Papers by Author: Abdul Razak Daud

Abstract: Thin films of copper oxide were successively deposited on glass substrates by sol-gel like spin coating for 40 s and annealed in air at different temperatures (200-400°C). Precursor solutions were prepared by dissolving cupric chloride in methanol. Various stabilizers and additives were used to enhance the solubility of cupric chloride and to improve the adhesion between the films and the glass substrates. Glucopone was used as a surfactant to reduce the surface energy. The evolution of oxide coatings under thermal treatment was studied by glancing incidence X-ray diffraction and scanning electron microscopy. Annealing the films in air at 300°C converts the films to CuO. The general appearances of the films were uniform and brownish in color.

Abstract: Electrochemical behavior of carbon steel in 1 M acetic acid (CH₃COOH) containing tetramethyl ammonium bromide (TMB) as the cationic inhibitor was investigated by potentiodynamic polarization technique and electrochemical impedance spectroscopy (EIS). The aim of this study is to evaluate the inhibition efficiency of cationic inhibitor for carbon steel corrosion. The electrochemical analysis revealed that inhibition efficiency significantly increased with the increasing of inhibitor concentration. Polarization study indicated that TMB acted as a mixed type inhibitor, which inhibited both cathodic and anodic reactions. The changes of impedance parameters by different inhibitor concentration showed a better protection due to formation of a thin film onto the steel surface. This study suggests that TMB is able to inhibit corrosion process of carbon steel in acidic medium with significant inhibition efficiency.

Abstract: Cuprous oxide (Cu₂O) thin films were formed onto indium tin oxide (ITO) coated glass substrate by sol-gel spin coating technique using different additives namely polyethylene glycol and ethylene glycol. It was found that the organic additives added had an important influenced on the formation mechanism of Cu₂O films and lead to different microstructures and optical properties. The films were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and ultraviolet-visible spectroscopy (UV-Vis). Based on the FESEM micrographs the grain size of film prepared by polyethylene glycol has smallest grain of about 83 nm with irregular shape. The highest optical absorbance film was obtained by the addition of polyethylene glycol.

Abstract: Cuprous oxide (Cu₂O) thin films were successfully grown on indium tin oxide (ITO) coated glass by sol-gel spin coating using diethanolamine (DEA) as a solubility agent. The films were annealed at 350 °C in 5% H₂ + 95% N₂ atmosphere. The films were characterized by X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM). Based on the SEM micrograph of the as obtained film, the film shows better coverage with the four sided pyramidal shape grain size of 108 nm. The prepared Cu₂O thin film was used as an active electrode for photoelectrochemical cell of ITO/Cu₂O/PVC-LiClO₄/graphite. The photovoltaic cell was tested using current-voltage characteristic under light illumination of 100 mW/cm².

Abstract: Copper oxide films were prepared via sol-gel like spin coating starting from methanolic solutions of cupric chloride onto the TiO₂ substrates. Films were obtained by spin coating under room conditions (temperature, 25-30 °C) and were subsequently annealed at different temperatures (200-400 °C) in oxidizing (air) and inert (N₂) atmospheres. X-ray diffraction (XRD) patterns showed crystalline phases, which were observed as a function of the annealing conditions. The film composition resulted single or multi-phasic depending on both temperature and atmosphere. The grain size of film was measured using scanning electron microscopy (SEM) and the surface roughness of thin films was characterized by atomic force microscopy (AFM). The grain size of which was annealed in air at 300 °C was 30.39 nm with the surface roughness of 96.16 nm. The effects of annealing atmosphere on the structure and morphology of copper oxide thin films are reported.

Abstract: In this paper, the optimization of cutting parameters is investigated to assess surface roughness and cutting force in the end milling of AlSi/AlN metal matrix composite. Eighteen experiments (L18) with five factors (cutting speed, feed rate, depth of cut, volume of particle reinforcement, and type of coated insert) were performed based on Taguchi designs of the experiment method. Two types of coating (TiB₂ and TiN/TiCN/TiN) of the carbide cutting tool were employed to machine various volumes of AlN particle (5%, 7% and 10%) reinforced AlSi alloy matrix composite under dry cutting conditions. Signal-to-noise (S/N) ratio and analysis of variance (ANOVA) were applied to investigate the optimum cutting parameters and their significance. The S/N analysis of the obtained results showed that the optimum cutting conditions for the cutting force were; A₂ (triple coating of the insert), B₂ (cutting speed: 200m/min), C₁ (feed rate: 0.6mm/tooth), D₁ (axial depth: 0.6mm) and E₁ (5% reinforcement). At the mean time, the optimum cutting conditions for surface roughness were; A₁ (single coating of insert), B₃ (cutting speed: 250m/min), C₂ (feed rate: 0.75mm/tooth), D₁ (axial depth: 0.6mm) and E₁ (5% reinforcement).The study confirmed that, with a minimum number of experiments, the Taguchi method is capable of determining the optimum cutting conditions for the cutting force and surface roughness for this new material under investigation.

Abstract: This paper deals with the current transport mechanism of solid state photoelectrochemical cells of ITO/Cu₂O/PVCLiClO₄/graphite as well as the physical properties of a component of a device affecting its performance. The principle of operation used in the photoelectrochemical cells is presented. The device makes use of ITO films, Cu₂O films, PVCLiClO₄ and graphite films as photoanode, photovoltaic material, solid electrolyte and counter electrode, respectively. The device shows rectification. The J_sc and V_oc obtained at 100 mW cm² were 3.2 x 10^-11 mA/cm² and 0.92 V, respectively.

Abstract: The aim of the study is to identify the effect of Ca in Mg-Mn alloy on electrochemical corrosion behavior for the development of high performance sacrificial anode. Mg alloys were fabricated by casting technique under an inert atmosphere. 0.35 ~ 1.11 wt.% of Ca were added as alloying element. The finding shows that the addition of small Ca in Mg-Mn anodes was found not significantly affecting the corrosion rate. However, small content of Ca was as much as necessary improving electronegativity of open circuit potential and modifying anodic polarization in promoting the instabilities of surface passive layer hence results in the further dissolution process between ion and alloy species underneath. No passivation occurs on the standard samples. Pitting profile only occur on Mg-Mn anode that has lower Ca content (0.35 wt. %). An XRD result shows no present of Mg₂Ca phase on the as-cast anode containing 1.11 wt. % Ca. As a conclusion, the influence of small content of Ca was profoundly modifying electrochemically behaviour of Mg containing Mn anodes except corrosion rate.

Abstract: Nanosilica powder produced from rice husk ash (RHA) via NaOH treatment has particle size in the range of 10-20 nm as revealed by transmission electron microscopy (TEM). The inhibitive action of nanosilicate from RHA on the corrosion of carbon steel SAE1045 in 0.5M HCl solution was studied using weight loss and potentio dynamic polarization methods. Result shows that the inhibition efficiency was increased with increasing of the inhibitor concentration. Nanosilicate was tremendously effective on carbon steel; exhibiting high inhibition efficiency attained 99%at optimum concentration of 175 ppm. Pitting was not observed on surface of carbon steel when the inhibitor was present. This finding was confirmed from surface morphology by scanning electron microscopy (SEM).

Abstract: Cuprous oxide (Cu₂O) thin films were formed onto three different substrates such as indium tin oxide (ITO) coated glass, titanium oxide (TiO₂) and n-Si substrates by sol-gel spin coating technique. It was found that the formation mechanism of Cu₂O films onto different substrates lead to different microstructures. The films were characterized by field-emission scanning electron microscopy (FESEM). Based on the FESEM micrographs the grain shape of film prepared were different on ITO, TiO₂ and n-Si substrate with 114 nm, 154 nm and 84 nm respectively. The results indicate that the choice of substrate strongly affect the film morphology, structural and optical properties. Keywords: Cu₂O, thin films, ITO, sol-gel, microstructures