Abdul Razak Daud

Effect of element additions on wear property of eutectic aluminium-silicon alloys

Abstract The effects of cerium, zinc and zirconium additions and subsequent heat treatment on wear of the eutectic aluminium-silicon alloys have been investigated in dry sliding against a steel counterface by using a pin-on-disc machine. Wear surfaces and debris were examined by scanning electron microscopy. Wear characteristics of both binary Al-Si alloys and a commercial LM 13 alloy, were also studied and compared with those of the AlSi alloy containing the Ce, Zn and Zr. The k-values of the ALSI (Al-12.3%Si), LM13, ASMC-1 (Al-12.3%Si-0.75%Mg-0.26%Ce) and ASMC-1 (heat-treated) obtained are 5.795 × 10−4, 4.750 × 10−4, 4.311 × 10-4 and 3.981 × 10−4 mm3N−1 m−1, respectively.

A review on radiation-induced nucleation and growth of colloidal metallic nanoparticles

This review presents an introduction to the synthesis of metallic nanoparticles by radiation-induced method, especially gamma irradiation. This method offers some benefits over the conventional methods because it provides fully reduced and highly pure nanoparticles free from by-products or chemical reducing agents, and is capable of controlling the particle size and structure. The nucleation and growth mechanism of metallic nanoparticles are also discussed. The competition between nucleation and growth process in the formation of nanoparticles can determine the size of nanoparticles which is influenced by certain parameters such as the choice of solvents and stabilizer, the precursor to stabilizer ratio, pH during synthesis, and absorbed dose.

Cratering on thermosonic copper wire ball bonding

Copper wire bonding offers several mechanical and electrical advantages as well as cost saving compared to its gold wire predecessor. Despite these benefits, silicon cratering, which completes the fracture and removal of bond pad underlayers, has been a major hurdle to overcome in copper wire bonding. Copper wire is harder than gold, and thus needs greater ultrasonic power and bond force to bond it onto metal pads such as aluminum. This paper reports a study on the influence of wire materials, bond pad hardness, and bonding-machine parameters (i.e., ultrasonic power and bond force) on silicon cratering phenomenon. Ultrasonic power and z-axis bond force were identified as the most critical bonding machine parameters in silicon cratering defects. A combination of greater bond force and lower ultrasonic power avoids silicon cratering and gives the desired effects. Results also show that a harder bond pad provides relatively good protection from silicon cratering.

Radiolytic Formation of Fe3O4 Nanoparticles: Influence of Radiation Dose on Structure and Magnetic Properties

Colloidal Fe3O4 nanoparticles were synthesized using a gamma-radiolysis method in an aqueous solution containing iron chloride in presence of polyvinyl alcohol and isopropanol as colloidal stabilizer and hydroxyl radical scavenger, respectively. Gamma irradiation was carried out in a 60Co gamma source chamber at different absorbed doses. Increasing the radiation dose above a certain critical dose (100 kGy) leads to particle agglomeration enhancement, and this can influence the structure and crystallinity, and consequently the magnetic properties of the resultant particles. The optimal condition for formation of Fe3O4 nanoparticles with a uniform and narrow size distribution occurred at a dose of 100 kGy, as confirmed by X-ray diffractometry and transmission electron microscopy. A vibrating sample magnetometry study showed that, when radiation dose increased, the saturation and remanence magnetization decreased, whereas the coercivity and the remanence ratio increased. This magnetic behavior results from variations in crystallinity, surface effects, and particle size effects, which are all dependent on the radiation dose. In addition, Fourier transform infrared spectroscopy was performed to investigate the nature of the bonds formed between the polymer chains and the metal surface at different radiation doses.

Corrosion inhibitive property of 4-amino-5-phenyl-4H-1,2,4-triazole-3-thiol for mild steel corrosion in 1·0M hydrochloric acid

Abstract The efficiency of 4-Amino-5-phenyl-4H-1,2,4-triazole-3-thiol (APTT) as corrosion inhibitor for mild steel metal in 1·0M HCl has been investigated. Weight loss, direct current (potentiodynamic polarisation), alternating current (electrochemical impedance spectroscopy), change of open circuit potential (OCP) with immersion time and scanning electronic microscopy were used to study the effect of APTT on the corrosion inhibition of mild steel. Results obtained from weight loss, potentiodynamic polarisation, impedance measurements and change of OCP with immersion time are in good agreement and indicated that the inhibitive efficiency of the inhibitor increases with the rise of concentration. Polarisation curves show that APTT is a mixed type inhibitor. Results showed that APTT performed excellent inhibiting effect for the corrosion of mild steel in 1·0M HCl solution and inhibition efficiency is higher than 90% at 80 × 10–5 M APTT. The high inhibition efficiency in terms of molecular adsorption and forming a protective film on the metal surface was discussed in this work. Adsorption of the inhibitor on the mild steel surface followed Langmuir adsorption isotherm and the value of the free energy of adsorption ΔG ads indicated that the adsorption of APTT molecule was a spontaneous process and was typical of chemisorptions. Surface photographs showed a good surface coverage on the metal surface.

Influence of rotational speed on mechanical properties of friction stir lap welded 6061-T6 Al alloy

The effect of rotational speed on macro and microstructures, hardness, lap shear performance and failure mode of friction stir lap welding on AA6061-T6 Al alloy with 5 mm in thickness was studied by field-emission scanning electron microscopy (FE-SEM). The results represent much closer hardness distribution in the upper and lower plates at the lowest rotational speed. It indicates the Fe-compounds in the fracture surface of the nugget zone by EDX.

Characterizations of Cuprous Oxide Thin Films Prepared by Sol-Gel Spin Coating Technique with Different Additives for the Photoelectrochemical Solar Cell

Cuprous oxide (Cu2O) thin films were deposited 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 a significant influence on the formation 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 using polyethylene glycol additive has smaller grains of about 83 nm with irregular shapes. The highest optical absorbance film was obtained by the addition of polyethylene glycol. The Cu2O thin films were used as a working electrode in the application of photoelectrochemical solar cell (PESC).

Characterization of Cuprous Oxide Thin Films Prepared by Sol-Gel Spin Coating Technique with Different Additives

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.

Surfactant Assisted Electrodeposition of Nanostructured CoNiCu Alloys

In order to obtain a desirable deposition thickness, nanostructured ternary CoNiCu alloys have been electrodeposited from salt solutions containing Co2+, Ni2+ and Cu2+ in the presence of a neutral surfactant alkyl polyglucoside (APG). Electrodeposition of CoNiCu was carried out in a three-electrode cell with indium-tin oxide (ITO) on glass plate, platinum wire and saturated calomel electrode (SCE) as working electrode, counter electrode and reference electrode, respectively. The nanostructured alloys were characterized by means of atomic force microscopy (AFM) and supported by field emission scanning electron microscopy (FESEM). The nanostructured CoNiCu alloys prepared in sulphate solutions in the presence of APG produced a thinner layer of nanoparticles of the alloys compared with the one deposited in the absence of APG. For a fixed deposition time, 160s and at an applied potential of − 875mV (SCE) the layer thickness was about 56 nm for electrodepositionin the presence of 3.25 wt.% APG and about 110 nm without APG. Only a small increase in thickness was observed when the potential was increased to more negative values i.e. − 875 to − 950 mV(SCE).

Wear behaviour of eutectic and hypoeutectic Al‐Si‐Mg‐Ce alloys

Purpose – The purpose of this paper is to study the wear behaviour of eutectic and hypoeutectic Al‐Si‐Mg‐Ce alloys.Design/methodology/approach – The eutectic and hypoeutectic alloys were prepared using permanent mould casting process by varied cerium (Ce) addition in the alloy from 1 to 3 wt%. Dry sliding wear tests were performed against a hardened carbon steel (Fe‐2.3%Cr‐0.9%C) using a pin‐on‐disc configuration with fixed sliding speed of 1 m/s and load 50 N at room temperature of ∼25 degree. Morphologies of both worn surfaces and collected debris were characterised by a scanning electron microscope (SEM) equipped with an energy dispersive X‐ray spectrometer (EDS).Findings – It was revealed that following the addition of cerium, intermetallic Al4Ce needle‐like structure was present in eutectic alloys whereas CeMg2Si2 blocky phase was present in the hypoeutectic alloys. The increasing of Ce addition up to 3.0 wt% in hypoeutectic alloy led to formation of AlCe3 intermetallic phase. The increase in cerium ...