Nano Ti Research Articles

Effects of added nano titanium on the microstructure and mechanical properties of vitrified bond diamond tools

• A large number of rutile TiO 2 phases were detected in the specimen added with 50 vol% nano Ti.

Efficient nano titanium electrode via a two-step electrochemical anodization with reconstructed nanotubes: Electrochemical activity and stability

A two-step anodization method was used to prepare an efficient nano Ti electrode (ENTE), based on the nano Ti electrode (NTE) that was synthesized by the traditional anodization method. The result of FESEM showed there were many nanopores and nanoparticles on the surface of the ENTE. Compared with Ti electrode, the ENTE exhibited an increased electrochemical activity of nitrate reduction, attributing to its ∼1.09-fold higher reduction peak current density. Values of average current efficiency towards nitrate reduction indicated that the electrochemical properties of different electrodes were raised in the order of ENTE (0.36) > NTE (0.25) > Ti electrode (0.15). The ENTE exhibited a ∼3.33-fold higher electroactive surface area than that of Ti electrode. The higher current density throughout the 1000 s and the ∼1.27-fold higher final current density at 1000 s suggested that the ENTE had a higher stability for nitrate electroreduction. The nitrate reduction efficiency increased with the increasing of initial nitrate-nitrogen concentration and temperature. Similar effect was obtained from current density below 50 mA cm−2. And under the neutral condition, a higher nitrate reduction efficiency was achieved. The curved surface and higher surface area due to the nanopores of the ENTE increased the nitrate concentration in the EDL and enhanced the potential of individual nitrate ions in the diffuse layer exponentially. This research provided a new route to assess a nano-electrode with high stability and a clear reaction mechanism in EDL.

Fire hazard of titanium powder layers mixed with inert nano TiO2 powder

Metallic dust layers are highly sensitive to ignition from common ignition sources, even when mixed with high percentages of inert solids. In turn, dust layer fires are a potential ignition source for dust explosions or other damaging fires. Flame spread velocity (FSV), as a potential parameter for evaluating fire hazard, was investigated for titanium powder layers mixed with inert nano TiO2 powder in both natural convection and in forced airflow conditions. Increased mass percentage of nano TiO2 powder decreased FSV of Ti powder mixtures as expected. The mixing ratio of nano TiO2 to fully suppress layer fires was 80% and 90% for micro and nano Ti powder, respectively. Mechanisms governing flame spread across a layer of nano Ti powder differed from those of a layer of micro Ti powder. FSV in no airflow conditions was higher than in aided airflow for micro Ti powder because conduction was the dominant heat transfer mechanism. However, FSV in no airflow was lower than in opposed airflow for nano Ti powder because convection/radiation was the dominant heat transfer mechanism. A fly fire phenomenon contributed to greater FSVs and higher fire hazard with nano Ti powder mixtures under aided airflow conditions.

Effects of sintering temperature and nano Ti(C,N) on the microstructure and mechanical properties of Ti(C,N) cermets cutting tool materials with low Ni-Co

The improvements of mechanical property as well as the microstructure of Ti(C,N) cermets cutting tool materials were presented. The influences of sintering temperature and nano Ti(C,N) had been studied. As rising the sintering temperature, the microstructure of Ti(C,N) cermets gradually became well-distributed, besides, the rim structure was gradually completed. The flexural strength improved obviously, but the changes of the hardness and the fracture toughness were relatively small. Nano Ti(C,N) had remarkable influence on the mechanical properties of Ti(C,N) cermets. The grain growth could be repressed by the addition of nano Ti(C,N). In the refinement microstructure, there were two typical core-rim structure, including a dark core with grayish rim structure and a bright core with grayish rim structure, besides, the formation mechanisms were both investigated. The flexural strength increased, nevertheless, the fracture toughness was slightly reduced, and the hardness kept constant. The fracture surface and crack propagation indicated that most cermets with coarse grains were easy to cause the transcrystalline fracture, meanwhile the intercrystalline fracture had the tendency to occur more in cermets with finer grains.

Effect of Ti–SiO2 nanoparticles on non-isothermal crystallization of polyphenylene sulfide fibers

Systematic studies of non-isothermal crystallization kinetics of polyphenylene sulfide (PPS) and PPS/Ti–SiO2 (1.0, 3.0 and 5.0 mass%) fibers raw materials were performed by DSC combining with SEM and polarized optical microscopy (POM). There are significant dependence of non-isothermal crystallization behavior and kinetics of PPS/Ti–SiO2 nanocomposites on the Ti–SiO2 content and cooling rate. Nano Ti–SiO2 acted as nucleating agents. Not only initial crystallization temperature was increased but also the rates of crystallization accelerated by analyzing relative degree of crystallinity, crystallization rate coefficient and crystallization rate parameter. Combining with POM images, non-isothermal crystallization kinetics was studied by Jeziorny, Ozawa and Mo’s equation. Spherulitic morphology of PPS has not been changed by nano Ti–SiO2, but the numbers of initial crystal nucleus increased and spherulitic size became smaller. Crystallization activation energy of PPS and PPS/Ti–SiO2 nanocomposites was estimated using isoconversional analysis of calorimetric data and proved that Ti–SiO2 increased effective energy barrier of crystallization due to its strong surface adsorption and the crystallization of PPS/Ti–SiO2 was more sensitive to temperature.

Electric spark ignition sensitivity of nano and micro Ti powder layers in the presence of inert nano TiO2 powder

Abstract: Metallic dust clouds have proven to be explosive even when mixed with high percentages of inert solids. In this paper, fire hazard of metallic dust layers was investigated as a potential ignition source. The minimum ignition energy and flame spread velocity of layered Ti powder mixed with different percentages of TiO 2 were determined using electric spark ignition. The results indicated that MIE of dust layers (MIEL) was far larger than that of dust clouds (MIEC) for Ti powder and its solid mixtures, likely due to a different ignition mechanism. As expected, MIEL of nano Ti powder was much lower than that of micro Ti powder. Once ignited, flame spread velocity of nano Ti powder layer reached 625 mm/s, a value far larger than the 5 mm/s for micro Ti powder.

Titanium With Nanotopography Induces Osteoblast Differentiation by Regulating Endogenous Bone Morphogenetic Protein Expression and Signaling Pathway.

We aimed at evaluating the effect of titanium (Ti) with nanotopography (Nano) on the endogenous expression of BMP-2 and BMP-4 and the relevance of this process to the nanotopography-induced osteoblast differentiation. MC3T3-E1 cells were grown on Nano and machined (Machined) Ti surfaces and the endogenous BMP-2/4 expression and the effect of BMP receptor BMPR1A silencing in both osteoblast differentiation and expression of genes related to TGF-β/BMP signaling were evaluated. Nano supported higher BMP-2 gene and protein expression and upregulated the osteoblast differentiation compared with Machined Ti surface. The BMPR1A silencing inhibited the osteogenic potential induced by Nano Ti surface as indicated by reduced alkaline phosphatase (ALP), osteocalcin and RUNX2 gene expression, RUNX2 protein expression and ALP activity. In addition, the expression of genes related to TGF-β/BMP signaling was deeply affected by BMPR1A-silenced cells grown on Nano Ti surface. In conclusion, we have demonstrated for the first time that nanotopography induces osteoblast differentiation, at least in part, by upregulating the endogenous production of BMP-2 and modulating BMP signaling pathway. J. Cell. Biochem. 117: 1718-1726, 2016. © 2015 Wiley Periodicals, Inc.

Growth and differentiation factor 5 (GDF-5)-functionalized, nanostructured titanium surfaces: in vitro and in vivo studies

Event Abstract Back to Event Growth and differentiation factor 5 (GDF-5)-functionalized, nanostructured titanium surfaces: in vitro and in vivo studies Renan B. Bueno1, 2, Lucas N. Teixeira1, Adriana L. De Almeida1, Andrey C. Soares3, Marcio M. Beloti1, Cassio E. Sverzut1, Osvaldo N. De Oliveira3, Antonio Nanci2, Adalberto L. Rosa1 and Paulo Tambasco De Oliveira1 1 University of São Paulo, Faculdade de Odontologia de Ribeirão Preto, Brazil 2 Université de Montréal, Faculté de Médecine Dentaire, Canada 3 University of São Paulo, Instituto de Física de São Carlos, Brazil It has been demonstrated that a nanostructured (Nano) titanium (Ti) surface obtained by treatment with 1:1 H2SO4/H2O2 and functionalized with growth and differentiation factor 5 (GDF-5) by simple adsorption promotes the enhancement of mineralized matrix formation in vitro[1]. In order to extend these findings, the present study aimed to evaluate 1) in vitro the acquisition of the osteogenic phenotype by rat calvaria-derived cell cultures grown on machined Ti and Nano Ti disc surfaces functionalized with 200 ng/mL GDF-5 by either simple adsorption or layer by layer (LbL) films, and 2) in rabbit tibia key parameters of bone formation adjacent to Nano Ti implants functionalized with GDF-5 by the two methods described above. The simple adsorption method was performed on the day before primary cell plating or implant placement in bone. Briefly, Ti discs and Nano Ti implants were incubated overnight at 4°C with 200 ng/mL recombinant human (rh) GDF-5 (PeproTech, Rocky Hill, NJ). The LbL films were generated by the electrostatic interaction between molecules containing opposite charges of ionic groups. The cationic polyelectrolyte and the polyanion used were, respectively, poly(allylamine hydrochloride) (PAH) and rhGDF-5; immersion time was 10 min for each solution. The growth of GDF-5 films was measured by ultraviolet–visible spectroscopy. The results showed that either the Ti surface topography or the method used for GDF-5 functionalization quantitatively affected mineralized matrix formation, with the higher osteogenic differentiation for the Nano Ti functionalized with GDF-5 by simple adsorption and the lower one for the LbL films, irrespective of the Ti surface topography on which they were mounted. Alkaline phosphatase activity was higher for cultures grown on the Nano Ti, including the GDF-5-functionalized Nano Ti, whose values, however, did not necessarily correspond to the higher osteogenic activity. Despite that, all groups expressed osteoblast differentiation markers, with a remarkable increase in osteopontin and osteocalcin mRNA levels for cultures grown on the LbL films. The microtomographic, histologic and histomorphometric analyses revealed no qualitative or quantitative differences in vivo among the Nano Ti implants, yet a tendency for enhanced bone formation was observed for the functionalized surfaces and, between them, for the LbL films. Taken together, our results contribute to a better understanding of osteoblastic cell and bone tissue responses to the functionalization of Nano Ti surfaces with rhGDF-5 aiming to optimize osseointegration. The State of São Paulo Research Foundation (FAPESP 2012/21330-6); The National Council of Scientific and Technological Development (CNPq, Brazil)

Effects of a micro/nano rough strontium-loaded surface on osseointegration.

We developed a hierarchical hybrid micro/nanorough strontium-loaded Ti (MNT-Sr) surface fabricated through hydrofluoric acid etching followed by magnetron sputtering and evaluated the effects of this surface on osseointegration. Samples with a smooth Ti (ST) surface, micro Ti (MT) surface treated with hydrofluoric acid etching, and strontium-loaded nano Ti (NT-Sr) surface treated with SrTiO3 target deposited via magnetron sputtering technique were investigated in parallel for comparison. The results showed that MNT-Sr surfaces were prepared successfully and with high interface bonding strength. Moreover, slow Sr release could be detected when the MNT-Sr and NT-Sr samples were immersed in phosphate-buffered saline. In in vitro experiments, the MNT-Sr surface significantly improved the proliferation and differentiation of osteoblasts compared with the other three groups. Twelve weeks after the four different surface implants were inserted into the distal femurs of 40 rats, the bone–implant contact in the ST, MT, NT-Sr, and MNT-Sr groups were 39.70%±6.00%, 57.60%±7.79%, 46.10%±5.51%, and 70.38%±8.61%, respectively. In terms of the mineral apposition ratio, the MNT-Sr group increased by 129%, 58%, and 25% compared with the values of the ST, MT, and NT-Sr groups, respectively. Moreover, the maximal pullout force in the MNT-Sr group was 1.12-, 0.31-, and 0.69-fold higher than the values of the ST, MT, and NT-Sr groups, respectively. These results suggested that the MNT-Sr surface has a synergistic effect of hierarchical micro/nano-topography and strontium for enhanced osseointegration, and it may be a promising option for clinical use. Compared with the MT surface, the NT-Sr surface significantly improved the differentiation of osteoblasts in vitro. In the in vivo animal experiment, the MT surface significantly enhanced the bone-implant contact and maximal pullout force than the NT-Sr surface.

Effect Of Ti Powder Addition On The Fabrication Of TiO2 Nanopowders

Abstract Sintered samples of Ti added TiO2 nanopowders were fabricated by combined application of magnetic pulsed compaction (MPC) and sintering. The effect of Ti nano powder on density, shrinkage and hardness of the samples were investigated as part of the study. The optimum processing conditions were found to be around 0.5 GPa MPC pressure and 1450°C sintering temperature, illustrating maximum density, hardness and minimum shrinkage. High pressure compaction using MPC was found to enhance density with increasing MPC pressure up to 0.9 GPa, and significantly reduce the total shrinkage (about 16% in this case) in the sintered bulks compared to other general processes (about 18%). While sintered samples blended with micro Ti showed presence of microstructural cracks, the samples with 1-2% nano Ti had less or no cracks on them. Overall, the inclusion of nano Ti indicated improvement in mechanical properties of TiO2 nanopowders sintered preforms as opposed to micro Ti-added TiO2.

Low temperature synthesis of nano Ti(C,N) by novel mechanical and thermal activation method

This paper presents a novel mechanical and thermal activation assisted carbothermal reduction (CR) method for synthesising Ti(C,N) powder at lower temperatures. Nano Ti(C,N) powder with approximately 30 nm grain size was synthesised by mixing powders of titanium, anatase, and carbon black. The starting powders were first milled for 10 to 40 h under N2/Ar atmosphere, and then vacuum heat treated for 1 h at 800 to 1050°C. Consequently, nano Ti(C,N) powder with approximately 30 nm grain size was synthesised. X-ray diffraction analysis shows that Ti(C,N) is partially formed during mechanical milling, and the remaining reactants react completely below 1050°C. However, when the unmilled starting powders are heat treated at 1050°C under N2 for 1 h, large amounts of reactants remain. Thermogravimetry and differential scanning calorimetry analysis shows that the CR reaction of activated TiO2 occurs at a lower temperature under N2 than under Ar or vacuum.

Minimum ignition temperature of nano and micro Ti powder clouds in the presence of inert nano TiO2 powder

Minimum ignition temperature (MIT) of micro Ti powder increased gradually with increases in nano-sized TiO2 employed as an inertant. Solid TiO2 inertant significantly reduced ignition hazard of micro Ti powder in contact with hot surfaces. The MIT of nano Ti powder remained low (583K), however, even with 90% TiO2. The MIT of micro Ti powder, when mixed with nano Ti powder at concentrations as low as 10%, decreased so dramatically that its application as a solid fuel may be possible. A simple MIT model was proposed for aggregate particle size estimation and better understanding of the inerting effect of nano TiO2 on MIT. Estimated particle size was 1.46–1.51μm larger than that in the 20-L sphere due to poor dispersion in the BAM oven. Calculated MITs were lower than corresponding empirically determined values for micro Ti powder because nano-sized TiO2 coated the micro Ti powder, thereby decreasing its reaction kinetics. In the case of nano Ti powder, nano-sized TiO2 facilitated dispersion of nano Ti powder which resulted in a calculated MIT that was greater than the experimentally determined value.

Minimum ignition energy of nano and micro Ti powder in the presence of inert nano TiO2 powder

The inerting effect of nano-sized TiO2 powder on ignition sensitivity of nano and micro Ti powders was investigated with a Mike 3 apparatus. “A little is not good enough” is also suitable for micro Ti powders mixed with nano-sized solid inertants. MIE of the mixtures did not significantly increase until the TiO2 percentage exceeded 50%. Nano-sized TiO2 powders were ineffective as an inertant when mixed with nano Ti powders, especially at higher dust loadings. Even with 90% nano TiO2 powder, mixtures still showed high ignition sensitivity because the statistic energy was as low as 2.1mJ. Layer fires induced by ignited but unburned metal particles may occur for micro Ti powders mixed with nano TiO2 powders following a low level dust explosion. Such layer fires could lead to a violent dust explosion after a second dispersion. Thus, additional attention is needed to prevent metallic layer fires even where electric spark potential is low. In the case of nano Ti powder, no layer fires were observed because of less flammable material involved in the mixtures investigated, and faster flame propagation in nanoparticle clouds.

Effect of WC on the microstructure and mechanical properties of nano Ti(C,N)-based cermets

In this paper, nano Ti(C,N)-based cermets with different WC additions were prepared by conventional powder metallurgy techniques. The microstructure of nano cermets was investigated by scanning electron microscope (SEM). The results showed that there existed three kinds of “core–rim” structure in nano cermets, i.e., “black core–white rim”, “white core–gray rim” and “gray core–white rim” structures. With the increase of WC addition, there were more “white core–gray rim” and “gray core–white rim” grains. The amount of the abnormal growth grains decreased and the grains became more homogeneous with the WC addition. The lattice parameter of Ti(C,N) would increase with the WC addition. The mechanical properties of nano cermets were also improved with the increase of WC addition.

Study on Infrared Absorption Characteristics of Ti and TiNx Nanofilms

Infrared detector has a wide range of applications. To fabricate an IR detector with good sensitivity, an efficient IR absorber is needed. In this paper, we theoretically and experimentally investigated the absorption characteristics of Ti, multi-layer structured Ti-SiO2 and TiNx-SiNx nano films. The multi-layer structured TiNx-SiNx films with different nitrogen contents and Ti nano films with different thicknesses were deposited by e-beam sputtering. For single nano Ti film, 35% absorptivity was obtained at a wavelength of 1.67μm when the film thickness was 15.3nm. A better IR absorption characteristic was achieved for multi-layer structured Ti-SiO2 nano film. In this structure, an absorption peak of appears at a wavelength of 9.5μm. Compared with the absorption behavior of single SiNx film, an additional nano TiNx film obviously improved IR absorption at a wider band. And a maximum IR absorptivity of 27% was obtained at the wavelength of 14μm.

Oxidative nanopatterning of titanium surfaces promotes production and extracellular accumulation of osteopontin

The bone-biomaterial interface has been characterized by layers of afibrillar extracellular matrix (ECM) enriched in non collagenous proteins, including osteopontin (OPN), a multifunctional protein that in bone controls cell adhesion and ECM mineralization. Physical and chemical aspects of biomaterial surfaces have been demonstrated to affect cell-ECM-substrate interactions. The present paper described the ability of oxidative nanopatterning of titanium (Ti) surfaces to control extracellular OPN deposition in vitro. Ti discs were chemically treated by a mixture of H2SO4/H2O2 for either 30 min [Nano(30') Ti] or 4 h [Nano(4h) Ti]. Non-etched Ti discs were used as control. Primary osteogenic cells derived from newborn rat calvarial bone were plated on control and etched Ti and grown under osteogenic conditions up to 7 days. High resolution scanning electron microscopy revealed that treated Ti discs exhibited a nanoporous surface and that areas of larger nanopits were noticed only for Nano(4h) Ti. Large extracellular OPN accumulation were detectable only for Nano(4h) Ti, which was associated with OPN-positive cells with typical aspects of migrating cells. At day 3, quantitative results in terms of areas of OPN labeling were as follows: Nano(4h) Ti > Nano(30') Ti > Control Ti. In conclusion, chemically nanostructured Ti surfaces may support the enhancement of endogenous extracellular OPN deposition by osteogenic cells in vitro depending on the etching time, a finding that should be taken into consideration in strategies to biofunctionalize implant surfaces with molecules with cell adhesion capacity.

Oxidative nanopatterning of titanium surfaces promotes production and extracellular accumulation of osteopontin

The bone-biomaterial interface has been characterized by layers of afibrillar extracellular matrix (ECM) enriched in non collagenous proteins, including osteopontin (OPN), a multifunctional protein that in bone controls cell adhesion and ECM mineralization. Physical and chemical aspects of biomaterial surfaces have been demonstrated to affect cell-ECM-substrate interactions. The present paper described the ability of oxidative nanopatterning of titanium (Ti) surfaces to control extracellular OPN deposition in vitro. Ti discs were chemically treated by a mixture of H2SO4/H2O2 for either 30 min [Nano(30') Ti] or 4 h [Nano(4h) Ti]. Non-etched Ti discs were used as control. Primary osteogenic cells derived from newborn rat calvarial bone were plated on control and etched Ti and grown under osteogenic conditions up to 7 days. High resolution scanning electron microscopy revealed that treated Ti discs exhibited a nanoporous surface and that areas of larger nanopits were noticed only for Nano(4h) Ti. Large extracellular OPN accumulation were detectable only for Nano(4h) Ti, which was associated with OPN-positive cells with typical aspects of migrating cells. At day 3, quantitative results in terms of areas of OPN labeling were as follows: Nano(4h) Ti > Nano(30') Ti > Control Ti. In conclusion, chemically nanostructured Ti surfaces may support the enhancement of endogenous extracellular OPN deposition by osteogenic cells in vitro depending on the etching time, a finding that should be taken into consideration in strategies to biofunctionalize implant surfaces with molecules with cell adhesion capacity.

Preparation of an Advanced Al<sub>2</sub>O<sub>3</sub> Based Nanocomposite Ceramic Die Material

Through the incorporation of nano sized Titanium Carbonitride powders into the Al2O3 matrix, an advanced Al2O3/Ti(C7N3) nanocomposite ceramic die material was fabricated by vacuum hot pressing technique. Effects of the content of nano Ti(C7N3) on the microstructure and mechanical properties of the nanocomposite ceramic die material were investigated. It indicates that both flexural strength and fracture toughness were increased noticeably compared with the pure micrometer sized alumina ceramic. Toughening mechanisms of the ceramic composite were also analyzed. It reveals that the intragranular/intergranular microstructures and the resulted transgranular/intergranular fracture modes are the main causes for the reinforcing and toughening of the nanocomposite ceramic die material.

Synthesis of nano Ti(C,N) powder by mechanical activation assisted carbothermal reduction nitridation

Nano Ti(C,N) powder was synthesised by mechanical activation assisted carbothermal reduction nitridation (MCRN) in this study. The starting powders of nano anatase/carbon black were activated first through high energy mechanical milling, then the milled powders were CRN treated at 1200 or 1250°C for 2 h, Ti(C,N) powder with average particle size of below 100 nm was obtained finally. Effects of main mechanical milling factors on anatase CRN reaction were investigated, including milling time, ball to powder weight ratio and milling speed. The mechanism of MCRN synthesising nano Ti(C,N) powder was also discussed in detail. The products were characterised by X-ray diffraction and scanning electron microscope. The results indicate that longer milling time, bigger ball to powder weight ratio and higher milling speed will be beneficial to MCRN reaction.

Nanostructured SPD Processed Titanium for Medical Implants

Nanostructured titanium (nTi) with essential enhanced strength and fatigue characteristics is an advanced material for dental implant applications. Nano Ti is commercially pure titanium, that was nanostructured by a special technique of severe plastic deformation. It is bio inert, does not contain even potentially toxic or allergenetic additives and has significantly higher specific strength properties than any other titanium applied in dental implants. Cylindrical threaded screw implants Nanoimplant® sized 2.4 mm in diameter and 12 mm in length were made from nTi. It is the first application of nTi dental implant in the world reported. Recently more than 250 successful clinical applications dealing with surgery on the front teeth were carried out. No complications were noticed during the early postoperative period and early loading. Laboratory cytocompatibility tests undertaken so far on mice fibroblast cells have indicated that nanocrystalline Ti surface has a significantly better property for cell colonisation and healing of tissue consequently.