• Journal of Powder Materials
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• v.22 no.4
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• pp.283-288
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• 2015

Two sintering methods of a pressureless sintering and a spark-plasma sintering are tested to densify the Fe-TiC composite powders which are fabricated by high-energy ball-milling. A powder mixture of Fe and TiC is prepared in a planetary ball mill at a rotation speed of 500 rpm for 1h. Pressureless sintering is performed at 1100, 1200 and $1300^{\circ}C$ for 1-3 hours in a tube furnace under flowing argon gas atmosphere. Spark-plasma sintering is carried out under the following condition: sintering temperature of $1050^{\circ}C$, soaking time of 10 min, sintering pressure of 50 MPa, heating rate of $50^{\circ}C$, and in a vacuum of 0.1 Pa. The curves of shrinkage and its derivative (shrinkage rate) are obtained from the data stored automatically during sintering process. The densification behaviors are investigated from the observation of fracture surface and cross-section of the sintered compacts. The pressureless-sintered powder compacts show incomplete densification with a relative denstiy of 86.1% after sintering at $1300^{\circ}C$ for 3h. Spark-plasma sintering at $1050^{\circ}C$ for 10 min exhibits nearly complete densification of 98.6% relative density under the sintering pressure of 50 MPa.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2016.11a
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• pp.197-197
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• 2016

Commercially pure titanium (CP Ti) and Ti-6Al-4V alloys have been widely used for biomedical applications. However, the use of the Ti-6Al-4V alloy in biomaterial is then a subject of controversy because aluminum ions and vanadium oxide have potential detrimental influence on the human body due to vanadium and aluminum. Hence, recent works showed that the synthesis of new Ti-based alloys for implant application involves more biocompatible metallic alloying element, such as, Nb, Hf, Zr and Mo. In particular, Nb and Hf are one of the most effective Ti ${\beta}-stabilizer$ and reducing the elastic modulus. Plasma electrolyte oxidation (PEO) is known as excellent method in the biocompatibility of biomaterial due to quickly coating time and controlled coating condition. The anodized oxide layer and diameter modulation of Ti alloys can be obtained function of improvement of cell adhesion. Manganese(Mn) plays very important roles in essential for normal growth and metabolism of skeletal tissue in vertebrates and can be detected as minor constituents in teeth and bone. Radio frequency(RF) magnetron sputtering in the various PVD methods has high deposition rates, high-purity films, extremely high adhesion of films, and excellent uniform layers for depositing a wide range of materials, including metals, alloys and ceramics like a hydroxyapatite. The aim of this study is to research the Mn coatings on the micro-pore formed Ti-29Nb-xHf alloys by RF-magnetron sputtering for dental applications. Ti-29Nb-xHf (x= 0, 3, 7 and 15wt%, mass fraction) alloys were prepared Ti-29Nb-xHf alloys of containing Hf up from 0 wt% to 15 wt% were melted by using a vacuum furnace. Ti-29Nb-xHf alloys were homogenized for 2 hr at $1050^{\circ}C$. Each alloy was anodized in solution containing typically 0.15 M calcium acetate monohydrate + 0.02 M calcium glycerophosphate at room temperature. A direct current power source was used for the process of anodization. Anodized alloys was prepared using 270V~300V anodization voltage at room. Mn coatings was produced by RF-magnetron sputtering system. RF power of 100W was applied to the target for 1h at room temperature. The microstructure, phase and composition of Mn coated oxide surface of Ti-29Nb-xHf alloys were examined by FE-SEM, EDS, and XRD.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2016.11a
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• pp.195-195
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• 2016

Titanium and its alloys are widely used as implants in orthopedics, dentistry and cardiology due to their outstanding properties, such as high strength, high level of hemocompatibility and enhanced biocompatibility. Hence, recent works showed that the synthesis of new Ti-based alloys for implant application involves more biocompatible metallic alloying element, such as, Nb, Hf, Zr and Mo. In particular, Nb and Hf are one of the most effective Ti ${\beta}-stabilizer$ and reducing the elastic modulus. Plasma electrolyte oxidation (PEO) is known as excellent method in the biocompatibility of biomaterial due to quickly coating time and controlled coating condition. The anodized oxide layer and diameter modulation of Ti alloys can be obtained function of improvement of cell adhesion. Silicon (Si) and magnesium (Mg) has a beneficial effect on bone. Si in particular has been found to be essential for normal bone and cartilage growth and development. In vitro studies have shown that Mg plays very important roles in essential for normal growth and metabolism of skeletal tissue in vertebrates and can be detected as minor constituents in teeth and bone. The aim of this study is to research Si and Mg doped hydroxyapatite film formation by plasma electrolytic oxidation. Ti-29Nb-xHf (x= 0, 3, 7 and 15wt%, mass fraction) alloys were prepared Ti-29Nb-xHf alloys of containing Hf up from 0 wt% to 15 wt% were melted by using a vacuum furnace. Ti-29Nb-xHf alloys were homogenized for 2 hr at $1050^{\circ}C$. Each alloy was anodized in solution containing typically 0.15 M calcium acetate monohydrate + 0.02 M calcium glycerophosphate at room temperature. A direct current power source was used for the process of anodization. Anodized alloys was prepared using 270V~300V anodization voltage at room. A Si and Mg coating was produced by RF-magnetron sputtering system. RF power of 100W was applied to the target for 1h at room temperature. The microstructure, phase and composition of Si and Mg coated oxide surface of Ti-29Nb-xHf alloys were examined by FE-SEM, EDS, and XRD.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.6 no.6
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• pp.468-472
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• 2005

In order to prevent adhering of molten glass on a mold wall, the wall is swabbed with lubricant oil before forming. However, the swabbing process can be removed from the entire processes of the glass forming if the mold wall is made of a porous sintered material. The purpose of the present study is to manufacture a sintered material(having a sintered density of $85{\~}90\%$)which is the most appropriate into. plane material for a glass mold. For the research, SUS310L-based coarse powder (${\~}150{\mu}m$) and SUS420J2-based fine powder ($40{\~}50{\mu}m$) were used for the compact materials, and effects of compaction pressure and sintering condition(atmosphere, temperature) were investigated. The results obtained were as fellows. (1) By means of solid phase sintering, a desired sintering density could not be achieved in any case when using a 310L-based powder having a large particle size. (2) When sintering green compacts(compaction pressure of $2ton/cm^2$) in a commercial vacuum furnace(at $1300^{\circ}C$ for 2 hours), the sintered compacts had densities of $6.2g/cm^3(79\%)$ for 310L + 0.03$\%$B, $6.6g/cm^3 (86\%)$ for 420J2, $7.3g/cm^3(95\%)$ for 420J2+(0.03)$\%$B, and $7.6g/cm^3(99\%)$ for 420j2+(0.06)$\%$B, respectively. As a result, it is regarded that sintered compacts having a desired porosity may be achieved by vacuum sintering the 420J2-based powder (low pressure compaction) and the 310L+0.03$\%$B-based powder (high pressure compaction).

• Korean Journal of Materials Research
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• v.11 no.6
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• pp.512-518
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• 2001

It has been well known that 6.5wt% Si steel sheets have excellent magnetic properties such as low core loss. high maximum permeability and low magnetostriction. In this work, we studied a method for producing 6.5wt% Si steel sheets using a chemical vapor deposition (CVD) method. The following is the procedure adopted in this work to produce 6.5wt% Si steel sheets; SiCl$_4$ gas is applied onto a low content-Si steel sheet placed in a tube furnace. Silicon atoms resulted from the decomposition of SiCl$_4$ are permeated through the surface of the steel sheet. Finally, by the diffusion process maintaining it under a high temperature the silicon atoms diffuse uniformly into the sheet. Through this process, 6.5wt% Si steel sheets can be obtained. The manufactured Fe-6.5wt% Si steel sheet with a thickness of 0.5mm exhibited a high frequency core loss (W$_{2}$1k/) of 8.92 W/kg. Its permeability increased from 37,100 to 53,300 at 1 tesular(T). The mechanical properties of the manufactured steel sheets were also estimated and the result showed that the workability was significantly improved by annealing in vacuum at 773k. Increased plastic deformation was also observed prior to fracture and the amount of grain boundary rupture was reduced.

• Journal of the Korean Vacuum Society
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• v.22 no.5
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• pp.238-244
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• 2013

Doping process using laser is an important process in fabrication of solar cell for heat treatment. However, the process of using the furnace is difficult to form a selective emitter doping region. The case of using a selective emitter laser doping is required an expensive laser equipment and induce the wafer's structure damage due to high temperature. This study, we fabricated a new costly plasma source. Through this, we research the selective emitter doping. We fabricated that the atmospheric pressure plasma jet injected Ar gas is inputted a low frequency (a few tens kHz). We used shallow doping wafers existing PSG (Phosphorus Silicate Glass) on the shallow doping CZ P-type wafer. Atmospheric plasma treatment time was 15 s and 30 s, and current for making the plasma is 40 mA and 70 mA. We investigated a doping profile by using SIMS (Secondary Ion Mass Spectroscopy) and we grasp the sheet resistance of electrical character by using doping profile. As result of experiment, prolonged doping process time and highly plasma current occur a deeper doping depth, moreover improve sheet resistance. We grasped the wafer's surface damage after atmospheric pressure plasma doping by using SEM (Scanning Electron Microscopy). We check that wafer's surface is not changed after plasma doping and atmospheric pressure doping width is broaden by increase of plasma treatment time and current.