Advanced Materials Research Vol. 795

Abstract: The wire material of filter mesh is made of 304 grade stainless steel. The failure to run properly was due to the impact of burst and torn. The client also expects that the failure was due to corrosion problems. A visual inspection on the strainer mesh was found covered by brownish rust layers and some scratches at the damaged area. The rusty wire mesh that was washed with pickling acid showed a clean and smooth surface. Energy dispersive spectroscopy (EDS) examination of the rusty wire mesh surface indicated that it was only normal oxide precipitates. Thus, it's proven that there were no signs of severe corrosion attack on the failed sample. SEM micrographs showed the unidirectional scratch effects exist in the damaged area. The fractography study was found there was a typical ductile structure on the fracture surface of the wire. It is proven that the wire mesh was actually still in good condition and has not experienced any embrittlement problems as if it exposed to any corrosive environment. The root cause of the failure is shown by the effect of scratches in which it is usually caused by a mechanical forceful push by a hard object or in other words, it is caused by human error factor.

Abstract: Tensile shear strength and ageing treatment of dissimilar 6063 aluminum alloy-316L stainless steel joint fabricated by spot welding were investigated. The results showed that tensile shear strength increased with the increasing of welding current. The enhancement of tensile shear strength of the joints was due to the enlargement of the nugget diameter. It was also found that the tensile shear strength values for heat treated joint almost similar to that of non-heat treated joint.

Abstract: The effects of both additions of fly ash and polystyrene (PS) beads were studied on compressive strength of foamed cement composites. The increasing amount of fly ash addition up to 6 wt. % has been found to increase the compressive strength of the foamed cement composites. It was found that fly ash has a potential as sand replacement materials in cement composites. The addition of 0.1 wt.% PS beads produced higher values of compressive strength after 14 days and 28 curing days respectively.

Abstract: This paper focused in details about dielectric properties of BT with different stoichiometry. In this research, BT was synthesis by solid state reaction between TiO₂ and BaCO₃ at constant sintering temperature of 1350 °C. Five different ratio of BT was characterized by using SEM, XRD, and IS. There have production of secondary phase when Ba was excessive. Impedance plot shows the relation between dielectric properties and stoichiometry of BT where the highest value of dielectric properties is comes from sample with Ba/Ti ratio equal of 1:1.

Abstract: The effect of excessive intermetallic growth to the reliability of solder joints become major problem in electronic assemblies industry. In this investigation, we used Sn-0.7Cu/1.0-Si3N4 composite solder to analyze its interfacial joint on Cu substrate. Various isothermal of aging times were carried in this study by using 24hrs, 240hrs, 480hrs, 600hrs and 720hrs at 150°C of aging temperature. The Cu-Sn IMC thickness was increase with increasing aging time and the diffusion coefficient of this composite solder is 1.16x10^-16m²/s.

Abstract: Since decades ago, corrosion is the crucial factors for million dollars loss in construction industry. Corrosion of reinforcement bar in ordinary Portland cement (OPC) concrete is mainly due to chloride and acid attack and also due to carbonation process. The degradation of geopolymer (GP) concrete is still widely studied and the mechanisms of degradation are still not conclusive. However, reinforcement bar in GP concrete is reported having lower corrosion rate than in OPC concrete. The fly ash geopolymer has high alkalinity which provides the passivity of the reinforcement bar. The superior properties of GP have encouraged researchers to do further investigation on its performance. This review paper will focus on corrosion performance of reinforcement bar in GP compared to OPC.

Abstract: LaYO₃ doped-ZrO₂ ceramic with the composition La_0.95Zr_0.05YO_3+δ was prepared via the solid state reaction. The samples were sintered at 1450 °C and sintering times in range of 6-15 hours have been varied for both doped and base samples in order to study its effect on its properties. The results showed that relative density increased remarkably with sintering time. The highest relative density was observed for the samples sintered for 15 hours. Scanning electron micrographs also proved that the porosity of the samples reduced when samples sintered for the longer time.

Abstract: The developments of lead-free solders have become a major concern to the researchers in electronic industry to replace the lead-containing materials. The concern is not just for low temperature solders but also for high temperature solders. The lead and lead-based compound are highly toxic which is dangerous to human health and environment. The highly suitable lead-free solder candidates for replacing high Pb high temperature solder are Au-Sn, Al-Zn, Zn-Sn, Sn-Sb, and Bi-Ag solders. However, Zn-Sn based solder has highly recommended as the best candidates in replacing high lead high temperature solder. This paper provides a short review of recent research on Zn-Sn based lead free high temperature solders with different additional alloying elements. The new novel alloy of Zn-Sn based for high temperature solder applications will be proposed in this paper.

Abstract: Nowadays, excessive growth intermetallic formation becomes the major issue in electronic packaging industry. The investigation on the effect of aging temperature to the intermetallic compound (IMCs) growth formation for Sn-0.7Cu/1.0-Si3N4 was studied. Isothermal aging process was carried out for 24 hours, with 5 difference aging temperature from 50°C up to 150°C. It is found that the Cu-Sn IMCs which appear after reflowed process, has grew rapidly when aging temperature was increased up to 125°C and started to reduced after 150°C aging temperature.

Abstract: Polyurethane (PU)/montmorillonite (MMT) composite foam were synthesized with reaction of diisocyanate with polyester polyol by a batch process. In this research, water was used as the blowing agent with TEGOSTAB B8407 and TEGOAMIN PMDETA as the surfactant and catalyst, respectively. Clay was used as filler for composite PU foam with the percentages varied from 0 wt% to 5 wt%. Polyurethane foam (Al-PU) sandwich composite was prepared using hand-lay up method where Al sheet was stacked onto PU foam using adhesive. The samples were characterized using flexural test analysis. Observations showed that PU foam has better failure deformation with flexural extension increased up to 9.44 mm. However, flexural stress and optimum load for sandwich composite are up to 3.63MPa and 410.78N respectively. Furthermore, Al sheet act as ductile skin to PU foam and prevent samples from rupture rapidly or avoiding the existence of brittle fracture. Modeling of composite using finite element software shows the ductile-like failure behavior in sandwich composite Al-PU foam even though the core itself is a rigid brittle foam.