Increasing TiO2 Content Research Articles

High performance PVDF-TiO2 membranes for water treatment

In order to obtain low-fouling membranes, TiO2 nanoparticles were entrapped in PVDF membranes prepared by the NIPS wet-process. Typical asymmetric membrane structure was obtained. Membrane structure, hydrophilic properties and permeability were improved in comparison with PVDF neat membrane when increasing TiO2 concentration up to an optimum concentration of 25%wt. Maximum permeate flux of 150L/h/m2 was successfully obtained. For TiO2 content beyond 25%wt, TiO2 particles agglomeration prevents the improvement of hydrophilic properties and permeability. Under UV irradiation, phenomena of super-hydrophilicity due to presence of TiO2 in the composite membrane permits to suppress pure water permeate flux decline and reach higher fluxes. Fouled composite membranes after BSA filtration were successfully cleaned using water and UV irradiation. Permeate flux was totally recovered after this cleaning.

TiO<sub>2</sub> Added Zn-Bi Based Varistors: Microstructure, I-V, Flow and Aging Characteristics

TiO2 was added in Zn-Bi based varistors to enhance the grain growth of ceramics and the effects of TiO2 addition on the microstructure, I-V, flow and aging characteristics of Zn-Bi varistors were studied. The voltage-gradient of samples decreased to minimum value of 30.6 V/mm when the TiO2 content was 0.6 mol%, but increased with further increasing TiO2 content. The variation trend of average grain size was just the opposite of the voltage-gradient. 0.6 mol% TiO2 added samples have a more unify microstructure and excellent three parameter values with IL=5.7μA, E1mA=30.6V/mm, α=25.8. After Dc aging at 125 oC for 7h, the voltage variation of samples is very slow (~-4.1%).

Tribological Properties of TiO2 Reinforced Nickel Based MMCs Produced by Pulse Electrodeposition Technique

Nickel–TiO2 composite coatings were prepared under pulse current conditions by co-deposition of TiO2 particles and nickel from a Watts type bath. The effect of TiO2 particle concentration was studied on microhardness, friction coefficient and wear resistance. The morphological features and the structures were studied by scanning electron microscope, X-ray diffraction analysis and 3D profilometry facilities. A wide particle size range (between 95 and 140 nm) was chosen to provide a high dispersion and load bearing ability for the co-deposited layers. It was determined that increasing the particle concentration in the electrolyte dramatically increased the co-deposited TiO2 particles in the coating. The results showed that the high concentration of TiO2 particles in the electrolyte yielded the highest amount of particles co-deposited in the plating layer. The influence of the co-deposited TiO2 volume on microstructure and tribological properties in the coating were investigated. The wear tests were carried out using a constant load by a reciprocating ball-on disk configuration. Wear loss and friction coefficients of Ni/TiO2 composites were decreased by increasing TiO2 content in the electrolyte because of the increasing content of TiO2 in the deposited layer. The change in wear mechanisms by changing TiO2 content was also determined.

Microstructure-corrosion resistance relationship of direct and pulse current electrodeposited Zn-TiO2 nanocomposite coatings

Zinc–TiO2 nano-composite coatings were synthesized by Direct Current (DC) and Pulse Current (PC) electrodeposition techniques. The effects of the plating parameters on the microstructure, codeposition percentage of TiO2 and corrosion behavior were investigated. The coatings morphology presents hexagonal grains perpendicularly oriented to the surface. Under DC conditions, TiO2 content of the coatings decreased with increasing TiO2 concentration of the electrolyte. Increasing applied current and TiO2 concentration in the bath leads to a fine microstructure with corrosion currents as low as 2.7µA/cm2. Under PC conditions, incorporation rate of nanoparticles tends to increase with increasing pulse frequency and decreasing current density. Incorporation of TiO2 increases microhardness of the zinc coatings by improving deposit structure.

The structural role of Ti in a thermally-treated Li2O − B2O3–Al2O3 glass system

A 50Li2O·45B2O3·5Al2O3 (LBA, in mol%) glass matrix doped with increasing TiO2 content was synthesized and its physical properties were investigated by differential thermal analysis (DTA), X-ray diffraction (XRD), and Raman spectroscopy. The thermograms showed typical vitreous curves with two clear crystallization peaks that are related to major crystalline phases in this glass system and in agreement with XRD results. The higher temperature crystallization peak (TC2) shifted towards the lower temperature peak (TC1) as TiO2 content increased. After specific heat treatments, the XRD measurements revealed the α-LiBO2, γ-LiAlO2 and LiTiO2 crystalline phase formations and the predominance of the first phase. The γ-LiTiO2 phase was particularly responsible for the variation in the second peak crystallization kinetics. In addition, crystal growth phase competition between γ-LiAlO2 and LiTiO2 occurred as TiO2 content increased; however, the main α-LiBO2 phase did not change. Raman spectra showed typical phonon modes associated with crystalline phases observed in XRD and main phases observed in DTA. Phonon modes were also associated with the LiTiO2 crystalline phase that was first observed in the glassy matrix.

Mechanical and moisture barrier properties of titanium dioxide nanoparticles and halloysite nanotubes reinforced polylactic acid (PLA)

Polylactic acid (PLA) has been larger used in biomedical field due to its low toxicity and biodegradability. The aim of this study was to produce PLLA nanocomposites, by melt extrusion, containing Halloysite nanotubes (HNT) and/or titanium dioxide (TiO2) nanoparticles. Immediately after drying, PLLA was mechanically homogenized with the nanofillers and then melt blended using a single screw extruder (L/D = 30) at a speed of 110 rpm, with three heating zones in which the following temperatures were maintained: 150, 150 and 160°C (AX Plasticos model AX14 LD30). The film samples were obtained by compression molding in a press with a temperature profile of 235 ± 5°C for 2.5 min, after pressing, films were cooled up to room temperature. The mechanical tests were performed according to ASTM D882-09 and the water vapor permeability (WVP) was measured according to ASTM E-96, in triplicate. The tensile properties indicated that the modulus was improved with increased TiO2 content up to 1g/100g PLLA. The Young's modulus (YM) of the PLA was increased from 3047 MPa to 3222 MPa with the addition of 1g TiO2/100g PLLA. The tensile strength (TS) of films increases with the TiO2 content. In both cases, the YM and TS are achieved at the 1% content of TiO2 and is due to the reinforcing effect of nanoparticles. Pristine PLA showed a strain at break (SB) of 3.56%, while the SB of nanocomposites were significant lower, for instance the SB of composite containing 7.5 g HNT/100g PLLA was around 1.90 %. The WVP of samples was increased by increasing the nano filler content. It should be expected that an increase of nanofiller content would decrease the mass transfer of water molecules throughout the samples due to the increase in the way water molecules will have to cross to permeate the material. However, this was not observed. Therefore, this result can be explained considering the molecular structure of both fillers, which contain several hydroxyl groups in the surface, making the end material more hydrophilic.

A Study on Microsized Titanium Oxide-Filled Epoxy with Enhanced Heat Conductivity for Microelectronic Applications

This article presents a study on the thermal conductivity characterization of microsized TiO2-filled epoxy composites. Titanium oxide (TiO2) particles of about 100 µm mean size are embedded in epoxy resin to develop composites by hand layup technique. Effective thermal conductivity values of these samples are measured using Unitherm Model 2022 in accordance with ASTM-E 1530 standards. The measured values are then compared with those obtained from a mathematical correlation deduced basing upon a one-dimensional heat conduction model developed by the authors previously. This study reveals that there is a significant improvement in thermal conductivity of the composites with increase in TiO2 content. With addition of 25 vol% of TiO2, the thermal conductivity of epoxy composite improves by about 223%. On comparing the measured conductivity values with those obtained from the theoretical model, it has been observed that the measured values are in very good agreement with the theoretical values for low filler concentrations (0–17.5 vol%). It is further seen that TiO2 particles show percolation behavior in epoxy matrix at about 17.5 vol% of filler content at which a sudden jump in the conductivity value is noticed.

Effect of TiO2 contents on the crystallization kinetics of PVDF in PVDF-diluent-TiO2 blends

Effect of TiO2 contents on the non-isothermal crystallization kinetics of poly(vinylidence fluoride) (PVDF) in PVDF-diluent–TiO2 blends was studied via differential scanning calorimetry method. Non-isothermal crystallization of PVDF was investigated by Jeziorny analysis and crystallizability analysis. Studies showed that the crystallization peak temperature of the blends increased from 363 to 375.6 K and the Avrami exponent decreased from 4 to 2.68, with the increase in TiO2 content from 0 to 3.0 wt%. Higher TiO2 content could hinder the growth of PVDF crystals in the blends. The blends with the TiO2 content of 0.45% had the largest crystallization rate (Zc = 0.97) and the maximum crystallizability (GR = 1.05). Hopefully, the introduction of TiO2 to the membrane mixture would be applied to control and adjust the structure of the membrane prepared.

Microwave Dielectric Properties and Thermally Stimulated Depolarization Currents Study of (1−x)Ba0.6Sr0.4La4Ti4O15–xTiO2 Ceramics

Microwave dielectric properties and thermally stimulated depolarization currents (TSDC) of (1−x)Ba0.6Sr0.4La4Ti4O15–xTiO2 (x = 0, 0.01, 0.02, 0.05, and 0.1) ceramics were studied. X‐ray diffraction analysis indicates that the specimens show a hexagonal perovskite structure; however, with an increase of x to 0.1, TiO2−δ as a secondary phase can be detected in the ceramics. The variation of TiO2 content has a significant effect on the dielectric properties of (1−x)Ba0.6Sr0.4La4Ti4O15–xTiO2 at microwave frequency. The dielectric permittivity of ceramics increases from 44 to 49 with the increase of TiO2 content. The Qf value is in the range of 39 300–53 400 GHz. However, the temperature coefficient of resonant frequency (τf) changes from −7.5 to–9.4 ppm/°C, and then turns to +3.9 ppm/°C. A near zero τf value can be obtained by tuning the content of TiO2 addition. TSDC was also employed to analysis the extrinsic loss mechanism. Utilizing a fixed polarization condition, the TSDC relaxation peaks are present, which are generated by oxygen vacancies. And the concentration of oxygen vacancies increases with the increase of TiO2 content. It can be concluded that the extrinsic dielectric loss is dominated by microstructure and oxygen vacancy defects.

Effect of TiO2 addition on viscosity and structure of CaO–Al2O3 based mould fluxes for high Al steel casting

High aluminium steel has received ever increasing attentions from many researchers with the perfect combination of strength to weight ratio and excellent ductility for use in automotive products. Due to addition of significant quantities of aluminium, a great challenge is to design a mould flux which is compatible with the steel and to guarantee smooth continuous casting process for ensuring the quality of billets. In this work, a mould flux of high Al steel in the casting is investigated by addition TiO2 to the flux for developing a new type of CaO–Al2O3 based mould flux. As the stability of TiO2 is stronger than SiO2, the reaction between mould fluxes and high Al steel could be reduced. The effect of TiO2 addition on the viscous behaviour of CaO–Al2O3 based mould flux for casting high Al steel were investigated by using the rotating spindle method. The water quenched glassy fluxes were analysed to identify between the structural relationship and the viscosity using Raman spectroscopy. It was found that the viscosity of fluxes decreased with the increasing TiO2 content. The SEM–EDS and X-ray diffraction analyses on the samples after the viscosity measurement indicate that there were three crystalline phases of CaO, Ca12Al14O33 and LiAlO2 in the sample free of TiO2. The addition of TiO2 leads to disappearance of CaO phase and crystallisation of perovskite phase. Raman spectral results have shown that the degree of polymerisation is reduced by increasing TiO2, which further explained the decrease in the viscosity of fluxes.

TiO2–PLLA nanocomposite coatings and free-standing films by a combined electrophoretic deposition-dip coating process

TiO2/PLLA nanocomposites were prepared using a two-step process involving electrophoretic deposition (EPD) and dip coating (DC). EPD was carried out first to obtain porous TiO2 nanostructured coatings while subsequent dip coating was performed using different concentrations of PLLA in dichloromethane (DCM) to obtain nanocomposite materials. According to SEM images, cracks in the TiO2 nanostructured coatings, developed upon drying, were filled with the polymer which led to improvement of the flexibility of the nanocomposite coatings. Similarly, a surface modification from hydrophilic to hydrophobic was obtained with the addition of the polymer. FTIR analysis showed characteristic bands of both materials, TiO2 and PLLA, both on the coating surface and at the interphase between the nanocomposite coating and the substrate. Hardness measurements showed a maximum value of 1.4GPa for TiO2–10wt% PLLA composite. For DMTA tests, detached layers were used and the storage and loss moduli were determined. TiO2–PLLA nanocomposite coatings showed higher values of storage modulus at higher temperature in comparison to pure PLLA samples. Also, there was a shift in the glass transition temperature (Tg) with increasing TiO2 content. In conclusion, the EPD–DC combined technique proposed here enables the fabrication of nanostructured coatings and free-standing layers in which the quantity of PLLA can be changed according to the intended application, i.e. it is possible to fabricate coatings with tailored degradability and suitable mechanical properties with low additions of PLLA or free standing films with increased flexibility, biodegradability and biocompatibility with high amounts of PLLA.

Influence of TiO2 Nanoparticles on the Morphological, Thermal and Solution Properties of PVA/TiO2 Nanocomposite Membranes

Polyvinylalcohol/titanium dioxide (PVA/TiO2) nanocomposite membranes were prepared by dispersing hydrophilic fumed TiO2 nanoparticles into the polymer matrix. The influence of TiO2 nanoparticles on the morphological, thermal and solution properties of PVA/TiO2 nanocomposite membranes was investigated using FESEM, XRD, DSC, TGA, rheometer, zeta sizer and contact angle meter. FESEM analysis shows that TiO2 nanoparticles up to 30wt% are dispersed homogeneously in the membranes without aggregation and covered by PVA polymeric chains. Above 30wt% TiO2 content, the level of aggregation increases, and at 50wt%, it was significant. The incorporation of TiO2 nanoparticles into the PVA matrix lowers the primary crystallinity of PVA and by inducing new crystalline regions due to TiO2; the overall crystallinity of the nanocomposite membranes is modified. Thermal stability of the composite membrane is improved by the addition of TiO2 nanoparticles. The increase of TiO2 concentration in PVA/TiO2 suspension has shown a transition in the regime of suspension from Newtonian to shear thinning starting at 10wt% TiO2. At low concentration of nanoparticles, the shear thinning behavior at lower shear rate is less. The shear thinning behavior increases as the concentration of TiO2 is increased. The conductivity of PVA/TiO2 dispersions is lower than PVA which indicates the formation of clusters, leading to decrease in number of charge carriers and their mobility. The zeta potential increases with increasing TiO2 content, which shows that PVA/TiO2 suspension is stable at higher content of TiO2. The hydrophilicity of PVA/TiO2 nanocomposite membranes increases as the loading of TiO2 is increased in the membrane.

Effect of TiO2 on the structural, thermal and optical properties of BaO–Li2O–diborate glasses

Glasses with a general composition of (30−x) BaO–xTiO2–70Li2B4O7, where x=5, 10, 15 and 20, in molar ratio, were prepared by the conventional melt quenching technique. Structural characterizations of the glasses were conducted through FTIR spectrometry and the variation of density values, which allowed the calculation of the glass molar volume (VM). The amorphous nature of the glasses was checked by X-ray diffraction. The compositional dependence of the glass transition (Tg) and crystallization (Tcr) temperatures was determined by differential scanning calorimetry (DSC) analysis. The thermal stability of the glasses increases with an increase of TiO2 content. The optical spectra were measured and the optical band gap was estimated. It was found that the band gap decreases with an increase of TiO2 content. The properties and structural features of glasses were discussed in terms of the relative proportion of former/modifier oxides.

Osteoblastic differentiation under controlled bioactive ion release by silica and titania doped sodium-free calcium phosphate-based glass

Sodium-free phosphate-based glasses (PGs) doped with both SiO2 and TiO2 (50P2O5-40CaO-xSiO2-(10−x)TiO2, where x=10, 7, 5, 3, and 0mol%) were developed and characterised for controlled ion release applications in bone tissue engineering. Substituting SiO2 with TiO2 directly increased PG density and glass transition temperature, indicating a cross-linking effect of Ti on the glass network which was reflected by significantly reduced degradation rates in an aqueous environment. X-ray diffraction confirmed the presence of Ti(P2O7) in crystallised TiO2-containing PGs, and nuclear magnetic resonance showed an increase in Q1 phosphate species with increasing TiO2 content. Substitution of SiO2 with TiO2 also reduced hydrophilicity and surface energy. In biological assays, MC3T3-E1 pre-osteoblasts effectively adhered to the surface of PG discs and the incorporation of TiO2, and hence higher stability of the PG network, significantly increased cell viability and metabolic activity indicating the biocompatibility of the PGs. Addition of SiO2 increased ionic release from the PG, which stimulated alkaline phosphatase (ALP) activity in MC3T3-E1 cells upon ion exposure. The incorporation of 3mol% TiO2 was required to stabilise the PG network against unfavourable rapid degradation in aqueous environments. However, ALP activity was greatest in PGs doped with 5–7mol% SiO2 due to up-regulation of ionic concentrations. Thus, the properties of PGs can be readily controlled by modifying the extent of Si and Ti doping in order to optimise ion release and osteoblastic differentiation for bone tissue engineering applications.

Microstructure optimization and optical and interfacial properties modulation of sputtering-derived HfO2 thin films by TiO2 incorporation

TiO2-doped HfO2 gate dielectric thin films have been deposited on Si(100) substrates by RF sputtering. The component, morphology, structure, optical and interfacial properties of Hf1−xTixO2 films related to TiO2 concentration are systematically investigated by atomic force microscope (AFM), X-ray diffraction (XRD), spectroscopic ellipsometry (SE), X-ray photoelectron spectroscopy (XPS), and Fourier transformation infrared (FTIR). By employing Cauchy–Urbach model, the optical constants, such as refractive index (n), extinction coefficient (k), absorption coefficient (α), and optical band gap (Eg) have been determined precisely. Measurements from XRD have confirmed that TiO2 incorporating into HfO2 films leads to the increase of the crystallization temperature of HfO2 films with increasing the TiO2 concentration. SE analyses have indicated that reduction in band gap and refractive index has been observed with increasing the TiO2 component in Hf1−xTixO2 films. The increase in Urbach parameter EU with the increase of TiO2 concentration also suggests the rise in disorder for Hf1−xTixO2 films. FTIR measurements for Hf1−xTixO2/Si gate stack indicate the existence of the interfacial layer regardless of the TiO2 concentration. For the 9% TiO2-doped HfO2 samples, the shift in FTIR characteristic peak suggests the formation of the silicate layer, which leads to the suppressed interfacial layer growth during deposition. As a result, it can be conclude that the TiO2 component in Hf1−xTixO2 films should be controlled precisely to guarantee interfacial properties of Hf1−xTixO2/Si gate stacks.

Investigating the solubility and cytocompatibility of CaO-Na2 O-SiO2 /TiO2 bioactive glasses.

This study aims to investigate the solubility of a series of titanium (TiO2 )-containing bioactive glasses and their subsequent effect on cell viability. Five glasses were synthesized in the composition range SiO2 -Na2 O-CaO with 5 mol % of increments TiO2 substituted for SiO2 . Glass solubility was investigated with respect to (1) exposed surface area, (2) particle size, (3) incubation time, and (4) compositional effects. Ion release profiles showed that sodium (Na(+) ) presented high release rates after 1 day and were unchanged between 7 and 14 days. Calcium (Ca(2+) ) release presented a significant change at each time period and was also composition dependent, where a reduction in Ca(2+) release is observed with an increase in TiO2 concentration. Silica (Si(4+) ) release did not present any clear trends while no titanium (Ti(4+) ) was released. Cell numbers were found to increase up to 44%, compared to the growing control population, with a reduction in particle size and with the inclusion of TiO2 in the glass composition.

Influence of Auxiliary Abrasive on the Resin Bond Used in Diamond Tools

The effects on the mechanical properties for three auxiliary abrasive with different hardness were researched by changing the content of the auxiliary abrasives in the phenolic resin-based bond in this paper. The abrasive tool sample's bending strength and Rockwell hardness were tested. It shows that with the increase of TiO2 content, the hardness and strength reduced firstly, but then increased; and when the content of TiO2 was 5%, the Rockwell hardness decreased by 30% and the bending strength fell by 44.98%. As the CeO2 content increases, the hardness of the abrasive tool changed little, while the bending strength decreased more, and when its content was 1%, the bending strength decreased by 25.63%. When the content of SiO2 is 3%, he bending strength decreased by 32.82%; and when its content is 5%, the Rockwell hardness reduced by 24.97%, and then its hardness has a substantial increase.

Effect of TiO2 addition on surface microstructure and bioactivity of fluorapatite coatings deposited using Nd:YAG laser

To study the effect of titania (TiO2) addition on the surface microstructure and bioactivity of fluorapatite coatings, fluorapatite was mixed with TiO2 in 1:0.5 (FA + 0.5TiO2), 1:0.8 (FA + 0.8TiO2), and 1:1 (FA + TiO2) ratios (wt%) and clad on Ti-6Al-4V substrates using an Nd:YAG laser system. The experimental results show that the penetration depth of the weld decreases with increasing TiO2 content. Moreover, the subgrain structure of the coating layer changes from a fine cellular-like structure to a cellular-dendrite-like structure as the amount of TiO2 increases. Consequently, as the proportion of TiO2 decreases (increase in fluorapatite content), the Ca/P ratio of the coating layer also decreases. The immersion of specimens into simulated body fluid resulted in the formation of individual apatite. With a lower Ca/P ratio before immersion, the growth of the apatite was faster and then the coating layer provided a better bioactivity. X-ray diffraction analysis results show that prior to simulated body fluid immersion, the coating layer in all three specimens was composed mainly of fluorapatite, CaTiO3, and Al2O3 phases. Following simulated body fluid immersion, a peak corresponding to hydroxycarbonated apatite appeared after 2 days in the FA + 0.5TiO2 and FA + 0.8TiO2 specimens and after 7 days in the FA + TiO2 specimen. Overall, the results show that although the bioactivity of the coating layer tended to decrease with increasing TiO2 content, in accordance with the above-mentioned ratios, the bioactivity of all three specimens remained generally good.

Investigation of the Viscosity and Structural Properties of CaO-SiO2-TiO2 Slags

The viscosity of CaO-SiO2-TiO2 slags was measured via the rotating cylinder method to reveal the effect of TiO2 on viscous flow of the slags. Furthermore, the structure of the ternary slags and the role of Ti4+ were investigated by Fourier transform infrared and Raman spectroscopy techniques. The results are beneficial for a better understanding of the behaviors of Ti-bearing silicate slags. The TiO2 additions lowered the viscosity and apparent activation energy of the slags. However, the degree of polymerization (DOP) of silicate network was found to be enhanced with increasing the TiO2 content, which is suggested by the increase in mole fraction of Q3 ([SiO4]-tetrahedra with three bridging oxygens) and the decrease in Q0. The Eq. [2] Q2 ↔ Q1 + Q3 was appropriate to express the relationship of different Qn species. The introduction of Ti4+ into the silicate network as network formers increased the DOP but weakened the strength of slag structure at the same time. Besides, a large proportion of Ti4+ exists in the slag in the form of \( TiO_{4}^{4 - } \) monomers, resulting in a decrease of viscosity with increasing TiO2 content.

Hydrogenation of m-Dinitrobenzene Over Pt Supported Catalysts on TiO2–Al2O3 Binary Oxides

Catalytic hydrogenation of m-dinitrobenzene over Pt/TiO2–Al2O3 catalysts was investigated. The effect of the enrichment of TiO2 was analyzed. The results showed that the increase in TiO2 content produced an enhancement in the activity of the catalyst. In these consecutive reactions, both rate constants (k1 and k2) were determined and it whatever the catalyst, k1 is higher than k2. The limiting step of the reaction was the transformation of m-nitroaniline to m-phenylenediamine. This behavior was explained by the modification in the acceptor-donor electron character of the group in the meta position.