Rice husk ash reinforcement in alumina : a review on mechanical and microstructural properties

Conventional ceramic materials such as alumina (AI₂O₃) is one of the commonly used material in research because it have relatively high hardness and stiffness, good corrosion and wear resistance, and excellent dielectric properties. Alumina have been used as catalyst for NO reduction, reducing wear in the soil and also as adsorbent for the removal of lead ions from aqueous solution. The application of alumina were restricted due to its brittleness and high susceptibility to fracture. The pore properties in alumina is also prized in some of its applications such as absorber or filters. Addition of rice husk ash (RHA) have been reported to influence the formation of pores in alumina. Alumina-ceramic matrix composite (AI₂O₃-CMC) have been fabricated through various types of techniques including hot pressing (HP), hot isotactic pressing (HIP) and liquid-phase sintering (LPS). In this review paper, an attempt has been made to summarize important research on the mechanical and microstructural properties of the AI₂O₃-CMC reinforced with RHA with several fabrication techniques

Intermetallic growth of SAC237 solder paste reinforced with MWCNT

The formation of intermetallic compound (IMC) layer at the interfaces of pad finishes has been studied. The growth of IMC layer as a reflow process and its properties were also discussed. In this study, solder alloy SAC237 (Sn: 99 wt.%, Ag: 0.3 wt.%, Cu: 0.7 wt.%), reinforced with 0.01 wt.% Multi-Walled Carbon Nanotubes (MWCNTs), was mixed to form a composite solder paste and soldered on Electroless Nickel Immersion Gold (ENIG) and Immersion Tin (ImSn) pad finishes. Reflow process was conducted in oven with specific reflow profile. The growth and properties of IMC layer were analysed using optical microscope with image analyser. Results showed that the thickness of IMC layer for ENIG and ImSn were 1.49 and 2.51 µm, respectively. Floating IMC and voids within the solder bulk and IMC layer were also identified in the samples. In addition, the measured wetting angle for ENIG and ImSn were 16.21° and 34.32°, respectively

Microstructural, physical and mechanical analysis of RHA pore modified porous alumina with aluminum as reinforcement

Porous ceramics are being used in many industrial applications and processes that require extreme environment exposure due to its chemical inertness to corrosive medium and its ability to withstand high temperatures. Tailoring the porosity through pore modifier is one of the method available to ensure that the strength of ceramic is homogeneous. In order to improve the strength of the porous ceramic, the addition of aluminium powders was explored in this research. With the addition of agricultural waste source pore modifier and aluminium as reinforcement, the microstructure, linear shrinkage, porosity (open, closed and total), density, hardness and failure strength of this ceramic composite were examined. The ceramic composites were fabricated through powder metallurgy processing routes. Alumina, Al2O3 with the respective amounts of 0 to 10 wt.% (intervals of 10 wt.%) of RHA and 0 to 10 wt.% (intervals of 2 wt.%) of aluminum, Al, were mixed homogeneously with 12 wt.% of sucrose solution. The mixtures were compacted and heat-treated for 1 h at each of the soaking temperatures of 200°C, 600°C and 1000°C followed by full sintering at 1550°C for 2 h in a furnace. The results have shown that open and total porosity increases with increasing amounts of RHA and aluminum. Meanwhile, the linear shrinkage, close porosity, density, hardness and failure strength was reduced. In this research, the strength was expected to increase with the addition of aluminum. However, due to the increasing percentage of the total porosity with the increased addition of aluminum, the samples behave inversely. Phase transformations to mullite (3Al2O3. 2SiO2) were seen in this research with the addition of RHA. This phase formation helps to increase the overall strength of the ceramic composites, showing that 10 wt% addition of RHA have a positive impact, not only as a medium to modify the pore formation, but it also has a positive effect on the strength property of the ceramic composite

Intermetallic growth of SAC237 solder paste reinforced with 0.01wt.% multi-walled carbon nanotubes

The formation of intermetallic compound (IMC) layer at the interfaces of pad finishes have been studied. The growth of IMC layer after as reflow process and its properties were also discussed. In this study, solder alloy SAC237 (Sn: 99 wt.%, Ag: 0.3 wt.%, Cu: 0.7 wt.%) reinforced with 0.01 wt.% Multi-Walled Carbon Nanotubes (MWCNTs) was mixed to form a composite solder paste and soldered on Electroless Nickel Immersion Gold (ENIG) and Immersion Tin (ImSn) pad finishes. Reflow process was conducted in oven with specific reflow profile. The growth and properties of IMC layer were analysed using optical microscope with image analyzer. Results show that the thickness of IMC layer for ENIG and ImSn were 1.49 µm and 2.51 µm respectively. Floating IMC and voids within the solder bulk and IMC layer were also identified in the samples. In addition, the measured wetting angle for ENIG and ImSn were 16.21° and 34.32°