Mian Li

Localized superplastic deformation of nanocrystalline 3Y-TZP ceramics under cyclic tensile fatigue at ambient temperature

Cyclic tensile fatigue tests were performed on 100±20 nm, and 0.35 μm 3Y-TZP ceramic specimens at room temperature. Localized superplastic deformation of the grains in the 100 nm material at and near to the fracture surfaces was first identified by AFM imaging. Slip band-like microfeatures, similar to those reported on some metals, were also unexpectedly seen to develop on the side faces. In contrast, the 0.35 μm specimens retained their equiaxed grain morphology after undergoing similar testing conditions. The micromechanisms underlining these phenomena were discussed. Grain boundary diffusion of the respective atomic species is reasoned to be the major governing process in operation. And the contribution of a dislocation slip mechanism is considered to play a possible or parallel role.

Facile preparation of in situ coated Ti3C2Tx/Ni0.5Zn0.5Fe2O4 composites and their electromagnetic performance

A novel family of Ti3C2Tx/ferrite composites with high reflection loss was developed using a facile in situ co-precipitation method. The as-synthesized Ti3C2Tx/ferrite composite with a 5 wt% Ti3C2Tx MXenes loading exhibited high reflection loss (−42.5 dB) at 13.5 GHz. The effective absorption bandwidth of the 5 wt% Ti3C2Tx/Ni0.5Zn0.5Fe2O4 composite reached ∼3 GHz (12–15 GHz) in the K-band. The incorporation of Ti3C2Tx MXenes improved the electromagnetic impedance of the Ti3C2Tx/Ni0.5Zn0.5Fe2O4 composite resulting from the enhanced electrical conductivity. The potential electromagnetic wave absorption mechanisms were revealed, which may contain magnetic loss, dielectric loss, conductivity loss, multiple reflections, and scattering. The technique is facile, fast, scalable, and favorable for the commercialization of this composite. This study provides a potential way to develop EM wave absorbing materials for a large family of MXenes/ferrite composites.

Copper–SiC whiskers composites with interface optimized by Ti 3 SiC 2

In the present work, we propose Ti3SiC2 as the interlayer material to improve the interfacial bonding properties of SiC whiskers-reinforced copper matrix composites. For the first time, Ti3SiC2 coating was in situ fabricated on the surface of SiC whiskers in a molten salt bath. Ti3SiC2-coated SiC whiskers- and bare SiC whiskers-reinforced copper matrix composites were fabricated by spark plasma sintering. The influence of the Ti3SiC2 interlayer on the interfacial properties, mechanical properties, and thermal conductivity of the composites was investigated. The results show that the Ti3SiC2 interlayer can largely improve the interfacial bonding properties of the composites. Therefore, the composites reinforced with Ti3SiC2-coated SiC whiskers exhibit much higher tensile strength than the composites reinforced with bare SiC whiskers. The results also show that the Ti3SiC2 interlayer could decrease the thermal conductivity of the composites in certain extent.

In situ formation of NaTi2(PO4)3 cubes on Ti3C2 MXene for dual-mode sodium storage

Due to the promising application of sodium ion batteries (SIBs) in stationary energy storage, great effort has been devoted to the development of anode materials, such as capacitance-type MXenes, battery-type metal sulfides/selenides and red phosphorus. However, these materials severely suffer from either low rate capability or insufficient lifespans. Toward this end, a dual-mode sodium storage concept is proposed based on the simultaneous incorporation of capacitance-type and battery-type electrochemical behavior. Correspondingly, a novel strategy of in situ formation of NaTi2(PO4)3 cubes on Ti3C2 MXene nanosheets in a liquid transformation way was developed to fabricate a dual-mode anode material (denoted as MXene@NTP-C). Acting as the anode material for SIBs, MXene@NTP-C shows outstanding rate capacities (49% capacity retention at 10 A g−1) and remarkable cycling performance (remaining stable after 10 000 cycles at 5 A g−1). Electrochemical and kinetic analyses reveal that this excellent performance was attributed to the dual-mode accommodation (46–71% capacitive contribution at 0.1–1 mV s−1) of sodium onto pseudocapacitance-type MXene and into battery-type NaTi2(PO4)3. The dual-mode sodium storage concept proposed here provides an opportunity to tackle the trade-off between energy and power densities.