Ethanol Medium Research Articles

Synthesis of 3-Alkyl-5-(diethylaminomethyl)-1-(1,3-thiazole)pyrazoles

By the reaction of 3-alkyl-5-(diethylaminomethyl) pyrazoles with chloroanhydride of monochloroacetic acid, the pyrazoles with chloromethyl carbonyl substituent have been synthesized. Due to presence of reactive COCH2Cl groups in a molecule, the pyrazoles have been subjected to heterocyclization with thicarbamides (thiobenzamide, thicarbamide and phenylthiocarbamide) in the presence of triethyleamine in a medium of ethanol, as a result of which the previously unknown 3-alkyl-5-diethylaminomethyl-1-(1,3-thiazol)substituted pyrazole derivatives have been obtained.

Self-Powered Hydrogen Production via Laser-Coordinated NiCoPt Alloy Catalysts in an Integrated Zn-Hydrazine Battery with Hydrazine Splitting.

This study proposes a novel approach for the rapid transformation of bimetallic NiCo-oxides into trimetallic NiCoPt alloys using a pulsed laser technique in an ethanol medium in the presence of Pt salts. The electrochemical results demonstrate the exceptional dual-functional activity of the optimized NiCoPt-10 alloy, effectively catalyzing both hydrogen evolution reaction (HER) and hydrazine oxidation reaction (HzOR). Specifically, the NiCoPt-10 alloy presents a low overpotential of 90 mV at 10 mA·cm-2 for HER and a small working potential of 0.068 V versus the reversible hydrogen electrode (RHE) at 10 mA·cm-2 for HzOR. In situ Raman spectroscopy and theoretical calculations delivered insights into the dual-functional activity of the NiCoPt alloy. Consequently, the overall hydrazine splitting (OHzS) electrolyzer, employing a NiCoPt-10||NiCoPt-10 configuration, required only 0.295 V to deliver 10 mA·cm-2. Notably, using this dual-functional NiCoPt-10 catalyst as the cathode combined with Zn foil as the anode in a Zn-hydrazine (Zn-Hz) battery, achieved efficient hydrogen (H2) production with an energy efficiency of 97%. Furthermore, self-powered H2 production is realized by integrating the Zn-Hz battery with the OHzS electrolyzer, demonstrating its excellent potential for practical applications. Thus, this rapid synthetic strategy can aid in designing effective electrocatalysts for addressing challenges in H2 energy production.

Structural characterization of degradation products of phenol red used as zero permeability marker in in-situ rat intestinal permeability studies by LCMS-IT-TOF

In this study, the quantitative determination of phenol red with using HPLC, the permeability marker widely used in gastrointestinal studies, and its stability in various apolar phase solvents were investigated. In addition, the mechanisms of degradation products obtained were tried to be elucidated by using the LCMS-IT-TOF device. The proposed HPLC method utilizes a Perkin Elmer C18, 5 μm, 250 mm × 4.6 mm i.d. column, a mobile phase consisting of phosphate buffer and methanol in the proportion of 50:50 (v/v) with apparent pH adjusted to 3.2 and detected at 430 nm using a photodiode array detector. The method exhibits linearity within the concentration range of 5–200 µg/mL, with a calculated R2 of 0.9981. In situ conditions, the recovery is in the range of 89.8–103.6 %. Furthermore, high-resolution mass studies were identified three degradation products that occur when phenol red was dissolved either ethanol or methanol medium. The method has a low cost of consumables and is very easy to apply to the procedure and analyze degradation products while easily applied to phenol red analysis in various mediums. High-resolution mass screening analysis confirmed the proposed structure of the degradation product. The validation and robustness studies were fulfilled to display the performance of the method in various analytical environments. The greenness and blueness evaluations of the developed method were also made in detail. The AGREE score of the method was calculated as 0.64, AGREEprep 0.68, MoGAPI 0.78, and BAGI scale score as 65.0. In short, the method is perfectly green, applicable, and practical. Finally, phenol red concentrations analyzed in samples obtained in in-situ animal studies were conducted to demonstrate the applicability of the developed method.

Topological Co(II)-malonate polymorph: Degradation properties of Naproxen and colorimetric recognition of acetone, Cr2O72−, and Fe3+

Two Co(II)coordination polymers namely, [Co(mal)(4,4`-bpy)0.5 (H2O)]n(1) and [Co(mal)(4,4`-bpy)0.5 (H2O)]n(2)are synthesized at ambient temperature, both complexes are based on {Co(RCOO)2}unitserving as 3D network along with sqc and fes topology and corroborated by many analytical techniques. CPs(1) crystallized in a 2D manner and then constructed a 3D hydrogen bonding network which was demonstrated monoclinic crystal system while(2)is a 3D supramolecular network that possesses a tetrahedral crystal system, according to topological analysis CPs(1) shows 5-C net and CPs(2) elaborates a 3-C net which proves both are completely different. A luminescence investigation was performed using both coordination polymers (CPs), which demonstrated effective colorimetric detection of acetone, Cr₂O₇²⁻, and Fe³⁺, with corresponding detection limits of 1.91, 2.57, and 0.29 ppm, respectively, in an ethanolic medium. Additionally, the catalytic degradation of Naproxen was evaluated for both catalysts, revealing significant degradation efficiencies of 90 % for catalyst (1) and 38 % for catalyst (2).

Thermodynamics of Micellization of SDS in the Presence of Promethazine Hydrochloride and Ethanol Medium

Thermodynamics of Micellization of SDS in the Presence of Promethazine Hydrochloride and Ethanol Medium

Palladium immobilized on functionalized halloysite: A robust catalyst for ligand free Suzuki–Miyaura cross coupling and synthesis of pyrano[2,3-c]pyrazole motifs via four component cascade reaction and their in-silico antitubercular screening

This research introduces a novel organically functionalized halloysite-supported palladium catalyst, HMF-EDA-TMS@HAL-Pd(II) that was synthesized and thoroughly characterized using various analytical techniques like HR-TEM, FEG-SEM, EDX, XPS, FTIR, XRD, TGA, ICP-AES, EXAFS and DFT studies. The catalyst exhibited exceptional performance in Suzuki–Miyaura cross coupling reactions, demonstrating high efficiency and reusability up to seven cycles in aqueous ethanol medium. Motivated by its promising catalytic activity, we extended our investigation to explore its applicability in the synthesis of pyrano[2,3-c]pyrazole motifs via a four-component cascade reaction affording the desired products in good to excellent yields with broad substrate scope under green reaction conditions. In-silico antitubercular screening of pyrano[2,3-c]pyrazole motifs against DprE1 enzyme have shown promising results with inhibition constants ranging between 0.030 and 0.1 μM for compounds 5b, 5k and 5 l. This protocol has the advantages of wide substrate scope, high yield, excellent functional group tolerance, high efficiency and environmental benign procedure. These findings emphasized the catalyst's versatility and potential in diverse organic transformations, highlighting its importance in advancing sustainable synthetic methodologies.

A Novel Synthesis Route of Phenyl Quinoline from Nitrochalcone with Hydrazine Hydrate in the Presence of Pd/C

Quinoline is widely known to have many biological activities. Therefore, the development of the synthesis method of a quinoline derivative framework is a priority. A phenyl quinoline derivative, 6,7-dimethoxy-2-phenylquinoline Q1, has been successfully synthesized via a novel one-pot reaction that involves reduction, cyclization, and followed by dehydration of nitrochalcone derivate, 3-(4,5-dimethoxy-2-nitrophenyl)-1-phenylprop-2-en-1-one C1. The reaction was carried out using 80 % hydrazine hydrate in the presence of 10% Pd/C as a catalyst in an ethanol medium. Target compound Q1 was afforded in a good yield of 69.18% in a relatively short reaction time of ±2 h.

Synthesis and structural studies on zinc(II) macrocyclic and hetrocyclic complexes derived from schiff base and mixed ligands of 1,4-dihydroquinoxaline-2,3-dione, orthophenylene diamine and hydroquinone

In this study two new zinc(II) complexes involving oxygen and nitrogen donor sequences derived from 1,4-dihydroquinoxaline-2,3-dione (QXD), o-phenylenediamine (OPD) and hydroquinone (HQ) were synthesized through a template procedure. The structural elucidation of these complexes was carried out using measurement of molar conductance in 1x10-3 M solution of DMSO and various spectral techniques; 1H and 13C NMR, FT-IR, UV-VIS and AAS. The results showed that the zinc(II) ion coordinates with the Schiff base ligands in octahedral geometry, leading to the formation of stable macrocyclic and heterocyclic structures. The cyclic ligand (L) was found to coordinate as NNNN donor, through four imine nitrogen atoms which were formed up on condensation of the –NH2 groups on o-phenylenediamine with C=O group on quinoxaline dione in a 2:2 mole ratio, in the presence of one mole equivalent of ZnCl2 in ethanol medium. It also indicates the formation of a new mixed ligand zinc(II) complex with an OO OO O O coordination around zinc(II). The study contributes to the understanding of the coordination chemistry of zinc(II) with Schiff bases and provides insights into the development of novel zinc-based complex compounds. KEY WORDS: Macrocyclic and mixed ligand, 1,4-Dihydroquinoxaline-2,3-dione, o-Phenylenediamine, Hydroquinone Bull. Chem. Soc. Ethiop. 2025, 39(1), 49-64. DOI: https://dx.doi.org/10.4314/bcse.v39i1.4

Antibacterial action of novel zeolite-based compositions depends upon doping with Ag(+) and Сu(2+) cations

Recently, there is a growing interest to exploration of sorption and catalytic properties of solid nanomaterials, in particular natural zeolites, as well as to study of their antimicrobial effects with the aim of potential using them as a principal component of disinfection and degassing remedies. The purpose of this work was to study the antimicrobial action of compositions based on the Transcarpathian clinoptilolite (CL) doped with Ag+ and Сu2+ cations or Ag microparticles (MPs). These compositions were subjected to mechanochemical modification in ethanol medium and with the addition of plant (Actinidia arguta) extract used as an antioxidant. Mechanochemical treatment (MChT) of all forms of CL MPs led to their grinding which caused better contact of CL with bacterial cells, while an increased content of larger pores improved their access to the active sites on the surface of the CL MPs. Treatment of CL samples with metallic silver used as a dopant with the help of the extract of Actinidia arguta plant did not increase the antibacterial activity regardless of treatment time. Treatment of AgNO3 with ethanol slightly increased the antibacterial action of the CL MPs towards Gram-positive bacteria and decreased it towards Gram-negative bacteria. The CL samples doped with copper and treated with ethanol and plant (Actinidia arguta) extract demonstrated comparable toxic action towards Bacillus subtilis regardless of grinding conditions. While such a treatment caused a significant decrease in the antibacterial activity towards Staphylococcus aureus and Pseudomonas aeruginosa strains, compared to the action of samples that were not treated with that plant extract. To address the potential biochemical mechanisms of the antibacterial action of the created zeolite-based compositions, their influence on generation of the reactive oxygen species (ROS) was studied using diphenylpicrylhydrazyl (DPH) fluorescent dye. Most versions of the CL composites demonstrated time-dependent antioxidant effect comparable with the effect of the ascorbic acid used as a positive control. Thus, the ROS generation is not the mechanism that is responsible for the antibacterial action of the created CL-based compositions. Probably, that action is explained by the peculiarities of interaction of doped CL microparticles with the surface of the bacterial cells. Keywords: antimicrobial action, clinoptilolite-based compositions, doping with Ag+ and Сu2+ cations, physicochemical treatment

Ultra-sensitive liquefied petroleum gas (LPG) sensor based on monometallic Ag nanospheres synthesized via microwave-assisted facile approach

We present the synthesis, analysis, and utility of polyvinylpyrrolidone (PVP) stabilized monometallic silver nanospheres for liquefied petroleum gas sensing at room temperature. We have synthesised silver nanospheres (Ag-NSs) in the diameter range of 13–21 nm using a microwave assisted method, which is both easy and fast, because microwave irradiation only takes 30 s. A solution of 0.1 M silver nitrate (AgNO3) in an ethanolic medium was microwave-irradiated to produce Ag-NSs. PVP was used as a stabilising agent throughout the process. Spin coating method was used to produce thin films of synthesised monometallic Ag-NSs. X-ray diffraction (XRD), scanning electron microscopy (SEM), acoustic particle sizer (APS), UV–visible absorption (UV–visible) and Fourier Transform Infrared (FT-IR) spectroscopy were used for characterising Ag-NSs. Based on the acoustic attenuation of the prepared sample, the acoustic particle sizer estimated the diameter of Ag-NSs to be around 17 nm. The deposited films were examined for LPG leakage detection at ambient temperature. This is the first report on monometallic Ag-NSs for leakage detection of LPG at room temperature operation below its lower explosive limit (LEL). The significant finding of the developed sensor is that it prompts the quick response (∼16 s) and recovery (∼64 s) as Ag enhances the reaction rate between the sensing film surface and adsorbed LPG, thereby, augments the sensitivity of sensor even below LEL. Moreover, the fabricated LPG sensor shows noteworthy reproducibility (measured up to six cycles) and stability up to 06 months after fabrication.

Hydrothermal liquefaction of southern yellow pine with downstream processing for improved fuel grade chemicals production

The hydrothermal liquefaction (HTL) technique for liquefying lignocellulose biomass feedstock is often associated with low biocrude yield and poor fuel properties. This study examined the HTL of southern yellow pine sawdust and the hydrotreatment (HYD) of produced biocrudes in an effort to address these challenges. Pine HTL treatment was performed within water and water–ethanol mixed reaction medium at 250, 300, and 350℃ temperatures using metallic iron (Fe) as a catalyst. The rising reaction temperature in a water medium and increasing ethanol content in a mixed reaction medium were found to be effective in enhancing the biocrude yield from the non-catalytic pine HTL process. Maximum non-catalytic biocrude yield of 18 wt.% was produced in water at 350℃, whereas the ethanol and water (1:1 on mass basis) mixture generated the highest biocrude yield of 34 wt.% at 300℃ without any catalyst. The iron catalyst facilitated a maximum of 29 wt.% of biocrude yield as opposed to 18 wt.% without the catalyst at 350℃ in water. The use of an iron catalyst also raised the calorific value of produced biocrudes by 2.5–14 % within 250-350℃ in both water and water–ethanol media. The catalytic and non-catalytic biocrude products were chosen to undergo HYD treatment at 400 °C under high hydrogen pressure (initial 1000 psi) using an alumina-supported cobalt-molybdenum catalyst. The HYD treatment reduced the oxygen content of upgraded oils by 36–60 % compared to the parent HTL biocrudes with 35–37 MJ/kg calorific values. The simulated distillation detected the maximum gasoline range compounds in upgraded oil from catalyst and water–ethanol conditions, whereas the GC–MS analysis revealed the production of increased aromatic hydrocarbons in all upgraded HYD oils. This work has demonstrated the potential of ethanol and inexpensive iron catalyst in enhancing the biocrude production from pine, which could be upgraded to better fuel using the HYD process.

Anticancer, Antioxidant and Antimicrobial Evaluation of Cr (III) and Rh(III) Complexes Derived from A New Mannich Base

The Mannich base ligand was synthesized in an ethanol medium through a condensation reaction of 2-mercaptobenzimidazole and ciprofloxacin at room temperature. Subsequently, several metal complexes of this ligand were prepared. To characterize both the base ligand and the metal complexes, various techniques were employed, including elemental analysis, FT-IR spectroscopy, UV-Vis spectroscopy, molar conductivity measurements, magnetic moment determination, and melting point analysis. The results were shown that the metal complexes formed have the formula [Cr(L)2Cl2] Cl.H2O and [Rh(L)2(H2O)2] Cl3.H2O, where L= mannich base ligand. Based on spectroscopic analytical, coordination with metal ions involves the 'N' donor atom of mannich base and 'N' atom of piprizaing ring, and two complexes are A six-coordinated octahedral structure is suggested. Molar conductivity of these complexes showed that they were electrolytic in nature. In this study, the anticancer and antioxidant potential of the Mannich base ligand and its metal complexes were investigated against MDA-MB-231 cell lines and using the DPPH free radical scavenging assay. Moreover, the in vitro efficacy of the ligand and its complexes against Gram-negative bacteria (E. coli) and Gram-positive bacteria (Staphylococcus aureus), as well as the fungal strain Candida albicans, was evaluated using the disc diffusion method. The results indicated that Cr (III) and Rh(III) complexes demonstrated the highest levels of cytotoxicity against MDA-MB-231 cell lines, enhances antioxidant and antimicrobial activity more than the free ligand. These findings suggest that these metal complexes may have promising applications in the development of novel anticancer, antioxidant and antimicrobial agents.

Properties of palladium-phosphorus catalysts supported on HZSM-5 zeolite in the direct synthesis of hydrogen peroxide

The properties of Pd/HZSM-5 and Pd–nP/HZSM-5 catalysts in direct synthesis and side processes of decomposition and hydrogenation of H2O2 under mild conditions in ethanol and aqueous-ethanol medium in the presence of an acid inhibitor were studied. Using HR-TEM, XRD and ICP MS methods, it was shown that as a result of modification with phosphorus, X-ray amorphous highly dispersed systems are formed, which represent structurally disordered solid solutions of phosphorus in palladium. The main reasons for the promoting effect of phosphorus on the yield of H2O2 are considered. It has been established that, along with phosphorus and acid modifiers, the use of a zeolite support in the H-form favors the inhibition of the side process of H2O2 decomposition.

Evaluation of a simultaneous approach to concentrate and preserve bioactive compounds with distinct polarities by employing supramolecular solvents (SUPRAS)

Supramolecular solvents (SUPRAS) have attracted attention as eco-friendly and highly effective solvents that can be tailored to solubilize compounds with distinct polarities. This study investigated the SUPRAS/equilibrium solution systems’ (SUPRAS-EqS) capacity to concentrate and preserve bioactive compounds through simultaneous solvent production and a liquid–liquid separation method. For this, β-carotene, quercetin, and curcumin were evaluated as molecular probes. SUPRAS-EqS systems were produced with octanoic acid (5 %, v/v), ethanol (20–––35 %, v/v), and acidified water (75–––60 %, v/v) and characterized concerning SUPRAS phase formation and their composition. Moreover, the SUPRAS phase’s ability to preserve these compounds during thermal exposure was evaluated at 313.15 K, 323.15 K, and 333.15 K and compared with an ethanolic medium. The outcomes demonstrated the formation of spherical supramolecular aggregates (10 to 20 μm), where the size of coacervates increased proportionally with the ethanol concentration. Concerning the separation efficiency provided by the SUPRAS phase, all compounds exhibited values superior to 83 %, and the systems produced with 22.5 % ethanol for quercetin and curcumin, and 27.5 % ethanol for β-carotene, presented the highest partition coefficient values. The SUPRAS phase promoted a more suitable environment to preserve the bioactive compounds than ethanol, and quercetin exhibited the highest half-life time values. Curcumin displayed the strongest activation energy in both the SUPRAS phase (48.88 kJ/mol) and the ethanol media (54.50 kJ/mol), indicating its high temperature dependence compared to the other compounds. These findings highlight the SUPRAS phase capacity to concentrate and stabilize bioactive compounds individually with different polarities.

Molecular interaction studies of L-proline in water and ethanol at different temperatures using dielectric relaxation, refractive index and DFT methods

The complex dielectric permittivity of L-Proline in water and ethanol solutions with molar concentrations ranging from 0.025 M to 0.15 M was measured by open-ended coaxial probe technique. The measurements were carried out across a frequency span of 0.02 < ν/GHz < 20 and temperatures varying from 298.15 K to 323.15 K. The densities (ρ) and refractive index (nD ) of the L-proline in aqueous and ethanol solutions were also determined to provide insights into the solute-solvent interactions in the system. The Havriliak-Negami equation was employed to compute the dielectric relaxation time of the mixtures. The relaxation time of L-Proline in an ethanol medium was found to be higher than that of L-Proline in an aqueous medium due to the greater degree of self-association of ethanol molecules. Additionally, the relaxation time of the mixtures lengthened with rising molar concentration, which is attributed to the presence of hydrogen bonds among L-Proline and aqueous/ethanol molecules. The strength of the hydrogen bond interaction of L-Proline in both mediums was calculated using single-point energy calculations employing IEFPCM/PCM solvation models through DFT/B3LYP and MP2 approaches with a 6-311 G ++ (d, p) basis set. The results were correlated with the hydrogen bond strength, Gibbs’ free energy of activation parameter, and dipole-dipole interactions. Communicated by Ramaswamy H. Sarma

Structure based release kinetics analysis of doxazosin mesylate sustained-release tablets using micro-computed tomography

The structures of solid dosage forms determine their release behaviors and are critical attributes for the design and evaluation of the solid dosage forms. Here, the three-dimensional (3D) structures of doxazosin mesylate sustained-release tablets (DM SRT) as reference listed drug (RLD) and a generic preparation were parallelly assessed by micro-computed tomography (micro-CT). There were no significant differences observed in the release profiles between the RLD and the generic formulation in the conventional dissolution, but the generic preparation released slightly faster in media with ethanol for an alcohol-induced dose-dumping test. With their 3D structures obtained via micro-CT determination, the unique release behaviors of both RLD and the generic were investigated for samples from dissolution tests to reveal the effects of internal fine structure on the release kinetics. The structural parameters for both preparations were similar in conventional dissolution test, whilst the dissolutions in ethanol media of RLD were more or less distinguished from that of generic preparations, attributing to their static and dynamic structures. Furthermore, the findings revealed that the presence of ethanol accelerated the dissolution and induced changes in the internal structure of both the RLD and the generic preparations. Moreover, the structure parameters like volume and area of outer contour, remaining solid volume and cavity volume were not equivalent between the two formulations in 40 % ethanol. In conclusion, the structure data obtained from this study provided valuable insights into the diverse release behaviors observed in various modified-release formulations in drug development and quality control.

Molecular spectroscopy, solvent effect, and DFT studies of azithromycin solvate

Azithromycin ethanol solvate monohydrate [C38H72N2O120.5(C2H6O)H2O], abbreviated by AZM-MH-EtOH, was synthesized by slow evaporation method and investigated by powder X-ray diffraction, Raman and infrared (IR) spectroscopy combined with density functional theory (DFT) studies. Electronic and vibrational properties were properly investigated based on a theoretical study of solvation effects, using implicit solvation and solute electron density models. The electronic and vibrational studies were evaluated under aqueous, ethanolic, and vacuum conditions. The electronic structure calculations indicated that the AZM-MH-EtOH is chemically more stable in solvents compared to vacuum condition. Ultraviolet–visible (UV–vis) measurements confirmed the stability of the material in ethanolic medium, due to higher absorbance values compared to the aqueous medium. Vibrational changes were observed in the Raman and IR bands, which have connection with hydrogen bonds. The experimental vibration modes showed better accordance with the predicted modes’ values under solvation effects, but a slight divergence is noticed when we compared to vibration modes obtained in vacuum. Furthermore, the results have revealed a greater affinity profile of AZM-MH-EtOH for water and ethanol solvents compared to theoretical data under vacuum condition.

Synthesis of Novel 6H‐Furo[3,2‐e]Indole Derivatives via One‐Pot Three Component Reactions

ABSTRACTA one‐pot, three‐component reaction of ethyl 5‐aminobenzofuran‐2‐carboxylate, arylglyoxals and cyclic 1,3‐dicarbonyl compounds in the presence of acetic acid as an organocatalyst in ethanol medium under reflux conditions provided a series of new 6H‐furo[3,2‐e]indole derivatives in good yields.

Robust carbon quantum dots supported cobalt oxide composite particles prepared by hydrothermal process for green hydrogen generation via sodium borohydride hydrolysis

Carbon quantum dots (CQDs), a new class of carbon nanostructures with a particle size of 10 nm, exhibit important properties such as easy surface functionalization, low cost, chemical inertness, water solubility and low toxicity. In this study, an effective catalyst was synthesized using cobalt oxide (Co3O4) metal nanoparticles dispersed on CQD support material obtained from sucrose by hydrothermal method (Co3O4-SCQD-HT). The resulting catalyst system was used for effective hydrogen (H2) production from sodium borohydride (NaBH4) hydrolysis. Hydrogen generation rate (HGR) values of 7041, 18,426 and 27,555 mlmin−1gcat−1 were obtained with Co3O4-SCQD catalysts synthesized during the hydrothermal process with water, ethanol and methanol solvents, respectively. The HGR values of the catalysts obtained in ethanol and methanol medium provided an improvement of approximately 2.5 and 4 times, respectively, compared to the catalyst prepared in water medium. The activation energy for NaBH4 hydrolysis by Co3O4-SCQD-HT was 29.92 kJmol−1. Transmission Electron Microscopy (TEM), Energy-dispersive X-ray spectroscopy (EDS), nitrogen adsorption/desorption, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Inductively coupled plasma optical emission spectroscopy (ICP-OES) and X-ray photoelectron spectroscopy (XPS) analyses were used for the characterization study. The average particle size for the Co3O4-SCQD-HT nanocomposite is approximately 3.27 nm. The presence of carbon (C), oxygen(O), nitrogen (N) and cobalt (Co) atoms was confirmed by XPS and EDS analysis.

Comparative study of microstructure and mechanical properties of Mg/B4C composites: Influence of sintering method and temperature

This present work compares the effect of heating methods including microwave and spark plasma sintering (SPS) process on the microstructure and mechanical properties of Mg–B4C. 5 wt%B4C mixed with Mg powders through high-energy mixer mill for 10 min at ethanol media. After mixing, the green bodies were prepared by uniaxially pressing the mixture. The microwave heating was done at sintering temperatures of 600, 650 and 700 °C without soaking time in graphite bed. While, in the case of SPS, the mixture of the powders was directly inserted into a graphite mold and sintering process was performed at 450 °C with initial and final pressures of 10 and 30 MPa at vacuum condition of 17 Pa, sequentially. The corresponding XRD patterns revealed Mg and B4C crystalline phase alongside the reaction product of MgB2 and also MgO byproduct. The FESEM investigations depict uniform distribution of B4C reinforcements at the Mg matrix. Moreover, increasing microwave sintering temperature led to decreasing pores at the microstructure of the prepared sample. The microstructure of SPSed sample revealed almost full densification compared to that of the microwave processed samples at all the sintering temperatures applied. Also, The XPS results show the presence of Mg, O, C and B elements on the surface of prepared composite, and HRTEM with HAADF-STEM images were obtained to study the interface of matrix and reinforcement. The highest bending strength and Vickers hardness of 116 ± 6 Hv and 231 ± 11 MPa were obtained for SPSed sample as well as for the highest relative density. Although the microwave sample was sintered at 700 °C at low pressure, sintering method demonstrated considerable mechanical properties in comparison to SPSed specimen, indicating a successful preparation method as a low-cost, energy- and time-saving process.