The highly exfoliated Ti
3
C
2
T
x
nanosheets were synthesized by selective etching of the starting material of Ti
3
AlC
2
using 40 % concentrated HF solution at 65 °C for 5 h. The effect of HF ...treatment temperature on the exfoliation degree was investigated by characterizing the morphology and microstructure of the Ti
3
C
2
T
x
nanosheets using SEM, XRD, and TEM. The results showed that the exfoliation degree of Ti
3
C
2
T
x
was increased with increasing temperature. The role of the termination groups produced during HF treatment on the exfoliation degree was discussed. The tribological property of the prepared Ti
3
C
2
T
x
nanosheets as additives in PAO8 base oil was measured. The maximum reduction of friction and wear was achieved under additive concentration of 0.8 wt% for the highly exfoliated Ti
3
C
2
T
x
nanosheets. The different effects of Ti
3
C
2
T
x
additives on the average friction coefficient and wear volume were analyzed, respectively.
A TiO2-Ti3C2Tx nanocomposite was prepared using a simple and facile one-step hydrothermal method. The small sized TiO2 nanoparticles were synthesized and assembled on the surface of Ti3C2Tx ...nanosheets using Ti3C2Tx itself as titanium source by in-situ technique. The microstructure of TiO2-Ti3C2Tx nanocomposite was characterized by means of XRD、FESEM、TEM、XPS and Raman, respectively. The effects of ethanol and hydrothermal holding time on the size of TiO2 nanoparticles were investigated. The results show that adding proper amount of ethanol into pure water results in decrease of the size of TiO2 nanoparticles. Under ethanol-water mixed solution, increasing the time of hydrothermal treatment results in growth and even aggregation of TiO2 nanoparticles. The TiO2 nanoparticles with average particle size of 30nm were obtained when the hydrothermal treatment was conducted in ethanol-water mixed solution at 200℃ for 12h.
A 2Cr13 steel was gas nitrided in pure NH
3 gas atmosphere at 793
K for 20
h. The microstructure, composition and microhardness of the nitrided samples were examined. The tribological behaviour of ...the nitrided 2Cr13 steel in air and vacuum was investigated in order to analyse effects of the nitriding on wear resistance of the 2Cr13 steel. The results show that the nitrided layer consists of a compound layer and diffusion zone. The nitriding increases both the surface hardness and wear resistance of 2Cr13 steel in air and vacuum, and the anti-wear characteristic of the nitrided 2Cr13 steel in vacuum is much higher than that in air. The nitrided layer exhibits a mild wear in air, and avoids the severe wear that happens on the unnitrided steel. While the adhesion dominates the wear process in vacuum. The material transfer between the wear couples helps to improve the tribological characteristics of the nitrided layer in vacuum.
The FeOOH has been a hotspot in the field of electrochemical research over recent years owing to its typical channel-type nanoporous structure and high theoretical specific capacitance. However, the ...poor electrical conductivity limits the applications in supercapacitors. In this investigation, the nanocomposites with amorphous FeOOH on Ti3C2Tx nanosheets were one-step chemically synthesized by using FeCl3·6H2O, NH4HCO3, and Ti3C2Tx(MXene) at room temperature. The nanocomposite samples have been characterized by XRD, SEM, TEM, XPS, cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS) measurements. The results show that the capacitive performance is remarkably improved by introducing highly conductive Ti3C2Tx and being composited with amorphous FeOOH. The specific capacitance of the as-prepared nanocomposite reaches 217 F g−1 at current density of 1 A g−1 which is much higher than that of amorphous FeOOH. It also exhibits good rate performance and high charge-discharge cycling stability. The enhancement in electrochemical performance is mainly attributed to the open layered structure with amorphous FeOOH nanoparticles uniformly distributed on Ti3C2Tx nanosheets, which has the enlarged electrode-electrolyte interface area, the shortened diffusion path of ions, and the improved electrical conductivity provided by the conductive Ti3C2Tx frame.
Display omitted
•A novel amorphous FeOOH-Ti3C2Tx nanocomposites were synthesized at room temperature.•Amorphous FeOOH nanoparticles uniformly distribute on surface of Ti3C2Tx nanosheets.•FeOOH/Ti3C2Tx nanocomposites exhibits high rate capability and excellent cycling stability.
Tribological behaviour of the nitrided layer sliding against self-mating under dry sliding and grease-lubricated conditions in vacuum was investigated on a pin-on-disk type tribometer, with the ...interaction among the nitrided layer and grease being focused on. The morphologies of the worn surfaces were observed by scanning electron microscopy (SEM). The chemical states of typical elements on the worn surfaces of the nitrided disks and pins were examined by means of X-ray photoelectron spectroscopy (XPS). The chemical compositions of grease samples taken from worn surfaces on the nitrided disks were analysed by Fourier transform infrared spectroscopy (FTIR). Experimental results show that under grease-lubricated conditions, the nitrided layer exhibits lower average friction coefficient and higher wear resistance than those for the dry sliding. In the former case, the wear of nitrided layer shows a transition from the mild adhesive to the severe adhesive wear and even to the delamination wear, with increasing normal load from 10 to 90
N. In the latter case, a transition takes place from the mild abrasive wear to the micro-fatigue type one with increasing the normal load. Tribochemical reactions occur between the nitrided layer and perfluoropolyalkyl ether (PFPE) grease during the lubricated sliding of the nitrided disks against self-mating in vacuum.
The FeOOH has been a hotspot in the field of electrochemical research over recent years owing to its typical channel-type nanoporous structure and high theoretical specific capacitance. However, the ...poor electrical conductivity limits the applications in supercapacitors. In this investigation, the nanocomposites with amorphous FeOOH on Ti3C2Tx nanosheets were one-step chemically synthesized by using FeCl3·6H2O, NH4HCO3, and Ti3C2Tx(MXene) at room temperature. The nanocomposite samples have been characterized by XRD, SEM, TEM, XPS, cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS) measurements. The results show that the capacitive performance is remarkably improved by introducing highly conductive Ti3C2Tx and being composited with amorphous FeOOH. The specific capacitance of the as-prepared nanocomposite reaches 217 F g−1 at current density of 1 A g−1 which is much higher than that of amorphous FeOOH. It also exhibits good rate performance and high charge-discharge cycling stability. The enhancement in electrochemical performance is mainly attributed to the open layered structure with amorphous FeOOH nanoparticles uniformly distributed on Ti3C2Tx nanosheets, which has the enlarged electrode-electrolyte interface area, the shortened diffusion path of ions, and the improved electrical conductivity provided by the conductive Ti3C2Tx frame.
The highly exfoliated Ti3C2Tx nanosheets were synthesized by selective etching of the starting material of Ti3AlC2 using 40 % concentrated HF solution at 65 °C for 5 h. The effect of HF treatment ...temperature on the exfoliation degree was investigated by characterizing the morphology and microstructure of the Ti3C2Tx nanosheets using SEM, XRD, and TEM. The results showed that the exfoliation degree of Ti3C2Tx was increased with increasing temperature. The role of the termination groups produced during HF treatment on the exfoliation degree was discussed. The tribological property of the prepared Ti3C2Tx nanosheets as additives in PAO8 base oil was measured. The maximum reduction of friction and wear was achieved under additive concentration of 0.8 wt% for the highly exfoliated Ti3C2Tx nanosheets. The different effects of Ti3C2Tx additives on the average friction coefficient and wear volume were analyzed, respectively.
The highly exfoliated Ti.sub.3C.sub.2T.sub.x nanosheets were synthesized by selective etching of the starting material of Ti.sub.3AlC.sub.2 using 40 % concentrated HF solution at 65 °C for 5 h. The ...effect of HF treatment temperature on the exfoliation degree was investigated by characterizing the morphology and microstructure of the Ti.sub.3C.sub.2T.sub.x nanosheets using SEM, XRD, and TEM. The results showed that the exfoliation degree of Ti.sub.3C.sub.2T.sub.x was increased with increasing temperature. The role of the termination groups produced during HF treatment on the exfoliation degree was discussed. The tribological property of the prepared Ti.sub.3C.sub.2T.sub.x nanosheets as additives in PAO8 base oil was measured. The maximum reduction of friction and wear was achieved under additive concentration of 0.8 wt% for the highly exfoliated Ti.sub.3C.sub.2T.sub.x nanosheets. The different effects of Ti.sub.3C.sub.2T.sub.x additives on the average friction coefficient and wear volume were analyzed, respectively.
Plasma- and gas-nitrided 2Cr13 samples were characterized using optical microscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD), and microhardness testing techniques. Nitrogen ...concentration profiles in the cross-sections of the nitrided samples were obtained by glow discharge optical spectroscopy (GDOS). Residual stress profiles along depth of the nitrided samples were measured using an X-ray stress tester. The tribological behaviour of the plasma- and the gas-nitrided samples in vacuum was investigated in order to analyse the effect of nitriding on wear resistance of the 2Cr13 steel. The results show the tribological properties of the 2Cr13 steel in vacuum are improved considerably by plasma nitriding and gas nitriding resulted from microstructure modification and surface hardening during nitriding. The plasma-nitrided samples have better wear resistance than the gas-nitrided samples under 30
N, while the gas-nitrided samples have higher wear resistance under 90
N. With increasing normal load from 30
N to 90
N, the wear mechanism shows a transition from mild adhesive and abrasive wear to severe adhesive or even delamination wear. The plasma-nitrided sample has thicker compound layer than the gas-nitrided sample, resulting that it exhibits more intensive delamination under high load of 90
N.
A 2Cr13 steel was modified by plasma nitriding. The microstructure, phase composition and microhardness of the nitrided samples were examined. The friction and wear behaviour of the nitrided and ...unnitrided samples sliding against self-mating under PFPE grease-lubricated conditions in vacuum was investigated on a pin-on-disk type tribometer, with the interactions among the nitrided layer and grease to be focused on. The morphologies of the worn surfaces were observed using a scanning electron microscope. The chemical states of several typical elements on the worn surfaces were examined by means of X-ray photoelectron spectroscopy. The chemical compositions of grease samples taken from the worn surfaces were analyzed by Fourier transform infrared spectroscopy (FTIR). Results show that the nitrided steel has better friction-reducing and anti-wear abilities than the unnitrided one under PFPE grease-lubricated conditions. In the former case, the wear of nitrided steel shows a transition from mild abrasive wear to fatigue one with increasing normal load. In the latter case, wear mechanism of unnitrided steel under all load applied is a combination of the severe abrasion and fatigue.
