Microstructural investigation on an Al 6061 T6 alloy subjected to ballistic impact C

Ballistic impact generates significant modifications in the microstructural patterns. High strain rate and local high temperature conditions work together in opposite way: the first causes strain hardening, while the second factor produces softening. Moreover, after the impact, the cooling process is responsible of other local modifications on the arrangement of dislocations and precipitates. Therefore an experimental analysis on Al 6061 T6 cut from the edge of a component subjected to ballistic impact has been carried on in order to investigate on the microstructural modifications. Considerations about the influence on the mechanical behavior and on the fracture propagation are reported. The crystallographic textures and the misorientation featuring the grains play in fact a significant role in the fracture mechanism. The comparison between the texture situation before and after the impact can allow to evaluate the localized straining of the material and to point out its dissipation efficiency as a function of the distance from the damaged surfaces © 2011 Published by Elsevier Ltd. Selection and peer-review under responsibility of ICM1

Platinum recycling going green via induced surface potential alteration enabling fast and efficient dissolution

The recycling of precious metals, for example, platinum, is an essential aspect of sustainability for the modern industry and energy sectors. However, due to its resistance to corrosion, platinum-leaching techniques rely on high reagent consumption and hazardous processes, for example, boiling aqua regia; a mixture of concentrated nitric and hydrochloric acid. Here we demonstrate that complete dissolution of metallic platinum can be achieved by induced surface potential alteration, an 'electrode-less' process utilizing alternatively oxidative and reductive gases. This concept for platinum recycling exploits the so-called transient dissolution mechanism, triggered by a repetitive change in platinum surface oxidation state, without using any external electric current or electrodes. The effective performance in non-toxic low-concentrated acid and at room temperature is a strong benefit of this approach, potentially rendering recycling of industrial catalysts, including but not limited to platinum-based systems, more sustainable

The Butterfly Fauna Of The Italian Maritime Alps:Results Of The «Edit» Project

Bonelli, Simona, Barbero, Francesca, Casacci, Luca Pietro, Cerrato, Cristiana, Balletto, Emilio (2015): The butterfly fauna of the Italian Maritime Alps: results of the EDIT project. Zoosystema 37 (1): 139-167, DOI: 10.5252/z2015n1a6, URL: http://dx.doi.org/10.5252/z2015n1a

Larval case architecture and implications of host-plant associations for North American Coleophora (Lepidoptera; Coleophoridae)

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Investigation of failure in a crankpin of a motorcycle engine

This study performs a failure analysis of a failed crankpin connecting the crank shaft with the piston rod in a motorcycle engine. The failed crankpin under examination is embedded in a 16NiCrMo12 alloy, a typical steel designed for carburizing treatment. The crankpin experiences a periodic compressive stress associated to the compression stroke featuring the cyclic movement of the piston rod imposed by the rotation of crank shaft. During the failure analysis, such mechanism has been associated to a pulsing fatigue phenomenon. The failure of the crankpin concerns the surface, which is affected by significant spalling phenomena causing the detachment of steel fragments, as the element is subjected to constant friction because of relative rotation. Since not all the produced crankpins undergo the observed damaging phenomena, the aim of the study is to identify the factors governing the failure phenomenon and to provide a working solution to the problem. The employed experimental techniques include microstructure analysis by means of optic microscopy and scanning electron microscopy, and hardness measurements. The combination of the obtained results has allowed us to identify the presence of large amounts of non-metallic inclusions underneath the surface as the cause of the damage

Viability study of the use of cast iron open cell foam as microbial fuel cell electrodes

Nowadays, the development of new green technologies has been promoted worldwide both by public and private institutions. In this context the research on microbial fuel cells (MFC) represents a promising alternative to carbon based energy sources. Unfortunately, this technology has been always affected by too low current density for allowing an intensive application in the industrial and civil field. The study deals with this limitation and focuses on the implementation of metallic foams, specifically cast iron based, as electrodes, increasing the exposed surface and thus the activity of the bacterial population. The pig iron was selected because of its low toxicity for the microorganisms and their metabolism, however its high melting point carries several problems for the manufacture process. Parallel to this, the realization of electrodes using foamed metals implies further issues related to the generation of correct pores size distribution and adequate bacterial activity. For instance, the metal foams are expected to be open-cell type, so that the mass transport might reach also the inner regions. In order to control these parameters the metal foams are produced by infiltration of cast iron on ceramic beds. Combining the previous data with the measurements of power generation efficiency the authors conclude the study attempting to design MFCs with metal foamed electrodes

Comparison between symmetric and asymmetric hot rolling techniques performed on duplex stainless steel 2205

In this work the alterations of mechanical properties of two 6xxx Aluminum alloys during different states of a production process are investigated. The mechanical properties are determined by means of the tensile test. Tensile tests are performed shortly after four steps in the production process: the shipment of the two alloys, a certain period of storage, uniaxial pre-stretching, and heat treatment that corresponds to the temperature profile during e-coating. Results are displayed as a function of orientation with reference to rolling direction, as a function of the level of uniaxial pre-stretching and as function of the temperature profile