Energy Dispersive X-ray Diffractometry Research Articles

Structural Properties of Cs<sup>1+</sup> Doped H<sub>3</sub>PMo<sub>12</sub>O<sub>40</sub> Nanocrystalline Polyoxometalate Thin Films

The microwave assisted chemical bath deposition (MA-CBD) technique were used to deposite nanocrystalline thin films of polyoxometalates like phosphomolybdic acid (PMA) (H3PMo12O40) and Cesium (Cs+) doped phosphomolybdic acid (Cs-PMA) (Cs3-PMo12O40). Thermo gravimetric and Differential thermal analysis (TGDTA), Fourier transform infrared spectroscopy (FTIR), Energy dispersive X-ray analysis (EDAX), X-ray diffractometry (XRD) and Scanning electron microscopy (SEM) tools are used for the thermal, structural, morphological and compositional analysis of microwave treated H3PMo12O40 and Cs3- PMo12O40 thin films. The completion of decomposition process at 600 oC of Cs3-PMo12O40 compound is confirmed from TGDTA analysis. The polycrystalline spinel cubic crystal structure of H3PMo12O40 and Cs3-PMo12O40 thin films were confirmed from X-ray diffractometer. The crystallite size of H3PMo12O40 and Cs3-PMo12O40 compound found to be in the range of 50 - 53 nm. The formation of H3PMo12O40 and Cs3-PMo12O40 materials were confirmed from the presence of main four absorption peaks observed in the range from 800 cm-1 to 1100 cm-1. The SEM microphotographs analysis identify the microwave assisted H3PMo12O40 and Cs3-PMo12O40 films have spherical shaped porous nanocrystalline morphology. The grain size of H3PMo12O40 and Cs3-PMo12O40 synthesized material found to be in the range of 10 - 12 A˚ The stoichiometric preparation of H3PMo12O40 and Cs3-PMo12O40 thin films with presence of P, Mo, O and Cs peaks of metal ions is observed from EDAX spectra.

Synthesis and in vitro bioactivity of sodium metasilicate-derived silicon-substituted hydroxyapatite

Structural alteration of synthetic implants aims to achieve better bioactivity, higher cellular response, and regulated degradability, all of which are critical criteria for a biomaterial to serve as a graft in bone regeneration. The aim of this work was to synthesize silicon-substituted hydroxyapatite and test its bioactivity in simulated body fluid (SBF) by proving the use of sodium metasilicate (Na2SiO3.9H2O) as an affordable precursor of silica. Thus, the study evaluated the in vitro bone-bonding capacity of hydroxyapatite (Ca10(PO4)6(OH)2) (HA) substituted with silicate ion (Ca10(PO4)6-x(SiO4)x(OH)2-x; SixHA). The SixHA with x = 0.4 was synthesized by utilizing a wet precipitation method with sodium metasilicate as a low-cost silica alternative for alkoxysilane precursors. The SixHA was then examined for properties such as morphology, elemental composition, phase composition, and the nature of chemical bonds using scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), X-ray diffractometry (XRD), and Fourier transformed infrared spectroscopy (FTIR), respectively. An in vitro bioactivity experiment was also carried out by incubating the SixHA in simulated body fluid (SBF) at 36.5 °C for 7 and 14 days. The obtained results revealed the substitution of SiO44- for some PO43- groups in the hydroxyapatite structure. The SixHA nucleated more apatite crystals on its surface and demonstrated some degradability during the periods of immersion in SBF. The characteristics of the SixHA imply that it could be used as a graft in bone restoration applications, thus signifying that sodium metasilicate could serve as an economic silica source for silicon-substituted hydroxyapatite production.

A comprehensive review of synthesis kinetics and formation mechanism of geopolymers.

Geopolymers are synthesized by alkali or acid activation of aluminosilicate materials. This paper critically reviews the synthesis kinetics and formation mechanism of geopolymers. A variety of mechanistic tools such as Environmental Scanning Electron Microscopy (ESEM) and in situ Energy Dispersive X-ray diffractometry (EDXRD), in situ Isothermal Conduction Calorimetry (ICC), in situ Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR), 1H low-field Nuclear Magnetic Resonance (NMR) and Isothermal Conduction Calorimetry (ISC), and others and phenomenological models such as the John-Mehl-Avrami-Kolmogorov (JMAK) model, modified Jandar model, and exponential and Knudson linear dispersion models were used to study the geopolymerization kinetics and many mechanisms were proposed for the synthesis of geopolymers. The mechanistic tools and phenomenological models provided new insights about geopolymerization kinetics and formation mechanisms but each of the techniques used possesses some limitations. These limitations need to be removed and new methods or techniques must be developed to overcome these challenges and get more detailed information about all types of geopolymers. The formation mechanism consists of three to four stages such as dissolution of raw materials, polymerization of silica and alumina, condensation, and reorganization. The Si/Al ratio above the Si/Al ratio of reactants is more suitable and it increases the rate or degree of reaction and produces a higher compressive strength geopolymer. The Na/Al ratio of 1, water-to-solid (W/S) ratio of 0.30-0.45, a temperature in the range of 30 °C to 85 °C, and a curing time of 24 hours are the best for the synthesis of geopolymers. The growing demand for geopolymers in various fields requires the development of new advanced techniques for further understanding of kinetics and mechanisms for tailoring the properties of geopolymers for specific applications.

Immobilisation of Molybdenum in a Sulphate-Reducing Bioreactor

This work presents a biological remediation process for molybdenum-bearing wastewater which may lead to the fabrication of biogenic Mo chalcogenide particles with (photo)catalytic properties. The process is based on dissimilatory sulphate reduction, utilising sulphate-reducing bacteria (SRB), and reductive precipitation of molybdate which is the predominant species of molybdenum in oxygenated water/wastewater. The SRB culture was established in a biofilm reactor which was fed with synthetic solutions containing sulphate (17.7 mM), molybdate molybdenum (2 mM), divalent iron (1.7 mM) and ethanol as the carbon/electron donor. The performance of the bioreactor was monitored in terms of pH, sulphate and molybdenum (Mo(VI) and total) content. The presence of thiomolybdate species was studied by scanning UV-Vis absorbance of samples from the reactor outflow while the reactor precipitates were studied via electron microscopy coupled with energy dispersive spectrometry, X-ray diffractometry and laser light scattering. A molar molybdate/sulphate ratio of 1:12.5 proved effective for molybdate reduction and recovery by 76% in 96 h, whereas sulphate was reduced by 57%. Molybdenum was immobilised in the sulphidic precipitates of the bioreactor, presumably via two principal mechanisms: (i) microbially mediated reduction and precipitation, and (ii) thiomolybdate formation and sorption/incorporation into iron sulphides.

Corrosion behaviour of plasma-sprayed baghdadite bioceramic coatings reinforced with carbon nanotubes

Bioceramics have been extensively used for the restoration and replacement of hard tissues, such as bones and teeth due to their physicochemical resemblance to these tissues. This study focuses on enhancing the properties of plasma-sprayed bioceramic coatings with the addition of carbon nanotubes. The coatings deposited include hydroxyapatite, baghdadite, and baghdadite with carbon nanotube reinforcement. The effect of incorporating carbon nanotubes into baghdadite coatings is thoroughly investigated in terms of microstructural, mechanical, and electrochemical properties. Multiple characterization techniques such as scanning electron microscopy, energy dispersive spectroscopy, X-ray diffractometry, and Raman spectroscopy have been employed to reveal microstructural details, elemental composition, and phase constituents of the deposited coatings. The results indicate that baghdadite coatings exhibit higher porosity compared to hydroxyapatite coatings. However, the addition of carbon nanotubes as reinforcement into baghdadite coatings effectively reduces porosity by integrating carbon nanotubes within the inter-lamellae structure and filling voids within the inter-splat regions. This integration also mitigates common post plasma spray defects including porosity, voids, and microcracks. The incorporation of 2 wt% carbon nanotubes into the baghdadite matrix results in a substantial 80% reduction in corrosion current density(Icorr). This reduction is attributed to the combined effects of reduced porosity, and improved structural integrity due to carbon nanotubes. Furthermore, the carbon nanotubes reinforced baghdadite coatings have indicated the healthy development of the MC3T3-E1 osteoblast cell line.

Preparation and corrosion resistance characterization of MAO coating on AZ31B magnesium alloy formed in the mixed silicate and phosphate electrolytes with pectin as an additive

AZ31B magnesium alloy as a medical implant material is hampered in its application due to its excessive corrosion rate in the human environment. This work used pectin as an electrolyte additive to prepare micro-arc oxidation (MAO) coatings on the surface of magnesium alloys. The surface and cross-section morphology, chemical composition of the coatings were examined using scanning electron microscopy, energy dispersive spectroscopy and X-ray diffractometry. The effect of pectin concentrations on the corrosion resistance of the coatings under simulated body fluid media was evaluated by electrochemical tests. The results showed that the addition of pectin could fill the pores (resulting in a reduction in porosity by 2.3 %) and micro-cracks within the coatings, increasing the corrosion resistance with the increase in pectin concentration. Notably, the MAO-0.75 coating exhibited densest coating structure and then best corrosion resistance with the corrosion current density as low as 1.259 × 10−6 A/cm2, which was four order of magnitudes lower compared to the substrate. The experimental results showed that the use of pectin as an additive prolongs the service life of magnesium alloy MAO coatings in simulated body fluids, thus giving them great potential as medical implant materials.

Graphene oxide immobilized 2-morpholinoethanamine as a versatile acid–base catalyst for synthesis of some heterocyclic compounds and molecular docking study

In this study, a new heterogeneous catalyst was synthesized based on graphene oxide (GO) as a natural material. On the surface of nanosheet graphene oxide, 2-Morpholinoethanamine was immobilized using a non-toxic, green, and simple method. This resulted in the preparation of a bifunctional acid–base nanocatalyst. The synthesized composite was fully characterized using various methods, including Fourier transform infrared spectrometry (FT-IR), scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDS), mapping, Raman spectroscopy, X-ray diffractometry (XRD), thermogravimetric analysis (TGA), and CHN elemental analysis. The catalytic reactivity of GO-mor was investigated in the one-pot synthesis of some benzo[b]pyran, pyrano[3,2-c]chromene, and polyhydroquinoline derivatives, yielding good efficiency and short reaction times. In addition, several recent studies have shown that some derivatives of pyran, chromene, and quinoline have remarkable anti COVID activity. Particularly, COVID-19 3CLpro/Mpro is considered a potential target for the treatment of this virus. For this purpose, docking models were constructed using the corresponding crystal structures with the synthesized derivatives. Based on the docking score and similarity of the binding mode to remdesivir and elvitegravir (the only approved drugs for the treatment of COVID-19), A2, B1, and C4 were selected as promising candidates for further research.

Herbal Extract-Induced Silver Nanoparticles For Antibacterial Cotton Fabric

Abstract Herbal extract-induced metallic nanoparticles have replaced the traditionally synthesized nanoparticles to achieve sustainability in antimicrobial textiles. Silver nanoparticles (NPs) were created by the bio-reducion of silver nitrate with eucalyptus corymbia leaf extract. The bi-lateral activities of herbal extract, like the reduction and capping of silver nanoparticles, have added new dimensions in the bactericidal sector. Silver nanoparticles were characterized by UV-visible spectroscopy, a particle size analyzer, Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), energy dispersive X-ray (EDX) and X-ray diffractometry. In this study these biosynthesized nanoparticles were applied on cotton fabric alone and along with chitosan by the pad-dry-cure method to create antibacterial clothing. Antibacterial efficiency was characterized using the colony counting method (serial dilution method). The treated fabric shows excellent antibacterial efficiency.

An ultrasensitive electrochemical sensor based on antimonene simultaneously detect multiple heavy metal ions in food samples.

Here, we constructed a novel ultra-sensitive electrochemical sensor based on ZIF-67@antimonene (AMNFs) nanocomposites which are based on the first-principles density functional theory the adsorption properties of antimonene on heavy metal ions were studied for simultaneous determination of Cu2+, Pb2+ and Hg2+. The ZIF-67@AMNFs was prepared by using ZIF-67 MOF surface loaded with a large amount of antimonene sheet. Its morphology and crystal structure were characterized by Transmission electron microscope (TEM), Energy Dispersive Spectroscopy (EDS), X-ray diffractometry (XRD) and X-ray photoelectron spectroscopy (XPS). Functional ZIF-67@AMNFs due to its unique layered structure, large active surface area, strong adsorption capacity and good electrical conductivity. In addition, the adsorption capacity of the sensor electrode for Cu2+, Pb2+ and Hg2+ was effectively enhanced. The detection limits of Cu2+, Pb2+ and Hg2+ were 0.01pM, 0.042pM and 0.031pM, respectively. The determination mechanism of Cu2+, Pb2+ and Hg2+ was further clarified based on the adsorption properties and electrochemical accumulation of antimonene on metal atoms. It has been successfully applied to the simultaneous determination of Cu2+, Pb2+ and Hg2+ in rice, sorghum, corn, milk, honey and tea samples, and has good practicability.

Microstructure and reduction behavior of Mo powders doped with La2O3 and ZrO2 oxides using the spray drying method

In the present contribution, we used the spray drying method for the preparation of molybdenum-based composite powders, which belong to an important class of high-temperature structural materials – oxide dispersion strengthened molybdenum alloys (ODS-Mo). Three types of materials were prepared via spray drying and subsequent steps of calcination and reduction, including undoped reference Mo, ODS-Mo doped with 1 wt% of La2O3, and ODS-Mo doped with 1 wt% of La2O3 and 1 wt% of ZrO2. The particular focus was given to precursor solution; specifically, the effects of type (aqueous or water-ethanol mixture) and chemical composition (the addition of La and Zr precursors) were studied in detail, which was rarely given attention in previous research. The morphological and microstructural changes of the particles during oxidation and reduction of sprayed-dried powders were extensively analysed by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDX), X-ray diffractometry (XRD), and X-ray photoelectron spectroscopy (XPS). The morphology and crystallinity of spray dried powders were controlled by the state of spraying precursor solution, i.e. homogeneous solution or particle suspension. Calcination at the temperatures of 500 °C and 650 °C produced spherical polycrystalline and slab-shaped monocrystalline MoO3 oxide particles. Subsequent reductive treatment of transformed calcined powders into metal-based powders took place with efficiency that depended mainly on the type of spraying solution (aqueous solution or water-ethanol suspension) and its chemical composition, in which case, the addition of La and Zr precursors resulted in lower efficiency than the addition of La alone. In terms of powder particle size, homogeneity of alloying elements, and reduction efficiency, the powders produced from water-ethanol suspensions were clearly superior to those produced from aqueous solutions.

A Composite Magnetosensitive Sorbent Based on the Expanded Graphite for the Clean-Up of Oil Spills: Synthesis and Structural Properties

Oil spills necessitate the development of effective methods for preventing their damaging effects on the environment. A number of physical, chemical, thermal, and biological methods are used to combat oil spills. Among them, sorption is considered to be efficient in removing thin oil films from water surfaces. Currently, there is an urgent need for simple methods of obtaining oil sorbents that include a magnetosensitive component to optimize the process of removing oil from the water surface. The purpose of the work is to obtain and research oil sorbents resistant to destruction, with increased bulk density and complex magnetosensitivity, based on thermally expanded graphite (TEG) with the inclusion of micro- and nano-particles of iron and its oxides. The structure and composition of the new composite material was characterized using scanning electron microscopy, energy dispersive X-ray analysis, X-ray diffractometry, thermogravimetric analysis, and laser diffraction particle sizing. The composite sorbent comprised TEG with the inclusion of iron-containing magnetosensitive particles. Metal-carbon nanoparticles (MCN) were used as the magnetosensitive component; they had a magnetosensitive iron core covered with a carbon shell. We used two methods of synthesis, namely (i) mechanical mixing of the TEG flakes and MCN particles, and (ii) applying a thermal shock (microwave processing) to the mixture of graphite intercalated with sulphuric acid and micro- and nanoparticles of iron and iron oxides. In the first case, MCN particles were fixed on the faces, edges, and other surface defects of the TEG flakes due to intermolecular forces, coordinate bonds, and electrostatic interaction. The strong adhesion of magnetosensitive iron/iron oxide and TEG particles in the second case was due to the mutual dissolution of iron and carbon components during the thermal shock, which formed an interfacial layer in which iron carbide is present. The presence of magnetosensitive components in the structure of the proposed oil sorbents allows the use of magnetic separation for the localization and removal of oil spills, increases the density of sorbents, and, accordingly, leads to a decrease in windage while retaining the advantageous properties of thermally expanded graphite. According to the results of laboratory studies, the efficiency of removing oil from the water surface is not lower than 95–96%.

Studies on fluorination of Fe3O4 (magnetite) by NH4HF2

Fluorination of magnetite (Fe3O4) by NH4HF2 was investigated using simultaneous thermogravimetry and differential thermal analysis (TG-DTA), and observing the morphology and phase changes using scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS) and X-ray diffractometry (XRD). The results indicate that fluorination with the involvement of oxygen begins at room temperature, peaks at 1784ºC, and is completed at 200ºC with the formation of only (NH4)3FeF6. On heating, (NH4)3FeF6 gradually releases NH4F by the formation of NH4FeF4 at 259ºC, then (NH4)0.l8FeF3 at 327ºC, and finally FeF3 with minor FeF2 at 400ºC due to the partial reduction of Fe (III) to Fe (II). At 550ºC, FeF3 is oxidized to FeOF/Fe2O3.

Controlled electrochemical surface exfoliation of graphite pencil electrodes for high-performance supercapacitors.

A controlled surface exfoliation method for graphite pencil electrodes using an environmentally friendly, low cost and scalable electrochemical process is reported. A simple direct current power supply in a neutral medium is used for inducing graphene formation on the electrode surface in a controlled manner. The electrochemical properties of the surface exfoliated electrode are characterized, displaying a >300× increase in the electrochemical surface area and >50× decrease in the electrode resistance after exfoliation. The surface graphene layer is characterized using electron microscopy, Raman, infrared, X-ray photoelectron, and energy dispersive X-ray spectroscopies and X-ray diffractometry showing a fully exfoliated surface, formation of surface defects and mild surface graphene oxidation while maintaining an intact graphitic crystal structure. The surface exfoliated electrode is tested as a supercapacitor demonstrating more than 2 orders of magnitude improvement over non-exfoliated electrode in both 3-electrode and 2-electrode setups and achieving a high areal capacitance of ∼54 mF cm-2. The benign nature, low cost, scalability of our controlled surface exfoliation methodology, and its significant impact on the electrochemical properties of the electrode make it very promising for further investigation in various applications such as energy storage and conversion, sensors, and catalysis.

Modification of Mg/Al-LDH by vanadate: effects on tribological properties and corrosion resistance.

In this study, Mg/Al layered double hydroxide (LDH) composite coatings were prepared on the surface of anodized 1060 aluminum alloy by an in situ growth method, and then the vanadate anions were embedded in the interlayer corridor of LDH by an ion exchange process. The morphology, structure and composition of the composite coatings were investigated using scanning electron microscopy, energy dispersive spectroscopy, X-ray diffractometry and Fourier transform infrared spectroscopy. Ball-and-disk friction wear experiments were carried out to measure the coefficient of friction, the amount of wear, and the morphology of the worn surface. The corrosion resistance of the coating is studied using dynamic potential polarisation (Tafel) and electrochemical impedance spectroscopy (EIS). The results showed that the LDH composite coating with unique layered nanostructure as a solid lubricating film can effectively improve the friction and wear reduction performance of the metal substrate. Chemical modification treatment by embedding vanadate anions in the LDH coating leads to the change of LDH layer spacing and the increase of interlayer channels, resulting in the best friction and wear reduction and corrosion resistance of the LDH coating. Finally, the mechanism of hydrotalcite coating as a solid lubricating film for friction and wear reduction is proposed.

Synthesis and Characterization of Nanozeolite from Sugarcane Bagasse Ash and Its Nutrient Loading Potential

Sugarcane bagasse, a known agricultural waste product in the Philippines with 88% silica (SiO2) content based on elemental analysis, is a viable starting material for zeolite synthesis. In this study, silica derived from sugarcane bagasse ash (SBA) collected from La Carlota, Negros Occidental, Philippines, was extracted via an alkaline extraction method using 2M NaOH and precipitation with 5 N H2SO4 under constant stirring at elevated temperature. Sodium aluminate was added as aluminum source then subjected to ageing at 80°C for 72 h to form the clinoptilolite-type zeolite crystals. Characterization using Scanning Electron Microscopy – Energy Dispersive X-ray Spectroscopy and X-Ray Diffractometry confirmed the successful synthesis of the SBA silica and clinoptilolite, with an Si/Al ratio of 1.59 and average pore diameter of 85.77 nm. Surface modification was done by adding CTAB, a cationic surfactant. Nutrient loading was performed using synthesized nanozeolite (SNZ) for N and K loading and surface modified synthesized nanozeolite (SMSNZ) for PK loading which was compared with nutrient loading performance of commercial natural zeolite. The nanozeolite was added to 1 M urea for N loading, 1 M potassium chloride (KCl) for K loading, and 1 M potassium dihydrogen phosphate (KH2PO4) for PK loading at 1:10 (solid: liquid) solution ratio for 8 h under constant stirring followed by filtration and air drying. Chemical characterization of the synthesized nanozeolite revealed that it has a total CEC of 199.30 meq 100 g-1, ICEC of 182.51 meq 100 g-1, and ECEC of 16.79 meq 100 g-1. Nutrient loading resulted in a 9.62% N and 17.01% K2O content using SNZ and a 13.35% P2O5 and 16.26% K2O content using SMSNZ, which were relatively higher compared to using a commercial natural zeolite. These can be attributed to the high internal CEC due to the high quantity of nanopores in the zeolite, which can capture and store the K+ and NH4+ ions via geometric fit, then release them to the soil on-demand via ion-exchange or occlusion. The surface modification with a surfactant drastically alters the surface chemistry of zeolite allowing simultaneous adsorption of anions (PO4-) externally and cations (K+) internally. The chemical characterization confirmed successful loading of N, K, and PK to synthesize nanozeolite from SBA-derived silica, and its potential as a controlled release fertilizer can be tested in further studies.

Fabrication and characterization of thin 116Cd target films for fusion measurements

Fabrication and characterization of thin target films of 116Cd by physical vapour deposition technique are reported. The target films were used in the study of nuclear fusion dynamics near the Coulomb barrier with a beam of 16O. Because of the low melting point of cadmium and its re-evaporation after deposition, coupled with availability of a very small quantity of isotopically enriched material, an unconventional method was employed to fabricate the targets. The prepared target films were characterized using Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDS), X-ray Diffractometry (XRD) and Rutherford Back-scattering Spectroscopy (RBS) to obtain their surface morphology, elemental composition, chemical composition and thickness, respectively. Thickness of the enriched target films were in the range of 20 –50 μg/cm2. Isotopic composition of one of the target films was ascertained in an in-beam experiment using a recoil mass spectrometer. It was observed that abundance of 116Cd in the fabricated target film was significantly lower than the value quoted by the supplier of the source material.

Mineralogical and Elemental Characterization of Conventional Asphalt of Peruvian Roadways by X-Ray Diffraction and Energy Dispersive X-ray Fluorescence

This research deals with the characterization of a sample of conventional asphalt, which is used for the manufacture of roadways in the city of Trujillo, Peru. The sample has been designed by using the Marshall method, through which the optimal content of the asphalt mixture was determined for an adequate combination of the aggregates. This method includes the determination of the optimum content of asphalt cement, stability, unit weight, air voids, flow, voids in the mineral aggregate, and flow stability. The Marshall test was carried out after dosing for the traditional mixture. We have used two techniques: energy dispersive X-ray fluorescence and X-ray diffractometry. The identification and quantification of the chemical elements present was carried out by using energy dispersive X-ray fluorescence, and the mineralogical analysis, by using X-ray diffractometry. This work is useful as a source of reference information. Subsequently, it will allow the implementation of procedures for modifying asphalt mixtures to optimize their performance.

Microstructural characterization and dry sliding wear behavior of boride layers grown on Invar-36 superalloy

Invar-36 is extensively used in fields where high corrosion resistance and dimensional stability are required. However, its hardness limits its use in tribological applications, such as in the manufacture of bulky composite tooling for the aerospace and automotive industries. In this paper, powder-pack-boriding is proposed for the production of the boride layer on Invar-36 superalloy at 975 °C for 5 and 7 h using the nano-sized boriding powder mixture of 90 wt% B4C and 10 wt% NaBF4 as a boron source. The grown boride layers were characterized using scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectroscopy (EDS), X-ray diffractometry (XRD), 2D- and 3D-profilometry, microhardness measurements and ball-on-plate type wear tests. Microstructural characterization revealed a complex and homogenous boride layer mainly consisting of NiB, FeB and Fe2NiB phases with 176.9–189.1 μm thickness. The surface hardness of Invar-36 increased from 150.7 to 1109.5 HV0.05 after the boriding process. The improvement in surface hardness of the grown boride layer enhanced the wear resistance of the Invar-36 superalloy by 28.6–105 times.

Effect of Oxidation Time on the Structure and Corrosion Resistance of Micro-Arc Oxidation Coating of AZ91D Magnesium Alloy in (NH4)2ZrF6 Electrolyte System

Micro-arc oxidation (MAO) coatings were obtained from an AZ91D magnesium alloy at different oxidation times (5, 10, 15, and 20 min), using a zirconium salt electrolyte system, with (NH4)2ZrF6 as the main salt. The morphology of the coatings was studied using a scanning electron microscope (SEM) and confocal laser scanning microscopy (CLSM). Energy dispersive spectrometry (EDS), X-ray diffractometry (XRD), and X-ray photoelectron spectroscopy (XPS) were employed to determine the type of element and the composition of its phase. The potentiodynamic polarization curve (PDP) was applied to illustrate the corrosion resistance of the coatings. We found the coatings had minor porosity and the best compactness when the MAO treatment time was 10 min. The coatings mainly comprised MgO, ZrO2, MgF2, and Zr3O2F8 phases and amorphous magnesium phosphate. Among the MAO coatings prepared in this experiment, the 10 min coating had the lowest corrosion current density (Icorr), and the Icorr was 4.864 × 10−8 A/cm2, which was three orders of magnitude lower than the uncoated AZ91D magnesium alloy.

Synthesis, characterization, and photocatalytic applications of novel sword-like copper oxide microparticles

• Novel CuO microparticles in sword-like morphology were prepared by microemulsion and calcination. • The major composition of the prepared materials was confirmed by XRD and EDS. • The photocatalytic property of the CuO microparticles was established using methylene blue model dye compound. • The degradation of methylene blue dye followed first-order kinetic model according to the general Langmuir–Hinshelwood mechanism. This letter aimed to synthesize novel copper oxide (CuO) microparticles via the microemulsion method followed by calcination. The synthesized material was characterized by scanning electron microscopy, energy dispersive spectroscopy, X-ray diffractometry, and diffuse reflectance spectroscopy techniques; and subsequently applied for the degradation of methylene blue (MB) using the heterogeneous photo-Fenton method. SEM images revealed the formation of homogeneous sword-like CuO microparticles. The XRD pattern and EDS spectrum confirmed that the main part of the material was CuO with the formation of Na 8 Cu 5 O 10 as an impurity. The photocatalytic degradation of MB followed the first-order kinetic model according to the general Langmuir–Hinshelwood mechanism. The as-prepared materials can be successfully applied in the visible-light-induced photocatalytic degradation of hazardous organic compounds and industrial wastewaters.