Titanium Compounds Research Articles

Catalytic Transformations of 4-tert-Butylphenol in Hydrogen Peroxide Solutions in the Presence of Titanium Oxide Compounds and Titanosilicates

Catalytic Transformations of 4-tert-Butylphenol in Hydrogen Peroxide Solutions in the Presence of Titanium Oxide Compounds and Titanosilicates

The Synergistic Antiwear Performances of Organic Titanium Compounds Containing Sulfur with Borate Ester Additive

Two oil-soluble organic titanium compounds (OTCs) such as titanium dialkyldithiocarbamate (TiDDC) and sulfurized titanate (TiS) were synthesized and identified by Fourier-transform infrared spectroscopy (FTIR). The antiwear and extreme pressure properties of TiDDC or TiS with borate ester containing nitrogen (BNO) additive in mineral base oils were evaluated by four ball tester. The results show that TiDDC and TiS not only possess good antiwear and load-carrying properties, respectively, but also exhibit good antiwear synergism with BNO additive without impairing extreme pressure performances. Moreover, the synergistic antiwear properties of the said additives are improved significantly under the optimum additives ratios. The topography of wear scar and the composition and chemical states of typical elements on the rubbing surfaces were analyzed by scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) and X-ray photoelectron spectrometer (XPS). The proposed synergistic antiwear mechanism involves an effective interaction between TiDDC or TiS and BNO additive, respectively.

Intercalation of alkali metals (Li, Na, and K) in molybdenum dinitride (MoN2) and titanium dinitride (TiN2) from first-principles calculations

We studied ternaries of nitrogen-rich titanium and molybdenum compounds combined with alkali metals (Li, Na, and K) as potential layered materials. LiMoN2 has already been synthesized with layered structure corresponding to intercalated 3R-MoS2, however efforts to completely deintercalate Li from LiMoN2 were unsuccessful. We studied ternaries MAN2 (A: Ti, Mo and M: Li, Na, K) having layered crystal structures, their deintercalation, and the layered binaries TiN2 and MoN2 within density-functional theory. We find that LiMoN2 and NaMoN2 have a layered structure isotypic to 2H-MoS2 with Li and Na ions filling interlayer spaces whereas LiTiN2 and NaTiN2 are isotypic to α-NaFeO2. Both KMoN2 and KTiN2 have a different kind of structure isotypic to SrTiN2 which differentiates K from Li and Na. Ternaries Li(Na)MoN2 and Li(Na)TiN2 are all metals and the alkali metal atoms are present as ions in these structures. Partially deintercalated ternaries suggest that layers can interact strongly and the material can loose its layered form. Furthermore, we find that binary MoN2 having a layered structure is not stable since monolayer MoN2 has a positive formation energy and N atoms belonging to neighboring layers interact and form N2 dimer in between Mo layers in which case formation energy becomes negative indicating that structure becomes more stable. These results can explain the decomposition of LiMoN2 during the experimental trials of complete deintercalation. In contrast, TiN2 has a negative formation energy already without interaction of N atoms belonging to neighboring layers.

A thermochemical and experimental study for the conversion of ilmenite sand into fine powders of titanium compounds

The adiabatic temperatures and equilibrium phases in the FeTiO3-αMg-C(B, Si)-kNaCl system (where α = 0.2–15, k = 0–3) were analyzed to predict the formation of fine powders of titanium compounds from natural ilmenite sand. From the parametric study, the critical variables were identified and optimized for the synthesis of FeTi, TiC, TiB2, and TiFeSi2 under a combustion regime. The experimentally measured temperatures were in good agreement with those predicted from thermochemical calculations in the 900–1800 °C range. The purified products were characterized using X-ray diffraction, transmission electron microscopy, and Raman spectroscopy. The fine powders of titanium compounds were mainly single phase with a purity of at least 95 wt%. Considering the various stages of the synthetic process, a mechanism is proposed to explain how the process of ilmenite recovery occurred.

Synthesis and Photocatalytic Activity of Nanosized Powder of Zn-Doped Titanium Dioxide

Nanosized powder materials made Zn-doped titanium dioxide with concentration of 0.1, 0.5, and 1.0 mol % Zn2+ have been synthesized from aqueous solutions of inorganic compounds of titanium modified with zinc(II) ions. The materials obtained have been studied by electron microscopy, thermogravimetric analysis, and powder X-ray diffraction. It has been found that if zinc ions introduced in titanium dioxide the stabilization of anatase modification takes place retaining size and morphology of particles. The materials synthesized have shown photocatalytic activity under ultraviolet and visible light irradiation. The highest photocatalytic activity has been found for material containing 0.1 mol % Zn2+ and calcined at 600°С.

Thermodynamic preconditions of the titanium compounds formation with interstitial elements (C, N, O, B) depending on temperature and pressure of gaseous medium

Титан належить до легких металів, які внаслідок низької питомої густини та низького модуля пружності мають значні переваги при використанні в автомобільній та авіаційній промисловостях. Застосування методів інженерії поверхні дозволяє розширити сфери використання титанових сплавів, забезпечити надійність та роботоздатність виробів з них, суттєво підвищити економічність їх експлуатації. Проведення попередніх термодинамічних розрахунків у системі «Ti-C-N-O-B» дозволить оптимізувати вибір схем та режимів обробок для формування тих чи інших сполук на метал, що підтверджує актуальність теми даної роботи. Наведено результати термодинамічного аналізу ймовірності утворення хімічних сполук у системі «Ti-C-N-O-B». Проведено ранжування утворення хімічних реакцій залежно від температури (Т = 100…1200°С) й тиску повітря (Р = 1,33∙10-8…1∙105 Pа). Показано, що найактивніше титан буде взаємодіяти з киснем, утворюючи твердий розчин втілення з подальшим утворенням оксидів. Наступними за ймовірністю будуть утворюватися нітриди, потім карбіди і до температури Т = 900°С – бориди титану. Виявлено, що вище температури Т = 900°С сполука TiB утворюватися не повинна, може відбуватися лише дифузійне насичення титану бором. Показано, що за контакту B2O3 та B2O2 з титаном ці оксиди будуть розпадатися й утворювати відповідно оксиди титану та бориди титану. За контакту титану з нітридом бору ймовірно буде відбуватися його дисоціація та утворення нітриду титану й бориду титану. Карбід бору B4C за контакту з титаном буде виступати як донор бору та вуглецю, а вище Р = 700°С він буде розкладатися на бор та вуглець. Зниження тиску повітря зменшує ймовірність утворення сполук, що містять кисень та азот. За температури Т = 800°С існуюча сполука B2O2 буде розкладатися і не буде утворюватися за тиску нижче Р = 1,33∙103 Pа. Подібна ситуація складеться для B2O3 за температури Т = 1000°С – ця сполука не може утворюватися за тиску нижче Р = 0,133 Pа. Зниження тиску до Р = 1,33 Pа за температури Т = 1000°С призводить до збільшення ймовірності утворення TiC ніж TiN. Доставляння бору через газову фазу оксиду B2O3 стає ймовірним вище температури Т = 950°С, коли тиск його насиченої пари стає вищим за Р = 1,33∙10-3 Pа.

Preparation of new photocatalytic materials using ion implantation method

The materials containing titanium supported on stainless steel foil 12X18N10T (AISI 321) were prepared by low temperature ion implantation method. Samples were investigated by means of XRD, SAXS, AFM, XPS and SEM methods. Any reflexes of titanium compounds were determined (XRD) but XPS data permit to identify the presence of titanium nitride, its oxide and oxynitride on surface samples. It was shown, that the synthesized samples are more active in visible range than under UV irradiation in photodegradation of benzene in aqueous solutions. Influence of pretreatment temperature on photoactivity of the samples is connected with nitrogen removal from synthesized composites.

A facile way to prepare carbon-coated Li4Ti5O12 porous fiber with excellent rate performance as anode in lithium ion battery

Carbon is an economy and effective material for improving the electron conductivity of Li4Ti5O12, coating carbon on Li4Ti5O12 is commonly through the means of calcinating the mixture of titanium, lithium and organic compounds in an inert atmosphere, which needs a careful control to avoid the reduction of Ti4+ in Li4Ti5O12 by the in-situ formed carbon. In this work, a facile way is applied to fabricate carbon on Li4Ti5O12 by using filter paper to absorb the solution containing Ti(OC4H9)4 and LiAC with a calcination at 700 °C in air. The formation of carbon on Li4Ti5O12 mainly related with the swelling property of the crystalliferous region in cellulose fiber. TEM image shows Li4Ti5O12 particles have the average diameter about 100 nm, which are coated by a thin layer of carbon with the thickness around 5 nm, and Li4Ti5O12 particles connect with each other by carbon, forming porous fiber, which facilitates the transfer of electron and Li+. In comparison with Li4Ti5O12 synthesized by sol-gel method, Li4Ti5O12/C present superior rate capability with the discharge capacity of about 165 mAh g−1 at 0.2 C and 141 mAh g−1 at 20 C.

Development of Porous Coatings Enriched with Magnesium and Zinc Obtained by DC Plasma Electrolytic Oxidation.

Coatings with developed surface stereometry, being based on a porous system, may be obtained by plasma electrolytic oxidation, PEO (micro arc oxidation, MAO). In this paper, we present novel porous coatings, which may be used, e.g., in micromachine’s biocompatible sensors’ housing, obtained in electrolytes containing magnesium nitrate hexahydrate Mg(NO3)2·6H2O and/or zinc nitrate hexahydrate Zn(NO3)2·6H2O in concentrated phosphoric acid H3PO4 (85% w/w). Complementary techniques are used for coatings’ surface characterization, such as scanning electron microscopy (SEM), for surface imaging as well as for chemical semi-quantitative analysis via energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), glow discharge optical emission spectroscopy (GDOES), and X-ray powder diffraction (XRD). The results have shown that increasing contents of salts (here, 250 g/L Mg(NO3)2·6H2O and 250 g/L Zn(NO3)2·6H2O) in electrolyte result in increasing of Mg/P and Zn/P ratios, as well as coating thickness. It was also found that by increasing the PEO voltage, the Zn/P and Mg/P ratios increase as well. In addition, the analysis of XPS spectra revealed the existence in 10 nm top of coating magnesium (Mg2+), zinc (Zn2+), titanium (Ti4+), and phosphorus compounds (PO43−, or HPO42−, or H2PO4−, or P2O74−).

Review of Hybrid Ion Capacitors: From Aqueous to Lithium to Sodium.

In this critical Review we focus on the evolution of the hybrid ion capacitor (HIC) from its early embodiments to its modern form, focusing on the key outstanding scientific and technological questions that necessitate further in-depth study. It may be argued that HICs began as aqueous systems, based on a Faradaic oxide positive electrode (e.g., Co3O4, RuO x) and an activated carbon ion-adsorption negative electrode. In these early embodiments HICs were meant to compete directly with electrical double layer capacitors (EDLCs), rather than with the much higher energy secondary batteries. The HIC design then evolved to be based on a wide voltage (∼4.2 V) carbonate-based battery electrolyte, using an insertion titanium oxide compound anode (Li4Ti5O12, Li xTi5O12) versus a Li ion adsorption porous carbon cathode. The modern Na and Li architectures contain a diverse range of nanostructured materials in both electrodes, including TiO2, Li7Ti5O12, Li4Ti5O12, Na6LiTi5O12, Na2Ti3O7, graphene, hard carbon, soft carbon, graphite, carbon nanosheets, pseudocapacitor T-Nb2O5, V2O5, MXene, conversion compounds MoS2, VN, MnO, and Fe2O3/Fe3O4, cathodes based on Na3V2(PO4)3, NaTi2(PO4)3, sodium super ionic conductor (NASICON), etc. The Ragone chart characteristics of HIC devices critically depend on their anode-cathode architectures. Combining electrodes with the flattest capacity versus voltage characteristics, and the largest total voltage window, yields superior energy. Unfortunately "flat voltage" materials undergo significant volume expansion/contraction during cycling and are frequently lifetime limited. Overall more research on HIC cathodes is needed; apart from high surface area carbon, very few positive electrodes demonstrate the necessary 10 000 or 100 000 plus cycle life. It remains to be determined whether its lithium ion capacitors (LICs) or sodium ion capacitors (NICs) are superior in terms of energy-power and cyclability. We discuss unresolved issues, including poorly understood fast-charge storage mechanisms, prelithiation and presodiation, solid electrolyte interface (SEI) formation, and high-rate metal plating.

X-ray emission spectroscopy optimization for chemical speciation in laboratory

K X-ray emission spectra emitted from carbon, aluminum, silicon, phosphorus, titanium, chromium, and manganese compounds were measured, using a compact lab-scale flat crystal X-ray fluorescence spectrometer. The sensitivity of K X-ray transitions line-shape, relative to the atom's chemical speciation, is considered. Spectrometer's optimization concerning high energy resolution takes place for each measured fluorescence transition. The detected changes on the measured X-ray line-shapes allow extracting the chemical speciation of the emitting atom. In-lab high-resolution X-ray emission spectroscopy is shown to be a highly versatile technique for materials chemical characterization.

Effects of Open Atmosphere Solutionizing Treatment on the Microstructural and Mechanical Properties of Porous 60NiTi Parts

Titanium alloys have been widely used for medical implants due to their good biocompatibility and excellent corrosion resistance. 60NiTi, an intermetallic nickel-titanium alloy containing approximately 60 wt.% Ni and 40 wt.% Ti, is a promising material for medical components such as implants and prostheses. 60NiTi is hard with good biocompatibility, highly corrosion resistant and has relatively low stiffness. In this study, conventional press-and -sinter method was employed to produce porous 60NiTi parts suitable for general bone replacement applications such as spinal and cranial inserts. The effect of solution treatment in a non-protected furnace and water quenching on the mechanical and microstructural properties of 60NiTi were investigated. It was found that this procedure produces a hard integral ceramic layer, a complex mixture of nickel and titanium oxide compounds, on the surface and around the pores of 60NiTi parts. Results showed that this heat treatment procedure causes the embrittlement of the parts due to an increase in oxide content. However, the produced ceramic surface can also enhance the resistance to corrosion, which is beneficial from a biocompatibility point of view.

Hydrothermal synthesis, structures and visible light harvest of three titanium complexes

Hydrothermal syntheses have been extensively used in the area of polyoxometalates and metal organic frameworks. However, the hydrothermal synthesis of crystalline titanium(IV) complexes is a daunting challenge. The reason is that the high reactivity and spontaneous hydrolysis of titanium(IV) ions always leading to fast precipitation of corresponding oxide rather crystalline compounds. Herein, we reported an effective way towards crystalline titanium(IV) complexes. In the presence of organic amines, we successfully isolated three titanium(IV) compounds. It is worth noting that organic amines play a vital role in the synthesis process, while the introduction of chromophores largely enhanced the visible light harvest.

Solid-Phase Synthesis in the Technology of Functional Materials Based on Titanium(IV)

A study was made of structural, morphological, and chemical transformations in solid-phase systems based on sulfate, oxide, and hydroxide compounds of titanium(IV) under the intense mechanical activation of solid particles. This enabled one to substantiate the phase formation mechanism initiated by the intense homogenization of the reaction mixture, which is accompanied by a decrease in the particle size, deformation of the particle structure, and the formation of a new active surface. The obtained results formed the physicochemical basis for developing an innovative nonwaste technology for producing a new grade of titanium dioxide in the rutile modification from titanium sulfate salt under a program performed by the Roscosmos State Corporation for Space Activities.

Relative L3 transition probabilities of titanium compounds as a function of the oxidation state using high-resolution X-ray emission spectrometry

The relative transition probabilities of the L3-fluorescence lines from different titanium oxides were determined using high-resolution X-ray emission spectrometry. A reliable deconvolution of the X-ray emission spectra, by means of both experimentally determined response functions and absorption correction, reduces the relative uncertainties of the relative transition probabilities to 10% for titanium and 15% for titanium dioxide. The relative L3 transition probability of metallic titanium amounts to 0.66 ± 0.07 for the Ll fluorescence line and 0.34 ± 0.07 for the Lα fluorescence line, respectively. Respective database values from existing literature vary up to a factor of 3, which shows that a determination of the fundamental parameters in the soft X-ray range with low uncertainties is needed in particular with respect to surface sensitive X-ray spectrometer methods. The relative L3 transition probability for titanium dioxide is slightly changed to 0.56 ± 0.08 for the Ll fluorescence line and 0.44 ± 0.08 for the group of fluorescence lines associated to the L3 transition of titanium dioxide that can be considered equivalent to the metal Lα fluorescence line.

Structural Transformations Occurring during the Formation of TiAl<sub>3</sub>-Based Composites Reinforced by TiB<sub>2</sub> or TiC Hard Particles

This work is devoted to investigation of the structure of Ti-TiAl3 composites reinforced by TiB2 or TiC hard particles and obtained by spark plasma sintering of elemental foils and ceramic powders. Sintering was carried out at the temperature of 830 oC under the pressure of 40 MPa during 10 minutes. Microstructure of the composites obtained was represented by alternated layers of titanium and intermetallic compound TiAl3. Also, it was found that at the Ti-TiAl3 interfaces thin intermediate layers were formed. Quantitative elemental analysis of these layers showed that Ti3Al, TiAl, and TiAl2 compounds, as well as Ti (Al) solid solution could be formed in these zones. Diffraction analysis did not reveal any transformations of initial reinforcing phases after sintering. Interlayers with titanium diboride had the average microhardness level of 3988 HV, and the average microhardness level of interlayers with TiC was 1610 HV.

Comparison of early osseointegration between laser-treated/acid-etched and sandblasted/acid-etched titanium implant surfaces.

This study was designed to compare the early osseointegration of titanium surfaces prepared via laser-treated/acid-etched (LA) and sandblasted/acid-etched (SLA) in dogs. Titanium implants were divided into two groups: Surfaces of the experimental group were treated via LA, while in the control group, surfaces were treated via SLA. The physical and chemical properties of LA and SLA surfaces were tested and compared. Sixteen implants with LA or SLA surfaces were placed into the tibias of four beagle dogs, each treatment group received two implants per single tibia. The dogs were sacrificed two and four weeks after implant placement. Scanning electron microscopy showed that both the LA and SLAs surface exhibited rough structures with micro pores sized 1-3 μm. In the LA surface, regular melting points were observed. However, in the SLA surface, the structure was irregular and few oxide aluminum particles still remained. Only titanium and a small amount of titanium compounds were detected on LA surfaces, while Al was found of SLA surfaces. The LA surface roughness was above that of SLA surfaces (LA: Ra: 2.1 μm; SLA: Ra :1.53 μm; P < 0.01). Both groups exhibited good osseointegration and no significant differences were found in the BIC% at two or four weeks between both groups (P > 0.05). Both groups exhibited good osseointegration; however, the LA surface was cleaner and more uniform than the SLA surface, and no significant differences were found between both groups.

Research in the Field of Preparing Molded and Unmolded Refractories Based on High-Alumina HCBS. Part 13. Effect of Firing Temperature on Phase Composition, Structure, and Some Properties of Materials Based on Composite Composition HCBS (Bauxite, Electrocorundum, Quartz Glass)1

The effect of firing temperature in the range 800 – 1640°C on the change in phase composition, structure, and some properties of specimen materials prepared on the basis of composite composition HCBS is studied. Four temperature ranges are stablished by a dilatometric method with a nonisothermal heating rate of 300°C/h corresponding to normal thermal expansion (up to 800°C), sintering accompanied by shrinkage (800 – 1150°C), mullitization accompanied by growth (1150 – 1400°), and sintering of mullitized material (1400 – 1500°C). A set of methods is used (XPA, dilatometric analysis, optical, and electron microscopy) to specify the phase composition and material structure in the firing temperature ranges noted. After firing at 1400 – 1640°C the material contains 38 – 42% mullite, 50 – 55% corundum, and balance glass phase and titanium compounds.

The effects of phase transformation on the structure and mechanical properties of TiSiCN nanocomposite coatings deposited by PECVD method

In the present study, the effects of phase transformations on the structure and mechanical properties of TiSiCN coatings were investigated. TiSiCN nanocomposite coatings were deposited on AISI H13 hot-work tool steel by a pulsed direct current plasma-enhanced chemical vapor deposition process at 350 or 500 °C, using TiCl4 and SiCl4 as the precursors of Ti and Si, respectively, in a CH4/N2/H2/Ar plasma as the source of carbon and nitrogen and reducing environment. Some samples deposited at 350 °C were subsequently annealed at 500 °C under Ar atmosphere. Super hard self-lubricant TiSiCN coatings, having nanocomposite structure consisting of TiCN nanocrystals and amorphous carbon particles embedded in an amorphous SiCNx matrix, formed through spinodal decomposition in the specimens deposited or annealed at 500 °C. In addition, it was revealed that either uncomplete or relatively coarse phase segregation of titanium compounds was achieved during deposition at 350 °C and 500 °C, respectively. On the contrary, by deposition at 350 °C followed by annealing at 500 °C, a finer structure was obtained with a sensible improvement of the mechanical properties of coatings. Accordingly, the main finding of this work is that significant enhancement in key properties of TiSiCN coatings, such as hardness, adhesion and friction coefficient, can be obtained by deposition at low temperature and subsequent annealing at higher temperature, thanks to the formation of a fine grained nanocomposite structure.

The Influence of the Synthesis Temperature on Phase Composition and Structure of Tenary Compounds Obtained from the Powder Mixture of the TiH2-Al-C System

This paper presents the results of an investigation of the features of phase and structure formation of a ternary compound during thermal sintering use of compacted TiH2-Al-C powder blends. The thermal sintering was carried out in a vacuum furnace at temperature 1150, 1300, and 1400 0С. The x-ray diffraction pattern and structural analysis show that the main phase after synthesis at 1150 0С is titanium carbide. The ternary Ti2AlC and intermetallic Ti3Al compound were also identified in the phase composition of the alloy. Increasing the sintering temperature to 1300 °C leads to significant increases in the content of Ti2AlC ternary compounds and accordingly decreases the content of titanium carbide TiC. Is propose a modified model thermal synthesis of ternary compounds of the Ti-Al-C system, which includes the melting of aluminum and its interaction with titanium at low-temperature stages of the process, the formation of the Ti3Al intermetallic compound, formation titanium carbide grains as a result of the interaction of the Al4C3 intermediate metastable phase with titanium or Ti3Al intermetallic compound and the synthesis of ternary Ti2AlC and Ti3AlC2 compounds as a result of the interaction of the Ti3Al intermetallic compound with carbon and Ti2AlC with titanium carbide TiC.