Advanced Materials Research Vol. 980

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: In this work, the influence of hybrid effect on carbon and glass fiber reinforced polymer (FRP) on the mechanical performance for structural application was studied. The hybrid fiber reinforced polymer (FRP) composites made from woven E-glass and carbon fibers with epoxy resin. The FRP hybrid composites were fabricated using vacuum-assisted resin transfer moulding process, which is capable of producing constant thickness with high volume fractions of composite panels compared to that of traditional wet hand lay-up method. Mechanical performance of the FRP hybrid composites were evaluated against full carbon or glass fiber reinforced polymer composites. Important properties such as tensile strength, flexural strength and volume fraction of reinforcement were determined according to the ASTM standards. It was found that the mechanical properties of carbon-glass hybrid composites exhibited significant improvement in term of strength and strain respectively compared to that of full glass FRP composites and full carbon FRP composites.

Abstract: Yttria-stabilized zirconia and alumina made significant contributions to the development of health care industry, specifically as orthopedic and dental materials. Both bioceramics are nearly inert ceramics, as they do not allow the interfacial bonding with tissue. Thus, it is necessary to provide bioactive surrounding as to elicit a specific biological response at the interface of material. This research reported the microstructure and bioactivity behavior of YSZ-Al₂O₃/10HAP with 30 wt. % and 60 wt. % of YSZ content. Powders were mixed before being compacted at 225MPa using uni-axial press machine. The composites were sintered at 1200 ̊C with heating rate of 10 ̊C/min. In-vitro bioactivity behavior of the composites were evaluated by immersing the composites into simulated body fluid. Results from x-ray diffraction pattern, confirmed the phase formation of apatite by the presence of Ca₂P₂O7, and CaO that might be useful on implant cell interaction in a body environment. The apatite formation was observed on the surfaces of the composites by SEM only after 9 days of immersion and subsequently apatite nucleation increased with prolonging immersion time. The dynamic changes in pH, between ion concentration in SBF and bioceramics surfaces correspondedwith an immersion time. Up to 30 days of immersion, the pH value of SBF stabilized approximately around pH 7.4-7.6, similar to the human blood plasma. Formation of apatite on composites surface of prepared YSZ-Al2O3/10HAP bioceramics may contribute to the improved biocompatibility and osteoconductivity.

Abstract: For slow release fertilizer application, oil palm empty fruit bunch-grafted-poly (acrylic acid-co-acrylamide) [OPEFB-g-P(AA-co-AAm)] hydrogel composites were synthesized via two techniques; Two Steps (T1) and in-situ (T2). Scanning electron microscopy of hydrogel composite T1 has higher surface area and holes while hydrogel T2 displays smoother and tighter surface. Water absorbency capacity of hydrogel T1 is 42.90 gram/gram (g/g) and hydrogel T2 is 39.96 g/g. WAC of hydrogel T2 has much better re-swelling ability compared to T1 after it went through five cycles of drying-swelling-drying process. Hence, T2 has produced a hydrogel composite that is reusable with great morphology properties.

Abstract: This paper presents a study on tensile properties of Nano Silicon Carbide (n-SiC) and oil palm fibre (OPF) reinforced epoxy composites. The dosage of n-SiC and OPF are limited to 0%, 1%, 3% & 5% by mass of the total epoxy material. As a part of the research, experimental study is carried out on n-SiC and OPF based epoxy composites to investigate the tensile strength of the composite material. The utilization of 1% n-SiC& 1% treated OPF shows an improvement in tensile strength compared to the pure epoxy. The experimental results are also compared with 3-D finite element analysis results and a good agreement is observed between the experimental and the finite element results.

Abstract: O-MMT treated unsaturated polyester based hybrid composites were prepared using keratin fiber obtained from chicken feathers. Fibers of similar dimension were selected to fabricate composites through hand lay-up method. The preparation and dimensional stability properties of keratin fiber as reinforcements in composites is outlined in this paper. Varying O-MMT contents in nancomposites is performed to investigate the effects on the dimensional stability (water absorption and thickness swelling) of the composites. Results indicated that increasing fiber content deteriorates dimensional stability of the composites and composites. However, improvements in dimensional stability of the keratin fibercomposites were observed with O-MMT. O-MMT treatment reduces the water absorption and thickness swelling, especially at 5wt% of O-MMT concentrationat all range of fiber content. At 5wt% concentration of O-MMt, 10wt% keratin fiber content marks the lowest water absorption and thickness swelling with rate of 0.65% and 1.93%, respectively. Adopting 10wt% of keratin fiber at 5wt% of O-MMT can be utilized for application requiring high dimensional stability.

Abstract: Efforts at utilizing ceramic materials with their undeniably interesting range of properties in automobile manufacture, has persisted for many years. The corrosion resistance, the resistance to oxidation at high temperatures, the capacity of its resistance to wear and the low relative density of these materials make them especially attractive candidates for use in the automotive engine block production. The limitations of ceramics materials in the area of low fracture toughness can be assuaged by using various methods of grain and boundary size strengthening. This paper presents a critical survey of some of the existing materials used in the production of automotive engine block, the existing methods of toughening and strengthening of ceramic composite materials with emphasis on methodologies, strengths and weaknesses.

Abstract: Gallium nitride (GaN) on silicon (Si) is governed by the possibility to use this family of semiconductor for novel optoelectronic devices. GaN layers are deposited by MOCVD on silicon Si (111) using AlGaN buffer layer. We have studied the microstructure quality of the films. From SEM, TEM and AFM observations, we have observed that the films exhibit a good quality: the films are highly oriented (0001) with a smooth surface morphology (roughness of 12nm). We have completely characterized the optical properties using the prism coupling technique.

Abstract: The aim of this work is to study the effect of austenizing time, tempering process and tempering time on corrosion rate of austenitic stainless steel in oxalic acid. The samples of typical 304 stainless steel were heated to 1050°C for 10, 20 and 30 minutes and quenched to room temperature in water, then tempered at 250°C, 400°C and 600°C for 30, 60 minutes for each tempering time. These samples were then immersed in 0.1M of oxalic acid and then their weight losses were measured after 30 days. The result obtained show that corrosion rate of all austenitic stainless steel samples decreased with an increase austenizing time, this behaviour is due to more homogenously of austenite, and the corrosion rate will be increased with increase the tempering temperature and tempering time, this behaviour is due different phases at microstructure below 400°C, and above of 400 to 600°C the corrosion rate will be increased due to formation of carbides which are non-uniform distributed at the grain boundaries and causes intergranular corrosion.