Tetrafluoroborate Research Articles

Innovative eco-friendly hydroxyethylcellulose matrix-based composite for enhanced gas separation: Insights from performance and structural characterization

With increasing concern for the environment, the demand for carbon dioxide separation, a key contributor to global warming, has escalated. Therefore, this paper focuses on carbon dioxide separation by creating an hydroxyethyl cellulose (HEC)(C2H6O2)x*(C6H7O2(OH)3)n/silver tetra fluoroborate (AgBF4)/aluminum nitrate (Al(NO3)3) composite film, demonstrating excellent separation performance with a permeance of 1.0 GPU and a selectivity of 100. Silver ions enhance the solubility of carbon dioxide, aiding in its separation, and we determined the optimal aluminum composition to stabilize the silver ions. To analyze this, we examined the cross-sections using SEM, confirming a selective layer of 1.7 μm for carbon dioxide separation. Furthermore, TGA, FT-IR, and NMR analyses were conducted to investigate the interaction between the polymer and additives. This revealed that the increased polymer chain due to the interaction between Ag and HEC, along with stabilized Ag facilitated by the addition of Al, maximized the interaction with carbon dioxide via the empty s-orbital. Additionally, SEM-EDX, UV–vis, XRD, XPS analyses were employed to elucidate the movement of ions within the membrane. These results provide insights into the performance of membranes based on cellulose polymer and offer valuable insights for future applications in gas separation technologies.

Influence of Ni2+ ions on the physical, structural, elastic, optical, and thermal aspects of oxy fluoro borate glasses mixed with sesquioxide ions (Al3+/Y3+/Sb3+)

Oxy Fluoro Borate (OFB) Glasses mixed with Sesquioxide ions (Al3+/Y3+/Sb3+) were synthesized using the traditional melt quenching technique. The properties of the structure of the glasses prepared are investigated by SEM, EDS and XRD methods. Variations in properties like density in glasses allow Nickel/Aluminium/Antimony/Yttrium ions to go through the borate glass matrix with an increase in respective dopant mole fraction. The decrease in the values of different elastic constants with B-O-Ni/Al/Sb/Y bonds and alsoby the function of NiO/Al2O3/Sb2O3/Y2O3 as a modifier and converting a portion of BO3 tetrahedral units into BO4octahedral units indicates the depolymerization in the glass matrix. The I.R. spectra and FTIR spectra show an increment in the occupation of cations Ni2+, Y3+, Sb3+ and Al3+ ions in the octahedral positions of the glass matrix with an enhancement in their molefraction. Creation of NBOs owing to the transformation of BO3 to BO4 units is greater in Al3+ and the smallest in Y3+ with an increment in the sesquioxide concentration at a 1.00 mol% NiO concentration. The dominance of the nickel ions octahedral occupancy in the glasses prepared is revealed by the optical absorption spectra, which may be because of the ligand fields produced by various ions of sesquioxides present within the glass matrix creating NBO and many trapped electrons at the donor centers. Photoluminescence spectra of the prepared glasses show the octahedral occupation of the Ni2+ ions that is indicated by the transitions 3A2g(F) ↔ 3T1g(P) and 3T1g(P) → 3T2g(F). The synthesized glasses exhibit effective luminescence by Nickel ions, and the AlNi and NiAl glass series exhibit superior luminescence properties owing to their highest emission cross-sections compared with the other series of prepared glasses.

Study the effect of L-arginine and L-tyrosine on the surface adsorption and micellar properties of long-chain imidazolium-based ionic liquid

The interfacial and bulk properties of the aqueous solutions of the long chain imidazolium-based ionic liquid (IL) viz. 1-decyl-3-methylimidazolium tetrafluoro borate [Dmim][BF4] within L-Arginine and L-Tyrosine have been investigated by surface tension, UV–Visible, fluorescence, viscosity, and FTIR spectroscopy. The surface activity of the [Dmim][BF4]-L-Try was more active on the surface than the [Dmim][BF4]-L-Arg. It's noteworthy to notice that the CMC values of [Dmim][BF4] in water and aqueous amino acids obtained by the UV–Vis spectroscopy method are the same as those determined using the surface tension approach. The additions of AAs function to minimize the CMC values of [Dmim][BF4] as well as the interfacial parameters. An IR probe and the v(C-N) region, which is sensitive to the microenvironment, are used to determine the structure and hydrogen-bonding properties of the IL and two amino acids, specifically the L-Arginine and L-Tyrosine binary systems. The excess IR spectra of the v(C-N) region exhibit positive peaks, which show that the mixing process was insufficient and that complexes with hydrogen bonds had formed in the mixes. The findings could be applied in the pharmaceutical industry to stabilize proteins and prevent protein aggregation.

Role of alkyl chain present in the cations of ionic liquids on stabilization of silver nanoparticle: DFT and TD-DFT studies

Understanding the preparation and stabilization of silver nanoparticles in ionic liquids is still needed to investigate. Various groups have reported the synthesis and stabilization of silver nanoparticles (Ag NPs) in ionic liquids (ILs) on varying the cation and anion. There is a need to understand the impact of alkyl chain present in the cation to understand the new interactions between the ILs with Ag NPs. Herein, the authors have designed the imidazolium ring based ionic liquids having tetrafluoroborate (TFB) as anion and the alkyl chain present on the cation is varied. The interactions have been studied through the DFT and TD-DFT calculations performed by Gaussian. Herein, free energy and other thermodynamic parameters of ILs with and without Ag are calculated. It came to know that the change in free energy for 3-Ag is least among all designed. 1-Ag is least stable as the change in free energy is positive at 298 K. On varying the alkyl chain, different types of interactions are observed. The same can be seen by localization of nucleophilic and electrophilic sites in the HOMO and LUMO of the ILs with and without Ag. Further, their dipole moments are also determined to understand the polarity of ILs with and without Ag and herein, no regular pattern is observed.

STUDY OF LITHIUM ION CHARGING AND DISCHARGING CHARACTERISTICS

Lithium –Ion batteries are now popular in majority of electronic portable devices like Mobile phone, Laptop, Digital Camera, etc. due to their long lasting power efficiency. These are the most popular rechargeable batteries with advantages like best energy density, negligible charge loss and no memory effect. Li-Ion battery uses Lithium ions as the charge carriers which move from the negative electrode to the positive electrode during discharge and back when charging. During charging, the external current from the charger applies an over voltage than that in the battery. This forces the current to pass in the reverse direction from the positive to the negative electrode where the lithium ions get embedded in the porous electrode material through a process called Intercalation. The Li- Ions pass through the non-aqueous electrolyte and a separator diaphragm. The electrode material is intercalated lithium compound. The negative electrode of the Li-Ion battery is made up of carbon and the positive electrode is a metal oxide. The most commonly used material in the negative electrode is Graphite while that in the positive electrode may be Lithium cobalt oxide, Lithium ion phosphate or Lithium manganese oxide. Lithium salt in an organic solvent is used as the electrolyte. The electrolyte is typically a mixture of organic carbonates like Ethylene carbonate or Diethyl carbonate containing lithium ions. The electrolyte uses anion salts like Lithium hexa fluoro phosphate, Lithium hexa fluoro arsenate monohydrate, Lithium per chlorate, Lithium hexa fluoro borate etc. Depending upon the salt used, the voltage, capacity and life of the battery varies. Pure lithium reacts with water vigorously to form lithium hydroxide and hydrogen ions. So the electrolyte used is non aqueous organic solvent. The electrochemical role of the electrodes charge between anode and cathode depends on the direction of current flow.

Experimental investigation on the thermophysical properties of the ionic liquid-based binary system for heat transfer applications

Based on the innovation in the development of ionic liquids, the aim of the present work is to investigate the thermophysical properties of novel hydrophilic ionic liquid 1-Ethyl-3-Methyl Imidazolium Tetra FluoroBorate (EMIMBF4) and water as binary systems experimentally at various mass fraction and at various temperatures. A room-temperature ionic liquid blended with deionized water in four different mass fractions as 20%, 15%, 10%, and 5% to prepare an ionic liquid and water binary mixture at room temperature. Thermal stability and the thermophysical characteristics of EMIMBF4 such as thermal conductivity, specific heat capacity, viscosity, and density, were measured in the temperature range of 25?C to 90?C. The results reveal that the specific heat capacity increased by 13%, and thermal conductivity enhanced 9%, at 5 wt.% mass fraction. The overall mass drop is reached 75.1% at 20 wt.% mass fractions.

Dual EGFR- and TfR-targeted gene transfer for sodium iodide symporter gene therapy of glioblastoma

Sodium iodide symporter (NIS) gene transfer for active accumulation of iodide in tumor cells is a powerful theranostic strategy facilitating both diagnostic and therapeutic application of radioiodide. In glioblastoma (GBM), the blood-brain barrier (BBB) presents an additional delivery barrier for nucleic acid nanoparticles. In the present study, we designed dual-targeted NIS plasmid DNA complexes containing targeting ligands for the transferrin receptor (TfR) and the epidermal growth factor receptor (EGFR), thus providing the potential for active transport across the BBB followed by targeting of tumor cells. Invitro 125I transfection studies confirmed TfR- and EGFR-dependent transfection efficiency and NIS-specific iodide uptake of dual-targeted polyplexes. Invivo gene transfer in mice bearing orthotopic U87 GBM xenografts was assessed at 48h after intravenous polyplex injection by positron emission tomography (PET) imaging using 18F-labeled tetrafluoroborate (TFB) as tracer. The tumoral 18F-TFB uptake of mice treated with dual-targeted polyplexes (0.56%± 0.08% ID/mL) was significantly higher compared with mice treated with EGFR-mono-targeted (0.33%± 0.03% ID/mL) or TfR-mono-targeted (0.27%± 0.04% ID/mL) polyplexes. In therapy studies, application of 131I induced a superior therapeutic effect of the dual-targeted therapy, demonstrated by a significant delay in tumor growth and prolonged survival.

Polymeric ionic liquid forms of PEI microgels as catalysts for hydrogen production via sodium borohydride methanolysis

• Ionic liquid (IL) forms of polyethyleneimine (PEI) as metal free catalyst for H 2 . • NaBH 4 methanolysis via PEI-X (X:Anion) catalyst for green H 2 production. • Highly reusable IL colloidal polymeric catalyst with low Ea in H 2 generation. • Green energy carrier, H 2 release from NaBH 4 via highly regenerable PEI-X catalyst. Ionic liquid (IL) forms of polyethyleneimine (PEI) microgels were prepared using anion exchange and direct acid treatment techniques employing tetrafluoroborate (TFB) and hexafluorophosphate (HFP) anions as well as their corresponding acids, tetrafluoroboric acid (TFBA) and hexafluorophosphoric acid (HFPA), respectively. Then, these polymeric ionic liquids (PIL) of PEI microgels were used as metal-free catalysts for hydrogen (H 2 ) production from sodium borohydride (NaBH 4 ) solution in methanol (methanolysis). The parameters affecting H 2 production rates such as the types of anions, the methods of PIL preparation, temperature, reusability, and regeneration of PEI-based microgels were investigated. In the dehydrogenation reaction of NaBH 4 in methanol catalyzed by PEI-based PIL microgels, the lowest Ea value in the temperature range of −10–40 °C was calculated as 16.0 ± 0.8 kJ/mol for PEI-HFP PIL microgel, prepared by anion exchange method. The reusability studies of PEI-TFB PIL microgels revealed that the catalytic activity was decreased to 89 ± 5% after 5 consecutive use with 100% conversions for every use. Additionally, independent of the anion exchange methods, PEI-based PIL microgels afford catalytic H 2 production from NaBH 4 methanolysis in a wide range of temperatures including subzero temperatures with facile regenerations by the treatments with TFBA and HFPA resulting in 100% recovery of catalytic activities at each regeneration. The metal-free PIL form of PEI microgel catalyst renders much better catalytic performances and advantages than metal nanoparticle-based catalysts for green H 2 production offering viable alternatives in industrial application.

Evaluation of [18F]tetrafluoroborate as a Potential PET Imaging Agent in a Sodium Iodide Symporter-Transfected Cell Line A549 and Endogenous NIS-Expressing Cell Lines MKN45 and K1.

[18F]tetrafluoroborate (TFB) has been introduced as the 18F-labeled PET imaging probe for the human sodium iodide symporter (NIS). Noninvasive NIS imaging using [18F]TFB has received much interest in recent years for evaluating various NIS-expressing tumors. Cancers are a global concern with enormous implications; therefore, improving diagnostic methods for accurate detection of cancer is extremely important. Our aim was to investigate the PET imaging capabilities of [18F]TFB in NIS-transfected lung cell line A549 and endogenous NIS-expressing tumor cells, such as thyroid cancer K1 and gastric cancer MKN45, and broaden its application in the medical field. Western blot and flow cytometry were used to assess the NIS expression level. Radioactivity counts of [18F]TFB, in vitro, in the three tumor cells were substantially higher than those in the KI inhibition group in the uptake experiment. In vivo PET imaging clearly delineated the three tumors based on the specific accumulation of [18F]TFB in a mouse model. Ex vivo biodistribution investigation showed high [18F]TFB absorption in the tumor location, which was consistent with the PET imaging results. These results support the use of NIS-transfected lung cell line A549 and NIS-expressing tumor cells MKN45 and K1, to investigate probing capabilities of [18F]TFB. We also demonstrate, for the first time, the feasibility of [18F]TFB in diagnosing stomach cancer. In conclusion, this study illustrates the promising future of [18F]TFB for tumor diagnosis and NIS reporter imaging.

Theoretical investigation of the density and the heat capacity of [EMIM][BF4] and its MWCNTs ionanofluids: Effect of temperature and MWCNTs concentration

The density and specific heat capacity is an important parameter for heat transfer fluids (HTFs) specially which used for cooling or heating purposes. In this study the density of ethyle methyl imidazolium tetrafluoro borate ionicliquids ([EMIM][BF4]) measured experimentally. In addition, the density (ρ) and the specific heat capacity (Cp) of the ionanofluid (INF) were calculated theoretically. The studied INF composed of multi-walled carbon nanotubes (MWCNTs) dispersed in the ionicliquid (IL) [EMIM][BF4] in the concentrations (0.5%, 1%, 3%, 5%, 7% and 9%). Scanning electron microscopy and differential scanning calorimetry measured for the used MWCNTs. The density and the specific heat capacity of pure [EMIM][BF4] and its INFs were plotted versus temperature in a graphs. The results show that the density of [EMIM][BF4] and its INFs decreased linearly with temperature. The density increased by 0.243%-3.968% for 0.5%-9% MWCNTs concentration in INFs, reaching maximum value of 1.329 g.cm-3 at 20 °C. In contrast the specific heat capacity of [EMIM][BF4] and its INFs increased linearly with temperature with an enhancement of about 0.417%-7.99% for 0.5%-9% concentration of MWCNTs reaching maximum value of 1.812 J/g.K at 358.15K with 9%MWCNT concentration. That’s mean the addition of MWCNT cause increasing both of the density and the specific heat capacity of INF.

Influence of Sm3+ ion concentration on the photoluminescence behavior of antimony lead oxy fluoro borate glasses

The synthesis and characterization of a new glass series with the chemical composition 70B2O3–20PbO-5Sb2O3–(5-X) NaF-XSm2O3 where X is 0.1, 0.5, 1.0, 1.5, 2.0 and 2.5 were discussed in detailed in this paper. The glasses were made by using the traditional melt quenching process, and their spectroscopic behavior was studied to understand their utility in the development of lasers, light-emitting diodes (LEDs) and optical devices. Fourier-Transform Infrared (FT-IR) spectroscopy and EDX studies have been conducted to identify the functional groups and elemental composition present in the as prepared undoped glass. Optical and luminescent behaviors of the as prepared glasses were studies using absorption, photoluminescence (PL) excitation, PL emission and PL decay spectral features. The strengths of absorption bands called oscillator strength were calculated by using absorption spectral data and subsequently subjected to Judd-Ofelt (J-O) analysis to estimation various radiative properties like radiative transition probability (AR), total radiative transition probabilities (AT), branching Ratios (βR) and the radiative lifetimes (τR) for the prominent fluorescent levels of the Sm3+ ions in the titled glasses. The experimental lifetimes (τexp) measured from the PL decay curves are correlated with τR to estimate quantum efficiency (ƞ) of the as prepared glasses. The quantum efficiency, emission cross sections and other radiative parameters along with the CIE coordinates estimated for the Sm3+ ions doped titled glasses finally allows us to contemplate its potentiality for the fabrication of optoelectronic devices in visible reddish-orange region.

Effect of TiO 2 Photoanode Films on the Performance of Dye Sensitized Solar Cell with Rauvolfia Vomitoria Fruit Extract

Dye sensitized solar cells (DSSC) were investigated using Rauvolfia vomitoria fruit extract as natural sensitized of TiO2 thin film. The cells were evaluated for various thicknesses of photoanode. The optical properties were analysed with UV-Vis spectroscopy and Fourier Transform Infrared spectroscopy (FT-IR). The morphology of the TiO2 surface was observed with a scanning electron microscope (SEM). Energy levels were estimated by cyclic voltammetry, in the presence of tetrabutalamonium tetrafluoroborate (TBATFB), in anhydrous acetonitrile solution (ACN). The results showed that the optimum thickness is 10 μm which achieved a short-circuit current density (Jsc) of 0.1 mA/cm² and an open voltage (Voc) of 0.65 V while the conversion efficiency ) is 0.055%.

Optical studies of chromium doped zinc oxy fluoro borate glasses – A possible disordered material for tunable LASERS

Melt-quenching technique adapted to prepare the (10-x)ZnO-30ZnF2-60B2O3: xCr2O3 (x: 0.2, 0.4, 0.6, 0.8, 1.0) (mol %) glasses. Various physical parameters are estimated with the help of experimental densities and refractive index. Optical absorption studies reveal that the chromium ions exist in Cr3+ state at very low concentrations, whereas the concentration increases chromium ions occupies both Cr3+ and Cr6+ state. Crystal field (Dq) and Racah parameters (B and C) are calculated by the crystal field relations. Direct and Indirect optical band gaps are calculated from the absorption edges. Finally, by means of optical studies, the behaviors of Cr ions in present glasses are discussed.

Tuning thin-film composite reverse osmosis membranes using deep eutectic solvents and ionic liquids toward enhanced water permeation

Deep eutectic solvents (DES) have invoked an enormous interest as inexpensive, greener and biorenewable solvents and additives with promising applications. In the present study, we investigated a choline chloride-urea based DES and a series of commercial ionic liquids (ILs) as additives including 1-hexyl-3-methyl-imidazolium chloride, 3-methyl-1-octyl-imidazolium tetra fluoroborate, N-butyl pyridinium and betaine monohydrate to modify the polyamide (PA) layer of reverse osmosis (RO) membranes. The ILs were selected from various categories to find better of them in RO modification. Accordingly, the DES and ILs with different concentrations were added to the MPD aqueous solution. The results of SEM and AFM analyses showed a smoother surface for the DES and ILs-modified membranes. The membrane modified with 1 wt% of DES achieved the pure water flux of 56.7 L/m2h and the observed salt rejection of 96.4%, exhibiting a 27% and 3% increase in water flux and salt rejection, respectively, as compared with the unmodified membrane. Among the used ILs, the membranes modified with N-butyl pyridinium and betaine monohydrate showed the best desalination performance, with the pure water flux of 78.9 L/m2h and 51.7 L/m2h and the NaCl rejection of 97.3% and 94.4%, respectively. Also, choline hydroxide IL was used for the surface modification of the SO3H-g-C3N4 nanosheets to examine efficiency of ILs on membranes, when located on nanosheet surface. The results of the desalination experiments showed that the incorporation of the modified nanosheets at low concentrations was effective in enhancing the membrane performance. Although increasing the concentrations of nanosheets in the PA layer of the membranes resulted in the enhanced water flux, the salt rejection was decreased.

Incremental diagnostic value of [18F]tetrafluoroborate PET-CT compared to [131I]iodine scintigraphy in recurrent differentiated thyroid cancer

IntroductionEfficient therapy of recurrent differentiated thyroid cancer (DTC) is dependent on precise molecular imaging techniques targeting the human sodium iodide symporter (hNIS), which is a marker both of thyroid and DTC cells. Various iodine isotopes have been utilized for detecting DTC; however, these come with unfavorable radiation exposure and image quality ([131I]iodine) or limited availability ([124I]iodine). In contrast, [18F]tetrafluoroborate (TFB) is a novel radiolabeled PET substrate of hNIS, results in PET images with high-quality and low radiation doses, and should therefore be suited for imaging of DTC. The aim of the present study was to compare the diagnostic performance of [18F]TFB-PET to the clinical reference standard [131I]iodine scintigraphy in patients with recurrent DTC.MethodsTwenty-five patients with recurrent DTC were included in this retrospective analysis. All patients underwent [18F]TFB-PET combined with either CT or MRI due to newly discovered elevated TG levels, antiTG levels, sonographically suspicious cervical lymph nodes, or combinations of these findings. Correlative [131I]iodine whole-body scintigraphy (dxWBS) including SPECT-CT was present for all patients; correlative [18F]FDG-PET-CT was present for 21 patients. Histological verification of [18F]TFB positive findings was available in 4 patients.Results[18F]TFB-PET detected local recurrence or metastases of DTC in significantly more patients than conventional [131I]iodine dxWBS and SPECT-CT (13/25 = 52% vs. 3/25 = 12%, p = 0.002). The diagnosis of 6 patients with cervical lymph node metastases that showed mildly increased FDG metabolism but negative [131I]iodine scintigraphy was changed: [18F]TFB-PET revealed hNIS expression in the metastases, which were therefore reclassified as only partly de-differentiated (histological confirmation present in two patients). Highest sensitivity for detecting recurrent DTC had the combination of [18F]TFB-PET-CT/MRI with [18F]FDG-PET-CT (64%).ConclusionIn the present cohort, [18F]TFB-PET shows higher sensitivity and accuracy than [131I]iodine WBS and SPECT-CT in detecting recurrent DTC. The combination of [18F]TFB-PET with [18F]FDG-PET-CT seems a reasonable strategy to characterize DTC tumor manifestations with respect to their differentiation and thereby also individually plan and monitor treatment. Future prospective studies evaluating the potential of [18F]TFB-PET in recurrent DTC are warranted.

Spectroscopic and luminescence properties of Ho3+ ions doped Barium Lead Alumino Fluoro Borate glasses for green laser applications

Optically transparent Barium Lead Alumino Fluoro Borate (BaPbAlFB) glasses doped with different concentrations of Ho3+ ions were prepared by using melt quench technique. Raman spectral studies were conducted to understand the structural groups present in the as prepared glasses at room temperature. Spectroscopic investigations such as optical absorption, excitation, emission and decay measurements were conducted to understand the visible photoluminescence (PL) and lasing potentialities of BaPbAlFB glasses. The bonding parameters (δ) estimated from the absorption spectral features were used to understand the nature of bonding between Ho3+ ions and the surrounding ligands. The Urbach energy values estimated from the absorption spectral data are used to verify the amorphous nature of the present glass system. The Judd-Ofelt (J-O) theory has been applied to the measured oscillator strengths of the absorption spectral features to estimate the best fit J-O parameters (Ωλ, λ = 2, 4, and 6) useful in evaluating various radiative parameters for the prominent fluorescent levels of Ho3+ ions in BaPbAlFB glasses. The experimental lifetimes (τexp) are found to be decreasing with increase in Ho3+ ion concentration owing to energy transfer. The quantum efficiency (η) of Ho3+ ions doped BaPbAlFB glasses were estimated by correlating the experimental lifetimes (τexp) with the radiative lifetimes (τR). The strong visible emission, large stimulated emission cross-section (σse), high branching ratio (βR) and relatively good quantum efficiency (η) obtained for 5S2→ 5I8 (green) transition of 1 mol% of Ho3+ ions doped BaPbAlFB glass reveals its suitability in designing and developing visible green lasers.

Development of AlB2 particles using inorganic halide salts and mechanical characterization of AlB2 reinforced AA6061 MMC’s

Insitu AA6061/AlB2 composites with different weight percent (0, 1, 3 & 5) AlB2 particles were fabricated through liquid metallurgy route involving a chemical reaction of exothermic nature between molten AA6061 alloy and an inorganic halide salt of potassium tetra fluoro borate (KBF4) at reaction temperatures from 800° to 850 °C using stir casting route. The fabricated composites were subjected to micro structural characterization using SEM and XRD. Microstructural studies revealed that the formation of insitu AlB2 particles decreased the size of the grain in Aluminium rich phase. Further examination shows uniform scattering of in-situ particles throughout the matrix. An attempt is made to find out the shape of the insitu particles. The processed composites were further analysed to get their mechanical characterization like tensile, hardness, compression and density properties. As the proportion of reinforcement particulates increased, the composites hardness, yield strength, ultimate tensile and compression strength of the developed composites were found to increase proportionally, however there is an abatement in ductility with increments in reinforcement content.

Dry sliding wear behaviour of A356-TiB<SUB align="right">2/TiC in-situ composites at ambient and elevated temperatures

A356-TiB2/TiC in-situ metal matrix composites have been developed through reactions between liquid aluminium and various chemicals, such as potassium hexa fluorotitanate (K2TiF6), potassium tetra fluoroborate (KBF4), and graphite (C), through flex assisted synthesis. In the present investigation, the distinct quantities of halide salts were added into molten aluminium to obtain 0, 2.5, 5, and 7.5% of TiB2/TiC-reinforced composites. The fabricated composites were examined by a scanning electron microscope (SEM) energy dispersive analysis (EDAX) X-ray diffraction analysis (XRD) and micro-hardness tests to evaluate the effects of adding the reinforcement. The wear behaviour of A356-TiB2/TiC composites was studied using a pin-on-disk apparatus. The influence of wt% of the reinforcement, sliding velocity, normal load, and temperature on wear rate (WR), coefficient of friction (COF), specific wear rate (SWR), and wear rate per unit wt% of the reinforcement. The worn out surfaces of A356-TiB2/TiC composites were carefully analysed with an SEM. TiB2 and TiC particles improved the wear resistance of composites at ambient and elevated temperatures. This result reveals that at elevated temperatures, the pure alloy was subjected to adhesive wear, whereas oxidation wear was more dominant in A356-TiB2/TiC composites.

Dry sliding wear behaviour of A356-TiB<SUB align="right">2/TiC in-situ composites at ambient and elevated temperatures

A356-TiB2/TiC in-situ metal matrix composites have been developed through reactions between liquid aluminium and various chemicals, such as potassium hexa fluorotitanate (K2TiF6), potassium tetra fluoroborate (KBF4), and graphite (C), through flex assisted synthesis. In the present investigation, the distinct quantities of halide salts were added into molten aluminium to obtain 0, 2.5, 5, and 7.5% of TiB2/TiC-reinforced composites. The fabricated composites were examined by a scanning electron microscope (SEM) energy dispersive analysis (EDAX) X-ray diffraction analysis (XRD) and micro-hardness tests to evaluate the effects of adding the reinforcement. The wear behaviour of A356-TiB2/TiC composites was studied using a pin-on-disk apparatus. The influence of wt% of the reinforcement, sliding velocity, normal load, and temperature on wear rate (WR), coefficient of friction (COF), specific wear rate (SWR), and wear rate per unit wt% of the reinforcement. The worn out surfaces of A356-TiB2/TiC composites were carefully analysed with an SEM. TiB2 and TiC particles improved the wear resistance of composites at ambient and elevated temperatures. This result reveals that at elevated temperatures, the pure alloy was subjected to adhesive wear, whereas oxidation wear was more dominant in A356-TiB2/TiC composites.

Saturated N-Heterocyclic Carbene Based Thiele's Hydrocarbon with a Tetrafluorophenylene Linker.

The synthesis of a SIPr [1,3-bis(2,6-diisopropylphenyl)-imidazolin-2-ylidene] derived Kekulé diradicaloid with a tetrafluorophenylene spacer (3) has been described. Two synthetic routes have been reported to access 3. The cleavage of C-F bond of C6 F6 by SIPr in the presence of BF3 led to double C-F activated compound with two tetrafluoro borate counter anions (2), which upon reduction by lithium metal afforded 3. Alternatively, 3 can be directly accessed in one step by reacting SIPr with C6 F6 in presence of Mg metal. Compounds 2 and 3 were well characterized spectroscopically and by single-crystal X-ray diffraction studies. Experimental and computational studies support the cumulenic closed-shell singlet state of 3 with a singlet-triplet energy gap (ΔES-T ) of 23.7 kcal mol-1 .