Musdalilah Ahmad Salim

Effect of calcination time on NiAl-Al2O3 using gel combustion synthesis method

This study was conducted in order to investigate the effect of calcination time on phase and microstructural characteristics of intermetallic matric composite (IMC), NiAl-Al2O3 powder. This powder was synthesized using gel combustion method with octyl alcohol as fuel. Upon completion of the combustion process, the loose powder was calcined at 1050°C for 1, 2 and 4 hours and characterized using XRD, FESEM and TEM. The crystallite size was calculated to be in the range of 29-30u2005nm. It was found that NiAl-Al2O3 exhibits high crystalline structure after calcination for 4 hours. Furthermore, longer calcination time also cause growth of the particle size. Findings indicate that high crystalline nanostructured NiAl-Al2O3 powder consisting of submicron particles can be successfully produced using gel combustion synthesis with longer calcination time.

Synthesis and Characterizations of SiO2-Ag Core-Shell Nanostructure Using Fatty Alcohols as Surface Modifiers

SiO2-Ag core-shell nanostructure with silica core (SiO2) and silver shell (Ag) nanoparticles with spherical morphology were successfully synthesized using a modified self-assembly sol-gel method. Ag nanoparticles at ca.10-50 nm were successfully attached on monodispersed silica spheres (SiO2) with diameter of ca. 450 nm. Renewable resources of palm oil, derived fatty alcohols (octyl-alcohol (C8), decyl-alcohol (C10) and dodecyl-alcohol (C12)) were employed as nonsurfactant surface modifiers prior to coating with Ag nanoparticles. X-ray diffraction (XRD) patterns of calcined SiO2-Ag core-shell nanostructure prepared with surface modifiers exhibited amorphous structure of SiO2 (core) and face-centered cubic (FCC) structure of metallic Ag nanoparticles (shell). The results obtained in the present work demonstrated the feasibility of employing fatty alcohols as potential nonsurfactant surface modifiers in synthesizing SiO2-Ag core-shell.

Effect of NH3 on Structural and Optical Properties of SiO2-CuO Core-Shell Nanostructure

CuO nanoparticles at ca. 20-50 nm were successfully coated on monodispersed silica spheres prepared by modified sol-gel method. A renewable palm oil based decyl-alcohol (C10) was employed as nonsurfactant surface modifier prior to coating with CuO. Various amounts of ammonia (NH3) (0-1 ml) was as catalyst during the modification process to study the effect in homogeneous deposition of CuO on silica surfaces. The homogeneous depositions of CuO on silica were achieved with the addition of 0.9 ml of NH3. The optical absorption peak and energy band gap (Eg) values were at ca. 1.8-2.18 eV suitable for semiconductor and optical sensor materials.

Facile Method of Enzyme Immobilization on Silica Quasi-Nanospheres (SiO2) Synthesized Using PODFA for Biosensing Applications

In this study, silica spheres (SiO2) nanomaterials were introduced as the support materials for glucose sensors. Glucose oxidase (GOx) was immobilized onto SiO2 spheres (SiO2/GOx) using physical adsorption (electrostatic interaction) method. The SiO2 spheres were synthesized in-house using a nonsurfactant template of palm oil derived fatty alcohols (PODFA). Based on FT-IR analyses, SiO2/GOx exhibited N-H absorbance at ca. 2990 cm-1 and O-H absorbance at ca. 3330 cm-1. One new absorbance peak was observed at ca. 2320 cm1 attributed to the bending vibration (νbend)of silane molecules (Si-H) obtained by the interaction of GOx and the surface silanols (Si-OH). UV-Vis analysis results exihibited the presence of a new broad peak for GOx/SiO2 sample at ca. 250 nm to 280 nm suggested to be assigned to H2O2, C=C and benzene ring from GOx. The optimum pH and optimum temperature for SiO2/GOx for GOx activity were ca. 7.0 and ca. 50°C respectively. The increase of glucose concentration from 2mM to 5mM resulted to the increment of absorbance value for both GOx and SiO2/GOxsuggesting succesful immobilization of GOx on SiO2 spheres. These materials were suitable for glucose detection at very small glucose concentrations particularly in salivary glucose detection.

Mechanical and wear properties of aluminum coating prepared by cold spraying

In this study, aluminum (Al) powders were deposited onto Al substrates using cold spray to form a coating. The main objective is to investigate and compare the microstructure, mechanical and wear properties of Al coating to that of the Al substrate. The microstructure of the coating and substrate were observed using Scanning Electron Microscope (SEM). Hardness was evaluated using the Vickers Hardness test and wear properties were investigated using a pin-on-disk wear test machine. The elemental composition of the coating and substrate was determined using Energy-dispersive X-ray spectroscopy (EDX). Results showed that the friction coefficient and specific wear rate decreased while wear rate increased linearly with increasing load. It was found that the coating exhibit slightly better mechanical and wear properties compared to the substrate.

Nonsurfactant Surface Modifications of Monodispersed Si-Cu Core-Shell Nanocomposite

Monodispersed silica spheres with particles size of ca. 450 nm were successfully synthesized using modified Stöber method. The synthesized monodispersed silica spheres were successfully coated with copper through modified sol-gel method employing nonsurfactant template and catalyst. A renewable nonsurfactant template, decyl-alcohol (C10) and catalyst were used to modify the silica surfaces prior to coating with copper. In order to study the effect of catalyst on copper deposition onto silica surfaces, ammonia was used as catalyst in various amounts. The X-ray diffraction patterns of Si-Cu core-shell exhibited a broad peak corresponding to amorphous silica networks and exhibited monoclinic CuO phase. It was found that samples modified in the presence of 1 ml catalyst exhibited relatively homogeneous deposition. The surface area of uncoated core (SiO2) was at ca. 7.04 m2/g and coated samples 1 ml catalyst was at ca. 8.21m2/g.

Modified Combustion Synthesis of ZnO Nanoparticles Using Renewable Fuel

Zinc oxide nanoparticles were successfully synthesized using cost effective modified combustion synthesis route employing zinc nitrate hexahydrate as oxidant and palm oil derived C8 fatty alcohol as fuel in various ratios. The calcined zinc oxide exhibited hexagonal phase with wurtzite structure. The crystallite sizes of the samples were ranging from ca. 28 to 40 nm. Therefore, palm oil derived C8 fatty alcohol successfully played the role as low-cost and renewable fuel to synthesize zinc oxide nanoparticles.

Modified Combustion Synthesis and Characterization of ZnO Nanoparticles Using Various Dispersants

Zinc oxide (ZnO) nanoparticles with hexagonal wurtize structure were successfully synthesized via simple, cost-effective and environmental friendly modified combustion synthesis route. Three different type of dispersants namely glycerol, palm oil derived fatty alcohol (C8) and fatty ester (C12) were employed to produce the nanoparticles. X-ray diffraction patterns of calcined ZnO nanoparticles indicated the successful formation of ZnO. The crystallite sizes were at ca. 39.42 nm, 27.62 nm and 30.27 nm for ZnO produced using glycerol, fatty alcohol (C8) and fatty ester (C12). The morphology was of spindle-like shape for ZnO produced using glycerol and pseudo-spherical shape for ZnO produced using palm oil derived fatty alcohol (C8) and fatty ester (C12). Energy dispersive X-ray analyses showed the existence of zinc and oxygen peak suggesting successful formation of ZnO using various renewable dispersant.

Renewable decyl-alcohol templated synthesis of Si-Cu core-shell nanocomposite

Monodispersed silica spheres with particles size of ca. 450 nm were successfully synthesized using a modified Stober method. The synthesized monodispersed silica spheres were successfully coated with copper using modified sol-gel method employing nonsurfactant surface modifiers and catalyst. A renewable palm oil based decyl-alcohol (C10) as nonsurfactant surface modifiers and catalyst were used to modify the silica surfaces prior to coating with copper. The X-ray diffraction patterns of Si-Cu core-shell exhibited a broad peak corresponding to amorphous silica networks and monoclinic CuO phase. It was found that samples modified in the presence of 1 ml catalyst exhibited homogeneous deposition. The surface area of core materials (SiO2) was at ca. 7.04 m2/g and Si-Cu core-shell was at ca. 8.21 m2/g. The band gap of samples prepared with and without catalyst was calculated to be ca. 2.45 eV and ca. 3.90 eV respectively based on the UV-vis absorption spectrum of the product.

Facile processing of Si-Cu core-shell as potential meta-atom materials

Monodispersed spheres of Si-Cu core-shell nanocomposite with silica as core and copper as shell were successfully synthesized by a modified two-step synthesis method. Spherical particles of silica core were first synthesized using a modified Stöber method using nonsurfactant template. The obtained monodispersed silica spheres were successfully coated with copper through a modified sol-gel method employing nonsurfactant template. A renewable nonsurfactant template (decyl alcohol) was successfully used to modify the silica surfaces. To study the effect of nonsurfactant template on copper deposition onto silica surfaces, various compositions of nonsurfactant template were used. The X-ray diffraction patterns of core-shell nanocomposite exhibited monoclinic copper crystalline phase and a broad peak characteristic of amorphous silica networks. The results from field emission scanning electron microscopy (FE-SEM) suggested that both monodispersed silica core as well as Si-Cu core-shell particle sizes were at ca. 560 nm. UV-Vis spectrum of Si-Cu core-shell exhibited a broad absorption peak centered at ca. 394 nm suggesting optical properties of these Si-Cu nanocomposite as potential meta-atom materials.