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Abstract A new cold worked, penetrative mechanical reinforcement method was evaluated for its potential to enhance joining between 2024-T3 aluminum matrix and glass fiber reinforced polymer (GFRP) for aerospace and automotive applications. In this study, the aluminum substrate surface was modified using a new cold working process which formed hooks directly from the substrate material. This surface was then treated with grit blast and Sol-Gel surface treatment before it was co-cured to both side of a GFRP, forming a single lap joint for testing. This type of joints was compared to a baseline bonded joint without mechanical reinforcement using the same surface treatment. The joint strength and fatigue performance of these sets of samples were experimentally evaluated under quasi-static and fatigue loading conditions. The bonded joints with penetrative mechanical reinforcements withstood greater peak load and higher strain prior to failure, as compared to non-reinforced bonded joints. Fatigue testing on the other hand showed better performance of non-reinforced joints over the reinforced ones. The failure surfaces of both quasi-static samples and fatigue samples were evaluated using a scanning electron microscope to determine failure mode(s). It was determined that the stress concentration at the base of reinforcements could be the main underlying cause for earlier onset of fatigue failure of reinforced samples. [ABSTRACT FROM AUTHOR]

While zero valent aluminum (ZVAl) is considered as a promising catalyst for Oxone activation, relevant studies are very limited and ZVAl is typically obtained by chemical-reagent grade aluminum. However, as aluminum is the third richest element on earth, many aluminum wastes (AWs) are readily available for preparing ZVAl without energy-intensive mining and metalworking. Herein, we propose for the first time to valorize AWs to prepare ZVAl via HCl-pretreatment; the resulting HCl-pretreated AW (HPAW) is evaluated for Oxone activation by decolorizing Amaranth (AMR) dye as a model test. Oxone activation behaviors by HPAW are investigated by examining various effects on AMR decolorization, including dosages of HPAW and Oxone, temperature, initial pH, and co-existing compounds. Even though electrons from HPAW can induce the formation of OH , the resulting OH could not effectively decolorize AMR. However, the electrons from HPAW can “activate” Oxone to generate SO 4 - , which completely and rapidly decolorizes AMR. This effective AMR decolorization is attributed to SO 4 - and also to OH derived from the reaction of water with SO 4 - . The Oxone activation by HPAW is much favorable under neutral conditions and at elevated temperatures, whereas the presence of co-existing compounds ( e.g. , NaCl and anionic surfactant) inhibits Oxone activation and then AMR decolorization significantly. HPAW can be also reused for Oxone activation even without regeneration. These features demonstrate that AW can be valorized easily by HCl-pretreatment and becomes an efficient heterogeneous catalyst for Oxone activation. [ABSTRACT FROM AUTHOR]

The dissimilar joints between 7A04 aluminum alloy rod and AZ31 magnesium alloy rod were produced by inertia friction welding. The effects of friction pressure on microstructure and mechanical properties of the joints were investigated. Results showed that intermetallic compounds (IMCs), mainly Al 12 Mg 17 and Al 3 Mg 2 , were formed at the interfaces. A large amount of microcracks were generated in IMCs interlayer. The thickness of IMCs layer decreased significantly with increasing friction pressure. The mechanical properties were assessed by tensile test and microhardness. The mechanical properties of joints largely lies on the characteristic of IMCs interlayers at the interface. The tensile strength of the joints increases remarkably with increasing friction pressure. The maximum tensile strength of 96 MPa was achieved under the friction pressure of 124 MPa. All the tensile specimens failed in quasi-cleavage fracture mode along the boundary between IMCs interlayer and Al base metal. [ABSTRACT FROM AUTHOR]

It has been shown in our previous effort in the development of an energy-based fatigue life prediction framework that, in order to obtain the fatigue toughness of a nonviscoplastic material at room temperature from the areas of hysteresis loops, a fatigue test need to be conducted at the ideal frequency to minimize the effect of nondamaging energy. For aluminum 6061-T6, the ideal frequency is 0.05 Hz. A fatigue test with such a low frequency requires extensive time to complete. Therefore, the present investigation focuses on modifying the energy-based framework in order to obtain the fatigue toughness from fatigue tests conducted at an arbitrary frequency higher than the ideal frequency. The fatigue toughness is calculated from the average strain range developed in a material during a fatigue test and the Ramberg–Osgood cyclic parameters. The measurement of average strain range by an extensometer associated with a nonviscoplastic test specimen at room temperature is independent of the test frequency. The cyclic parameters are obtained from the fatigue lives at two different stress ranges which are also independent of the test frequency at room temperature. Similar to the case of the previous framework, the modified framework is found to predict the room temperature fatigue life of aluminum 6061-T6 with a promising accuracy. [ABSTRACT FROM AUTHOR]

We have developed novel catalyst supports using aluminum etched with microchannels as microreactors. The novel catalyst support contains ∼1–3.5 μm microchannels (∼10,000–15,000 microchannels/mm 2 ) formed on the metal aluminum foil substrate by etching. Flow was through an applied porous membrane. The aim was to provide a reaction space with short controlled residence time and high catalytic activity. We confirmed whether reactions occur in the 1.7 μm membrane microchannels and evaluated the performance of this membrane compared with alumina granular. Methanol steam-reforming activity of the catalytic membrane shows it is an effective catalyst. Comparison with a crushed catalytic membrane shows that the reaction occurs in membrane microchannels. We deduce that there is no diffusive resistance at all temperatures because the membrane microchannel diffusive length is short compared with granular-type reactor channels. [ABSTRACT FROM AUTHOR]

For this study, seamless square tubes of aluminum alloys EN AW-6060 and EN AW-6082 were extruded with axial variable wall thickness by applying an axial moveable stepped mandrel. The microstructures in thick-walled and thin-walled sections of these tubes were investigated and correlated to the extrusion conditions. The results for EN AW-6060 revealed fibrous grains at low ram velocity ( v ram = 0.8 mm/s) and thus low strain rate. In these cases, peripheral coarse grains were also observed on the tube surfaces. Applying a higher v ram = 3.3 mm/s lead to a fully recrystallized microstructure. For EN AW-6082 the fibrous microstructure was predominant. This was attributed to the Mn-content of this alloy, which acts as an inhibitor for recrystallization. Only at the highest values of strain, strain rate and temperature a recrystallized microstructure was observed for this alloy. EBSD analyzes of boundary misorientation angles indicate that geometric dynamic recrystallization seems to be the predominant mechanism at low strain rates. The facts that the amount of low angle boundaries significantly decreased as subgrains were removed and the amount of high angle grain boundaries is increased revealed that recrystallization occurred at higher strain rates and strains. Furthermore, the transition areas, where the wall thickness was gradually reduced were investigated. Due to increasing strain and thus increasing strain rate, thin-walled tube segments show lower grain size than thick-walled sections. It was also revealed that the PCG layer thickness remained about constant with increased strain, but since the tube wall thickness was reduced, the recrystallized fraction increased for higher strains. [ABSTRACT FROM AUTHOR]

The objective of this research was to develop a powder metallurgy (PM) counterpart to the wrought aluminum alloy 2618 utilizing press-and-sinter technology. Each starting blend was prepared from a strategic combination of prealloyed aluminum coupled with elemental and master alloy additions and was processed through uni-axial die compaction coupled with controlled atmosphere sintering. All of the PM alloys responded well to sintering with near full theoretical density realized. The most desirable PM product contained minor additions of tin and silicon. Whereas tin imparted enhanced densification, silicon promoted appreciable gains in hardness and tensile properties. It was also determined that the beneficial effects of silicon persevered after prolonged thermal exposure at 260 °C provided that a nominal concentration of 0.2 wt% was maintained. The final press-and-sinter PM product offered mechanical properties and thermal stability that were comparable to the wrought target. [ABSTRACT FROM AUTHOR]

Formation of linear polyenes -(CH=CH)- during thermal dehydration of thin layers (9-20 μm) of poly(vinyl alcohol) containing phosphotungstic-acid and aluminum-chloride catalysts was investigated. It was found that the concentration of long-chain ( n ≥ 8) polyenes in films containing phosphotungstic acid increased smoothly with increasing annealing time although the kinetics of the dehydration were independent of the film thickness. The polyene ( n ≥ 8) formation rate in films containing aluminum chloride dropped quickly with decreasing film thickness and increasing annealing time. As a result, long-chain polyenes practically did not form regardless of the annealing time for a film thickness of 11 μm. [ABSTRACT FROM AUTHOR]

Aluminum-doped zinc oxide (AZO) thin films are prepared by a low temperature (100 °C) aqueous solution deposition method with a subsequent UV post-deposition treatment at 140 °C. Film growth is governed by the retrograde solubility of zinc-ammine complexes at basic conditions (pH 11.4). Aluminum was introduced into the film as a dopant by co-precipitation, either using an aluminum metal foil or aluminum nitrate as a precursor. As the presence of Al ions in the solution influences the film morphology as well as the opto-electronic properties, different profiles of the dopant supply were examined and optimized with respect to the optical and electrical properties of the AZO layer. It was found that independent of the chosen aluminum precursor a linearly increasing dopant concentration in the solution is favorable for achieving dense, highly transparent (<8% absorption between 400 and 900 nm) AZO thin films with a lowest resistivity of 3.4 × 10−3 Ω cm. [ABSTRACT FROM AUTHOR]