TiAl/Ti2AlC composites were prepared by in-situ hot pressing of TilAl/C powders mixtures and sintered at different temperatures were investigated by X- ray diffraction （ XRD ） of samples. The reaction procedure of T...TiAl/Ti2AlC composites were prepared by in-situ hot pressing of TilAl/C powders mixtures and sintered at different temperatures were investigated by X- ray diffraction （ XRD ） of samples. The reaction procedure of Ti-Al-C system could be divided into three stnges. Below 900℃ , Ti reacts with Al to form TiAl intermetallics ; above 900 ℃ , C reacts with remain Ti to form TiC triggered by the exothermal reaction of Ti and Al ; TiAl reacts with TiC to produce dense TiAl/Ti2AlC compasites.In the holding stage, ternary Ti2AlC develops to layered polycrystal and composites pyknosis in the meanwhile. The mechanism of synthesis and microstructure was especially discussed.展开更多
Cu/Ti2AlC composites were fabricated by vacuum hot-pressing technique. Phase composition was analyzed by XRD and morphology of fracture was observed by SEM. Physical performance such as density, resistivity, hardness ...Cu/Ti2AlC composites were fabricated by vacuum hot-pressing technique. Phase composition was analyzed by XRD and morphology of fracture was observed by SEM. Physical performance such as density, resistivity, hardness and friction coefficient with different volume fraction of Cu/Ti2AlC composites were studied. When the content of Ti2AlC increased from 10% to 70%, the relative density reduced from 99.38% to 90.56% and the resistivity increased significantly. Hardness reached the maximum value when Ti2AlC was at 60% and friction coefficient declined with the increasing of Ti2AlC. Cu/Ti2AlC composites, showing good conductivity properties and friction performance. Oxidation resistance enhanced obviously with the content of Ti2AlC increasing. Cu-60%Ti2AlC sample possessed optimum thermal shock resistance, and no cracking was found at 600 ℃ cycled for 10 times and 900 ℃ cycled for 1 time.展开更多
By using the spark plasma sintering process, Ti2AlC/TiAlcomposite with the addition of Niobium （Nb） was prepared in-situ and the microstructure of Ti2AlC/TiAl （Nb） composite was investigated by means of transmissi...By using the spark plasma sintering process, Ti2AlC/TiAlcomposite with the addition of Niobium （Nb） was prepared in-situ and the microstructure of Ti2AlC/TiAl （Nb） composite was investigated by means of transmission electron microscopy （TEM） and high-resolution electron microscopy （HREM）. The results indicate that new-formed Ti2AIC particles disperse with a high degree of uniformity and well combine with the matrix. In the area of phase interface the d-spaces of Ti2AlC （100） and TiAI （110） were measured as 0.2648 nm and 0.2991 nm,respectively. The atom arrangement beside the interface was only partly corresponding, existing in semicoherent state. On the contrary, in the area of grain interface the d-spaces of TiAl （100） and TiAl （110） were measured as 0.2462 nm and 0.2631 nm,respectively and the atom arrangement beside the interface was almost corresponding, existing in coherent state.展开更多
The interfacial reaction behavior of Al and Ti_(3)AlC_(2)at different pouring temperatures and its effect on the microstructure and mechanical properties of the composites were investigated.The results show that the a...The interfacial reaction behavior of Al and Ti_(3)AlC_(2)at different pouring temperatures and its effect on the microstructure and mechanical properties of the composites were investigated.The results show that the addition of3.0 wt.%Ti_(3)AlC_(2)refines the average grain size ofα(Al)in the composite by 50.1%compared to Al6061 alloy.Morphological analyses indicate that an in-situ Al_(3Ti)transition layer of-180 nm in thickness is generated around the edge of Ti_(3)AlC_(2)at 720℃,forming a well-bonded Al-Al_(3Ti)interface.At this processing temperature,the ultimate tensile strength of A16061-3.0 wt.%Ti_(3)AlC_(2)composite is 199.2 MPa,an improvement of 41.5%over the Al6061 matrix.Mechanism analyses further elucidate that 720℃is favourable for forming the nano-sized transition layer at the Ti_(3)AlC_(2)edges.And,the thermal mismatch strengthening plays a dominant role in this state,with a strengthening contribution of about 74.8%.展开更多
In this work,flexible photothermal PVA/Ti_(2)O_(3) composite films with different amount(0 wt%,5 wt%,10 wt%,15 wt%)of Ti_(2)O_(3) particles modified by steric acid were prepared by a simple solution casting method.The...In this work,flexible photothermal PVA/Ti_(2)O_(3) composite films with different amount(0 wt%,5 wt%,10 wt%,15 wt%)of Ti_(2)O_(3) particles modified by steric acid were prepared by a simple solution casting method.The microstructures,XRD patterns,FTIR spectra,UV-Vis-NIR spectra thermo-conductivity,thermo-stability and photothermal effects of these composite films were all characterized.These results indicated that Ti_(2)O_(3) particles were well dispersed throughout the polyvinyl alcohol(PVA)matrix in the PVA/Ti_(2)O_(3) composite films.And Ti_(2)O_(3) particles could also effectively improve the photothermal properties of the composite films which exhibited high light absorption and generated a high temperature(about 57.4℃for film with 15 wt%Ti_(2)O_(3) amount)on the surface when it was irradiated by a simulated sunlight source(1 kW/m^(2)).展开更多
Ti_(2)AlC/TiAl composites with different volume fractions were prepared by hot pressing technology,and their reinforced structural characteristics and mechanical properties were evaluated.The results showed that when ...Ti_(2)AlC/TiAl composites with different volume fractions were prepared by hot pressing technology,and their reinforced structural characteristics and mechanical properties were evaluated.The results showed that when the reinforced phase volume fraction of Ti_(2)AlC was 20%,three-dimensional interpenetrating network structures were formed in the composites.Above 20%,Ti_(2)AlC phase in the composites accumulated and grew to form thick skeletal networks.The microplastic deformation behavior of Ti_(2)AlC phase,such as kink band and delamination,improved the fracture toughness of the composites.Comparative analysis indicated that the uniform and small interconnecting network structures could further reinforce the composites.The bending strengths of composites prepared with 20 vol.%Ti_(2)AlC reached(900.9±45.0)MPa,which was 25.5% higher than that of TiAl matrix.In general,the co-continuous Ti_(2)AlC/TiAl composite with excellent mechanical properties can be prepared by powder metallurgy method.展开更多
Magnesium composites reinforced by N-deficient Ti_(2)AlN MAX phase were first fabricated by non-pressure infiltration of Mg into three-dimensional(3D)co-continuous porous Ti_(2)AlN_(x)(x=0.9,1.0)preforms.The relations...Magnesium composites reinforced by N-deficient Ti_(2)AlN MAX phase were first fabricated by non-pressure infiltration of Mg into three-dimensional(3D)co-continuous porous Ti_(2)AlN_(x)(x=0.9,1.0)preforms.The relationship between their mechanical properties and micro-structure is discussed with the assessment of 2D and 3D characterization.X-ray diffraction(XRD)and scanning electron microscopy detected no impurities.The 3D reconstruction shows that the uniformly distributed pores in Ti_(2)AlN_(x) preforms are interconnected,which act as infiltra-tion tunnels for the melt Mg.The compressive yield strength and microhardness of Ti_(2)AlN_(0.9)/Mg are 353 MPa and 1.12 GPa,respectively,which are 8.55%and 6.67%lower than those of Ti_(2)AlN/Mg,respectively.The typical delamination and kink band occurred in Ti_(2)AlN_(x) under compressive and Vickers hardness(V_(H))tests.Owing to the continuous skeleton structure and strong interfacial bonding strength,the crack ini-tiated in Ti_(2)AlN_(x) was blocked by the plastic Mg matrix.This suggests the possibility of regulating the mechanical performance of Ti_(2)AlN/Mg composites by controlling the N vacancy and the hierarchical structure of Ti_(2)AlN skeleton.展开更多
The fabrication process of Sm2O3 doped CeO2 reinforced Ti3AlC2 nano composites including the nano particle dispersion process by a hetero-coagulation process was developed using in-situ synthesis and densification pro...The fabrication process of Sm2O3 doped CeO2 reinforced Ti3AlC2 nano composites including the nano particle dispersion process by a hetero-coagulation process was developed using in-situ synthesis and densification process of Ti3AlC2. The effects of Sm2O2 doped CeO2 nano particles on mechanical properties of Ti3AlC2 were investigated. It was found that the presence of 20SDC nano particles in Ti3AlC2 was very effective to improve the mechanical properties of Ti3AlC2 without spoiling the unique characteristics of Ti3AlC2temary carbide.展开更多
Uncontrollable Li dendrite growth and infinite volume fluctuation during durative plating and stripping process gravely hinder the application of metallic Li electrode in lithium-oxygen batteries.Herein,oxygen vacancy...Uncontrollable Li dendrite growth and infinite volume fluctuation during durative plating and stripping process gravely hinder the application of metallic Li electrode in lithium-oxygen batteries.Herein,oxygen vacancy-rich TiO_(2)(Vo-TiO_(2))nanoparticles(NPs)uniformly dispersing on Ti_(3)C_(2)T_(x)(Vo-TiO_(2)/Ti_(3)C_(2) T_(x))with excellent lithiophilicity feature are presented as effective composite anodes,on which a dense and uniform Li growth behavior is observed.Based on electrochemical studies,mutiphysics simulation and theoretical calculation,it is found that Vo-TiO_(2) coupling with three dimensional(3 D)conductive Ti_(3)C_(2) T_(x) MXene forms highly ordered lithiophilic sites which succeed in guiding Li ions flux and adsorption,thus modulating the uniform Li nucleation and growth.As a result,this composite electrode is capable of preserving Li with high areal capacity of~10 mAh cm^(-2) without the presence of dendrites and large volume expansion.Consequently,the as-prepared Vo-TiO_(2)/Ti_(3)C_(2) T_(x)@Li anode shows outstanding performance including low voltage hysteresis(~19 mV)and superior durability(over 750 h).When assembling with the Vo-TiO_(2)/Ti_(3)C_(2) T_(x)@Li anodes,lithium-oxygen batteries also deliver enhanced cycling stability and improved rate performance.This work demonstrates the effectiveness of oxygen vacancies in guiding Li nucleating and plating behavior at initial stage and brings a promising strategy for promoting the development of advanced Li metal-based batteries.展开更多
AgCl/Ti_(3)C_(2)@TiO_(2)ternary composites were prepared to form a heterojunction structure between AgCl and TiO_(2)and introduce Ti3C2 as a cocatalyst.The as-prepared AgCl/Ti_(3)C_(2)@TiO_(2)composites showed higher ...AgCl/Ti_(3)C_(2)@TiO_(2)ternary composites were prepared to form a heterojunction structure between AgCl and TiO_(2)and introduce Ti3C2 as a cocatalyst.The as-prepared AgCl/Ti_(3)C_(2)@TiO_(2)composites showed higher photocatalytic activity than pure AgCl and Ti_(3)C_(2)@TiO_(2)for photooxidation of a 1,4-dihydropyridine derivative(1,4-DHP)and tetracycline hydrochloride(TCH)under visible light irradiation(λ>400 nm).The photocatalytic activity of AgCl/Ti_(3)C_(2)@TiO_(2)composites depended on Ti_(3)C_(2)@TiO_(2)content,and the catalytic activity of the optimized samples were 6.9 times higher than that of pure AgCl for 1,4-DHP photodehydrogenation and 7.3 times higher than that of Ti_(3)C_(2)@TiO_(2)for TCH photooxidation.The increased photocatalytic activity was due to the formation of a heterojunction structure between AgCl and TiO_(2)and the introduction of Ti3C2 as a cocatalyst,which lowered the internal resistance,sped up the charge transfer,and increased the separation efficiency of photogenerated carries.Photogenerated holes and superoxide radical anions were the major active species in the photocatalytic process.展开更多
文摘TiAl/Ti2AlC composites were prepared by in-situ hot pressing of TilAl/C powders mixtures and sintered at different temperatures were investigated by X- ray diffraction （ XRD ） of samples. The reaction procedure of Ti-Al-C system could be divided into three stnges. Below 900℃ , Ti reacts with Al to form TiAl intermetallics ; above 900 ℃ , C reacts with remain Ti to form TiC triggered by the exothermal reaction of Ti and Al ; TiAl reacts with TiC to produce dense TiAl/Ti2AlC compasites.In the holding stage, ternary Ti2AlC develops to layered polycrystal and composites pyknosis in the meanwhile. The mechanism of synthesis and microstructure was especially discussed.
基金Funded by Hubei Province Natural Science Foundation(No.2012FFB00608)the Youth Science and Technology Morning Program of Wuhan(No.201150431129)+1 种基金the Youth Science and Technology Program of Hubei Province Education Department(No.20121407)National Natural Science Foundation of China(No.51273059)
文摘Cu/Ti2AlC composites were fabricated by vacuum hot-pressing technique. Phase composition was analyzed by XRD and morphology of fracture was observed by SEM. Physical performance such as density, resistivity, hardness and friction coefficient with different volume fraction of Cu/Ti2AlC composites were studied. When the content of Ti2AlC increased from 10% to 70%, the relative density reduced from 99.38% to 90.56% and the resistivity increased significantly. Hardness reached the maximum value when Ti2AlC was at 60% and friction coefficient declined with the increasing of Ti2AlC. Cu/Ti2AlC composites, showing good conductivity properties and friction performance. Oxidation resistance enhanced obviously with the content of Ti2AlC increasing. Cu-60%Ti2AlC sample possessed optimum thermal shock resistance, and no cracking was found at 600 ℃ cycled for 10 times and 900 ℃ cycled for 1 time.
基金Funded by the Shandong Provincial Natural Science Foundation (No.22003F02)
文摘By using the spark plasma sintering process, Ti2AlC/TiAlcomposite with the addition of Niobium （Nb） was prepared in-situ and the microstructure of Ti2AlC/TiAl （Nb） composite was investigated by means of transmission electron microscopy （TEM） and high-resolution electron microscopy （HREM）. The results indicate that new-formed Ti2AIC particles disperse with a high degree of uniformity and well combine with the matrix. In the area of phase interface the d-spaces of Ti2AlC （100） and TiAI （110） were measured as 0.2648 nm and 0.2991 nm,respectively. The atom arrangement beside the interface was only partly corresponding, existing in semicoherent state. On the contrary, in the area of grain interface the d-spaces of TiAl （100） and TiAl （110） were measured as 0.2462 nm and 0.2631 nm,respectively and the atom arrangement beside the interface was almost corresponding, existing in coherent state.
基金financially supported by the National Natural Science Foundation of China(No.51965040)Science and Technology Project of Jiangxi Provincial Department of Transportation,China(No.2022H0048)。
文摘The interfacial reaction behavior of Al and Ti_(3)AlC_(2)at different pouring temperatures and its effect on the microstructure and mechanical properties of the composites were investigated.The results show that the addition of3.0 wt.%Ti_(3)AlC_(2)refines the average grain size ofα(Al)in the composite by 50.1%compared to Al6061 alloy.Morphological analyses indicate that an in-situ Al_(3Ti)transition layer of-180 nm in thickness is generated around the edge of Ti_(3)AlC_(2)at 720℃,forming a well-bonded Al-Al_(3Ti)interface.At this processing temperature,the ultimate tensile strength of A16061-3.0 wt.%Ti_(3)AlC_(2)composite is 199.2 MPa,an improvement of 41.5%over the Al6061 matrix.Mechanism analyses further elucidate that 720℃is favourable for forming the nano-sized transition layer at the Ti_(3)AlC_(2)edges.And,the thermal mismatch strengthening plays a dominant role in this state,with a strengthening contribution of about 74.8%.
基金Funded by the Youth Backbone Teacher Training Plan in University of Henan Province(No.21220028)Science and Technology Research Project of Henan Province(No.242102321066)+2 种基金Natural Science Foundation of Henan Province(No.232300420312)Henan University of Technology Young Backbone Teacher Training Plan(No.21421260)the Innovation Training Program for College Students in Henan Province(No.202310463046)。
文摘In this work,flexible photothermal PVA/Ti_(2)O_(3) composite films with different amount(0 wt%,5 wt%,10 wt%,15 wt%)of Ti_(2)O_(3) particles modified by steric acid were prepared by a simple solution casting method.The microstructures,XRD patterns,FTIR spectra,UV-Vis-NIR spectra thermo-conductivity,thermo-stability and photothermal effects of these composite films were all characterized.These results indicated that Ti_(2)O_(3) particles were well dispersed throughout the polyvinyl alcohol(PVA)matrix in the PVA/Ti_(2)O_(3) composite films.And Ti_(2)O_(3) particles could also effectively improve the photothermal properties of the composite films which exhibited high light absorption and generated a high temperature(about 57.4℃for film with 15 wt%Ti_(2)O_(3) amount)on the surface when it was irradiated by a simulated sunlight source(1 kW/m^(2)).
基金the financial supports from the National Natural Science Foundation of China(No.52065009)the Joint Funds of the Science and Technology Foundation of Guizhou Province,China(No.20157219)the Science and Technology Planning Project of Guizhou Province,China(No.20191069).
文摘Ti_(2)AlC/TiAl composites with different volume fractions were prepared by hot pressing technology,and their reinforced structural characteristics and mechanical properties were evaluated.The results showed that when the reinforced phase volume fraction of Ti_(2)AlC was 20%,three-dimensional interpenetrating network structures were formed in the composites.Above 20%,Ti_(2)AlC phase in the composites accumulated and grew to form thick skeletal networks.The microplastic deformation behavior of Ti_(2)AlC phase,such as kink band and delamination,improved the fracture toughness of the composites.Comparative analysis indicated that the uniform and small interconnecting network structures could further reinforce the composites.The bending strengths of composites prepared with 20 vol.%Ti_(2)AlC reached(900.9±45.0)MPa,which was 25.5% higher than that of TiAl matrix.In general,the co-continuous Ti_(2)AlC/TiAl composite with excellent mechanical properties can be prepared by powder metallurgy method.
基金financially supported by the National Natural Science Foundation of China(No.52175284)the State Key Lab of Advanced Metals and Materials(No.2021-ZD08)the Beijing Government Funds for the Cons tructive Project of Central Universities(No.353139535)。
文摘Magnesium composites reinforced by N-deficient Ti_(2)AlN MAX phase were first fabricated by non-pressure infiltration of Mg into three-dimensional(3D)co-continuous porous Ti_(2)AlN_(x)(x=0.9,1.0)preforms.The relationship between their mechanical properties and micro-structure is discussed with the assessment of 2D and 3D characterization.X-ray diffraction(XRD)and scanning electron microscopy detected no impurities.The 3D reconstruction shows that the uniformly distributed pores in Ti_(2)AlN_(x) preforms are interconnected,which act as infiltra-tion tunnels for the melt Mg.The compressive yield strength and microhardness of Ti_(2)AlN_(0.9)/Mg are 353 MPa and 1.12 GPa,respectively,which are 8.55%and 6.67%lower than those of Ti_(2)AlN/Mg,respectively.The typical delamination and kink band occurred in Ti_(2)AlN_(x) under compressive and Vickers hardness(V_(H))tests.Owing to the continuous skeleton structure and strong interfacial bonding strength,the crack ini-tiated in Ti_(2)AlN_(x) was blocked by the plastic Mg matrix.This suggests the possibility of regulating the mechanical performance of Ti_(2)AlN/Mg composites by controlling the N vacancy and the hierarchical structure of Ti_(2)AlN skeleton.
文摘The fabrication process of Sm2O3 doped CeO2 reinforced Ti3AlC2 nano composites including the nano particle dispersion process by a hetero-coagulation process was developed using in-situ synthesis and densification process of Ti3AlC2. The effects of Sm2O2 doped CeO2 nano particles on mechanical properties of Ti3AlC2 were investigated. It was found that the presence of 20SDC nano particles in Ti3AlC2 was very effective to improve the mechanical properties of Ti3AlC2 without spoiling the unique characteristics of Ti3AlC2temary carbide.
基金financially supported by the National Natural Science Foundation of China(Grant No.21905033)the Science and Technology Department of Sichuan Province(Grant No.2019YJ0503)the State Key Laboratory of Vanadium and Titanium Resources Comprehensive Utilization(2020P4FZG02A)。
文摘Uncontrollable Li dendrite growth and infinite volume fluctuation during durative plating and stripping process gravely hinder the application of metallic Li electrode in lithium-oxygen batteries.Herein,oxygen vacancy-rich TiO_(2)(Vo-TiO_(2))nanoparticles(NPs)uniformly dispersing on Ti_(3)C_(2)T_(x)(Vo-TiO_(2)/Ti_(3)C_(2) T_(x))with excellent lithiophilicity feature are presented as effective composite anodes,on which a dense and uniform Li growth behavior is observed.Based on electrochemical studies,mutiphysics simulation and theoretical calculation,it is found that Vo-TiO_(2) coupling with three dimensional(3 D)conductive Ti_(3)C_(2) T_(x) MXene forms highly ordered lithiophilic sites which succeed in guiding Li ions flux and adsorption,thus modulating the uniform Li nucleation and growth.As a result,this composite electrode is capable of preserving Li with high areal capacity of~10 mAh cm^(-2) without the presence of dendrites and large volume expansion.Consequently,the as-prepared Vo-TiO_(2)/Ti_(3)C_(2) T_(x)@Li anode shows outstanding performance including low voltage hysteresis(~19 mV)and superior durability(over 750 h).When assembling with the Vo-TiO_(2)/Ti_(3)C_(2) T_(x)@Li anodes,lithium-oxygen batteries also deliver enhanced cycling stability and improved rate performance.This work demonstrates the effectiveness of oxygen vacancies in guiding Li nucleating and plating behavior at initial stage and brings a promising strategy for promoting the development of advanced Li metal-based batteries.
基金This work was supported by the Opening Project of the Key Laboratory of Green Chemistry of Sichuan Institutes of Higher Education(LZJ2002)the Open Project of Chemical Synthesis and Pollution Control Key Laboratory of Sichuan Province(CSPC2016-3-2).
文摘AgCl/Ti_(3)C_(2)@TiO_(2)ternary composites were prepared to form a heterojunction structure between AgCl and TiO_(2)and introduce Ti3C2 as a cocatalyst.The as-prepared AgCl/Ti_(3)C_(2)@TiO_(2)composites showed higher photocatalytic activity than pure AgCl and Ti_(3)C_(2)@TiO_(2)for photooxidation of a 1,4-dihydropyridine derivative(1,4-DHP)and tetracycline hydrochloride(TCH)under visible light irradiation(λ>400 nm).The photocatalytic activity of AgCl/Ti_(3)C_(2)@TiO_(2)composites depended on Ti_(3)C_(2)@TiO_(2)content,and the catalytic activity of the optimized samples were 6.9 times higher than that of pure AgCl for 1,4-DHP photodehydrogenation and 7.3 times higher than that of Ti_(3)C_(2)@TiO_(2)for TCH photooxidation.The increased photocatalytic activity was due to the formation of a heterojunction structure between AgCl and TiO_(2)and the introduction of Ti3C2 as a cocatalyst,which lowered the internal resistance,sped up the charge transfer,and increased the separation efficiency of photogenerated carries.Photogenerated holes and superoxide radical anions were the major active species in the photocatalytic process.
