Effect Of Mn Content Research Articles

One-pot synthesis, characterization and ammonia-selective catalytic reduction performance of MnSAPO-18 molecular sieves

A one-pot synthetic method was used to prepare novel MnSAPO-18 catalysts with high crystallinity that were employed to efficiently scrub NOx in the flue-gas denitration reaction. In the controllable synthesis of MnSAPO-18, the effect of Mn content, organic amine templates, Mn precursors as well as hydrothermal crystallization time on the SCR performance of the resulting MnSAPO-18 catalysts and the structure-activity relationship of these samples was also investigated. The optimum combination of these variables in the hydrothermal synthesis process appeared to be using N,N-Diisopropylethylamine as the organic templates, manganese acetate as the Mn precursor, a crystallization time of 24 h and Mn content of n(MnO)/n(Al2O3) = 0.2 in the synthesis gel. The optimum Mn0.2SAPO-18-2 catalyst exhibited nearly 95% NOx conversion and 90% N2 selectivity in temperature range of 275–375 °C with a space velocity of 37,500 h−1. In the low-cost seed-assisted, one-pot synthesis of Mn0.2SAPO-18-1.0DIPEA-Seed, it was found that this sample had almost comparable activity as the Mn0.2SAPO-18-2 in the traditional one-pot method. These novel catalysts were characterized using the H2-TPR, NH3-TPD, XRD, FESEM, DR UV–Vis and ESR analysis. The results of these characterizations showed that the optimum SCR performance of Mn0.2SAPO-18-2 was closely related to its abundant high valence framework manganese, suitable surface acidity and high redox capability. Thus, Mn0.2SAPO-18-2 was shown to be a promising catalyst for NH3-SCR removal of NOx and this fabrication technique appeared to be potentially valuable for application in industry.

Effect of Mn content on the microstructure and corrosion resistance of Al-Cu-Mg-Mn alloys

Effect of Mn content on the microstructure and corrosion resistance of Al-Cu-Mg-Mn alloys was examined by optical microscope (OM), scanning electron microscope (SEM), tensile tests, pitting corrosion and electrochemical tests. It is shown that increase of Mn content can accelerate the aging process of the Al-Cu-Mg-Mn alloys, which is beneficial to shorten heat treatment time. Polarization curves indicate that the corrosion current density and corrosion rate of Al-4Cu-2Mg-1.2Mn alloy are the lowest compared with Al-4Cu-2Mg-0.6Mn and Al-4Cu-2Mg-0.9Mn alloys for both the as-cast and heat-treated conditions. Electrochemical impedance spectroscopy (EIS) tests also demonstrate that Al-4Cu-2Mg-1.2Mn alloy displays the highest resistance. The maximum pitting corrosion depth of the as-aged Al-4Cu-2Mg-1.2Mn and Al-4Cu-2Mg-0.6Mn alloys is about 65 µm and 110 µm, respectively. Therefore, Mn addition can improve the mechanical properties and corrosion resistance of the Al-Cu-Mg alloys.

Development of biomedical Ti-Nb-Zr-Mn alloys with enhanced mechanical properties and corrosion resistance

In order to develop a new biomedical titanium alloy with excellent mechanical properties and corrosion resistance, a series of newly designed Ti-24Nb-4Zr-xMn (x = 0, 1, 3, 5 wt%) alloys based on Mo equivalent method and d-electron alloy design theory were successfully fabricated by mechanical alloying and spark plasma sintering. The effect of Mn content on the microstructures, mechanical properties and corrosion resistance of the Ti-Nb-Zr-Mn alloys were systematically investigated. The results showed that moderate Mn is beneficial to the formation of the fine and uniform α'' and β grain, which is helpful to improve the mechanical properties. Among all the investigated alloys, Ti-24Nb-4Zr-3Mn alloy prepared under 40 MPa (TNZ3M-40) exhibited the highest compressive strength (2336 MPa) and large strain (~ 35%). In addition, the electrochemical measurements showed that the addition of Mn can further improve the corrosion resistance, and the corrosion potential and corrosion current density in Ringer's solution are − 0.207 V and 27.28 nA/cm2 for TNZ3M-40, respectively. This study offers a potential strategy for developing biomedical Ti-Nb-Zr-Mn alloys with high performance for biological implantation.

Effect of Mn content on electrochemical performance and energy density of LiFe1-xMnxPO4/C

In this work, LiFe1-xMnxPO4/C (x = 0, 0.2, 0.5) composite materials are synthesized to obtain high energy density lithium ion battery cathode materials. The prepared materials were characterized by XRD, XPS, SEM, TEM, CV, EIS and galvanostatic charge-discharge testing. The effect of the Mn content on the structure, morphology and electrochemical performance of LiFe1-xMnxPO4/C is studied in detail. It is found that LiFe0.5Mn0.5PO4/C not only possesses the highest specific energy, but also has the best rate performance. The discharge capacities at 5C of LiFe1-xMnxPO4/C (x = 0, 0.2, 0.5) are 97.2, 98.8, 107.8 mAh g−1, and the specific energies are 235.0, 248.5 and 299.3 Wh kg−1, respectively. It is calculated that LiFe0.5Mn0.5PO4/C has the highest conductivity and lithium ion diffusion coefficient because of its dispersed particle state and suitable carbon layer thickness. The analysis of the influence of different Mn contents on the electrochemical performance and energy density of LiFe1-xMnxPO4/C solid solution materials carried out based on the difference in material structure and morphology provides guidance for the subsequent research and industrial production of these materials.

Enhancing mechanical properties of twin-roll cast Al–Mg–Si–Fe alloys by regulating Fe-bearing phases and macro-segregation

The existence of coarse Fe-bearing phases and macro-segregation under the twin-roll casting (TRC) condition has always been a restrictive factor for the preparation of high-performance Al alloys. In this work, the effect of Mn contents on the formation of Fe-bearing phases, macro-segregation behavior and mechanical properties of TRC Al-0.5Mg-0.7Si-0.1Fe-xMn (x = 0, 0.1, 0.3 and 0.5 wt.%) alloys have been investigated. The macro-segregation region in the as-cast 0Mn alloy is found to contain coarse secondary phases consisting of Al, Fe, Mg and Si. In as-cast 0.1Mn and 0.3Mn alloys, macro-segregation has been alleviated due to the transformation of π-AlFeMgSi phase to α-Al(FeMn)Si phase, as a result of the inhibited peritectic reaction to form the π-AlFeMgSi phase by the addition of Mn. However, with further increasing the amount of Mn, coarse intermetallic compounds at the center region tend to form in the 0.5Mn alloy, which aggravates macro-segregation again. The 0.1Mn alloy exhibits a better combination of yield strength (287 MPa) and elongation (18.9%) than that of the 0Mn alloy (274 MPa, 15.9%) under the artificial aging condition. The higher yield strength of the 0.1Mn alloy is mainly due to the formation of fine α-Al(FeMn)Si particles that make a strong contribution to dispersion strengthening. This work provides a reference for weakening macro-segregation via regulating Fe-bearing phases, which is of great importance in developing AA6xxx series TRC alloys with high performance.

Effect of Mn Content on the Passivation and Corrosion of Al0.3Cr0.5Fe2MnxMo0.15Ni1.5Ti0.3 Compositionally Complex Face-Centered Cubic Alloys

Al0.3Cr0.5Fe2MnxMo0.15Ni1.5Ti0.3 (x = 0, 0.25, 0.5, 1) compositionally complex alloys are synthesized and annealed at 1,070°C to form two-phase alloys with a face-centered cubic (fcc) matrix and a second phases enriched in Al, Ti, and Ni with slightly reduced density, raw element costs, and passivating elements distributed across both phases. The global corrosion resistance is evaluated in 0.01 M and 0.1 M NaCl at both natural pH and pH 4. Overall corrosion resistance is suggested to be optimized at Mn concentrations of 5.0 at%, indicated by pitting potentials comparable to or exceeding those of 316L stainless steel. Improvements in corrosion resistance and optimization of Mn concentration are further assessed by polarization, impedance, and gravimetric analysis after extended aqueous exposure. The fate of individual elements during the dissolution and passivation processes is evaluated with in situ atomic emission spectroelectrochemistry and ex situ x-ray photoelectron spectroscopy. Passivity was derived from combinations of Ti4+, Cr3+, and Al3+ oxides in an undetermined solid solution or complex oxide. Enhanced corrosion resistance is attributed to the improved chemical homogeneity of passivating elements within the two-phase microstructure, while the decreased corrosion resistance of alloys with higher Mn concentrations is attributed to high Mn dissolution rates and/or destabilization of the passive films. The underlying determinants of the role of Mn in the design of corrosion-resistant lightweight compositionally complex alloys are discussed.

Effect of Mn Content on the Reaction between Fe-xMn (x = 5, 10, 15, and 20 Mass pct) Steel and CaO-SiO2-Al2O3-MgO Slag

Medium- and high-Mn steels have excellent properties but are very difficult to be commercially produced because of the high content of some alloy elements. To enhance the understanding of the reaction between medium/high-Mn steel and refining slag which is significantly different from the conventional steels, steel and slag composition and the inclusions were investigated by equilibrium reaction between Fe-xMn (x = 5, 10, 15, and 20 mass pct) and CaO-SiO2-Al2O3-MgO top slag at 1873 K in the laboratory. Furthermore, the effect of Mn content on inclusion transformation and steel cleanliness was also explored. After slag–steel reaction, both contents of MnO in slag and Si in steel increased. Most MnO inclusions in master steel transformed to MnO-SiO2 and MnO-Al2O3-MgO. With the increase in Mn content, the amount share of MnO type inclusions decreased and that of MnO-Al2O3-MgO type increased. In addition, both the number density of observed inclusions and the calculated oxygen content in inclusions increased. Thermodynamic analysis indicates that the composition change of steel and slag and the transformation of inclusions are mainly the consequence of the reaction between Mn in molten steel and SiO2 and MgO in top slag. The dissolved Mn in medium/high-Mn steel presents a strong reactivity.

Effect of Mn content on the microstructure and mechanical properties of Mg–6Li–4Zn-xMn alloys

The as-cast Mg–6Li–4Zn-xMn alloys were prepared and extruded at 280 ​°C with an extrusion ratio of 25:1. The effects of Mn content on the microstructure and mechanical properties of Mg–6Li–4Zn-xMn alloys were investigated in this study. The XRD results show that Mg–6Li–4Zn–xMn alloys consisted of α-Mg (hcp) ​+ ​β-Li (bcc) duplex structured matrix, MgLi2Zn and Mn phases. The grains of the extruded Mg–6Li–4Zn–xMn alloys were refined by dynamic recrystallization during the extrusion process. The EBSD results show that the extruded alloys had basal textures. The grain size of the extruded alloys decreased while the basal texture was strengthened with the increasing Mn addition. The TEM results show that a large amount of nanoscale Mn precipitates existed in the extruded Mg–6Li–4Zn–1.2Mn alloy, which can effectively inhibit the dynamic recrystallized (DRXed) grains growth during the hot extrusion and is beneficial to the improvement of mechanical properties. Mg–6Li–4Zn–1.2Mn alloy in this research possesses the best mechanical properties with the ultimate tensile strength and yield strength of 321 ​MPa, 250 ​MPa, respectively.

Formaldehyde Total Oxidation on Manganese-Doped Hydroxyapatite: The Effect of Mn Content

An aqueous impregnation method using manganese (II) nitrate precursor, followed by calcination at 400 °C, was carried out for the preparation of manganese doped hydroxyapatite catalysts (MnxHap; x = Mn wt.%: 2.5, 5.0, 10, 20, and 30 based on MnO2). Methods of characterization including inductively coupled plasma spectroscopy (ICP), N2 physisorption, X-ray Diffraction (XRD), Fourier-Transform Transmission Infrared (FT-IR), Raman, and Thermal gravimetric analysis (TGA/MS) analysis were used for the identification of Mn species and its surrounding environment. Raman spectroscopy indicated the presence of the ε-MnO2 phase for Mn20Hap and Mn30Hap in agreement with the XRD results and the presence of β-MnOOH species for Mn5Hap and Mn10Hap. The formaldehyde total oxidation was investigated on these catalysts and it was shown that Mn5Hap was the most active catalyst, achieving a normalized rate of formaldehyde (HCHO) conversion into CO2 per mole of Mn of 0.042 h−1 at a temperature of 145 °C. The well dispersed oxidized manganese species on Hap with a medium Mn AOS (average oxidation state) were mainly responsible for this performance. Since HCHO was retained on the surface of all catalysts during the catalytic test, the combined Diffuse Reflectance Infrared Fourier Transform spectroscopy (DRIFT) experiment at room temperature and thermodesorption (TD)-FTIR identified formate species as their oxidation consumed surface OH groups. A stability test and moisture effect study showed that the presence of water vapor has a beneficial effect on the performances of the catalyst.

Photoluminescence, Optical Energy Gap and Electrical properties of Mn-Doped ZnO Nanorods Synthesized by CBD Method

In this work, un-doped and Manganese doped Zinc Oxide Nanorods (NRs) thin films were grown on the glass substrates using chemical bath deposition method (CBD) at 80 °C temperature. The effect of Mn content (0, 2 and 4%) on the structural, morphology, optical and photoluminescence characteristics of ZnO NRs films was investigated. The XRD patterns of un-doped and Mn-doped ZnO NRs demonstrate sharp and strong peaks together with high crystalline structure. The FESEM images showed that the nanorods of ZnO and Mn:ZnO were well-aligned and distributed throughout the films. The absorption edge was observed to be blue-shifted and the optical energy gap was found to be widening from (3.21, to 3.31) eV with increased Mn content. The photoluminescence spectrum (PL) of Mn-doped samples was examined, at room temperature, and revealed of highly UV emission, whereas the green-yellow wavelengths emissions were enhanced with increased Mn content. Current-voltage (I-V) characteristics showed that the photocurrents of all prepared samples are enhanced and the Mn doped samples showed a good response, under UV light.

Effect of Mn Content on Structural Evolution and Magnetic Properties of ZnO Particles

ZnO dilute magnetic semiconductor (DMS) is one of the most promising materials for room temperature ferromagnetic applications. In this paper, Zn1-xMnxO (x = 0.00, 0.03, 0.06, and 0.09) samples were prepared through Mn-doped ZnO by using sol-gel method. And the intrinsic relationship between the point defects and magnetic properties were investigated. The hexagonal wurtzite structure of ZnO was confirmed by X-ray diffraction (XRD) measurement in all prepared samples. The morphological features of prepared samples were studied by scanning electron microscopy (SEM). The distribution of Mn element was analyzed by energy dispersive X-ray analysis (EDAX). The number of oxygen vacancies (Vo) is varied with increasing Mn content by X-ray photoelectron spectroscopy (XPS). A suitable Vo density in Zn1-xMnxO (x = 0.03) samples is considered to be important and has positive effect on the ferromagnetism. Magnetic properties were tested by vibrating sample magnetometer (VSM). The anti-ferromagnetism exchange interaction between Mn ions is the main reason to cause the diamagnetic properties.

Effects of Mn Content and Grain Size on Hydrogen Embrittlement Susceptibility of Face-Centered Cubic High-Entropy Alloys

The effects of Mn content and grain size on the hydrogen embrittlement resistance of face-centered cubic (FCC) CrCoFeMnNi high-entropy alloys were examined using tensile testing at an initial strain rate of 10−4 s−1. The most important finding of this study was that the combined effect of Mn removal and grain refinement provided nearly complete resistance to hydrogen embrittlement with over 800 MPa tensile strength in FCC high-entropy alloys, even after 100 MPa hydrogen gas charging.

Biocompatibility of Ti-Mn-N films with different manganese contents

Ti-Mn-N films were deposited on CoCrMo alloys and Si substrate by reactive magnetron sputtering. The effects of Mn content on the structure, surface composition and surface energy of Ti-Mn-N film were investigated by XRD, SEM, XPS, and contact angle measurements. Primary mouse osteoblasts were cultured on the Ti-Mn-N films for 1 and 3 d to evaluate cell adhesion and cell viability. RAW264.7 macrophages were cultured on the Ti-Mn–N films for 24 h to evaluate the cell activation and inflammatory cytokine release. The results showed that after culturing for 3 days, there were a greater number of osteoblasts on the 2.2%Mn-TiN and 4.4%Mn-TiN films as compared to the other films. When the Mn content was higher than 4.4 at.%, the osteoblasts viability on Ti-Mn-N films was reduced. In addition, the results of the released inflammatory factors showed that Ti-Mn-N films induced a lower inflammatory response than that induced by CoCrMo alloy, while demonstrating the same excellent biocompatibility as that of TiN film. Hence, Ti-Mn–N films with 2.2 at.% and 4.4 at.% Mn have potential application on the surface modification of dental implant.

Effects of Mn Content on Mechanical Properties of FeCoCrNiMnx (0 ≤ x ≤ 0.3) High-Entropy Alloys: A First-Principles Study

Effects of Mn content on mechanical properties of FeCoCrNiMnx (0 ≤ x ≤ 0.3) high-entropy alloys (HEAs) are investigated via first-principles calculations combining EMTO–CPA method. Related physical parameters, including lattice constant, elastic constants, elastic modulus, Pugh’s ratio, anisotropy factors, Poisson's ratio, Cauchy pressure, Vickers hardness, yield strength, and energy factor, are calculated as a function of Mn content. The results show that the resistances to bulk, elastic, and shear deformation decrease with increasing Mn content. Pugh’s ratio \({B \mathord{\left/ {\vphantom {B G}} \right. \kern-\nulldelimiterspace} G}\) indicates that the ductility of FeCoCrNiMnx HEAs has a remarkable reduction between 22 and 24% of Mn content. Meanwhile, Cauchy pressure suggests that the atomic bonding transforms from metallic to directional characteristic from 22 to 24% of Mn content. Vickers hardness and yield strength of FeCoCrNiMn HEA are intrinsically larger than those of FeCoCrNi HEA. Dislocation nucleation easily occurs in FeCoCrNiMn HEA compared to FeCoCrNi HEA, and large dislocation width in FeCoCrNiMn0.2 HEA results in low stacking-fault energy, which easily induces twinning deformation. This work provides a valuable insight for further theoretical and experimental study on the mechanical properties of FeCoCrNiMnx (0 ≤ x ≤ 0.3) HEAs.

Effect of Mn content on crystal structure, magnetic properties and magnetocaloric effect of NdCo2-xMnx compounds

ABSTRACT The crystal structure, magnetic properties and magnetocaloric effect (MCE) of NdCo2-xMnx (x = 0.0–0.5) compounds have been investigated. X-ray diffraction (XRD) analysis has revealed that all the compounds crystallize in the MgCu2-type cubic Laves phase structure (C15-type, Fd-3m). The lattice parameter a increases from 7.2987 Ǻ (x = 0.0) to 7.4020 Ǻ (x = 0.5) and the Curie temperature from 102 to 202 K as the Mn content increases to x = 0.5. Under an external field change from 0 to 5 T, a maximum magnetic entropy changes (ΔSM ) value of 8.75 J/kg K was obtained for NdCo2. With an increase of Mn content, the calculated ΔSM shows an obvious decrease with a broader peak. However, the relative refrigerating capacities (RCP) of the NdCo2–x Mn x compounds are larger than the parent compound. The Arrott curves and universal curves of the rescaled ΔSM confirmed that the NdCo2–x Mn x compounds undergo a second-order phase transition.

Effects of Mn content on recrystallization resistance of AA6082 aluminum alloys during post-deformation annealing

The microstructural evolutions under as-homogenized and as-deformed conditions and after the post-deformation annealing of AA6082 aluminum alloys with different Mn content (0.05 wt.%-1 wt.%) were studied by optical, scanning electron, and transmission electron microscopies. The results showed that the presence of a large amount of α-Al(Mn,Fe)Si dispersoids induced by Mn addition significantly improved the recrystallization resistance. In the base alloy free of Mn, static recrystallization occurred after 2 h of annealing, and grain growth commenced after 4 h of annealing, whereas in Mn-containing alloys, the recovered grain structure was well-retained after even 8 h of annealing. The alloy with 0.5% Mn exhibited the best recrystallization resistance, and a further increase of the Mn levels to 1% resulted in a gradual reduction of the recrystallization resistance, the reason for which was that recrystallization occurred only in the dispersoid-free zones (DFZs) and the increased DFZ fraction with Mn content led to an increase in the recrystallization fraction. The variation in the dispersoid number density and a coarsening of dispersoids during annealing have a limited influence on the static recrystallization in Mn-containing alloys.

Effect of Mn content on microstructure, tensile and impact properties of SA508Gr.4N steel for reactor pressure vessel

The effect of manganese (Mn) on the microstructure, tensile and impact properties of SA508Gr.4N steel has been experimentally investigated. The influence of Mn content on the substructure of SA508Gr.4N steel was investigated using the scanning electron microscope, electron back-scattered diffractometer and transmission electron microscope. It was found that the increased Mn content had a beneficial effect on both strength and toughness. Examination of microstructure revealed smaller size of block and larger number of high-angle grain boundaries with higher Mn content. The change of the ultimate tensile strength and toughness with increasing Mn content was attributed to the increased hardenability, the number of high-angle grain boundaries and the crack propagation path by the block refining.

Effect of Mn Content on the Characteristics of Inclusions in Ti-Containing Steel Welds

Steel weld metals containing Ti were prepared with Mn contents of 0.35%–2.98%. The inclusion characteristics in the weld metals were investigated by means of thermodynamic calculations coupled with electron probe microanalyses and transmission electron microscopy. The results show that with an increase in Mn content, the primary constituent phases of the inclusions are changed from pseudobrookite to a combination of pseudobrookite and spinel and eventually to a mixture of (Mn–Si–Al)-oxide, spinel and ilmenite. Ti3O5, MnTi2O4 and MnTiO3 are the primary constituents of the pseudobrookite, spinel and ilmenite solid solutions, respectively. Spinel and ilmenite have higher amounts of Mn but lower amounts of Ti compared with that of pseudobrookite. The formation of large amounts of ilmenite and spinel leads to the development of a Mn-depleted zone (MDZ) in the vicinity of the matrix/inclusion interface. Acicular ferrite has a Baker–Nutting orientation relationship with MnTi2O4.

Effects of Mn Content and Carbon Equivalent on Impact Characteristics in Heavy Section Spheroidal Graphite Cast Iron

Effects of Mn Content and Carbon Equivalent on Impact Characteristics in Heavy Section Spheroidal Graphite Cast Iron

Effect of Mn content on the microstructure and phase transformation temperatures of the Cu-Al-Mn-Ag shape memory alloys

Effect of Mn content on the microstructure and phase transformation temperatures of the Cu-Al-Mn-Ag shape memory alloys