Development of proving ground field test for establishment of vehicle accelerated corrosion test procedure in Malaysia

This paper presents the field tests conducted as part of activity to establish the vehicle accelerated corrosion test procedure in Malaysia, initiated by the national car manufacturer company, PROTON, Malaysia. Vehicle accelerated corrosion test is a combination of corrosion exposures and durability cycles to accelerate the corrosion process and detect potential failures that may occur during in-service conditions. PROTON conducts the vehicle accelerated corrosion test at external test centres in overseas. However, due to the different climatic of test location, some of the corrosion problems were found to be varied and many did not address the actual corrosion problems detected in Malaysia markets. Hence, the primary aim of this study is to establish a suitable corrosion driving procedure to accommodate the hot and humid environment using facilities in PROTON Test Track. Three corrosion driving procedures were designed based on the number of corrosion exposures and designated as Field Tests 1, 2 and 3. Analysis ruled out that Field Test 3 provides moderate corrosion rate of 0.077-0.842 mm/year and potentially to be the best suited for accelerated corrosion test procedure in Malaysia due to its close replication of actual cosmetic corrosion behaviour observed in Malaysia

Surface treatment of Al7075 Matrix by TiC particles via hybrid ball milling and tungsten inert gas cladding

Surface composite coatings of Al7075 containing titanium carbide (TiC) particles were fabricated using a hybrid ball milling and gas tungsten inert (TIG) cladding process. Initially, TiC particles were deposited on the surface of Al7075 substrate within ball milling process. The surface melting of Al7075 was then performed by TIG welding at two different current intensities of 80 A and 100 A. From microstructural point of view, a dense, uniform and metallurgically well-bonded Al7075-TiC coating was successfully obtained on the surface of Al7075 substrate which confirmed by SEM, XRD and EDX as well as micro-hardness results. However, composite coating TIG cladded at lower welding current of 80 A provided better properties compared to composite coating cladded at 100 A. The micro-hardness and wear properties of Al7075-TiC coating were found to be significantly improved as compared to Al7075 substrate due to the well dispersed and dense TiC particles

The effect of the addition of CNTs on the microstructure, densification and mechanical behavior in al-CNT-al2o3 hybrid nanocomposites

The effects of the addition of carbon nanotubes (CNTs) on the morphology and microstructure of Al-Al2O3 nanocomposites and the subsequent effects on their densification and mechanical behavior are studied. From the morphologic study, ball milling was found to be more intensified in the presence of 2 wt.% of CNTs wherein steady state was reached after 5 h of milling. The addition of CNTs as a mixing agent facilitates dispersion of Al2O3 nanoparticles and exerts extensive grain refinement. Compressibility and sinterability were found to be positively correlated with the milling time. Compressibility and sinterability were improved by increasing milling time owing to severe particle size reduction and minimizing the agglomeration of reinforcement particles. The micro-hardness (HV), nano-hardness (HN) and Young’s modulus (E) values of Al-2CNT-10Al2O3 nanocomposites increased by ~ 19%, 26% and 34%, respectively, as the milling time proceeds. At each milling time, Al-2CNT-10Al2O3 nanocomposites possess superior mechanical properties compared with Al-10Al2O3 nanocomposites owing to the morphologic and microstructural variations caused in the presence of CNTs

Elastic and thermodynamic properties of cerium‐doped yttrium aluminum garnets

Cerium-doped yttrium aluminum garnets (Y3-xCexAl5O12, Ce:YAGs) are promising yellow light-emitting components of solid-state white light-emitting diodes. Although there have been numerous studies examining the effects of Ce concentrations on the luminescent properties of Y3-xCexAl5O12, the impacts of Ce dopant on the elastic and thermodynamic properties are not well understood. In this work, we used resonant ultrasound spectroscopy (RUS) to determine the effects of Ce doping (0.025, 0.1, 1 at. %) on the elastic and thermodynamic properties of Y3-xCexAl5O12. The elastic moduli calculated via the Voigt–Reuss–Hill (VRH) method demonstrated that low Ce dopant concentrations (≤0.1 at. %) induced negligible effects on the elasticity of the YAG host matrix, while a high Ce concentration (1 at. %) yielded significant softening. RUS spectral analysis and SEM images suggested that the elastic softening originated from microstructural differences induced at higher Ce dopant concentrations. In addition, we demonstrated an increase in elastic anisotropy at higher Ce concentrations, which further elucidated the correlations between structure and elasticity of Y3-xCexAl5O12. Debye temperatures (θD), heat capacities (Cp), and thermal conductivities (κ) were calculated for Ce:YAGs through the relations of RUS-derived parameters (sound velocities, elastic moduli) and previously determined thermal expansion coefficients. Ce:YAG was found to have a significant reduction in θD, Cp, and κ at Ce concentrations ≥1 at. %. Lastly, extrapolation of Cp and κ to higher temperatures allowed the modeling of thermal stress experienced by Y3-xCexAl5O12 disks up to 1073.15 K