Excellence in Research and Innovation for Humanity

International Science Index

Commenced in January 1999 Frequency: Monthly Edition: International Paper Count: 3

Chemical, Molecular, Nuclear, Materials and Metallurgical Engineering

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  • 3
    Effect of Retained Austenite Stability in Corrosion Mechanism of Dual Phase High Carbon Steel
    Dual-phase high carbon steels (DHCS) are commonly known for their improved strength, hardness, and abrasive resistance properties due to co-presence of retained austenite and martensite at the same time. Retained austenite is a meta-stable phase at room temperature, and stability of this phase governs the response of DHCS at different conditions. This research paper studies the effect of RA stability on corrosion behaviour of high carbon steels after they have been immersed into 1.0 M NaCl solution for various times. For this purpose, two different steels with different RA stabilities have been investigated. The surface morphology of the samples before and after corrosion attack was observed by secondary electron microscopy (SEM) and atomic force microscopy (AFM), along with the weight loss and Vickers hardness analysis. Microstructural investigations proved the preferential attack to retained austenite phase during corrosion. Hence, increase in the stability of retained austenite in dual-phase steels led to decreasing the weight loss rate.
    Influence of Ag Nanoparticles Patterned on Well Aligned SiOx Nanowire Arrays for Enlarged Photodetection

    Silver (Ag) nanoparticles (NPs) patterned SiOx nanowire (NW) arrays were synthesized on Si substrates by using a catalytic free technique called Glancing Angle Deposition (GLAD) technique. The successful growth of Ag patterned SiOx NWs on Si substrate is manifested through the field emission gun scanning electron microscopy with energy dispersive spectroscopy analysis and transmission electron microscope analysis. The Ag patterned SiOx NW consists of ~140 nm SiOx NW and ~20 nm Ag NPs. The TEM image also reveals the crystalline nature of Ag NPs and amorphous nature of SiOx NWs. The photoluminescence spectrum of the sample shows broad band emission exhibiting peak values at 374 nm and 667 nm at excitation wavelength of 250 nm that corresponds to Ag NPs and SiOx NWs, respectively. The Ag patterned SiOx NWs exhibit a low bandgap of 1.9 eV due to the significant reduction in the recombination of holes and electrons in the SiOx layer. The Ag patterned SiOx NW-based device shows improvements in photodetection under white-light illumination compared to dark condition. This occurs due to the hole trapping process at the metal- Ag patterned SiOx NW interface states that efficiently reduced the depletion width under reverse bias. Moreover, the Schottky height at the junction is also reduced, which in turn enhanced the electron tunneling process. It is also interesting to know that the device exhibited a low turn on voltage (~0.6 V) as well as a fast response of 0.16 s (rise time) and 0.17 s (fall time) which makes it a potential application in optoelectronics.

    Tensile Properties of 3D Printed PLA under Unidirectional and Bidirectional Raster Angle: A Comparative Study

    Fused deposition modeling (FDM) gains popularity in recent times, due to its capability to create prototype as well as functional end use product directly from CAD file. Parts fabricated using FDM process have mechanical properties comparable with those of injection-molded parts. However, performance of the FDM part is severally affected by the poor mechanical properties of the part due to nature of layered structure of printed part. Mechanical properties of the part can be improved by proper selection of process variables. In the present study, a comparative study between unidirectional and bidirectional raster angle has been carried out at a combination of different layer height and raster width. Unidirectional raster angle varied at five different levels, and bidirectional raster angle has been varied at three different levels. Fabrication of tensile specimen and tensile testing of specimen has been conducted according to ASTM D638 standard. From the results, it can be observed that higher tensile strength has been obtained at 0° raster angle followed by 45°/45° raster angle, while lower tensile strength has been obtained at 90° raster angle. Analysis of fractured surface revealed that failure takes place along with raster deposition direction for unidirectional and zigzag failure can be observed for bidirectional raster angle.