| 1. |
- Ahmed, Naeem, et al.
(författare)
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The Hydrophilization and Subsequent Hydrophobic Recovery Mechanism of Cold Plasma (CP) Treated Bambara Groundnuts
- 2022
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Ingår i: Materials Science Forum. - : Trans Tech Publications. - 0255-5476 .- 1662-9752. ; 1055, s. 161-169
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Tidskriftsartikel (refereegranskat)abstract
- Plasma hydrophilization and subsequent hydrophobic recovery in Bambara groundnuts are studied for the first time. Bambara groundnut seeds were treated with cold plasma (CP) for 10 seconds at 10 watts using water as a monomer. The contact angle, as well as physical and chemical changes, were used to determine the kinetics of hydrophobic recovery. The hydrophilic state of Bambara groundnut seeds had decreased after 60 days, but not to original hydrophobicity, and also the recovery rate is slower than those observed on synthetic polymer. However, this slower hydrophobic recovery makes CP treatment as an effective method for long-term seed storage.
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| 2. |
- Choudary Ratnala, Dilipkumar, Doktorand, et al.
(författare)
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Development of Functionally Graded Metal–Ceramic Systems by Directed Energy Deposition : A Review
- 2023
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Ingår i: Materials Science Forum. - : Trans Tech Publications. - 0255-5476 .- 1662-9752. ; 1107, s. 105-110
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Tidskriftsartikel (refereegranskat)abstract
- Ceramics and metals are the two vastly explored classes of materials whose individual characteristics and targeted applications differ significantly. Continuous thrust for space exploration and energy generation demands materials with a wide range of properties. To tackle this demand, ceramic-metal combined structures that club heat, wear, and corrosion resistance of ceramics to the high toughness, good strength, and better machinability of metals are desirable. While various processing routes to combine ceramics and metals have been developed through the years, solutions to address problems associated with the interface, thermal property mismatch, and poor adhesion need to be explored. In this context, Functional Graded Materials (FGMs) have attracted particular attention by virtue of their ability to avoid sharp interfaces and local stress concentrations. Out of all, Additive Manufacturing (AM) routes, particularly the Directed Energy Deposition (DED) technique, is emerging as a productive technique capable of fabricating a wide range of metal-ceramic graded structures. This paper specifically discusses metal-ceramic FGMs ́ capability as a potential high-temperature material with customized multifunctional material properties. It further outlines the primary concerns with the realization of metal-ceramic graded structures and major techniques developed to mitigate problems encountered in processing them. Specific emphasis is laid on the powder-based Laser DED (L-DED) technique of FGM fabrication owing to its control over complex geometries and microstructural engineering.
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| 3. |
- Dumitrescu, Delia, et al.
(författare)
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Orange Waste Films as a Raw Material for Designing Bio-Based Textiles : A Hybrid Research Method
- 2022
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Ingår i: Materials Science Forum. - Switzerland : Trans Tech Publications, Ltd.. - 0255-5476 .- 1662-9752. ; 1063, s. 3-14
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Tidskriftsartikel (refereegranskat)abstract
- Bio-based textiles are an emerging area of cross-disciplinary research, involving material science and design and contributing to textile sustainability. An example of a bio-based textile is an orange-waste film, which is plant-based and biodegradable and possesses mechanical properties which are comparable to some commodity plastics. The research project presented in this article aimed to explore orange-waste film as a new material for textile and fashion design and highlights how experimental co-design processes and innovation involving orange waste film as a textile material adds a new layer of material understanding to both textile design and technology-driven material research. Material-development methods were used to develop the orange-waste film, as were textile design methods with a focus on surface design. The results show that material variables such as tensile strength and elongation are dependent on the grinding process and drying temperature used for the raw material, as these determined the quality and durability of the orange-waste film and its applicability to the field of textile design. The use of orange waste in the creation of textiles opens up more ways of thinking about and working with materials, and orange waste could become a desirable raw material for textile design on the basis that it introduces certain aesthetic and functional possibilities through its visual and tactile expression and material behaviour, in addition to defining methods of producing textiles.
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| 4. |
- Lee, Geon Hee, et al.
(författare)
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Measurement and Analysis of Body Diode Stress of 3.3 kV Sic-Mosfets with Intrinsic Body Diode and Embedded SBD
- 2023
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Ingår i: Materials Science Forum. - 0255-5476 .- 1662-9752. ; 1091, s. 55-59
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Tidskriftsartikel (refereegranskat)abstract
- SiC MOSFETs display reliability issues related to the quality of SiO2/SiC interface and bulk material due to the presence of near interface traps and point and extended material defects [1]. These material related issues give rise to a degradation of device reliability and ruggedness. One of them are basal plane dislocations (BPDs) introduced in the drift-layer during the epitaxial growth process which causes a s.c. bipolar degradation. Growth and movement of BPDs fueled by recombination energy has a very significant impact on conduction loss and on-resistance degradation. For 3.3 kV voltage capability, the probability of the appearance of BPDs is greater because the drift region is about three times larger compared to 1.2 kV devices [2-3]. We present measurement results and analysis of bipolar degradation in 3.3 kV MOSFETs with conventional body diode and embedded schottky barrier diode (SBD). The measurements were performed applying 50 % and 80 % of rated current with duty cycle 80 %, under total time of 100 hrs at constant case temperature of 54 °C. The 3rd-quadrant performance of both types of MOSFETs in pre-stress conditions was characterized at 25 and 150 °C with different gate biases of -10 V, 0 V, and +17 V. To evaluate the bipolar degradation, the diode conduction characteristics were measured at 25 °C after different stressing times by diode conduction the MOSFET output characteristics were measured at 25 and 54 °C before and after stressing the intrinsic body diode and embedded SBD. No VSD shift was observed in diode conduction characteristics. The results indicate that the MOSFETs were fabricated on appropriate material with a sufficiently low number basal plane dislocation (BPD). The on-state resistance with VGS = +17 V was decreased by temperature due to increased JFET resistance rather than bipolar degradation. On the other hand, the on-state resistance with VGS = +11 V was impacted by the increased temperature and VTH instability.
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| 5. |
- Pujante, Jaume, et al.
(författare)
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Hot Stamped Aluminium for Crash-Resistant Automobile Safety Cage Applications
- 2021
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Ingår i: Materials Science Forum. - : Trans Tech Publications. - 0255-5476 .- 1662-9752. ; 1016, s. 445-452
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Tidskriftsartikel (refereegranskat)abstract
- Hot stamping, also known as press hardening in the context of sheet steel, has steadily gained relevance in the automotive industry, starting off as a specialist application and turning into a staple technique in the production of safety cage products in little more than a decade. However, despite the weight reduction offered by martensitic steels, further improvement could be obtained by substituting these components by high-performance aluminium. In this regard, the very same process of hot stamping could be employed to attain the required combination of shape complexity and mechanical properties at a reasonable cost for mass-market application, if the limitations imposed by cycle time and process window could be overcome. In this work, the feasibility of hot stamping of 6000-series aluminium alloy sheet is studied, first in dilatometry experiments and later in semi-industrial conditions in a pilot facility. A cycle time shortening strategy is employed, and compared to the conventional thermal cycle in terms of implementation and obtained results. In addition to basic characterization, aluminium thus processed is studied in terms of fracture toughness, in order to obtain data relevant to crashworthiness that can be readily compared with alternative materials.
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| 6. |
- Öberg, Christian, 1989-, et al.
(författare)
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Plastic deformation and creep of two ductile cast irons, SiMo51 and SiMo1000, during thermal cycling with large strains
- 2024
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Ingår i: Materials Science Forum. - Switzerland : Trans Tech Publications Inc.. - 0255-5476 .- 1662-9752.
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Tidskriftsartikel (refereegranskat)abstract
- Cyclic deformations of two ferritic, ductile cast irons, SiMo51 and SiMo1000, were studied in air and Ar using a new method, SRTC (stress relaxation with thermal cycling). Locked specimens were thermally cycled up to 800 °C with isothermal holds, varying temperature interval, heating/cooling rates and hold times. A description of the mechanical response to thermal cycling of a locked specimen is given.
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| 7. |
- Yuan, Zimo, et al.
(författare)
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Localized Lifetime Control of 10 kV 4H-SiC PiN Diodes by MeV Proton Implantation
- 2022
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Ingår i: Materials Science Forum. - : Trans Tech Publications Ltd. - 1662-9752. - 9783035727609 ; , s. 442-446
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Konferensbidrag (refereegranskat)abstract
- In this paper, proton implantation with different combinations of MeV energies and doses from 2×109 to 1×1011 cm-2 is used to create defects in the drift region of 10 kV 4H-SiC PiN diodes to obtain a localized drop in the SRH lifetime. On-state and reverse recovery behaviors are measured to observe how MeV proton implantation influences these devices and values of reverse recovery charge Qrr are extracted. These measurements are carried out under different temperatures, showing that the reverse recovery behavior is sensitive to temperature due to the activation of incompletely ionized p-type acceptors. The results also show that increasing proton implantation energies and fluencies can have a strong effect on diodes and cause lower Qrr and switching losses, but also higher on-state voltage drop and forward conduction losses. The trade-off between static and dynamic performance is evaluated using Qrr and forward voltage drop. Higher fluencies, or energies, help to improve the turn-off performance, but at a cost of the static performance. © 2022 The Author(s).
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