Effects of N2 plasma modification on the surface properties and electrochemical performance of Ni foam electrodes for double-chamber microbial fuel cells

Autoren: Mozhgan Gholami-Kermanshahi, Ming-Cheng Lee, Günther Lange, Shih-Hang Chang

This study assessed the feasibility of using a plasma-modified Ni foam as an anode to improve the electrochemical performance of double-chamber microbial fuel cells (MFCs). Scanning electron microscopy results showed that Ni foam exhibited an open cellular structure and rough surface morphology, providing a large contact area between bacteria and anodes in the MFCs. N2 plasma modification did not influence the surface morphology of the Ni foam, whereas the hydrophobic surfaces of the Ni foam became highly hydrophilic. X-ray photoelectron spectrometer results revealed that Ni–N and NH3 functional groups, formed on the surface of the Ni foam during the N2 plasma modification, were responsible for its highly hydrophilic surface. Electrochemical measurements demonstrated that the highest power density of the MFC configured with an unmodified Ni foam anode electrode (166.9 mW m-2) was much higher than those of the MFCs configured with dense Ni rod (5.1 mW m-2) or graphite rod (29.5 mW m-2) anodes because Ni foam combined the advantages of an open cellular structure and good electrical conductivity. The highest power density of MFC configured with Ni foam was further improved to 247.1 mW m-2 after 60 min N2 plasma treatment owing to the high hydrophilicity of the N2 plasma-modified Ni foam electrodes, which facilitated bacteria adhesion and biofilm formation.

Effects of carbon nanotube addition on the microstructures, martensitic transformation, and internal friction of Cu–Al–Ni shape-memory alloys

Autoren: Mozhgan Gholami-Kermanshahi; Yuan-Chien Hsiao; Günther Lange; Shih-Hang Chan

In this study, we analyze the influences of carbon nanotube (CNT) addition on the martensite transformation and internal friction of Cu–Al–Ni shape-memory alloys (SMAs). X-ray diffraction and differential scanning calorimetry results demonstrate that Cu–13.5Al–4Ni–xCNT (x = 0, 0.2, 0.4, 0.6, and 0.8 wt%) SMA/CNT composites exhibit a β1(DO3)⇄ß´1(18R) martensitic transformation. The martensitic transformation temperatures and transformation enthalpies of the martensitic transformation peaks for the Cu–13.5Al–4Ni–xCNT (x = 0–0.8 wt%) composites gradually decrease with the increase in the amount of CNT addition. Compared to the Cu–13.5Al–4Ni SMA, the Cu–13.5Al–4Ni–xCNT (x = 0.2–0.8 wt%) SMA/CNT composites exhibit significant improvements in the amount of dissipation of energy (storage modulus (E′)) and mechanical strength. However, the tan δ of the internal friction peak gradually decreases with the increase in the CNT content above 0.6 wt%. The reduction in tan δ is attributed to the decrease in the magnitude of the austenite-to-martensite transformation and precipitation of γ2 (Cu9Al4) phase particles, which impede the interface motion in between the parent/martensitic phase and martensitic phase.

Effect of Alloying Elements (Nb, Ag) on the Damping Performance of Cu–Al–Mn Shape Memory Alloys

Autoren: Mozhgan Gholami-Kermanshahi; Yu-Yan Wu; Günther Lange; Shih-Hang Chang

This study investigates the damping properties of Cu–Al–Mn shape memory alloys (SMAs) with various chemical compositions and the effects of the addition of quaternary alloying elements Ag and Nb on the microstructure, martensitic transformation behavior, and damping capacity of SMAs. Compared to other Cu–12Al–xMn (x = 4–7 wt. %) SMAs, Cu–12Al–5Mn has a more significant inherent and intrinsic internal friction (IFPT + IFI) peak above room temperature. The addition of Ag or Nb to Cu–12Al–5Mn reduced the grain size, thereby increasing the hardness of the alloys; however, the damping capacity and temperature of the IFPT + IFI peak decreased simultaneously. The addition of Ag to Cu–12Al–5Mn significantly reduced the damping capacity (IFPT+IFI peak) because of the notable decrease in the amount of transformed martensite. Moreover, the addition of Nb to Cu–12Al–5Mn caused the AlNb3 phase to precipitate, limiting the mobility of the martensite variant interfaces and slightly decreasing the damping capacity (IFPT + IFI peak). Among the Ag- and Nb-doped Cu–12Al–5Mn SMAs, Cu–12Al–5Mn–1 Nb showed not only a significantly higher hardness but also a higher IFPT + IFI peak, with tan δ exceeding 0.01 at approximately 50 °C.

ScienceDirect: Journal of Alloys and Compounds; 3. October 2022

6th Cellular Materials CellMAT 2020 (07.10.-09.10.2020)

Fiber and Fiber-Surface Treatment Effects in Foamability of Carbon Fiber Reinforced Aluminum Alloy Composites Foam

Light materials have become very important in most manufacturing sectors such as aviation and transportation industries. Much research has been done to improve the mechanical properties of lightweight materials, especially lightweight, high-performance aluminum foam composite materials. The mechanical properties of carbon fiber reinforced aluminum foam have the potential to depend on wetting and bonding of carbon fiber in the aluminum matrix. This paper provides a systematic design and procedure for developing aluminum foam composites using carbon fiber as a reinforcement and AlMg4Si8 alloy as a matrix (AMFC-aluminum matrix foam composite) were produced by powder metallurgy. Nickel coating on the carbon fiber surface is applied to control the reactivity of the interface of the fiber with aluminum during the manufacture of the composite to improve wettability between carbon fiber and aluminum. The effects of chemical oxidation and nickel coating on carbon fiber in the wettability of carbon fiber in aluminum foam were confirmed scanning electron microscopic analysis. Digital images produced by the imaging system are used with the MATLAB algorithm to determine the surface porosity and pore areaof aluminum foam in an efficient manner. The results can have important implications for the processing of carbon fiber reinforced aluminum foam composites and their mechanical properties.

Zertifikat für die erfolgreiche Teilnahme an der Asia Pacific Conference von Herrn Ferdinandus Damanik

Chemical oxidation and electroless deposition nickel coating of MWCNT (Multi-walled carbon nanotubes) have been carried out to improve the distribution and the wettability of MWCNT in the aluminum foam. MWCNT reinforced AlMg4Si8 foam (AMFC-aluminum matrix foam composite) were produced by
powder metallurgy. The effects of chemical oxidation and nickel coating on MWCNT in the dispersion of MWCNT in the aluminum foam were confirmed by scanning electron microscopic analysis. Observation of the distribution of the MWCNT in the aluminum foam matrix showed that the technique is effective in dispersing and increase the wettability of the MWCNT coated nickel within the aluminum foam matrix.

NEUES BUCH "METALLSCHÄUME" erscheint im Juli 2020

G. Lange

Metallschäume: - Herstellung, Eigenschaften, Potenziale und Forschungsansätze – mit Schwerpunkt auf Aluminiumschäume; DE GRUYTER GmbH Verlag; ISBN-13: 978-3-11-068155-0; Veröffentlichung am 22. Juli 2020

IN-TECH 2019

Das Fachgebiet Metallische Werkstoffe und Verbundwerkstoffe ist dieses Jahr mit dem Thema "Effect of Nickel coated of Carbon Fiber on Distribution of Carbon Fiber Reinforced Aluminium (AlSi7) Foam Composite by Powder Metallurgy" vertreten. 

IN-TECH 2019

Taschenbuch für Aluminiumschäume

T. Hipke, G. Lange, R. Poss;
Taschenbuch für Aluminiumschäume; Neudruck der 1. Auflage;
Beuth Verlag GmbH; Berlin; 2014; ISBN 978-3-410-22071-8