Spherical Ti Powders Research Articles

Microporous Ti implant compact coated with hydroxyapatite produced by electro-discharge-sintering and electrostatic-spray-deposition.

A single pulse of 1.5 kJ/0.7 g of atomized spherical Ti powder from 300 μF capacitor was applied to produce the porous-surfaced Ti implant compact by electro-discharge-sintering (EDS). A solid core surrounded by porous layer was self-consolidated by a discharge in the middle of the compact in 122 μsec. Average pore size, porosity, and compressive yield strength of EDS Ti compact were estimated to be about 68.2 μm, 25.5%, and 266.4 MPa, respectively. Coatings with hydroxyapatite (HAp) on the Ti compact were conducted by electrostatic-spray-deposition (ESD) method. As-deposited HAp coating was in the form of porous structure and consisted of HAp particles which were uniformly distributed on the Ti porous structure. By heat-treatment at 700 degrees C, HAp particles were agglomerated each other and melted to form a highly smooth and homogeneous HAp thin film consisted of equiaxed nano-scaled grains. Porous-surfaced Ti implant compacts coated with highly crystalline apatite phase were successfully obtained by using the EDS and ESD techniques.

다공성 티타늄 임플란트의 담지물질 방출거동

Purpose: This study was performed to investigate the release behavior of bioactive materials as a BMP-2 embedding on the porous titanium implant. Methods: Porous Ti implant samples were fabricated by sintering of spherical Ti powders in a high vacuum furnace. Specimens diameter and height were 4mm and 10mm. Embedding materials were used to stamp ink. Sectional images, porosity and release behavior of porous Ti implants were evaluated by scanning electron microscope(SEM), mercury porosimeter and UV-Vis-NIR spectrophotometer. Results: Internal pore structure was formed fully open pore. Average pore size and porosity were <TEX>$8.993{\mu}m$</TEX> and 8.918%. Embedding materials were released continually and slowly. Conclusion: Porous Ti implant was fabricated successfully by sintering method. Particles are necking strongly each other and others portions were vacancy. Therefore bioactive materials will be able to embedding to porous Ti implants. If the development of the fusion implant of the bioactive material will be able to have the chance to several patients.

다공성 티타늄 임플란트의 생리활성물질 담지특성에 관한 연구

Purpose: Surface modification is important techniques in modern dental and orthopedic implants. This study wasperformed to try embedding of bioactive materials in porous Ti implants.Methods: Porous Ti implant samples were fabricated by sintering of spherical Ti powders in a high vacuumfurnace. It’s diameter and height were 4 and 20 . Embedding process was used to suction and vacuum chamber.Loading properties of porous Ti implants were evaluated by scanning electron microscope(SEM), confocal laserscanning microscope(CLSM), and UV-Vis-NIR spectrophotometer.Results: Internal pore structure was formed fully open pore. Average pore size and porosity were 10.253and17.506%.Conclusion: Porous Ti implant was fabricated successfully by sintering method. Particles are necking strongly eachother and others portions were vacancy. This porous structure can be embedded to bioactive materials. Thereforebioactive materials will be able to embedding to porous Ti implants. Bioactive materials embedding in the porousTi implant will induced new bone faster.

Improvement of sintering behaviour of titanium by colloidal techniques

The conventional sintering of titanium requires high temperatures to obtain high densities and low porosity, giving rise to microstructures with high grain size, and high interstitial contents, both of which adversely affect the mechanical properties obtained. A novel approach is reported which uses fine (10 µm) spherical Ti powder to improve the sintering behaviour, together with a small percentage of alumina particles (0·5 µm) to restrict grain growth. Colloidal techniques were used to form spherical agglomerates, 50–300 µm in size, of Ti powder with alumina particles dispersed homogenously on the Ti surface. These agglomerates present good compressibility and make it possible to sinter effectively at low temperatures, increasing the relative density and decreasing grain size.

Preparation of Spherical Titanium Powders from Polygonal Titanium Hydride Powders by Radio Frequency Plasma Treatment

This paper describes a novel dehydrogenation and spheroidization method using in-situ radio frequency (RF) thermal plasma treatment process to prepare spherical titanium (Ti) powders. Polygonal titanium hydride (TiH2) powders were successfully converted into spherical Ti powders and the size of the powders decreased from 30 to 21µm by means of evaporation at the powder surface during the plasma treatment. Contaminants in the final products were drastically decreased due to the evaporation and emission of vapors during the plasma treatment.

Ignition of Titanium Powder Layers by Electrostatic Discharge

Titanium powder heating and ignition by an electrostatic discharge (ESD) or spark was investigated. The effect of powder layer thickness and morphology was determined. Ti powder was chosen for these experiments because it is commonly found in energetic formulations, used for materials preparation by self-propagating high-temperature synthesis, and is extensively used in powder metallurgy. Two Ti powders were used: spherical powder with a volume mean diameter of 82 µm and sponge powder with a volume mean diameter of 30 µm. ESD current and voltage were measured in real time; powder ignition was characterized using an optical sensor and photographs of the produced burning particles. Different ignition modes were observed for powders with different morphologies and placed in layers with different thickness. For both spherical and sponge Ti powders prepared as monolayers, ESD initiation resulted in fragmentation of the initial particles. Produced particle fragments were ejected from the sample holder and burned as individual fine metal droplets. The burn times for such fragments were substantially shorter than expected for particles present in the starting Ti powders. Sponge powder placed in thicker layers ignited generating individual burning particles with combustion times close to those expected based on the particle size distribution. Spherical Ti powder placed in thicker layers was difficult to ignite and only a few short individual particle streaks were observed, which could be attributed to the finest particles present in the sample. When a titanium powder (either spherical and sponge) was placed in a layer with thickness greater than 0.1 mm, significant fusing of the particles was observed which reduced the powder heating by the discharge's Joule energy.

A Study of Multi-Surface Treatments on the Porous Ti Implant for the Enhancement of Bioactivity

【Porous Ti implant samples were fabricated by the sintering of spherical Ti powders in a high vacuum furnace. To increase their surface area and biocompatibility, anodic oxidation and a hydrothermal treatment were then applied. Electrolytes in a mixture of glycerophosphate and calcium acetate were used for the anodizing treatment. The resulting oxide layer was found to have precipitated in the phase form of anatase $TiO_2$ and nano-scaled hydroxyapatite on the porous Ti implant surface. The porous Ti implant can be modified via an anodic oxidation method and a hydrothermal treatment for the enhancement of the bioactivity, and current multi-surface treatments can be applied for use in a dental implant system.】

Mechanical Properties of Electro-Discharge-Sintered Porous Titanium Implants

Porous surfaced Ti implant compacts were fabricated by electro-discharging-sintering (EDS) of atomized spherical Ti powders. Powders of <TEX>$50-100{\mu}m$</TEX> in diameter were vibratarily settled into a quarts tube and subject to a high voltage and high density current pulse in Ar atmosphere. Single pulse of 0.7 to 2.0 kJ/0.7 gpowder, from 150, 300, and <TEX>$450{\mu}F$</TEX> capacitors was applied in less than <TEX>$400{\mu}sec$</TEX> to produce twelve different porous-surfaced Ti implant compacts. The solid core formed in the center of the compact shows similar microstructure of cp Ti which was annealed and quenched in water. Hardness value at the solid core was much higher than that at the particle interface and particles in the porous layer, which can be attributed to both heat treatment and work hardening effects induced by EDS. Compression tests were made to evaluate the mechanical properties of the EDS compacts. The compressive yield strength was in a range of 12 to 304MPa which significantly depends on input energy. Selected porous-surfaced Ti-6Al-4V dental implant compacts with a solid core have much higher compressive strengths compared to the human teeth and sintered Ti dental implants fabricated by conventional sintering process.

Surface characteristics of porous titanium implants fabricated by environmental electro-discharge sintering of spherical Ti powders in a vacuum atmosphere

A single pulse of 1.5 kJ, from a 300 μF capacitor, was applied to 0.7 g of atomized spherical Ti powders to produce a porous-surfaced implant compact by environmental electro-discharge sintering (EEDS) in a low vacuum atmosphere. A solid core was formed by a discharge in the middle of the compact which is surrounded by a porous layer. Ti, C and O were the main constituents, with a smaller amount of N. The EEDS implant surface was lightly oxidized and was primarily in the form of TiO 2 . The lightly etched sample showed the surface form of metallic Ti, indicating that the EEDS breaks down the oxide film of the as-received Ti powder during the discharge process. However, a small amount of N in the form of nitride, which was also found in the as-received Ti powder, was not changed in its chemical state by EEDS.

Synthesis of porous titanium implants by environmental-electro-discharge-sintering process

Porous Ti implants with various porosities were first fabricated by environmental-electro-discharging-sintering (EEDS) of atomized spherical Ti powders. Powders in two size range (50–100 and 200–250 μm) were settled by vibration into a quarts tube and subjected to a high voltage and high density current pulse. A single pulse of 0.75–2.0 kJ/0.7 g-powder, using 150, 300 and 450 μF capacitors, was applied to produce fully porous and porous-surfaced Ti implant compacts. The solid core was automatically formed in the center of the compact after discharge and porous layer consisted of particles connected in three dimensions by necks. The solid core and neck sizes increased with an increase in input energy and capacitance. On the other hand, pore volume decreased with increased capacitance and input energy due to the formation of a solid core. Capacitance and input energy are the only controllable discharge parameters even though the heat generated during a discharge is the unique parameter that determines the porosity of compact. It was shown that EEDS of spherical Ti powders can efficiently produce fully porous and porous-surfaced Ti implants with various porosities in short times (<400 μs) by manipulating the discharging conditions such as input energy and capacitance including powder size.

One-step process for the fabrication of Ti porous compact and its surface modification by environmental-electro-discharge-sintering of spherical Ti powders

A single pulse of 1.0 kJ/0.7 g of atomized spherical Ti powders from 300 μF capacitor was applied to produce a porous-surfaced Ti compact by environmental-electro-discharge-sintering (EEDS). A solid core was automatically formed by a discharge in the middle of the compact which is surrounded by a porous layer, which increased the porous compact's compressive yield strength from 52 to 125 MPa. The surface of the EEDS compact has been instantaneously modified by a discharge into the form of primarily Ti nitride from TiO2. Therefore, EEDS can fabricate a Ti porous-surfaced compact with a solid core and simultaneously modify its surface chemistry in times as short as 122 μs.

Mechanical properties of environmental-electro-discharge-sintered porous Ti implants

Porous-surfaced Ti implant compacts were first fabricated by environmental-electro-discharging-sintering (EEDS) of atomized spherical Ti powders. Single pulses of 0.75 to 2.0 kJ/0.7 g powder, from 150, 300, and 450 μF capacitors, were applied to produce 12 different porous-surfaced implant compacts in an Ar atmosphere. The solid core formed in the center of the compact shows similar microstructure of cp Ti which was annealed and quenched in water. Hardness value on the solid core was much higher than that at the particle interface or on particles in the porous layer. This can be attributed to both heat treatment and work hardening effects induced from the EEDS. The compressive yield strength was in a range of 12 to 303 MPa and significantly depended on input energy. Selected porous-surfaced Ti implant compacts with a solid core have much higher compressive strengths compared to the human teeth and sintered Ti implants fabricated by conventional sintering process.

チタン焼結体の歯科補綴物への応用

Powder metallurgy is a metal processing technology. Porous titanium produced from powder is widely used. The method is applied to titanium, which is not easy to cast as it sinters under melting point. In prosthetic dentistry, powder metallurgy can be applied to high fusing metal that is biocompatible. In this study, we examined the mechanical characteristics of the Ti sheet produced by sintering and discussed its application to dental prosthesis manufacturing. Ti sheets of 1-mm thickness, in which a binder was added to spherical Ti powder, were produced with the Doctor Blade Method. The sintering was carried out between 900-1150 degrees C at 6 temperatures. The sintered compact was evaluated by dimensional change rate, hardness test, bending strength, tensile strength and SEM observation. Another compact was sintered on the refractory cast. Mechanical strength significantly increased with sintering temperature. In addition, excellent mechanical strength was acquired by adding crushed powder and performing the de-binder process. In the sintering on the refractory cast, pre-baking for more than 100 minutes and sintering at over 1050 degrees C was needed for practical application. It thus seems possible to apply sintered titanium to dental prostheses. However, it will be necessary to examine the control of the shrinkage of the sintered compact in the future too.

Synthesis and Process Development of Ultrafine Ti Powder by Sodium Flame Encapsulation Method

Synthesis and process development of nano-size Ti powder by SFE(Sodium/halide Flame Encapsulation) method were investigated. Four concentric coflow burner was used and its flame configuration was <TEX>$TiCl_4/Ar/Na/Ar$</TEX> in order from the center. Flame has been controlled by the various processing parameters such as temperature of burner and flow rates of both <TEX>$TiCl_4$</TEX>(g) precursor and Na(g). It was found that yellow-colored flame was shown in the flow rates of 70cc/min of <TEX>$TiCl_4$</TEX>(g) precursor and 2 <TEX>$\ell$</TEX> /min of Na(g) which were regarded as optimum flame condition. The powders encapsuled by NaCl were produced having the average powder size of 250nm. The results of X-ray diffraction showed that powders from the optimized condition consisted of pure Ti and NaCl. TEM analysis confirmed that the several Ti powders of 20-100nm were encapsulated with NaCl. After removing sodium chloride by heat treatment, the spherical Ti powders with the size range of 80 to 150nm were obtained.