In recent years, random metacomposites with tunable negative permittivity have aroused widespread attention because of their distinctive properties and broad potential prospects. It is indicated that an enormously negative permittivity with a large value is not conducive to performance optimizing and impedance matching. In this article, the 2D Mxene Ti3C2Tx was selected as the conductive phase instead of metal and carbon materials to fabricate Ti3C2Tx/poly(vinylidene fluoride) metacomposites. The results of dielectric properties indicated that the conductive Ti3C2Tx networks were formed by Ti3C2Tx contacting with each other near the percolation threshold (ƒc). The as‐obtained metacomposites containing 75 wt% Ti3C2Tx generated percolating phenomenon. Additionally, when the fraction of Ti3C2Tx was below ƒc, the frequency dispersion behaviors of conductivity were in accordance with the Jonscher's power law, which proved that conducting mechanism was dependent on hopping conduction. While above ƒc, the conductivity conformed to the Drude model and Lorentz model, which demonstrated a conductive behavior. Furthermore, the real part of permittivity transformed to negative value at 75 wt%, which can be explained as the existence of the low‐frequency plasma oscillation and electric‐dipole‐induced resonance. The dielectric loss of the metacomposite was also analyzed by the imaginary permittivity spectra. Small negative permittivity values in the range of −550 to −400 were observed, owing to the low free carrier concentration in composites. The appearance of weakly negative permittivity opened up a new direction in negative dielectric materials by 2D layered Ti3C2Tx nanomaterials.
In this study, the oxidation behavior of 2Cr13 stainless steels with/without TiC particles was investigated in a simulated marine environment at 550°C. The results showed that TiC particles greatly accelerated the oxidation rate of 2Cr13 steel during the cyclic oxidation reaction. At the same time, the effect of acceleration was alleviated by the small size and uniform distribution of TiC particles. As galvanic corrosion in the vicinity of TiC particles occurred in 3.5% NaCl solution spray, more NaCl particles deposited on the alloy surface, especially in the area around TiC particles. At 550°C, some shell‐like oxidation products were generated on the 2Cr13 steel surface due to TiC addition, and then the porous oxidation products provided poor protective ability. Besides, the defect and stress in the oxide scale was reduced due to the small size and uniform distribution of TiC particles in 2Cr13 steel.
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