1,721,093 research outputs found
Influence of laser powder bed fusion process parameters on the properties of CuZn42 components: case study of the laser surface energy density
No full textAlthough additive manufacturing (AM) technologies have been rarely used to produce lead-containing brass, the same AM technologies have never been adopted to produce lead-free brass parts based on the CuZn42 alloy. This study aims to fill the gap, demonstrating the feasibility of lead-free brass alloys by laser powder bed fusion (LPBF) technology and investigating structural and mechanical properties of the produced specimens, focusing attention on the role of surface energy density on material properties. Starting from a raw powder of CuZn42 alloy containing alpha, beta and gamma brass phases, fully dense samples with high hardness values were obtained by LPBF. The structural and mechanical properties of the samples were investigated by scanning electron microscopy (SEM), energy-dispersive microanalysis (EDS), X-ray diffraction (XRD) and density and hardness measurements. Results showed that density, hardness and the relative amount of the brass phases depend on the surface energy density (SED) E-s. The investigated range of SED allowed defining the process window ranging from 2 J/mm(2) to 10 J/mm(2), within which fully dense samples can be obtained. A linear dependence of hardness on density was also found, suggesting that deformation mechanisms are mainly due to the presence of residual pores and internal cavities rather than to microstructural features, such as the relative amount of brass phases and crystallographic defects. All results obtained in this work demonstrated, for the first time, that LPBF is suitable to produce components based on the CuZn42 alloy, and that structural and mechanical properties of the produced parts can be properly designed by controlling SED
Single step plasma deposition of hydrocarbon thin films containing Pt nanoclusters for fuel cells applications
No full textStudy of quality and composition of zinc anodes for cathodic ship protection
No full textQuality and composition of the sacrificial zinc anodes are main issues in order to guarantee an efficient cathodic ship protection avoiding possible malfunctioning and failures. In the present study, sacrificial zinc anodes samples of different provenance and origins have been investigated, used for the galvanic protection of ships, and the composition has been identified able to guarantee satisfactory efficiency. This study concerns also the methodological approach to select and use one or more analysis techniques suitable for this purpose. Both traditional and advanced characterization techniques have been taken into account, actually, particularly useful for adequately interpreting chemical properties and other features of the considered materials
Nanoscale characterization of metal alloys produced by laser powder bed fusion (LPBF) technology
No full textAdvanced characterization at the nanoscale of Co-Cr-Mo-W, and Ti6Al4V alloys produced by Laser Powder Bed Fusion (LPBF) has been carried out in order to investigate the structural features responsible of the material performances. The alloys considered in this study are key materials in advanced field such as aerospace, automotive and biomedicine, while LPBF is becoming the reference for fabrication of metal parts by additive manufacturing (AM). Combining advanced metallic materials with innovative production technologies results in unexpected mechanical properties of final products. In this study, several characterization techniques including scanning (SEM) and transmission (TEM) electron microscopy, X-ray diffraction (XRD) and neutron-based techniques have been used to investigate the materials at the nanoscale
Laser Powder Bed Fusion: tailoring the microstructure of alloys for biomedical applications
No full textAdditive manufacturing (AM) is particularly attractive for biomedical applications, where complex geometries and a high degree of individualization are required. Laser powder bed fusion (LPBF) is an AM technology exploiting the action of a solid-state laser to locally melt a metal powder according to a computer aided design (CAD) model. In the present study, the EOS Cobalt Chrome SP2 (Co-Cr-Mo-W) and Ti64 (Ti6Al4V) powders were sintered by the system equipped with a Yb fiber laser. During LPBF, the Co-Cr-Mo-W metal powder undergoes total melting followed by rapid cooling, giving rise to athermal martensitic phase transformation from the high-temperature γ (fcc) phase to the low-temperature ε (hcp) phase. This produces an intricate network of thin ε-lamellae inside the γ phase matrix. After the firing cycle this structure is maintained, and a massive presence of coarse precipitates is also observed. Owing to the rapid cooling taking place during LPBF, in Ti6Al4V sintered samples only the acicular martensitic α' phase is present. The firing cycle induces the β phase formation at the α plate boundaries and this microstructure leads to reduced values of strength, with respect to those of the as-sintered samples. The highlighted behaviors show that by tuning the post-production heat treatments it is possible to tailor the microstructure and the mechanical properties
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