Papers by Keyword: Ta

Abstract: Different Ta concentrations together with stochiometric grain refiner (Al-2.2Ti-1B) in Al-Si-Mg based alloys were investigated with the aim to elucidate grain refinement mechanisms. Post-solidification microstructure was characterised using optical microscopy and scanning electron microscopy (SEM), with a special focus on the Ta-rich layer (more likely to be Al₃Ta) on the basal planes (0001) of TiB₂. A significant grain refinement was observed by using the solute Ta together with stochiometric grain refiner (Al-2.2Ti-1B). In order to further elucidate the formation of Ta-rich layer on the basal planes (0001) of TiB₂, the Density Functional Theory (DFT) calculation were also performed to determine the interface energies of different interfaces and sandwich configurations, including Al (111), Al₃Ti (112) and Al₃Ta (112) at the interface of TiB₂ basal plane (0001). It was found that the interface energy for Ti-terminated TiB₂ at the interface throughout all configurations involved in this paper is lower than that for B-terminated TiB₂, indicating that Ti-terminated TiB₂ is more favourable. It was also found that the Al₃Ta configuration yields the same interface energies as the Al₃Ti configuration. Furthermore, the interface energy of the sandwich configuration also shows nearly identical values along the TiB₂ // Al₃Ti and TiB₂ // Al₃Ta interface energy, strongly indicating that the solute Ti can be fully replaced by the solute Ta.

Abstract: Multihole ZnO hierarchical architectures were prepared by tartaric acid assisted hydrothermal synthesis, TA acts as a capping agent and structure-directing agent during the synthesis. Hydrazine acts as alkali source. XRD confirmed that that all ZnO possess the hexagonal wurtzite structure, and the crystalline of the sample turns better after annealed. The PL spectra can be tuned by changing TA concentration. The FTIR spectra of ZnO nanostructures shows the main absorbance peaks of all samples are located at about 547 cm−1, which are attributed to the vibrations of elongation of ZnO without any other bonds.

Abstract: In order to optimize the Ta content of a newly developed 3rd generation Ni₃Al-based single crystal superalloy, a series of alloys with the varying of Ta content of 3.0, 4.2, 4.5, 6.0wt. % were prepared. The experimental results showed that with the addition of Ta, the size and volume fraction of bulky γ' phase significantly increased while the primary dendrite arm spacing decreased. Meanwhile, the difficulty of solution treatment significantly increased with increasing Ta content. And the thermodynamic calculation results showed that the volume fractions of γ' phase in this series of alloys were significantly higher than those of typical Ni based single crystal superalloys, indicating that the 3rd generation Ni₃Al based single crystal superalloys can serve in the temperature of 1150oC to 1200oC.

Abstract: Low density polyethylene (LDPE) films contains BHA, BHT or BHA, BHT, TA were successfully produced by extrusion. Three types of antioxidant films that were L(LDPE), LBB(LDPE+0.5%BHA+0.5%BHT), and LBBT(LDPE+0.5%BHA+0.5%BHT+0.5%TA) was designed. The Mechanics, moisture permeability, scanning electron microscopy (SEM) and antioxidant activity of the film were detected. The results showed that antioxidant consisting of BHA, BHT and TA has a better compatibility with LDPE film. The antioxidant film has a better performance on mechanical strength and the rate of DPPH radical scavenging ability, but poor to water vapor transmission rate.

Abstract: Titanium dioxide also known as titania is a ceramic material. It is probably the most investigated inorganic oxide in recent years because of its non toxic nature, chemical stability and its potential effectiveness for destruction of toxic organic compounds in industrial effluents. In the present study pure and Ta doped TiO2 nanosize particles were prepared by sol-gel method. Samples with doping concentrations varying from 0.50 to 1.50 at % Ta and calcinations temperatures from 300 to 900 oC were synthesized. Changes taken place in phase transformation of the samples doped with Ta and undoped TiO2 were investigated. The effect of dopant concentration, calcinations temperature and particles size on anatase to rutile phase transformation was studied in detail. The samples were analyzed by various standard analytical tools.

Abstract: In this research, the effect of Ta addition on the formation, thermal stability and corrosion behavior of Ti-Zr-Cu-Pd bulk metallic glasses were investigated. The results revealed with minor addition of Ta, higher corrosion resistance and compressive strength as well as large plastic deformation were achieved. Minor addition Ta is effective for the formation of more protectively passive film during the process of anodic polarization. In addition, proper volume fraction nanoparticle with small size is responsible for the large plastic deformation of the as-cast Ti-based bulk metallic glasses with 1% Ta addition.

Abstract: (W,Ti)C-10%Co system cermets doped with Ta, Nb or V grain growth inhibitor were prepared in this work. The effect of Ta, Nb and V on the microstructure and mechanical properties of (W0.8783Ti0.0976VB0.0242)C-10%Co systems was investigated. The results show that the three elements play an important role on the WC grain growth and shape; the cermets appeared uniformly distributed as whiskers or thin platelets. V results in the hardest material, Ta causes the material to become harder compared with (W0.9Ti0.1)C-10%Co cermets. But the hardness of cermets with Nb addition decrease because of the increasing of porosity.

Abstract: In those traditional ways of treating alkali weight-reduction wastewater, the COD removal is greatly considered, while recovering terephthalic acid (TA) by valuable resource according to the principles of sustainable development is less involved. In this research, recovery of high pure TA from alkali weight-reduction has been researched by purified mother liquid with coagulation-sedimentation. The purity of TA obtained was investigated by various methods, results has shown that the characters of TA was great improved in view of high recovery rate by coagulation-sedimentation on conditions of pH 7.0-8.0 of wastewater and 200-250mg/l in quantity of PAC, so coagulation-sedimentation by pretreatment is an effective method. The study is also very useful in recycling of PET or treating TA industrial wastewater.

Abstract: The critical current density, jc, of high-pressure synthesized MgB2-based balk materials correlates with the amount and distribution of higher borides (MgB12) and Mg-B-O inclusions, which in tern correlates with the synthesis temperature and presence of additions (Ti, Ta, SiC). High-pressure-synthesized materials with near MgB12 composition of matrix exhibited superconducting transition temperature, Tc, of about 37 K, rather high jc (5∙105 and 103 A/cm2 in 0 T and 3.5 T, respectively, at 20 K) and doubled matrix microhardness: 25±1.1 GPa at 4.9 N –load as compared to materials with MgB2).

Abstract: Orientation-imaging microscopy offers unique capabilities to quantify the defects and damage evolution occurring in metals following dynamic and shock loading. Examples of the quantification of the types of deformation twins activated, volume fraction of twinning, and damage evolution as a function of shock loading in Ta are presented. Electron back-scatter diffraction (EBSD) examination of the damage evolution in sweeping-detonation-wave shock loading to study spallation in Cu is also presented.