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Thermomechanical Treatment During Rolling and Cooling
Published in Vladimir B. Ginzburg, Metallurgical Design of Flat Rolled Steels, 2020
Similarly to aluminum nitride, vanadium nitride provides grain refinement. The range of vanadium and nitrogen contents that will give the necessary amount of aluminum nitride for grain refinement is given by: ([Vt]−0.02)([Nt]−0.02×14/51)=1.6×10−4 where [Vt] = total vanadium content of the steel, wt%. For example, for an electric arc steel, with a typical nitrogen content of 0.008wt%N, the vanadium content is equal to 0.084wt%V.
Carbon Nanomaterials for Sandwich-Type Energy-Storage Devices
Published in Kun Zhou, Carbon Nanomaterials, 2020
Compared to simple CNFs, porous and hierarchical CNFs demonstrate enhanced specific capacitance by offering relatively large electrode/electrolyte interface for charge transfer reactions [38]. Kim et al. prepared zinc oxide containing porous activated CNFs (ZnO/ACNFs) through one-step electrospinning using zinc acetate and polyacrylonitrile, followed by thermal treatment [19]. The zinc acetate could enhance the reaction rate catalytically and create more pores on the surface of CNFs during the thermal treatment. The energy density of the ZnO/ACNFs electrode reached 22.7–17.7 Wh kg−1 at a power density of 400–4000 W kg−1. Na et al. synthesized high-capacitance nitrogen and fluorine-doped mesoporous CNFs (NFMCNFs) using a hydrothermal treatment to introduce porosity and a vacuum plasma process to introduce heteroatoms into the carbon lattice [39]. Ran et al. fabricated hierarchically porous CNF@VN nanoparticles using the method of phase-separation mediated by the PAA-b-PAN-b-PAA tri-block copolymer assembled on the surface of CNFs [40]. After thermal treatment under NH3/N2 atmospheric conditions, plenty of vanadium nitride (VN) nanoparticles were formed from NH4VO3 and distributed uniformly on the CNF surface. A capacitance of 240.5 F g−1 was generated by the CNF@VN electrode at 0.5 A g−1.
Inorganic Materials-Based Next-Generation Supercapacitors
Published in Inamuddin, Rajender Boddula, Mohd Imran Ahamed, Abdullah Mohamed Asiri, Inorganic Nanomaterials for Supercapacitor Design, 2019
Muhammad Aamir, Arshad Farooq Butt, Javeed Akhtar
Metal nitrides have shown good electrochemical properties, and high thermal stability. In this context, vanadium nitride has been the most extensively explored material for supercapacitance application. The high specific supercapacitance of about 1340 Fg−1 with 1.6 × 106 Sm−1 electrical conductance was reported for this material (Choi, Blomgren, and Kumta 2006). Electrochemical performance of the vanadium nitride depends upon the heat treatment of material during synthesis. For example, at elevated temperature of about 1000°C, the crystallite size of the material was increased, which results in decease of specific supercapacitance. The origin of supercapacitance performance of the metal nitride materials is based on the surface oxide or oxynitride groups and double-layer charging. VN nanoparticles undergo aggregation that results in poor electrochemical performance and ineffective contact; to overcome this issue, the 1D VN nanofibers were fabricated by an electrospinning method (Xu, Wang et al. 2015b). These nanofibers have shown high specific capacitance of about 291.5 Fg−1 at 0.5 Ag−1. Thermally stable layered vanadium bronze was synthesized and has shown specific capacitance of about 1937 mF cm−3 (Bi et al. 2015). However, limited rate capability is associated with these metal nitrides. The rate capability can be increased by fabricating the VN/CNT composite, which has more ability to retain the specific capacitance compared to pure VN materials (Ghimbeu et al. 2011).
Tribological Behavior of VN-MoS2/Ag Composites over a Wide Temperature Range
Published in Tribology Transactions, 2021
Weiqi Jing, Shuangming Du, Shu Chen, Eryong Liu, Huiling Du, Hui Cai
Vanadium nitride (VN) ceramics are widely used as structural materials in cutting tools and abrasives, due to their high melting point, high hardness, and high thermochemical stability (8). Gassner et al. (9) deposited a VN coating by magnetron sputtering technology and the friction coefficients of the VN coating at 700 °C were 0.37 and 0.32 with alumina balls and stainless steel balls, respectively. The VO2 and V2O5 generated on the contact interface played an excellent lubricating role. Aouadi et al. (10) prepared a VN/Ag “adaptive” lubricating coating by magnetron sputtering technology, and the friction coefficient of this coating at 25–1000 °C was 0.37–0.12. However, the wear rate of the VN/Ag coating was not reported. Further analysis indicated that the continuous lubrication mechanism of the VN/Ag adaptive lubricating coating in a wide temperature range was dominated by the variation of lubricating phases with test temperature, which acted as an adaptive lubrication.