A hybrid membrane pseudocapacitive deionization (MPDI) system consisting of a hydrated vanadium pentoxide (hV O )-decorated multi-walled carbon nanotube (MWCNT) electrode and one activated carbon electrode enables sodium ions to be removed by pseudocapacitive intercalation with the MWCNT-hV O electrode and chloride ion to be removed by non-faradaic electrosorption of the porous carbon electrode. The MWCNT-hV O electrode was synthesized by electrochemical deposition of hydrated vanadium pentoxide on the MWCNT paper. The stable electrochemical operating window for the MWCNT-hV O electrode was between -0.5 V and +0.4 V versus Ag/AgCl, which provided a specific capacity of 44 mAh g (corresponding with 244 F g ) in aqueous 1 m NaCl. The desalination performance of the MPDI system was investigated in aqueous 200 mm NaCl (brackish water) and 600 mm NaCl (seawater) solutions. With the aid of an anion and a cation exchange membrane, the MPDI hybrid cell was operated from -0.4 to +0.8 V cell voltage without crossing the reduction and oxidation potential limit of both electrodes. For the 600 mm NaCl solution, the NaCl salt adsorption capacity of the cell was 23.6±2.2 mg g , which is equivalent to 35.7±3.3 mg g normalized to the mass of the MWCNT-hV O electrode. Additionally, we propose a normalization method for the electrode material with faradaic reactions based on sodium uptake capacities.

Due to their applicability for manufacturing dense, hard and stable coatings, Physical Vapor Deposition (PVD) techniques, such as High Power Impulse Magnetron Sputtering (HiPIMS), are currently used to deposit transition metal nitrides for tribological applications. Cr-Al-N is one of the most promising ceramic coating systems owing to its remarkable mechanical and tribological properties along with excellent corrosion resistance and high-temperature stability. This work explores the possibility of further improving Cr-Al-N coatings by modulation of its microstructure. Multilayer-like Cr1−xAlxN single films were manufactured using the angular oscillation of the substrate surface during HiPIMS. The sputtering process was accomplished using pulse frequencies ranging from 200 to 500 Hz and the resulting films were evaluated with respect to their hardness, Young’s modulus, residual stresses, deposition rate, crystallite size, crystallographic texture, coating morphology, chemical composition, and surface roughness. The multilayer-like structure, with periodicities ranging from 250 to 550 nm, were found associated with misorientation gradients and small-angle grain boundaries along the columnar grains, rather than mesoscopic chemical modulation of the microstructure. This minute modification of microstructure along with associated compressive residual stresses are concluded to explain the increased hardness ranging from 25 to 30 GPa, which is at least 20% over that expected for a film of the same chemical composition grown by a conventional PVD processing route.

Nickel/carbon nanotube (Ni/CNT) composites with varying amounts of CNTs are deformed by high-pressure torsion (HPT) at different deformation temperatures to high strains, where no further refinement of the Ni matrix microstructure is observed. Mean Ni grain sizes increase with increasing HPT deformation temperature, while the size of the CNT agglomerates is significantly reduced. Additionally, the distribution of the agglomerates in the metal matrix becomes more homogenous. To investigate the mechanical performance of the HPT-deformed composites, uniaxial tensile and compression tests are conducted. Depending on the HPT deformation temperature and the resulting microstructure, either brittle or ductile fracture occurs, and the ultimate tensile strength varies between 900 and 2100 MPa. Increased HPT deformation temperatures induce a decrease in the anisotropy of the mechanical properties, mainly caused by a shrinking of the CNT agglomerates. It is shown, that tuning the HPT deformation temperature is the key for optimizing both the microstructure and the mechanical performance.

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