Key Engineering Materials Vols. 594-595

Abstract: The effects of hydrochloric acid (HCL) modification of the surface area, morphology and physico-chemical properties of Sayong kaolinite clay was investigated in this study. Sayong kaolinite clay was refluxed with different concentration of HCL (1M, 5M and 10M) at 100 °C for 4 hours and followed by calcination at 500 °C at 1 hour. The samples of untreated and treated clay were characterized by different analytical equipment such as BET Surface Area Analyzer, X-Ray Fluorescence (XRF), Fourier Transform Infrared (FTIR), Thermogravimetric Analyzer (TGA) and Field Emission Scanning Electron Microscopy (FESEM). The acid treatment increased the surface area of the Sayong kaolinite clay almost three times from 24.46 m²/g to the maximum value which is 64.04 m²/g once treated with 5M HCL. The increasing of the surface area is due to the formation of amorphous silica phase and removal of the octahedral Al³⁺ cations and other impurities (such as Mg²⁺, K⁺, Ca⁺ etc.) when the acid strength is increasing as reported in XRF analysis. FTIR study shows the change of the peak intensity of several types of structural OH groups that presently in the untreated and acid treated samples. TGA-DTA profiles shows that acid treatment increased the amount of physisorbed water as the acid concentration is increased. There are three of endothermic peaks was observed in the untreated sample which centered at 49 °C, 275 °C and 520 °C. However, when the clay samples treated with acid, it has increased the physisorbed water and decreased the structural and coordinated water which caused the change in the endothermic curves in the treated sample.

Abstract: The effect of filler size to the flexural properties of the calcium carbonate (CaCO₃) filled with unsaturated polyester (UP) composites have been experimentally investigated. The filler was derived from the shell of local clam known as Polymesoda bengalensis. The ground shells were graded into eight different sizes according to the sieve aperture size of which they could pass through. The sample with 4 wt% CaCO₃ reinforced with UP was fabricated. Then, the flexural test was done according to the ASTM D790. The result shows that for micron size filler, the flexural modulus was improved as the powder was filled into the UP matrix composite and the maximum value achieved at 574.81 μm mean diameter filler size. However, the infusion of the micron size CaCO₃ filler into the UP matrix decreases the flexural strength of the composites.

Abstract: Carbon nanotubes-talc (CNTs-talc) hybrid compound has been successfully synthesized via chemical vapour deposition (CVD) method. A gas mixture of methane/nitrogen (CH₄/N₂) was used as the carbon source and nickel as the metal catalyst for the growth of CNT hybrid compound. Talc works as substrate or support material which is combined with nickel to form a complex metal-talc catalyst that will react with carbon source to produce the hybrid compound. To study the effect of different calcinations temperature, four different calcinations temperature, 300 °C (C-talc300), 500 °C (C-talc500), 700 °C (C-talc700) and 900 °C (C-talc900) were used. Among these four calcination temperatures for synthesis the multi-walled carbon nanotubes (MWCNTs), C-talc500 is the most optimum calcination temperature to perform catalytic decomposition by reacting in methane atmosphere at 800 °C to produce the CNT-talc hybrid compound.

Abstract: Lost circulation is one of the most troublesome encountered in drilling due to uncontrolled flow of mud into the formation that likely to be caused of unsuccessful filter cake. The lost circulation material (LCM) is the additives that added to the drilling fluid to control loss of mud to the formation. In this research, the lemongrass was used as LCM. The objectives of this experiment are to investigate the effect of lemongrass as LCM to the filtrate and filter cake thickness and to determine the effective size of lemongrass as LCM. The experiments were conducted to measure the filtrate and filter cake thickness with different size and different based of drilling fluid. Low Pressure Low Temperature (LPLT) filter press is for water based mud (WBM) and High Pressure High Temperature (HPHT) filter press is for oil based mud (OBM) were used to perform the filtration process under static condition and constant filtration time which is 30 minutes. Both WBM and OBM are prepared four samples with three difference sizes of LCM and native mud. The sizes of lemongrass are 150 microns, 250 microns and 500 microns. After each experiment, the filtrate volume and filter cake thickness were determined to represent. The result shows that lemongrass able to perform a good LCM in both WBM and OBM based on filtrate volume and filter cake thickness. For WBM, the mud with LCM is lower filtrate volume than native mud which is less than 6.0 ml and for OBM, the mud with LCM is lower filtrate volume than native mud which is less than 5.0 ml. Both WBM and OBM show the thickness of filter cake obtained was in the range of 2 to 25 mm. The result also shows that the effective size of LCM is 150 micron due to less filtrate volume and filter cake thickness compare to other size of LCM which is 250 microns and 500 microns. The findings revealed that then lemongrass with the size of 150 microns is the suitable material to be used as LCM to replace conventional LCM.

Abstract: This paper highlights on the hydrogen production through photocatalytic activity by using hematite nanoparticles synthesized from self-combustion method based on different stirring period. The morphologies and microstructures of the nanostructures were determined using Field-Emission Scanning Electron Microscope (FESEM), X-Ray Diffractometer (XRD) and Particle Size Analyser (PSA). Besides that, surface area analyser was used to determine the BET surface area of the hematite samples. The hematite nanocatalyst as-synthesized are proven to be rhombohedral crystalline hematite (α-Fe₂O₃) with particle diameters ranging from 60-140 nm. The BET specific surface area of hematite samples increased from 5.437 to 7.6425 m²/g with increasing stirring period from 1 to 4 weeks. This caused the amount of hydrogen gas produced from photocatalytic water splitting to increase as well.

Abstract: In general, filament winding technique is used to fabricate the composite pipes using continuous fiber and matrix resin. In this study, fly ash based geopolymer resin composites reinforced by continuous glass fiber were used for fabrication and synthesized by different curing and sintering temperature, different pattern and different viscosity of geopolymer. The effects of that parameter on the product were investigated. The compressive properties of the resulting composite were determined on an Instron Universal Testing under compression mode and the results show that the helical pattern with low viscosity cured at 75°C give the highest strength.

Abstract: Recent research shows that the by-product materials such as fly ash can be used as raw material in producing aggregates and lightweight aggregates. The usage of this material can improve the quality of the aggregates produced compared to conventional in term of structurally strong, physically stable, durable, and environmentally inert. However, volcano ash also has a potential to be used as artificial geopolymer aggregate due to high Si and Al contents. This volcano ash is almost dominated by quartz phase and sulfur. Volcano ash has plate-like structure. The structure of original volcano ash shows more layer stick together to form the bigger structure due to the existence of water. More large pores can be clearly observed at sintering temperature of 1000 °C and contribute to less density and have potential to be used as lightweight artificial geopolymer aggregate.

Abstract: The problem of lead poisoning resulting from the use of lead shot in hunting waterbirds and shooting sports has led to the partial ban, voluntary restriction and complete ban of lead shot in some countries. The ban resulted in the alternatives like copper shot, tungsten-tin shot, bismuth-tin, steel shot, etc. These alternatives are still expensive and other possible alternatives have not been explored up to date. There is therefore need to ban lead shot world-wide and step up research into the alternatives (green shot).

Abstract: Foamed concrete as aerated concrete widely used in range of constructions application, no exception to structure shield. As structure shield is important to resist on impact loading. Whilst, Rice Husk Ash (RHA) as agro-waste potentials as filler for foamed concrete. RHA that is produced by uncontrolled burning under 700oC during ± 6 hours obtain the granules contain the carbon and porous. The granules of RHA may fill the porous in matrix foamed concrete without remove the characteristic the foamed concrete its self-as aerated concrete. This investigation RHA has been used as a replacement for fine aggregate. Target density 1800 kg/m³ of foamed concrete both of with and without RHA have been produced to compare their strength and characteristic of impact resistance. SEM and EDS test has been conducted to determine microstructure and chemical composition of foamed concrete with RHA. The results showed that granules of RHA filled the porous and bonded with the denser part into matrix. The presence of granules of RHA has been changing the role of the air cell of porous in foamed concrete when it was subjected to impact loading. Also the granules of RHA give the foamed concrete denser without losing its characteristic of porous entirely.

Abstract: In this study, ductile Ni-resist alloy with a minimum 18 wt. % nickel composition was modified. Up to 12 wt. % manganese was added together with 10 wt. % nickel before undergoing the inoculation process at various percentages to investigate the effects of the alloying elements on both its microstructure and mechanical properties.. The results showed that increasing inoculation did reduce carbide formation and further led to improved tensile value and decreased hardness value. Moreover, inoculation led to a uniform distribution of free graphite. The experimental results show the inoculation process refined the modified alloyed iron microstructure and improved its mechanical properties.