The porosity of titanium foams obtained from the space holder technique was theoretically analyzed in the cases of volume shrinking, retaining and expanding during sintering. The relationship between porosity and spac...The porosity of titanium foams obtained from the space holder technique was theoretically analyzed in the cases of volume shrinking, retaining and expanding during sintering. The relationship between porosity and spacer content was compared under different conditions. The kind of volume change of macropores during sintering was discussed. The results indicate that the relationship between porosity and spacer content depends on the decreased volume of macropores and the volume of micropores in cell-walls in the first case, while the porosity will be greater than the spacer content for the other two cases. It proves that the volume change of macropores during sintering decreases based on theory and practice.展开更多
One of the biggest challenges in the biocompatibility of implantable metals is the prevention of the stress shielding effect,which is related to the coupling of the bone-metal mechanical properties.This stress shieldi...One of the biggest challenges in the biocompatibility of implantable metals is the prevention of the stress shielding effect,which is related to the coupling of the bone-metal mechanical properties.This stress shielding phenomenon provokes bone resorption and the consequent adverse effects on prosthesis fixation.However,it can be inhibited by adapting the stiffness of the implant material.Since the use of titanium(Ti)porous structures is a great alternative not only to inhibit this effect but also to improve the osteointegration of orthopedic and dental implants,a brief description of the techniques used for their manufacturing and a review of the current commercialized implants produced from porous Ti assemblies are compiled in this work.As powder metallurgy(PM)with space holder(SH)is a powerful technology used to produce porous Ti structures,it is here discussed its potential for the fabrication of medical devices from the perspectives of both design and manufacture.The most important parameters of the technique such as the size and shape of the initial metallic particles,the SH and binder type of materials,the compaction pressure of the green form,and in the sintering stage,the temperature,atmosphere,and time are reviewed according to the bibliography reported.Furthermore,the importance of the porosity and its types together with the influence of the mentioned parameters in the final porosity and,consequently,in the ultimate mechanical properties of the structure are discussed.Finally,a few examples of the PM-SH application for the manufacturing of orthopedic implants are presented.展开更多
Titanium cenosphere syntactic foam of varying relative densities with coarse cenospheres was developed through powder metallurgy route at lower compaction loads. The cold compaction load was varied in the range of 60 ...Titanium cenosphere syntactic foam of varying relative densities with coarse cenospheres was developed through powder metallurgy route at lower compaction loads. The cold compaction load was varied in the range of 60 to 75 MPa to obtain the foams of different relative densities. A function of cold compaction load between crushing tendency of cenosphere and relative density was investigated. The compressive deformation behavior of these foams was studied, and empirical relationships among plateau stress, elastic modulus, densification strains and energy absorption are formulated considering their practical significance. The performance indices of the developed foam in comparison with dense titanium were studied and it was found that the foam is superior alternative to titanium for engineering applications.展开更多
Lithium-sulfur(Li-S)batteries are promising candidates for next-generation energy storage devices due to their high energy density,low cost,and environmental friendliness.However,their practical application remains li...Lithium-sulfur(Li-S)batteries are promising candidates for next-generation energy storage devices due to their high energy density,low cost,and environmental friendliness.However,their practical application remains limited by the polysulfide shuttle effect,sulfur volume expansion,and poor electronic conductivity of S and Li2S.In this study,titanium carbide(TiC)was grown on Ti foam using chemical vapor deposition(CVD)to construct a binder-free,highly conductive,and porous TiC-Ti three-dimensional(3D)framework sulfur host for enhancing the Li-S battery performance.This 3D framework combines highly porous Ti foam with the polar surface of CVD-synthesized TiC nanoflowers,enabling efficient electron and ion transport,anchoring polysulfides to mitigate the shuttle effect,and accommodating sulfur volume expansion for enhanced cycling stability.Our study demonstrated that Li-S batteries utilizing TiC-Ti 3D framework@S cathodes achieved a high initial discharge capacity of 1506 mAh·g^(−1) at 0.1 C and maintained 93.3%of their capacity after 500 cycles at 1 C,with an exceptionally low average capacity decay of 0.01%per cycle.Additionally,the TiC-Ti 3D framework@S cathodes exhibited reduced charge transfer resistance after cycling,indicating enhanced interfacial reaction kinetics and stability.These findings confirm that the CVD-synthesized TiC-Ti 3D framework can serve as an efficient binder-free sulfur host,which provides a promising material and structural strategy for high-performance Li-S battery design.展开更多
基金Project(51174243)supported by the National Natural Science Foundation of ChinaProject(106112015CDJZR135502)supported by the Fundamental Research Funds for the Central Universities,China
文摘The porosity of titanium foams obtained from the space holder technique was theoretically analyzed in the cases of volume shrinking, retaining and expanding during sintering. The relationship between porosity and spacer content was compared under different conditions. The kind of volume change of macropores during sintering was discussed. The results indicate that the relationship between porosity and spacer content depends on the decreased volume of macropores and the volume of micropores in cell-walls in the first case, while the porosity will be greater than the spacer content for the other two cases. It proves that the volume change of macropores during sintering decreases based on theory and practice.
基金the Ministry of Science and Innovation of Spain for financial support(Nos.RTI2018098075-B-C21 and RTI2018-098075-B-C22)the EU through the European Regional Development Funds(No.MINECO-FEDER,EU)+1 种基金Generalitat de Catalunya(No.2017SGR-1165)the KTT Excellence Program,funded by the European Union through the European Regional Development Fund(EDF),the Government of Catalonia and the UPC。
文摘One of the biggest challenges in the biocompatibility of implantable metals is the prevention of the stress shielding effect,which is related to the coupling of the bone-metal mechanical properties.This stress shielding phenomenon provokes bone resorption and the consequent adverse effects on prosthesis fixation.However,it can be inhibited by adapting the stiffness of the implant material.Since the use of titanium(Ti)porous structures is a great alternative not only to inhibit this effect but also to improve the osteointegration of orthopedic and dental implants,a brief description of the techniques used for their manufacturing and a review of the current commercialized implants produced from porous Ti assemblies are compiled in this work.As powder metallurgy(PM)with space holder(SH)is a powerful technology used to produce porous Ti structures,it is here discussed its potential for the fabrication of medical devices from the perspectives of both design and manufacture.The most important parameters of the technique such as the size and shape of the initial metallic particles,the SH and binder type of materials,the compaction pressure of the green form,and in the sintering stage,the temperature,atmosphere,and time are reviewed according to the bibliography reported.Furthermore,the importance of the porosity and its types together with the influence of the mentioned parameters in the final porosity and,consequently,in the ultimate mechanical properties of the structure are discussed.Finally,a few examples of the PM-SH application for the manufacturing of orthopedic implants are presented.
文摘Titanium cenosphere syntactic foam of varying relative densities with coarse cenospheres was developed through powder metallurgy route at lower compaction loads. The cold compaction load was varied in the range of 60 to 75 MPa to obtain the foams of different relative densities. A function of cold compaction load between crushing tendency of cenosphere and relative density was investigated. The compressive deformation behavior of these foams was studied, and empirical relationships among plateau stress, elastic modulus, densification strains and energy absorption are formulated considering their practical significance. The performance indices of the developed foam in comparison with dense titanium were studied and it was found that the foam is superior alternative to titanium for engineering applications.
文摘Lithium-sulfur(Li-S)batteries are promising candidates for next-generation energy storage devices due to their high energy density,low cost,and environmental friendliness.However,their practical application remains limited by the polysulfide shuttle effect,sulfur volume expansion,and poor electronic conductivity of S and Li2S.In this study,titanium carbide(TiC)was grown on Ti foam using chemical vapor deposition(CVD)to construct a binder-free,highly conductive,and porous TiC-Ti three-dimensional(3D)framework sulfur host for enhancing the Li-S battery performance.This 3D framework combines highly porous Ti foam with the polar surface of CVD-synthesized TiC nanoflowers,enabling efficient electron and ion transport,anchoring polysulfides to mitigate the shuttle effect,and accommodating sulfur volume expansion for enhanced cycling stability.Our study demonstrated that Li-S batteries utilizing TiC-Ti 3D framework@S cathodes achieved a high initial discharge capacity of 1506 mAh·g^(−1) at 0.1 C and maintained 93.3%of their capacity after 500 cycles at 1 C,with an exceptionally low average capacity decay of 0.01%per cycle.Additionally,the TiC-Ti 3D framework@S cathodes exhibited reduced charge transfer resistance after cycling,indicating enhanced interfacial reaction kinetics and stability.These findings confirm that the CVD-synthesized TiC-Ti 3D framework can serve as an efficient binder-free sulfur host,which provides a promising material and structural strategy for high-performance Li-S battery design.
