Mn Ti Research Articles

Elemental Mercury Oxidation over Fe–Ti–Mn Spinel: Performance, Mechanism, and Reaction Kinetics

The design of a high-performance catalyst for Hg0 oxidation and predicting the extent of Hg0 oxidation are both extremely limited due to the uncertainties of the reaction mechanism and the reaction kinetics. In this work, Fe-Ti-Mn spinel was developed as a high-performance catalyst for Hg0 oxidation, and the reaction mechanism and the reaction kinetics of Hg0 oxidation over Fe-Ti-Mn spinel were studied. The reaction orders of Hg0 oxidation over Fe-Ti-Mn spinel with respect to gaseous Hg0 concentration and gaseous HCl concentration were approximately 1 and 0, respectively. Therefore, Hg0 oxidation over Fe-Ti-Mn spinel mainly followed the Eley-Rideal mechanism (i.e., the reaction of gaseous Hg0 with adsorbed HCl), and the rate of Hg0 oxidation mainly depended on Cl• concentration on the surface. As H2O, SO2, and NO not only inhibited Cl• formation on the surface but also interfered with the interface reaction between gaseous Hg0 and Cl• on the surface, Hg0 oxidation over Fe-Ti-Mn spinel was obviously inhibited in the presence of H2O, SO2, and NO. Furthermore, the extent of Hg0 oxidation over Fe-Ti-Mn spinel can be predicted according to the kinetic parameter kE-R, and the predicted result was consistent with the experimental result.

Lamprophyres of the Tomtor Massif: A result of mixing between potassic and sodic alkaline mafic magmas

The paper presents data on inclusions in minerals of the least modified potassic lamprophyres in a series of strongly carbonatized potassic alkaline ultramafic porphyritic rocks. The rocks consist of diopside, kaersutite, analcime, apatite, and rare phlogopite and titanite phenocrysts and a groundmass, which is made up, along with these minerals, of potassic feldspar and calcite. The diopside and kaersutite phenocrysts display unsystematic multiple zoning. Chemically and mineralogically, the rock is ultramafic foidite and most likely corresponds to monchiquite. Primary and secondary melt inclusions were found in diopside, kaersutite, apatite, and titanite phenocrysts and are classified into three types: sodic silicate inclusions with analcime, potassic silicate inclusions with potassic feldspar, and carbonate inclusions, which are dominated by calcite. Heating and homogenization of the inclusions show that the potassic lamprophyres crystallized from a heterogeneous magma, with consisted of mixing mafic sodic and potassic alkaline magmas enriched in a carbonatite component. The composition of the magmas was close to nepheline and leucite melanephelinite. The minerals crystallized at 1150–1090°C from the sodic melts and at 1200–1250°C from the potassic ones. The sodic mafic melts were richer in Fe than the potassic ones, were the richest in Al, Mn, SO3, Cl, and H2O and poorer in Ti and P. The potassic mafic melts were not lamproitic, as follows from the presence of albite in the crystallized primary potassic melt inclusions. The diopside, the first mineral to crystallize in the rock, started to crystallize in the magmatic chamber from sodic mafic melt and ended to crystallize from mixed sodic–potassic melts. The potassic mafic melts were multiply replenished in the chamber in relation to tectonic motions. The ascent of the melts to the surface and rapidly varying P–T parameters of the magma were favorable for multiple separations of carbonatite melts from the alkaline mafic ones and their mixing and mingling.

Precipitation behaviour of oxide in directionally solidified aerospace bearing steel

The directional solidification enables independently control of the holding temperature and withdrawal rate over a given range. This technology was used to investigate the precipitation behaviour of oxide in aerospace bearing steel M50NiL. Most of the oxides are Si–Al–Mn–Ti–O complex inclusions with spherical shape. With the increase of withdrawal rate, the size and volume fraction of oxides decrease. In contrast, the diameter and volume fraction increase remarkably with the increase of holding temperature. The composition of oxides with different sizes varies with holding temperature. The holding temperature of 1550°C accompanied with a cooling rate over 95.7°C min−1 is deemed as the optimal solidification parameters for M50NiL steel, which can significantly reduce the size and volume fraction of oxides.

Crystal structure and magnetic properties of Bi1−x Ca x Fe1−x Mn(Ti) x O3 ceramics across the phase boundary

Crystal structure and magnetic properties of BiFeO3 compounds co-doped with Ca and Mn ions as well as Ca and Ti ones were studied using diffraction and magnetometry techniques. Crystal structure of the Bi1−xCaxFe1−xMnxO3 ceramics with x 0.25 show complex magnetic behavior associated with the coexistence of antiferromagnetic matrix and magnetic clusters. Compounds co-doped with Ca and Ti ions with rhombohedral structure testify nearly three times larger remnant magnetization as compared with that observed for Ca|Mn-doped series, and magnetic state of the compounds with x > 0.1 remains to be homogeneous weak ferromagnetic one up to x ~ 0.3, and above this concentration, magnetic structure is disrupted because of diamagnetic dilution.

Fabrication and thermomechanical characterization of a new Cu–Al–Ni–Mn–Ti shape memory alloy bolt

Industry experts in product innovation are always developing proposals and more effective solutions appropriate to the needs of some high-tech industrial areas, creating advanced technologies that increase the reliability of systems used in these areas. In this context, advanced materials are frequently studied to obtain more reliability in bolted joints, avoiding problems, such as leaks in pipelines or constant maintenance. In this work, a novel superelastic bolt was developed from a Cu–Al–Mn–Ni–Ti shape memory alloy (SMA) to increase reliability in bolted connections. The superelastic phenomenon presented by SMA allows full or partial recovery of large strains, between 4 and 8 % in tensile mode. This capability can be useful for the development of various industrial applications, especially in areas that require new high-technologies such as aerospace, automotive, energy and oil and gas sectors. Thus, this paper describes the fabrication and thermomechanical characterization of a superelastic bolt from a copper based SMA. The selected Cu–Al–Mn–Ni–Ti superelastic SMA was processed using plasma melting followed by metal injection molding for minimizing bolt manufacturing machining steps. After the manufacture of the SMA bolt, it was carried out thermomechanical characterization using DSC thermal analysis and reversible tensile testing at increasing temperatures between 35 and 90 °C. The results show that the superelastic bolt has good mechanical properties, demonstrating a great capacity for strain recovery and energy dissipation by mechanical hysteresis.

Aliovalent MnTi and GaTi substitution in high-temperature piezoelectric (x)Bi(Zn0.5Zr0.5)O3—(y)BiScO3—(100 – x − y)PbTiO3

Aliovalent substitution of 1–2 % Mn and Ga for Ti has been carried out in the high-temperature ternary system (x)Bi(Zn0.5Zr0.5)O3—y)BiScO3—(100−x−y)PbTiO3 near the morphotropic phase boundary, specifically 2.5BZZ-37.5BS-60PT in an attempt to reduce the loss tangent. Modifications of this particular composition were chosen due its high-Curie temperature of 420 °C and excellent piezoelectric coefficient of 520 pm/V. Dielectric, piezoelectric, and electromechanical properties were characterized as a function of temperature, frequency, and electric field for all compositions. Small concentrations of Mn and Ga were shown to increase both the electrical and mechanical quality factors, with a Q m and Q e of 300 and 150, respectively, from room temperature up to 300 °C for Mn-doped compositions.

Simulated structural and magnetic behavior of Mn–Ti intercalated dichalcogenide crystals

We present the results of extensive Monte Carlo simulations of intercalated manganese–titanium (Mn–Ti) layered TiS2 crystals. The computational model involves mixtures of Mn and Ti in various percentages placed on a triangular lattice with fixed lattice sites and up to five layers. The range of concentrations of intercalated Mn studied was 5% ⩽ XMn ⩽ 33% and for Ti, 0% ⩽ XTi ⩽ 15%, where XA denotes the percentage of the total number of lattice sites occupied by species A. The species are allowed to interact spatially through a screened Coulomb potential and magnetically with external and RKKY field terms. Structurally, the pure Mn systems present as disordered at very low densities and evolve through a 2 × 2 structure (perfect at XMn = 25%) up to a × lattice (perfect at XMn = 33%), with variations of the two ‘perfect’ lattice structures depending on density. Changes in density for pure Mn systems as well as those intercalated with both Mn and Ti dramatically affects the system’s structural and magnetic properties, and the magnetic behavior of various morphological features present in the system are discussed. The RKKY interaction is adjusted based on the intercalant compositions and is very sensitive to structural variations in the intercalant layers. The composition ranges studied here encompass and exceed those that are experimentally accessible, which helps place experimentally relevant densities in perspective.

Complex permittivity and relaxation processes in CaCu3Ti(4−x)MnxO12

The effects of Mn-doping on CaCu3Ti4O12 (CCTO), i.e. the electrical properties of CaCu3Ti(4−x)MnxO12 were studied in order to get a deep insight into the origin of the colossal dielectric constant of CCTO. It was found that 1mol% substitution of Mn for Ti decreases the dielectric constant largely to a factor of 1/100, supporting the point of view that the native defects are responsible for the dielectric response of CCTO.

Microstructure of HIPed and SPSed 9Cr-ODS steel and its effect on helium bubble formation

Two 9Cr-ODS steels with the same nominal composition were consolidated by hot isostatic pressing (HIP, named COS-1) and spark plasma sintering (SPS, named COS-2). Helium ions were implanted into COS-1, COS-2 and non-ODS Eurofer 97 steels up at 673 K. Microstructures before and after helium ion implantations were carefully characterized. The results show a bimodal grain size distribution in COS-2 and a more uniform grain size distribution in COS-1. Nanoscale clusters of GP-zone type Y–Ti–O and Y2Ti2O7 pyrochlore as well as large spinel Mn(Ti)Cr2O4 particles are all observed in the two ODS steels. The Y–Ti-enriched nano-oxides in COS-1 exhibit higher number density and smaller size than in COS-2. The Y–Ti-enriched nano-oxides in fine grains of COS-2 show higher number density and smaller size than that in coarse grains of COS-2. Nano-oxides effectively trap helium atoms and lead to the formation of high density and ultra-fine helium bubbles.

Fabrication of low-cost beta-type Ti–Mn alloys for biomedical applications by metal injection molding process and their mechanical properties

Titanium and its alloys are suitable for biomedical applications owing to their good mechanical properties and biocompatibility. Beta-type Ti–Mn alloys (8–17 mass% Mn) were fabricated by metal injection molding (MIM) as a potential low cost material for use in biomedical applications. The microstructures and mechanical properties of the alloys were evaluated. For up to 13 mass% Mn, the tensile strength (1162–938MPa) and hardness (308–294HV) of the MIM fabricated alloys are comparable to those of Ti–Mn alloys fabricated by cold crucible levitation melting. Ti–9Mn exhibits the best balance of ultimate tensile strength (1046MPa) and elongation (4.7%) among the tested alloys, and has a Young’s modulus of 89GPa. The observed low elongation of the alloys is attributed to the combined effects of high oxygen content, with the presence of interconnected pores and titanium carbides, the formation of which is due to carbon pickup during the debinding process. The elongation and tensile strength of the alloys decrease with increasing Mn content. The Ti–Mn alloys show good compressive properties, with Ti–17Mn showing a compressive 0.2% proof stress of 1034MPa, and a compressive strain of 50%.

Economic minerals of the Kovdor baddeleyite-apatite-magnetite deposit, Russia: mineralogy, spatial distribution and ore processing optimization

The comprehensive petrographical, petrochemical and mineralogical study of the Kovdor magnetite-apatite-baddeleyite deposit in the phoscorite–carbonatite complex (Murmansk Region, Russia) revealed a spatial distribution of grain size and chemical composition of three economically extractable minerals — magnetite, apatite, and baddeleyite, showing that zonal distribution of mineral properties mimics both concentric and vertical zonation of the carbonatite-phoscorite pipe.The marginal zone of the pipe consists of (apatite)-forsterite phoscorite carrying fine grains of Ti–Mn–Si–rich magnetite with ilmenite exsolution lamellae, fine grains of Fe–Mg-rich apatite and finest grains of baddeleyite, enriched in Mg, Fe, Si and Mn. The intermediate zone accommodates carbonate-free magnetite-rich phoscorites that carry medium to coarse grains of Mg–Al-rich magnetite with exsolution inclusions of spinel, medium-grained pure apatite and baddeleyite. The axial zone hosts carbonate-rich phoscorites and phoscorite-related carbonatites bearing medium-grained Ti–V–Ca-rich magnetite with exsolution inclusions of geikielite–ilmenite, fine grains of Ba–Sr–Ln-rich apatite and comparatively large grains of baddeleyite, enriched in Hf, Ta, Nb and Sc. The collected data enable us to predict such important mineralogical characteristics of the multicomponent ore as chemical composition and grain size of economic and associated minerals, presence of contaminating inclusions, etc. We have identified potential areas of maximum concentration of such by-products as scandium, niobium and hafnium in baddeleyite and REEs in apatite.

An application of PIXE technique to Proto Crustal Rocks: Geo chemical evaluation of Granulitic Charnockites of Eastern Ghats, Andhrapradesh, India

In this work, PIXE has been used for a variety of Precambrian proto crustal rocks in the form of granulitic charnockites,Eastern Ghats AP,India.In previous study of exterior part of the charnockite hill elemental analysis using electron microprobe analysis, the elements in host charnockites no Na, traces of Mn,Ca and high Ti,Cl,F (Biotite), no Mn, low Na,and high K,Cl (Hastingsite), and Cl, Fe (Apatite) were only detected, but by using PIXE technique in addition to the above twenty two trace elements are identified. PIXE is highly sensitive and non-destructive method for multi elemental analysis in a variety of Precambrian charnockite rocks down to levels of a few parts per million. The samples chosen for analysis from the central portion of a charnockite hill near Visakhapatnam airport. A big reticular mass of relict litho logical body which is compositionally and physically different from host chatnockite was observed in the central portion of the hill. These experiments are carried out using a 3MV pelletron accelerator facility at the Institute of physics, Bhubaneswar. A collimated proton beam of 2mm diameter is made to fall on to the sample, and the beam current is kept at 20na. A high resolution Si(Li) detector(160ev FWHM at 5.9kev energy) is employed in the present experiments and the Guelph PIXE (GUPIX) software package is used to analyze the spectra. The elements identified in this Precambrian charnockite rock are Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Se, Br, Rb, Sr, Y, Zr, Nb, Mo, Ru, Ag, Pb..From this study these rocks are early crust(proto crust) rocks. These samples are to belong to a very important geological phase and further work on petrography and REE (Rare Earth Elements in Geology)of the rock is indeed to firmly establish its exact parentage.

Al2O3-modified Ti–Mn–O nanocomposite coated with nitrogen-doped carbon as anode material for high power lithium-ion battery

Al2O3-modified Ti–Mn–O nanocomposite coated with nitrogen-doped carbon using simple method exhibits remarkable rate performance.

The mineralogy, geochemistry and health risk assessment of deposited particulate matter (PM) in Kraków, Poland

One of the most important air contaminants in Krakow is particulate matter (PM), especially during winter months. Deposited PM was sampled between November 2014 and January 2015 and November 2015 and January 2016. The PM deposition amounted to 0.0646 g/m2 per day in the centre of Krakow and 0.0328 g/m2 in the northern district of the city. The allowed value of annual dust deposits (0.547 g/m2 per day) was not exceeded. The XRD and SEM-EDS analysis showed that quartz, calcite, potassium feldspar, plagioclase, kaolinite, and gypsum were the main mineralogical components of the deposited PM. Only in a few samples were illite, dolomite, and apatite observed. Significant concentrations were measured (ICP-MS) for Ca, Fe, Mg, Al, K, Si, Na, and Mn, and high concentrations for Ti, Cu, Zn, As, Pb, Cr, Ti, V, Li, Sr and Ni. The highest estimated daily intakes (EDI) for resuspended PM, were stated for ingestion exposure pathway than for dermal contact, and finally for inhalation, both for children and adults, as well as, for carcinogenic and non-carcinogenic elements. The mean hazard quotient (HQ) values for all three exposure pathways decreased in the following order: Fe > Al > Zn > Mn > Sr > Cu > Ba > Cr > Pb > V > Ni > Li > As > Sn > Zr > Co > Cd > Be, for children and adults. The hazard index values for all elements in each exposure pathway (HIelem) and for single elements in all exposure pathways (HIpath) were <1, both for children and adults. The risk values from all three exposure pathways were unacceptable in the case of Cr, both for children and adults, and in the case of As for children. The total non-carcinogenic risk (HItotal) values in all three exposure pathways for all elements were <1, however in case of children the risk value pointed to a low risk level. The total carcinogenic risk (Rtotal) values in all three exposure pathways for As and Cr exceeded the acceptable level, both for children and adults.

Amorphous nanosized Al–Ti–Mn trimetal hydrous oxides: synthesis, characterization and enhanced performance in arsenic removal

Arsenite oxidation and arsenate adsorption on surface of amorphous nanosized Al–Ti–Mn trimetal hydrous oxides.

Improvement in mechanical strength of low-cost β-type Ti–Mn alloys fabricated by metal injection molding through cold rolling

In order to develop new low-cost and high-strength β-type titanium alloys, a Ti–13Mn was fabricated by metal injection molding. For improving its tensile strength, Ti–13Mn was subjected to cold-rolling at reduction ratios of 60% and 90%, respectively. The solutionized Ti–13Mn has pores and titanium carbide (Ti carbide) precipitates and consists of a β phase and an athermal ω phase. The porosity of the alloy decreases from 6.1% to 0.01% after cold-rolling at a reduction ratio of 90%. Moreover, during cold-rolling, the Ti carbides are fragmented and a deformation-induced ω phase is formed. The ultimate tensile strength, 0.2% proof stress, Vickers hardness, and Young's modulus of Ti–13Mn increase from 888 MPa to 1852 MPa, from 827 MPa to 1823 MPa, from 279 Hv to 461 Hv, and from 96 GPa to 108 GPa, respectively, after cold-rolling at a reduction ratio of 90%. On the other hand, the elongations of both the solutionized and cold rolled Ti–13Mn are less than 2%. Although the elongation of Ti–13Mn is less than 2%, the tensile strength of the cold rolled Ti–13Mn is extremely high compared with that of existing titanium alloys. This large-improvement in the tensile strength of the cold rolled Ti–13Mn is attributed to the increase in the dislocation density, decrease in grain size, decrease in porosity, and formation of a deformation-induced ω phase.

Experimental and numerical study on formation mechanism of linear macro-segregation in low-pressure die casting of Al–Cu–Mn–Ti Alloy

The formation mechanism of linear macro-segregation in Al–Cu–Mn–Ti alloy cylindrical shell casting was studied by characterizing samples by X-ray detection, microscopic examinations, composition analysis, and simulation of the heat transfer of Al–Cu–Mn–Ti alloy cylindrical shell casting in the solidification process. Numerical and experimental results indicated that linear macro-segregation always occurred in the portion of casting connected with the slit gating system, because of the great hot tearing tendency, the hot cracks formed could be fed by the melt through the slit gating system with an excellent temperature gradient and feeding angle. According to significant effect of floatation of lower density α-Al grains, the solute gradient was formed along the vertical direction of the slit gating system. The hot cracks near the bottom of casting were fed by melt with high concentration of Cu and so, they were cicatrized by the eutectic structure/α-Al + Al2Cu at a temperature of 548℃.

Preparation and capacitance properties of Mn-doped TiO2 nanotube arrays by anodisation of Ti–Mn alloy

Ti–Mn (Mn: 3.0, 7.0, 10.0 wt%) alloys were prepared by a power metallurgical method. Mn-doped TiO2 nanotube arrays have been achieved directly by anodising the Ti–Mn alloys. Morphologies, crystal structure, chemical composition, supercapacitor performances of samples were characterised by scanning electron microscopy, X-ray diffraction, inductively coupled plasma optical emission spectrometry, and electrochemical analysis, respectively. The effects of manganese content, scan rate, current density, and annealing temperature on the capacitive properties were studied. Results show that doping Mn into TiO2 nanotube arrays obviously enhanced their capacitive properties. The nanotube arrays prepared from Ti–Mn alloy (Mn: 7.0 wt%) exhibited the best capacitive performance and after annealed at 300 °C, the areal capacitance reached up to 1662.5 μF/cm2 at a current density of 5.0 μA/cm2. The retention of capacitance was 89.0% when the current density changed from 5.0 to 12.5 μA/cm2 and capacitance retention was 84.6% after 2000 cycles. The factors that contributed to the superior areal capacitance of the film have also been discussed.

Effect of titanium alloying on the structure, the phase composition, and the thermoelastic martensitic transformations in ternary Ni—Mn—Ti alloys

The effect of gallium alloying on the structure, the phase composition, and the properties of quasibinary Ni50Mn50–zGaz (0 ⩽ z ⩽ 25 at %) alloys is studied over a wide temperature range. The influence of the alloy composition on the type of crystal structure in high-temperature austenite and martensite and the critical martensitic transformation temperatures is analyzed. A general phase diagram of the magnetic and structural transformations in the alloys is plotted. The temperature–concentration boundaries of the B2 and L21 superstructures in the austenite field, the tetragonal L10 (2M) martensite, and the 10M and 14M martensite phases with complex multilayer crystal lattices are found. The predominant morphology of martensite is shown to be determined by the hierarchy of the packets of thin coherent lamellae of nano- and submicrocrystalline crystals with planar habit plane boundaries close to {011}B2. Martensite crystals are twinned along one of the 24 \(24\left\{ {011} \right\}{\left\langle {01\bar 1} \right\rangle _{B2}}\) “soft” twinning shear systems, which provides coherent accommodation of the martensitic transformation–induced elastic stresses.

Microstructures, mechanical properties and cytotoxicity of low cost beta Ti–Mn alloys for biomedical applications

The microstructures, mechanical properties and biocompatibility of low cost β-type Ti-(6-18)Mn alloys were investigated after solution treatment. Ti–9Mn exhibits the best combination of tensile strength and elongation among the fabricated alloys, and its performance is comparable to or superior to those of Ti–6Al–4V ELI (Ti-64 ELI) in terms of every parameter evaluated. A hardness of 338 HV, a Young’s modulus of 94GPa, a 0.2% proof stress of 1023MPa, an ultimate tensile strength of 1048MPa and elongation of 19% were obtained for Ti–9Mn. Furthermore, the cell viability and metallic ion release ratios are comparable to those of commercially pure titanium, making this alloy promising for biomedical applications. The Young’s modulus is also lower than that of Ti-64 ELI (110GPa), which can possibly reduce the stress shielding effect in implanted patients. Statement of significanceThis study evaluates mechanical and biological performance of low cost solution treated β-type Ti-(6, 9, 13 and 18mass%)Mn alloys. It includes alloys containing a Mn content range higher than most previously published works (which is around or lower than 8mass%). Furthermore, the effects of the ω phase and the β phase stability of the alloys over some mechanical properties and microstructures are discussed. Ion release behavior under simulated body fluids and cell viability are also evaluated. For the case of the Ti–9Mn, a mechanical and biological performance that is comparable to or superior than that of the widely used Ti–6Al–4V ELI and commercially pure Ti was observed.