Abstract: Kenaf bast fibers were prepared into two types as untreated and maleic anhydride (MA) treated. Unsaturated polyester (UPE) resin was used as matrix and applied onto the kenaf bast fibers using hand lay-up method. Transverse and longitudinal flexural properties of unidirectional long kenaf bast fiber reinforced unsaturated polyester composites were performed and the effect of fiber modification and loading were studied. It is found that the transverse flexural strength of both types of composites decreases with the increasing of kenaf loading. Contrary, longitudinal flexural strength of both composites increases with the increasing of kenaf loading. Improved transverse and longitudinal flexural properties are shown by MA treatment of kenaf bast fiber. The interactions between fiber and matrix of fractured flexural surface were also observed by scanning electron microscope (SEM).
Abstract: Aluminium matrix composites (AMCs) are increasingly become attractive materials for advanced applications including aerospace and automotive applications because of their properties can be tailored through the addition of selected reinforcements. On viewing from both scientific and technological aspects, their excellent mechanical properties and relatively low production cost makes them a very viable candidate for a variety of applications. This paper focused on the suitable and common methods used to fabricate the AMCs such as powder metallurgy, stir-casting, squeeze casting and compo-casting method. The advantages and disadvantages of those fabrication methods are discovered through this paper.
Abstract: In this paper, the effect of thermal aging to the Sn-Zn and Sn-Zn-Bi solders on Cu substrate was studied. Sn-Zn was chosen and the effect of addition of Bi was investigated in this work. In this research, Sn-9Zn and Sn-6Zn-4Bi were subjected to thermal aging for 24h, 72h, 120h at 75°C and 100°C respectively. Both solder shown increased of thickness intermetallic layer with increasing time. However, Sn-9Zn recorded higher increment of intermetallic layer compared to Sn-6Zn-4Bi. The hardness of solder joint on Cu substrate was decreased for both solders with increasing aging time.
Abstract: This work investigated the effects of 1.0 wt. % TiO2 particles addition into Sn-Cu-Ni solder paste to the growth of the interfacial intermetallic compound (IMC) on Cu substrate after isothermal aging. Sn-Cu-Ni solder paste with TiO2 particles were mechanically mixed to fabricate the composite solder paste. The composite solder paste then reflowed in the reflow oven to form solder joint. The reflowed samples were then isothermally aged 75, 125 and 150 ° C for 24 and 240 h. It was found that the morphology of IMCs changed from scallop-shape to a more uniform planar shape in both Sn-Cu-Ni/Cu joints and Sn-Cu-Ni-TiO2 /Cu joint. Cu6Sn5 and Cu3Sn IMC were identified and grew after prolong aging time and temperature. The IMCs thickness and scallop diameter of composite solder paste were reduced and the growth of IMCs thickness after isothermal aging become slower as compared to unreinforced Sn-Cu-Ni solder paste. It is suggested that TiO2 particles have influenced the evolution and retarded the growth of interfacial IMCs.
Abstract: The evaluation of the strength and bondability of gold, Au ball bond requires a new approach to provide a more detail data. Nanoindentation test was used as a new approach to evaluate the strength distribution and bondability of Au ball. Au ball bonds that experienced different value of wire bonding parameter namely bonding force, bonding time, bonding power, and stage temperature were used as samples for the present analysis. The distribution of strength based on hardness and reduced modulus values located at the bonding area of Au ball bonds were found to be related with the values of the wire bonding parameter. Nanoindentation test was found to be a suitable approach to analyze and evaluate the bondability of Au ball bond in a localized and detailed manner. In addition, the responsible mechanism for the thermosonic Au wire bonding can be identified and analyzed by using the results obtained from the nanoindentation test.
Abstract: Sn-3Ag-3Bi-3In solder has been investigated to improve the understanding of microstructure formation in this solder during solidification and soldering to Cu and Ni substrates. The as-solidified microstructures of Sn-3Ag-3Bi-3In samples were found to consist of a significant fraction of βSn dendrites with a complex eutectic between the dendrites. In total five phases were observed to form during solidification: βSn, Ag3Sn, Bi, ζAg and a “Sn-In-Bi” ternary compound. Soldering of Sn-3Ag-3Bi-3In to substrates changed the phase equilibria in the system and caused the formation of additional phases: Cu6Sn5 during soldering to Cu and Ni3Sn4 and metastable NiSn4 during soldering to Ni. It is shown that metastable NiSn4 forms as a primary phase in a complex 5-component Sn-3Ag-3Bi-3In-Ni system. In and Bi were detected in solid solution in the βSn matrix in amounts of ~1.5-2at% and ~1.2at% respectively. Bi also existed as fine particles of two distinct types. (i): sub-micron (<500nm) coral-like particles and (ii) facetted particles measuring up to 7-8 μm.
Abstract: The wettability and mechanical properties of solder the joint of Sn-Cu-Ni-xSi3N4 had been investigated. In this study, five different silicon nitride (Si3N4) percentage addition were chosen (0 wt. %, 0.25 wt. %, 0.5 wt. %, 0.75 wt. %, and 1.0 wt. %). Contact angle measurement demonstrated that with Si3N4 addition, the wetting perfomances had been improved with the decrease of wettability contact angle. It is believed that the Si3N4 particles suppresses the interfacial IMC growth and thus improves the shear strength. Interfacial IMC thickness measurement and shear strength results showed that with thinner IMC layer (by increasing amount of wt.% of Si3N4), the higher the shear strength of the joint. Fracture surface of sheared samples shows a combination of both brittle and ductile fracture.
Abstract: This paper investigates the effect of 1 wt% TiO2 on the formation of primary and interfacial Cu6Sn5 in Sn-0.7wt%Cu and Sn-0.7wt%Cu-0.05wt%Ni solder pastes soldered on a Cu substrate using a real-time synchrotron imaging technique. It was found that TiO2 had altered the nucleation time of the primary Cu6Sn5 intermetallics and increased the number of particles observed. In addition, a more planar Cu6Sn5 interfacial layer had formed in joints made with TiO2 reinforced solders. This indicated that TiO2 promotes nucleation of primary Cu6Sn5 intermetallics in the early stages of soldering while being a barrier for further growth of interfacial Cu6Sn5 intermetallics. The synchrotron imaging technique provides direct evidence of the sequence of events in the soldering reaction and how these are influenced by TiO2 reinforcement.
Abstract: Nowadays, interest in developing environmental friendly construction material was increased. As the result, many researches have been done to make use of waste material for engineering purposes. This paper present the results of laboratory experiments on the potential of raw rice husk (RH) cement mortar with addition of foam as drainage material. Mechanical properties which are compressive strength, density, water absorption and porosity have been investigated in order to identify the potential of this material to function as drainage material. Total of eight set of sample were tested to determine those properties. Aqueous foam generated from chemical based foaming agent was used in this study to enhance the drainage ability and also reducing the density of the cement based mixture. More over to simulate the real application at site, an infiltration model was developed to determine the drainage and infiltration characteristic of this material. The permeability of the sample used in the infiltration model has been tested using constant head test to verify the validity of the infiltration model. From the result obtained, it can be concluded that the compressive strength and density of sample decreases with percentage of raw rice husk used while the additional of foam has further reducing the compressive strength and density. Both water absorption and porosity showing the opposite trend compared to the compressive strength. This drainage material can be pre-designed between 1.60N/mm2 – 10.12 N/mm2 for compressive strength, 1392kg/m3 - 1841kg/m3 for density, 21% - 34% for water absorption and 31% - 42% for porosity. From the result of infiltration model, it was observed that this material having good drainage ability with the permeability of 15% foamed rice husk sample is 1.57x10-3.
Abstract: Utilization of waste materials such as waste tire rubber in the building industry can help prevent environmental pollution whilst contributing to the design of more economical buildings. Preliminary studies show that workable rubberized portland cement concrete mixtures can be made provided that appropriate percentages of tire rubber are used in such mixtures. This article provides the overview of some of published paper using tire waste rubber in portland cement concrete. The researchers mostly investigated the properties of fresh and hardened concrete. The workability, density, air content, unit weight, compressive strength, modulus of elasticity, freezing and thawing resistance, abrasion resistance and thermal properties of the waste tire rubber in concrete were discussed.