Improving and optimizing the target properties of ceramics via the high entropy strategy has attracted significant *** earth niobate is a potential thermal barrier coating(TBCs)material,but its poor high-temperature p...
详细信息
Improving and optimizing the target properties of ceramics via the high entropy strategy has attracted significant *** earth niobate is a potential thermal barrier coating(TBCs)material,but its poor high-temperature phase stability limits its further *** this work,four sets of TBCs high-entropy ceramics,(Sm1/5Dy1/5Ho1/5Er1/5Yb1/5)(Nb1/2Ta1/2)O4(5NbTa),(Sm1/6Dy1/6Ho1/6Er1/6Yb1/6Lu1/6)(Nb1/2Ta1/2)O4(6NbTa),(Sm1/7Gd1/7Dy1/7Ho1/7Er1/7Yb1/7Lu1/7)(Nb1/2Ta1/2)O4(7NbTa),(Sm1/8Gd1/8Dy1/8 Ho1/8Er1/8Tm1/8Yb1/8Lu1/8)(Nb1/2Ta1/2)O4(8NbTa)are synthesized using a solid-state reaction method at 1650 ℃ for 6 ***,the X-ray diffractometer(XRD)patterns display that the samples are all single-phase solid solution structures(space group C2/c).Differential scanning calorimetry(DSC)and the high-temperature XRD of 8NbTa cross-check that the addition of Ta element in 8HERN increases the phase transition temperature above 1400 ℃,which can be attributed to that the Ta/Nb co-doping at B site introduces the fluctuation of the bond strength of Ta-O and ***,compared to high-entropy rare-earth niobates,the introduction of Ta atoms at B site substantially reduce thermal conductivity(re-duced by 44％,800 ℃)with the seven components high entropy ceramic as an *** low thermal conductivity means strong phonon scattering,which may originate from the softening acoustic mode and flattened phonon dispersion in 5-8 principal element high entropy rare earth niobium tantalates(5-8NbTa)revealed by the first-principles ***,the Ta/Nb co-doping in 5-8NbTa systems can further optimize the insulation performance of oxygen *** oxygen-ion conductivity of 8NbTa(3.31 × 10-6 S cm-1,900 ℃)is about 5 times lower than that of 8HERN(15.8 × 10-6 S cm-1,900 ℃)because of the sluggish diffusion effect,providing better oxygen barrier capacity in 5-8NbTa systems to inhibit the overgrowth of the thermal growth oxide(TGO)of *** addition,influenced by lattice dis-
The rapid advancement and proliferation of Cyber-Physical Systems (CPS) have led to an exponential increase in the volume of data generated continuously. Efficient classification of this streaming data is crucial for ...
详细信息
In the digital world, text data is produced in an unstructured manner across various communication channels. Extracting valuable information from such data with security is crucial and requires the development of tech...
详细信息
High-dimensional and incomplete(HDI) matrices are primarily generated in all kinds of big-data-related practical applications. A latent factor analysis(LFA) model is capable of conducting efficient representation lear...
详细信息
High-dimensional and incomplete(HDI) matrices are primarily generated in all kinds of big-data-related practical applications. A latent factor analysis(LFA) model is capable of conducting efficient representation learning to an HDI matrix,whose hyper-parameter adaptation can be implemented through a particle swarm optimizer(PSO) to meet scalable ***, conventional PSO is limited by its premature issues,which leads to the accuracy loss of a resultant LFA model. To address this thorny issue, this study merges the information of each particle's state migration into its evolution process following the principle of a generalized momentum method for improving its search ability, thereby building a state-migration particle swarm optimizer(SPSO), whose theoretical convergence is rigorously proved in this study. It is then incorporated into an LFA model for implementing efficient hyper-parameter adaptation without accuracy loss. Experiments on six HDI matrices indicate that an SPSO-incorporated LFA model outperforms state-of-the-art LFA models in terms of prediction accuracy for missing data of an HDI matrix with competitive computational ***, SPSO's use ensures efficient and reliable hyper-parameter adaptation in an LFA model, thus ensuring practicality and accurate representation learning for HDI matrices.
In situ phase separation precipitates play an important role in enhancing the thermoelectric properties of copper sulfides by suppressing phonon *** this study,Cu1.8S composites were fabricated by melting reactions an...
详细信息
In situ phase separation precipitates play an important role in enhancing the thermoelectric properties of copper sulfides by suppressing phonon *** this study,Cu1.8S composites were fabricated by melting reactions and spark plasma *** complex structures,namely,micron-PbS,Sb_(2)S_(3),nano-FeS,and multiscale pores,originate from the introduction of FePb_(4)Sb_(6)S_(14)into the Cu1.8S *** effective element(Fe)doping and multiscale precipitates,the Cu_(1.8)S+0.5 wt%FePb_(4)Sb_(6)S_(14)bulk composite reached a high dimensionless figure of merit(ZT)value of 1.1 at 773 ***,the modulus obtained for this sample was approximately 40.27 GPa,which was higher than that of the pristine *** study provides a novel strategy for realizing heterovalent doping while forming various precipitates via in situ phase separation by natural minerals,which has been proven to be effective in improving the thermoelectric and mechanical performance of copper sulfides and is worth promoting in other thermoelectric systems.
The as-cast Mg-2.0Zn-1.5Sn-xZr(x=0,0.4,0.6,0.8,1.0 wt%)alloy was rolled with the pressure less than 5%each *** microstructure,mechanical properties,corrosion properties and biocompatibility of the alloy were *** micro...
详细信息
The as-cast Mg-2.0Zn-1.5Sn-xZr(x=0,0.4,0.6,0.8,1.0 wt%)alloy was rolled with the pressure less than 5%each *** microstructure,mechanical properties,corrosion properties and biocompatibility of the alloy were *** microstructure of the alloy was observed and analyzed by scanning electron microscope,and the tensile test was carried out by universal tensile *** corrosion resistance of the alloy in Hank's solution was studied by hydrogen evolution experiment and electrochemical test,and the biocompatibility of the alloy was tested by L929 *** results show that Mg-2Zn-1.5Sn-xZr alloy has excellent mechanical *** elongation of Mg-2Zn-1.5Sn-xZr alloy decreases with the increase of Zr content,but the tensile strength first increases and then decreases with the increase of Zr *** the Zr content is 0.8 wt%,the maximum tensile strength of the alloy is 235 *** results of hydrogen evolution experiment and electrochemical analysis show that the corrosion resistance of the alloy is the best when the Zr content is 0.8 wt%,and all the five alloys have high *** conclusion,the rolled alloy has good properties and has broad application prospects in the field of biomaterials.
The generation and evaluation of severely high thermal stress(σ)is known to be responsible for failure of thermal barrier coatings(TBCs)during thermal *** is crucial and challenging to capture fluctuations inσcaused...
详细信息
The generation and evaluation of severely high thermal stress(σ)is known to be responsible for failure of thermal barrier coatings(TBCs)during thermal *** is crucial and challenging to capture fluctuations inσcaused by the phase transition,which has motivated us to develop a high-throughput multiscale evaluation method forσin TBCs that considers the phase transition of the top ceramic materials by coupling first-principles calculations with finite element *** method quantitatively evaluates and visualizesσof the real TBC structure under thermal cycling by multifield ***,the thermophysical properties calculated by the first-principles calculations consider the effects of temperature and phase transition,which not only reduces the cost of obtaining data but also has a more physical *** this work,rare earth tantalites(RETaO_(4))are introduced as ceramic layers,and the results demonstrate thatσundergoes a rapid escalation near the phase transition temperature(T_(t)),particularly in the TBCs_GdTaO_(4) system,where it rises from 224 to 435 *** discontinuity inσmay originate from the significant alterations in Young’s modulus(increase by 27%–78%)and thermal conductivity(increase by 53%–146%)near T_(t).The TBCs_NdTaO_(4) and TBCs_SmTaO_(4) systems exhibit noteworthy temperature drop gradients and minimalσfluctuations,which are beneficial for extending service lifetime of *** approach facilitates the prediction of failure mechanisms and provides theoretical guidance for the reverse design of TBC materials to obtain low thermal stress systems.
In this work,Mg(0001)/AlB_(2)(0001)interfaces with various terminations and stacking orders were constructed,and the atomic and electronic structures and adhesion work(Wad)of the interface were investigated using the ...
详细信息
In this work,Mg(0001)/AlB_(2)(0001)interfaces with various terminations and stacking orders were constructed,and the atomic and electronic structures and adhesion work(Wad)of the interface were investigated using the first-principles ***,during the geometry optimization process,the B-mid-top(B-MT)Mg(0001)/AlB_(2)(0001)interface exhibits the most significant interface changes and manifests the least *** movement of Mg atoms in the first layer of the Mg surface slab,along the normal direction,results in a structure akin to the structurally optimized hexagonal close-packed(HCP)*** B-HCP interface demonstrates the highest stability,the largest ideal Wad,and the smallest interface *** interface enhances the binding strength of the Mg-side sub-interface,but diminishes the binding strength of the AlB_(2)-side ***,Mg atoms can form metallic/covalent mixed bonds with Al atoms on the Al-terminal AlB_(2) surface and form ionic bonds with B atoms on the B-terminal AlB_(2) ***(0001)/AlB_(2)(0001)interface has good bonding *** research provides strong theoretical support for an in-depth understanding of Mg/AlB_(2) interface characteristics.
Substantial environmental and economic benefits can be achieved by recycling used lithium-ion batteries. Hydrometallurgy is often employed to recover waste LiNi_(x)Co_(y)Mn_(z)O_(2) cathode materials. As Ni, Co and Mn...
详细信息
Substantial environmental and economic benefits can be achieved by recycling used lithium-ion batteries. Hydrometallurgy is often employed to recover waste LiNi_(x)Co_(y)Mn_(z)O_(2) cathode materials. As Ni, Co and Mn are transition metals, they exhibit similar properties;therefore, separating them is difficult. Thus, most researchers have focused on leaching processes, while minimal attention has been devoted to the separation of valuable metals from waste LiNi_(x)Co_(y)Mn_(z)O_(2) cathode materials. Herein, we propose an environment-friendly, gentle process involving the usage of pyrometallurgy and hydrometallurgy to gradually leach valuable metals and effectively separate them. Interestingly, Li is recovered through a reduction roasting and water leaching process using natural graphite powder, Ni and Co are recovered through ammonia leaching and extraction processes and Mn is recovered through acid leaching and evaporation–crystallization processes. Results show that ~87% Li, 97.01% Co, 97.08% Ni and 99% Mn can be leached using water, ammonia and acid leaching processes. The result obtained using the response surface methodology shows that the concentration of (NH4)2SO3 is a notable factor affecting the leaching of transition metals. Under optimal conditions, ~97.01% Co, 97.08% Ni and 0.64% Mn can be leached out. The decomposition of LiNi_(x)Co_(y)Mn_(z)O_(2) is a two-step process. This study provides valuable insights to develop an environment-friendly, gentle leaching process for efficiently recycling valuable metals, which is vital for the lithium-ion battery recycling industry.
The AA5052 aluminum alloy is widely used in automobile and aerospace manufacturing,and with the development of light-weight alloys,it is required that these materials exhibit better mechanical *** studies have demonst...
详细信息
The AA5052 aluminum alloy is widely used in automobile and aerospace manufacturing,and with the development of light-weight alloys,it is required that these materials exhibit better mechanical *** studies have demonstrated that the addition of Sc to aluminum alloys can improve both the microstructure and properties of the *** this study,the effect of Sc on the Fe-rich phase and properties of the AA5052 aluminum alloy was studied by adding 0%,0.05%,0.2%,and 0.3%*** results show that with the increase of Sc,the coarse needle-like Fe-rich phase gradually transforms into Chinese-script and then nearly spherical particles,reduce the size of Fe-rich phase,and refine the grain with increase of high angle grain boundaries(HAGBs).These microstructure changes enhance the strength of the AA5052 alloy through Sc *** ductility of the alloy is obviously improved because the addition of a lower amount of Sc changes the morphology of Fe-rich phase from needle-like into a Chinese-script,and it is subsequently reduced as a result of significant increase in HAGBs with increasing Sc content.
暂无评论