Tracking the changes in the structural, optical and photoluminescent properties of CuCo2O4/MnS nanocomposites with different composition ratios

(1−x)CuCo2O4/xMnS (x = 0, 0.25, 0.5) nanocomposite samples were formed using hydrothermal and thermolysis procedures. X-ray diffraction (XRD) phase analysis showed the formation of only CuCo2O4 phase necessitating the inclusion of Mn and S ions into the CuCo2O4 lattice. Fourier-transform infrared spectroscopy (FTIR) analyses confirmed the presence of Mn and S ions in the nanocomposite samples. Rietveld refinement method was applied to determine the cation distribution of the different ions between different sites. The cell parameter (a) has no fixed trend of change. The average crystallite size is almost the same for all samples with an average of 15 nm. The effect of insertion of Mn and S ions into the CuCo2O4 on the diffused absorbance, extinction coefficient, refractive index, dielectric properties, and nonlinear optical parameters was discussed in detail. The pristine CuCo2O4 nanoparticles have two direct optical band gaps (1.65, 2.74) eV which are decreased to (1.59, 2.56) and (1.58, 2.54) eV for the MnS content x = 0.25 and 0.5, respectively. The two indirect optical band gaps of pristine CuCo2O4 changed irregularly as the MnS amount increased in the nanocomposite. The PL spectrum of CuCo2O4 is shifted to higher wavelength in the visible region upon alloying with MnS. The photoluminescence (PL) intensity of the nanocomposite samples is smaller than that of CuCo2O4 sample. The emitted PL colors depended on the amount of Mn and S ions in the CuCo2O4 matrix.

Effect of Fire Temperature and Exposure Time on High-Strength Steel Bolts Microstructure and Residual Mechanical Properties

In this study, the influence of different fire conditions on tempered 32CrB3 steel bolts of Grade 8.8 was investigated. In this research different temperatures, heating time, and cooling methods were correlated with the microstructure, hardness, and residual strength of the bolts. Chosen parameters of heat treatments correspond to simulated natural fire conditions that may occur in public facilities. Heat treated and unheated samples cut out from a series of tested bolts were subjected to microstructural tests using light microscopy (LM), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), XRD phase analysis, and the quantitative analysis of the microstructure. The results of the microstructure tests were compared with the results of strength tests, including hardness and the ultimate residual tensile strength of the material (UTS) in the initial state and after the heat treatments. Results of the investigations revealed considerable microstructural changes in the bolt material as a result of exposing it to different fire conditions and cooling methods. A conducted comparative analysis also showed a significant effect of all such factors as the temperature level of the simulated fire, its duration, and the fire-fighting method on the mechanical properties of the bolts.

Fabrication and Characterization of Dental Implants with Yttria- Stabilized Zirconia

Introduction: Zirconium oxide or zirconia have been used for the fabrication of dental implants due to their biocompatibility, hardness, toughness, compressive strength and chemical stability. The aim of this study is investigating the effect of sintering time on the properties of zirconia dental implant. Materials and Methods: In this research, which was performed at Department of Dental and Biomedical Materials Science, Nagasaki University, Nagasaki, Japan, at 2019, zirconia-yttria mol.% 3 powder was pressed and sintered at 1450°C at different times (5 samples for each condition) and the effect of time on the phase, structural and mechanical properties of the sintered samples was investigated. One-way ANOVA statistical analysis was performed with the 0.05 level of significance using Graph Pad Prism 6 software. Results: The results of XRD phase analysis show that sintering time change has a significant effect on the phase changes of the samples and the Vickers hardness of the samples shows a significant increase with increasing sintering time due to shrinkage and decrease in porosity of the samples. But the 12 hour times of sintering caused phase changes in the samples which is not desirable. Conclusion: Therefore, for the fabrication of zirconia parts with minimum porosity and optimum hardness, a moderate sintering time (6 hours) is recommended.

Effect of Nano Copper on the Densification of Spark Plasma Sintered W–Cu Composites

In the present work, nano Cu (0, 5, 10, 15, 20, 25 wt.%) was added to W, and W–Cu composites were fabricated using the spark plasma sintering (S.P.S.) technique. The densification, microstructural evolution, tensile strength, micro-hardness, and electrical conductivity of the W–Cu composite samples were evaluated. It was observed that increasing the copper content resulted in increasing the relative sintered density, with the highest being 82.26% in the W75% + Cu25% composite. The XRD phase analysis indicated that there was no evidence of intermetallic phases. The highest ultimate (tensile) strength, micro-hardness, and electrical conductivity obtained was 415 MPa, 341.44 HV0.1, and 28.2% IACS, respectively, for a sample containing 25 wt.% nano-copper. Fractography of the tensile tested samples revealed a mixed-mode of fracture. As anticipated, increasing the nano-copper content in the samples resulted in increased electrical conductivity.

Failure analysis of SA210-C steel pipe in power plant

The reason and mechanism of the failure of SA210-C steel liquid wall were analyzed by means of macro morphology analysis, chemical composition analysis, microstructure analysis and XRD phase analysis. The test results show that the main reason for the failure of SA210-C steel water wall tube is the corrosion under the inner wall scale, and the long-term unqualified boiler water quality is the main factor causing the corrosion of water wall.

The Vibrational Spectroscopy of the Valence Bonds of Cu-Doped TiO2 Using Electronegativity Principle Quantitative Calculations

The purpose of this study is to investigate the influence of Cu on TiO2 phase transformation and regioselectivity. TiO2 samples doped with different amounts of Cu2+ ions were synthesized by the sol-gel method. The phase and vibrational mode were characterized by X-ray diffraction (XRD), Fourier infrared spectroscopy (FTIR), and transmission electron microscope (TEM). The XRD phase analysis shows that the lattice parameters have not changed after Cu incorporation. In addition, the content of rutile increased obviously after Cu doping. This indicated that the addition of Cu obviously promoted the transformation from anatase phase to rutile phase. The vibration frequencies were calculated based on the principle of electronegativity. All types of bonds were qualitatively and quantitatively analyzed. The content of TiA-O, TiR-O, and H-O in the undoped TiO2 samples is 23.87%, 16.30%, and 7.41%, respectively. In the same way, the content of TiA-O, TiR-O, H-O, Cu A i -O, and Cu R i -O in the 2.5 mol%Cu-doped TiO2 samples is 21.23%, 18.56%, 7.34%, and 0.98%, respectively. For the 5 mol%Cu-doped TiO2 samples, the content of TiA-O, TiR-O, H-O, Cu A i -O, Cu R i -O, Cu A s -O, and Cu R s -O is 18.75%, 20.11%, 7.47%, 2.56%, 3.9%, 1.55%, and 2.35%, respectively. Cu was not present at substitutional sites in the 2.5 mol% doped sample, but Cu was present in the 2.5 mol% doped sample. It is indicated that Cu was more likely to exist in the form of interstitial position in the TiO2 lattice, with the number of Cu atoms in the interstitial position reaching saturation, and this forced Cu to replace Ti. The TEM shows that the stripes of different periods and orientations overlapped each other to form the Moiré patterns. In addition, the diffraction patterns of the Moiré image were slightly different from that of the matrix. The Cu replaced Ti position and the Cu atoms mixed into interstitial sites in the TiO2 lattice. The theoretical calculation was consistent with the experimental results.

Synthesis of Ziegler-Natta Catalyst using Malaysian Ilmenite Derived TiCl4 via Recrystallization Method: A Statistical Approach

In the current study, Ziegler-Natta (Z-N) catalyst was synthesized via recrystallization method using MgCl2 as a support, AlCl3 as an activator and TiCl4 as a transition metal source. The TiCl4 used in the study was derived from Malaysian ilmenite through a sequential pyrometallurgical and hydrometallurgical process of ilmenite concentrate conversion to TiCl4. The recrystallization method of synthesis of the heterogeneous Z-N catalyst was studied by varying the synthesis parameters, such as the combined amount of MgCl2 and AlCl3, temperature, and amount of TiCl4, using statistical design of experiments. The investigation aimed at determining the best conditions for synthesizing the heterogeneous Z-N catalyst. The synthesis conditions posed a significant influence on the Ti content present in the catalyst product. The morphological and elemental analysis of SEM-EDX showed good spherical nature of the prepared catalysts. The XRD phase analysis detected the peaks of MgCl2, MgCl2-Ethanol, MgCl2/TiClx, and TiO2. The IR spectra confirmed the presence of the Mg-Cl bond at 1635 cm−1 and Ti-Cl bonds at 602 cm-1 and 498 cm-1. The produced catalyst contained a small amount of TiO2, which could be due to the seepage of moisture during the analysis or storage of the sample. The most favourable combination of the studied parameters was determined based on the Ti content in the catalyst product. Therefore, the best conditions for synthesizing the heterogeneous Z-N catalyst with high Ti content (181.1 mg/L) was at a combined amount of 2 g of MgCl2 for 6 g of AlCl3, crystallization temperature of 80 °C, and 2 mL dosage of TiCl4. Copyright © 2020 BCREC Group. All rights reserved

Study of the Morphology and Properties of Biocompatible Ca-P Coatings on Mg Alloy

Magnesium alloys are considered as potential biomaterials for use in orthopedic implantology. The main barrier to the use of Mg alloys in medicine is their overly fast and irregular degradation in body fluids. The use of protective calcium phosphate coatings to increase the corrosion resistance of Mg alloy (AM50 alloy: 4 wt.% Al, 0.3 wt.% Mn, 0.2 wt.% Zn, rest Mg) was examined in this study. The scientific goal of the study was the assessment of the influence of calcium phosphate layer morphology on the corrosion process in Ringer’s solution. Modification of the coating morphology was obtained by changing the chemical composition of the phosphatizing bath using NaOH (NaAM50 sample) or ZnSO4 (ZnAM50 sample). In practice, a more dense and uniform coating could be obtained by the immersion of AM50 alloy in a solution containing ZnSO4 (ZnAM50 sample). In this study, an adhesion test performed on the ZnAM50 sample indicated that the critical load was 1.35 N. XRD phase analysis confirmed that the obtained coatings included dicalcium phosphate dihydrate (CaHPO4*2H2O). The coatings prepared on the NaAM50 and ZnAM50 samples are effective barriers against the progress of corrosion deeper into the substrate. After 120 h immersion in Ringer’s solution, the volume of the evolved hydrogen was 5.6 mL/cm2 for the NaAM50 and 3.4 mL/cm2 for the ZnAM50 sample.

Study of Metallurgical and Mechanical Behavior of Laser Butt-Welded Dissimilar Joint of Inconel and Stainless Steel

High energy density welding processes like laser and electron beam welding are capable of welding dissimilar plates with much ease due to high power density and low heat input in spite of the varying thermos-physical properties of the used alloys. The present work is aimed to check the feasibility of joint prepared with laser welding of SS 316L and Inconel 718 plates. The experiments are designed to study the effect of welding speed on the mechanical and metallurgical behavior of the joints without any offset to joint line. The formation of laves phases is confirmed by energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) phase analysis. These laves phase are micro-segregation of Nb, Fe, C and Cr, which is because of high temperature in a small area of fusion zone (FZ) due to intense heat of laser source. Micro-segregation of different elements has led to micro-fissures, which is detrimental for the joints operating at elevated temperature. Cooling rate and peak temperature during welding play the significant role in obtaining a sound quality joint. The present work gives an insight on feasibility of laser welded joint of SS 316L and Inconel 718 with suitable selection of welding speed during laser welding.

Examination of Natural and Standard Fe3O4 Powders Using X-Ray Absorption Near-Edge Spectroscopy (XANES)

Investigation of Fe K-edge X-Ray Absorption Near Edge Spectroscopy (XANES) spectra of Fe3O4 (FeO.Fe2O3) from natural source compared with the Fe3O4 standard is presented. The natural Fe3O4 powder was prepared from ironstone of Tanah Laut, Kalimantan Selatan by co-precipitation method. XANES measurements in transmission mode were performed at the Synchrotron Light Research Institute (SLRI), Nakhon Ratchasima, Thailand. XRD phase analysis confirms that the synthesized Fe3O4 powder is a single phase, but it cannot determine the proportion of Fe2O3 and FeO in the structure. TEM measurement confirms that the particle size of natural Fe3O4 about 10 nm. Qualitative analysis of the pre-edge XANES data revealed that the absorbing atom in the XAS measurement is Fe3+. Meanwhile, the absorption edge (E0) values of natural and standard Fe3O4 powders were 7126.44 eV and 7125.02 eV, respectively. The proportion was then acquired using XANES data analysis through Linear Combination Fitting (LCF). It was found that the natural Fe3O4 sample consisted of 98 wt. % Fe2O3 and 2 wt.% FeO, while the standard Fe3O4 powder consisted of 96 wt. % Fe2O3 and 4 wt. % FeO. The mechanism of the absorption in both samples is also described and compared.