patent due to their excellence physical and mechanical properties. In this work, linear low density polyethylene (LLDPE) was used as matrix between aluminium sheets to produce aluminium/LLDPE/aluminium (APEA) laminate composite. The maleic anhydride grafted polyethylene, PE-g-MAH, with concentration between 0% - 3% was used as coupling agent. The -glycidoxy propyl trimethoxy silane (-GPS) has been used to enhanced the mechanical properties of laminate composite. The lap shear strength increased with the increasing percentage of PE-g-MAH with the application of -GPS. Surface analysis suggested that this increment was associated with the chemical state of the compound involved.

Abstract: The principal aim of this project was to achieve a better understanding of the various parameters that contribute to the tensile properties. These parameters were manipulated in order to improve and produced PPnanoclay/ Polypropylene (PP) reinforced oil palm empty fruit bunch composite material (OPEFB). OPEFB fibre was treated with sodium hydroxide (NaOH) in order to improve the tensile properties of the composites. Thus, in this study the oil palm empty fruit bunch fibres were used as a filler and PPnanoclay/ PP composite as the matrix material. Tensile test was used to assess the effect on the tensile strength and tensile modulus of OPEFB/PPnanoclay/PP composites. Morphologies of the composites were examined using a scanning electron microscope (SEM). The average tensile properties obtained were tensile strength 22 MPa at 180 µm and Young’s modulus 2120 MPa at 355 µm treated.

Abstract: Fly ash is waste of coal combustion which can be used in Aluminum alloy. In this research Aluminum is mixed with fly ash that used powder metallurgy method. Aluminum powder is produced by Merck German which is in irregular form and has homogeneous particles, while fly ash is got from residual combustion coal in forging section of Politeknik Negeri Sriwijaya (Polsri) mechanical workshop which is processed until grains size 140 and 270 mesh. Aluminum Powder had mixed with weight fraction 5 % of fly ash for an hour then is pressed with holding time 60 and 120 seconds, compacting pressure are 139 N/mm2 and 275 N/mm2 using cold iso-static pressing. After that green body is resulted then is being sintered until 5500C. Taguchi Method orthogonal L4 is used to find out factors which influence optimum condition of Brinell’s hardness Aluminum/5% fly ash. The result of analysis using ANOVA is grains size factor, holding time, and compacting pressure has affected significantly to hardness of Aluminum/5% fly ash.

Abstract: Thermoplastic sago starch (TPSS) was produced by plasticizing with glycerol through melt blending before being compression moulded. The investigated TPSS was prepared at glycerol/starch weight fraction of 40/60, 35/65 and 30/70. The functional groups composition, tensile strength, density, moisture content and water absorption were evaluated and compared at different glycerol/starch ratio. The compatibility of the glycerol as the plasticizer in the TPSS was proven by Fourier transform infrared spectroscopy (FTIR) where glycerol could form stable hydrogen bond with sago starch. This preliminary study demonstrated that the stress at maximum load was only applicable for lower glycerol/starch ratio of 30/70. The density of TPSS was inversely proportional to the increment of glycerol/starch ratio whereas moisture content and water absorption had opposite relationship.

Abstract: The study highlights melon seed oil as possible cutting fluid for machining processes. The properties of melon seed oil were investigated. Formulation of oil-in-water with addition of some additives was carried out and the results obtained suggest that melon seed oil possesses the relevant properties as a base material for oil-in-water emulsion cutting fluid.

Abstract: This paper discusses the inclusion of hybrid nanofillers nanoclay and multi-walled carbon nanotubes (MWNTs) as reinforcing agents to improve the thermal properties of TPNR. The laser flash technique was also employed to determine the thermal conductivity, thermal diffusivity and specific heat capacity of the nanocomposite. Two types of hybrid nanofillers were introduced into TPNR, which are untreated hybrid composites (UTH) prepared from MWNTs (without acid treatment)-nanoclay and treated hybrid composites (TH), consisting of acid treated MWNTs and nanoclay. The thermal properties of treated hybrid composites are better than untreated hybrid composites. The thermal conductivity of untreated hybrid composites that were sintered at 30 to 150 oC did not show a monotonous change with MWNTs as the filler has a high thermal conductivity compared to nanoclay. The results showed that the thermal diffusivity decreased with the increasing of temperature. The specific heat of all the measured samples increases linearly with the measured temperature from 30°C to 150°C.