Tuan Zaharinie

Temperature Effects on Material Behavior of Aerospace Aluminum Alloys for Subsonic and Supersonic Aircraft

This review-cum-research paper reports the effects of temperature and time exposure on the material behavior of the aerospace aluminum alloys currently in use in subsonic and supersonic aircraft. The research reported in this paper involves experimental study of the microstructural characterization and temperature effects on the hardness behavior of the age-hardenable 2024-T3 aluminum alloy; the latter was acquired by one of the authors from Royal Malaysian Air Force (RMAF) aerospace industry. The ALCLAD 2024-T3 alloy is being used in C-130 Hercules aircraft by the RMAF. Recent research on various aluminum alloys being used and being considered for application in Concorde is also reviewed.

A bio-based, facile approach for the preparation of covalently functionalized carbon nanotubes aqueous suspensions and their potential as heat transfer fluids

In this study, we propose an innovative, bio-based, environmentally friendly approach for the covalent functionalization of multi-walled carbon nanotubes using clove buds. This approach is innovative because we do not use toxic and hazardous acids which are typically used in common carbon nanomaterial functionalization procedures. The MWCNTs are functionalized in one pot using a free radical grafting reaction. The clove-functionalized MWCNTs (CMWCNTs) are then dispersed in distilled water (DI water), producing a highly stable CMWCNT aqueous suspension. The CMWCNTs are characterized using Raman spectroscopy, X-ray photoelectron spectroscopy and transmission electron microscopy. The electrostatic interactions between the CMWCNT colloidal particles in DI water are verified via zeta potential measurements. UV-vis spectroscopy is also used to examine the stability of the CMWCNTs in the base fluid. The thermo-physical properties of the CMWCNT nano-fluids are examined experimentally and indeed, this nano-fluid shows remarkably improved thermo-physical properties, indicating its superb potential for various thermal applications.

Effects of annealing parameters on grain-growth behavior of HAYNES ® -718 superalloy

Annealing heat-treatment experiments at temperatures in the range of 1050 to 1150°C (1323 to 1423K) for durations in the range of 20 min to 22 h were conducted for HAYNES 718 superalloy plate. Grain sizes for the as-received and the annealed samples of the superalloy were measured by application of quantitative metallographic techniques. The grain-growth exponents, n, for the kinetic relationship (dD/dt = kt n ) were then computed, and the n values were found to lie in the range of 0.067 to 0.183. The microstructures of the as-received and annealed samples were critically compared for applications of the superalloy at high temperatures.

Microstructural analysis of brazing sapphire and Inconel 600 for sensor applications

Abstract The development of sapphire-based sensors for gas pressure application is growing in demand because of their appealing characteristics that could withstand high temperatures and harsh operating conditions. However, the joining process of sapphire to other materials, especially metals, is difficult to achieve because of dissimilar physical and mechanical properties. In this study, a direct brazing process was successfully demonstrated to bond sapphire to sapphire and sapphire to Inconel 600 using BAg-8 + 1·5Ti filler metal. Silver-based brazing filler metal with active element of Ti was believed to promote wetting in brazing of ceramic surfaces. The results have shown that a reaction layer is present between the sapphire and the brazed layer. There is also a variation in the phase formation between the sapphire/sapphire and the sapphire/Inconel 600 joints because of the influence of elements from the Inconel 600.

Brazing of Inconel 600 by active filler metal

Abstract Inconel 600 alloy was brazed at three different brazing temperatures 830, 865 and 900°C for 30 minutes. An active filler metal, Ag–Cu–Ti, was utilised to study its effects on bonding strength by the diffusion of some elements with Inconel 600 during brazing. The experiment was carried out in a high vacuum chamber at 1 × 10−4 Pa. Scanning electron microscope–energy dispersive spectroscopy and electron probe microanalysis was conducted for element identification and a shear test served to evaluate the bonding strength. The results show that good bonding was achieved and two continuous reaction layers were formed in the brazed area. The reaction layers were crossing in the middle in most areas at 865°C compared to 830 and 900°C. It was revealed that a stronger Ti–Ni interaction than Ti–Cu influenced the formation behaviour of reaction layers and the highest shear strength identified was at 865°C.

The Influence of Adding Porous Interlayer in the Brazing of Ceramic to Metal

In the brazing of ceramic to metal, large coefficient of thermal expansion (CTE) mismatch between both materials will induce high residual stresses, reducing the strength of the joint. In addition, low wettability between ceramic and metal could increase weak phases at the joint interface. A porous interlayer is introduced in the brazing process to overcome the effect of residual stresses and formation of weak phases between ceramic and metal, in this study, the effect of porous interlayer in the brazing of sapphire to Inconel 625 and the brazing of diamond to stainless steel were investigated. Active filler material containing titanium (Ti) was utilized to enhance the wettability of the ceramic-metal joint. It was anticipated that utilizing the porous interlayer for direct brazing would reduce the thermal expansion between both materials. Preliminary experimental results have shown that good bonding between sapphire/filler alloy/porous layer/Inconel 625 was achieved and no voids were detected in the brazing layer. Similar observation was also detected in the brazing of stainless steel/filler alloy/porous interlayer/ diamond.

A Study on Interfacial Reaction and Titanium Distribution in Brazing Sapphire to Inconel 600 Using Cu/Ni Porous Composite

In this study, a Cu/Ni porous composite was introduced when brazing sapphire to Inconel 600 using a special active filler metal of BAg-8 + 2Ti. The aim of the research is to investigate the Ti distributionin the Cu/Niporous composite and braze joint. The brazing was carried out in brazingtemperature of 830°C for 30 minutes by a vacuum environment (10-4 Pa). The interface of braze joint/sapphire and braze joint/Inconel 600 were observed by an electron microscope followed by elements analyzing using SEM-EDS. The observation and analysis shows that there is a black and thin reaction layer at braze joint/sapphire interface and a non-uniform of reaction layer was formed at braze joint/Inconel 600 interface. The formation of reaction layer is influenced by thermodynamic activity of Ti during brazing.