Papers by Author: Norinsan Kamil Othman

Abstract: The behavior of Fe-12Cr-2Mo stainless steel exposed isothermally in tube furnace at 700°C for 10 h had been studied in different environments; of mixed environment (Ar-20%O₂ with coated Na₂SO₄-50%NaCl salts), molten salt (Na₂SO₄-50%NaCl) and dry oxygen (Ar-20%O₂) atmospheres. The exposed samples were characterized by using optical microscopy (OM), scanning electron microscope (SEM), energy dispersive X-ray (EDX) and X-ray diffraction (XRD). The results indicated that, sample exposed in mixed environments undergoes highest corrosion rate compared with other samples. The main phase exists in all samples generally were iron-rich oxides which non-protective and thick. Conversely, EDX analysis on cross-sectional samples revealed the Cr-enrichment developed underneath the iron-rich oxide scales as the chromium concentration increases towards near the substrate. In presence of salt mixture, the oxide scales undergo spallation, however there is no crack observed. The catastrophic corrosion sample was occurred in combined environment due to the oxidation induced by the chloridation and sulfidation phenomena as well.

Abstract: Hot dipped aluminizing is the one of the most famous and effective method of the surface protection. The growth behavior in the intermetallic layer by introducing a different dipping time and various of molten aluminium temperature had been detail investigated. The result showed that the top portion of the coated steel substrate is compose of a thin layer of α-Al₂O₃, followed by thicker Aluminium pure layer, thinner layer of FeAl₃ , and then a much thicker of Fe₂Al_{5 .} The inter-metallic layer is ‘thick’ and exhibits a finger-like growth into the steel. The thickness of Al-Fe intermetallic layer on the steel base is increased with the increasing of hot dipping temperature and time. The micro hardness testing result shown that increasing of the aluminizing temperature was increased the hardness of the intermetallic layer.

Abstract: Effect of gamma radiation (1.33 MeV) and high temperature storage of semiconductor package towards micromechanical properties has been investigated. The in-house fabricated Quad Flat No Lead was exposed to gamma radiation with the dose of 5 Gy. Afterwards, high temperature storage was performed at 150 °C for 10, 100 and 1000 hours. Subsequently, the three point bending technique was carried out to obtain the micromechanical properties of semiconductor package. The fracture of the packages caused by three point bending test was subjected to 3D CT scan to capture the image of the fracture. Irradiated package shows the decreasing in their strength with increasing doses of gamma radiation. However, the strength of the package was improved after high temperature storage for 10 hours and decreased as the storage period is extended. Further analysis exhibited that high temperature storage for 10 hours is reveal as good thermal treatment for package in radioactive environment application.

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: Great interests in metallic oxides have emerged because of the possibility to modify the properties of these materials for different applications such as catalysis or sensors. In this work, CuO, ZnO and CuO-ZnO nanoparticles were prepared by a novel sol-gel route under ultrasonic condition using triethanolamine as an emulsifying surfactant. Fine powders were obtained when the pH of the sols were increased to 13 using NaOH. Particle sizes of the produced oxide materials were in the range of 3-4 nm, 40-50 x 100-150 nm (diameter x length) and 100-200 nm for CuO, ZnO and CuO-ZnO, respectively. The molar ratio of triethanolamine to metal nitrate precursors was set at 2:3. TEM micrographs of these particles were obtained to elucidate the morphology of the nanoparticles. Experimental results show that the band gap energies (E_g) for CuO, ZnO and CuO-ZnO were found to be 2.71, 3.35 and 2.82 eV, respectively.

Abstract: The purpose of this study is to evaluate the effect of filler metals in the gas metal arc welding (GMAW) process on the Aluminium alloy of AA 6061-T6 welded joints. 6 mm thickness plate with single V butt configuration was used and welded using two different fillers ER 4043 and ER 5356 and controlled welding parameters. The relationship between hardness and microstructure of the welded parts were studied and compared and the results showed that the post weld mechanical property has decreased especially for the filler ER 5356. The hardness at the heat affected zone (HAZ) of ER 5356 also has reduced almost 85% compared to the hardness of AA 6061 base metal. The microstructure of ER 4043 welding material shows the shape of columnar grains and dendrite structure. Microstructure morphology of ER 5356 welding material shows dendrites and intermetallic particles (Mg2Si) have partially dissolved and scattered in the welding material.

Abstract: The Reduced Modulus value for the bonded Au ball bond that have undergone three different time intervals of high temperature storage (HTS) have been obtained by using nanoindentation test. Twelve indentations have been made at three different locations (Au, IMC and Si area) across the bonded ball bonds to evaluate the variation of Reduced Modulus with the location of indentation. It was shown that the Reduced Modulus value for the indentations at IMC area is increased with the increment of HTS time interval. It was also observed that the Reduced Modulus at the Au area was increased with the increment of the HTS exposure time. No particular pattern was noted to describe the changes of Reduced Modulus with the location of the indentations that have been made. It was also found that the average Reduced Modulus for Au obtained through nanoindentation with value of 107 GPa has higher value compared to that of the Young’s modulus value obtained through actual tensile test with value of 79 GPa.

Abstract: The possible source of die edge cracking for Flip Chip Ceramic Ball Grid Array (FC-CBGA) package due to thermal cycling have been investigated in this study. Finite Element Analysis (FEA) models were used to analyze the effect of underfill fillet geometry on interfacial stresses between die edge and the underfill fillet. The input parameters of FC-CBGA from industry was used for simulation and the properties of commercial underfill were extracted by using Thermal Mechanical Analyzer (TMA) and Dynamic Mechanical Analyzer (DMA). Die stress distribution for different fillet height were generated to depict variation of stress due thermal loading. The variation of tensile stress due different fillet height and width were discussed for parameters optimization.

Abstract: Fe-Cr binary model alloys (Cr: 25 wt %) with additions of 0.09 wt% lanthanum were subjected to cyclic oxidation experiments at 700oC. All model alloys were exposed in five different gases; Ar-20O2, Ar-20O2-5H2O, Ar-5O2-20H2O, Ar-10H2-5H2O (pO2 = 3.64 x 10-22 atm) and Ar-10H2-20H2O (pO2 = 7.37 x 10-21 atm) all in volume %. Very low weight gains were observed in all gases of Fe-25Cr-0.09La. However, breakaway oxidation occurred on La-free alloy experienced increased weight gain in Ar-5O2-20H2O due to formation of iron-rich oxide. The addition of La (<0.1 wt%) to the Fe25Cr retarded the growth of iron-rich oxide in Ar-5O2-20H2O.