Cetatech Inc.

Sacheon, South Korea

Cetatech Inc.

Sacheon, South Korea
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Johnson J.L.,ATI Engineered Products | Park S.J.,Pohang University of Science and Technology | Kwon Y.-S.,Cetatech Inc. | German R.M.,San Diego State University
Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science | Year: 2010

Liquid-phase sintering of high-purity, submicron, co-reduced W-15Cu powders at temperatures of 1463 to 1623 K (1190 to 1350 °C) produces W grain sizes ranging from 0.6 to 1.2 μm while maintaining less than 2 pct porosity. Measured thermal conductivities of 185 to 221 W/(m•K) are related to the grain size and contiguity, which ranged from 0.51 to 0.62. The effects of composition and microstructure on thermal conductivity are further investigated with a model based on a computational cell that allows adjustment of the grain shape to produce selected matrix volume fractions and contiguities. The model considers porosity, the effects of transition metal impurities on the thermal conductivities of the W and Cu phases, and the role of an interfacial resistance between W grains. The effects of grain size and contiguity on thermal conductivity are shown for thermal boundary conductances ranging from 0 to 1.7 × 1010 W/(m2•K). Comparison of the model predictions with those of prior models, the experimental results, and previously reported thermal conductivities shows that impurities are highly detrimental to the thermal conductivity, but the thermal boundary conductance is a significant factor for high-purity W-Cu. © 2010 The Minerals, Metals & Materials Society and ASM International.


Park D.Y.,Pohang University of Science and Technology | Lee S.W.,Pusan National University | Park S.J.,Pohang University of Science and Technology | Kwon Y.-S.,Cetatech Inc. | Otsuka I.,Epson Atmix Corporation
Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science | Year: 2013

In rapidly evolving powder injection molding technology, the wide prevalence of various microstructures demands the powders of smaller particle sizes. The effects of particle size on the sintering behavior are critical to not only shape retention of microstructure but also its mechanical properties. This study investigates the effects of three different particle sizes on the sintering behavior of the 316L stainless steel (STS316L) samples, prepared by powder injection molding, via the dilatometry experiments. For this purpose, the STS316L powders of three different mean particle sizes, i.e., 2.97, 4.16, and 8.04 μm, were produced for STS316L. The samples for the dilatometry test were prepared through powder-binder mixing, injection molding, and solvent and thermal debinding. Dilatometry experiments were carried out with the samples in a H2 atmosphere at three different heating rates of 3, 6, and 10 K/min. The shrinkage data obtained by dilatometry experiments was collected and analyzed to help understand the densification and the sintering behaviors in terms of particles size and heating rate. The master sintering curve (MSC) model was used to quantify the effects of particle sizes. In addition, we investigated the microstructure evolutions in terms of particles sizes. © 2012 The Minerals, Metals & Materials Society and ASM International.


Patent
Cetatech Inc. and B&L Biotech Co. | Date: 2010-09-22

Disclosed are a scaler tip for a dental implant using a Powder Injection Molding (PIM) of silver, copper, a silver alloy, or a copper alloy, and a method for manufacturing the scaler tip. The scaler tip includes a shank portion, and a work portion extendedly formed from an end of the shank portion and including a curved portion. Here, the scaler tip is formed by performing the PIM on at least one metal powder of silver, copper, the silver alloy, and the copper alloy.


Patent
B & L Biotech Co. and Cetatech Inc. | Date: 2015-05-29

The invention relates to a method for manufacturing an ultrasonic tip for an apicoectomy, such that the tip has a shape suitable for the shape of a tooth root, comprising the steps of: forming a feedstock by mixing a metal powder including stainless steel with a binder; injecting the feedstock to form an injection-molded part having a plurality of projections integrally formed on the surface thereof; performing debinding to remove the binder from the injection-molded part; sintering the injection-molded part; and performing annealing to increase the ductility and facilitate the bending of the sintered part.


Patent
B & L Biotech Co. and Cetatech Inc. | Date: 2010-08-25

The invention relates to a method for manufacturing an ultrasonic tip for an apicoectomy, such that the tip has a shape suitable for the shape of a tooth root, comprising the steps of: forming a feedstock by mixing a metal powder including stainless steel with a binder; injecting the feedstock to form an injection-molded part having a plurality of projections integrally formed on the surface thereof; performing debinding to remove the binder from the injection-molded part; sintering the injection-molded part; and performing annealing to increase the ductility and facilitate the bending of the sintered part.


Patent
Cetatech Inc. and B&L Biotech Co. | Date: 2013-01-02

The invention relates to a method for manufacturing an ultrasonic tip for an apicoectomy, such that the tip has a shape suitable for the shape of a tooth root, comprising the steps of: forming a feedstock by mixing a metal powder including stainless steel with a binder; injecting the feedstock to form an injection-molded part having a plurality of projections integrally formed on the surface thereof; performing debinding to remove the binder from the injection-molded part; sintering the injection-molded part; and performing annealing to increase the ductility and facilitate the bending of the sintered part.


Patent
Cetatech Inc. and B&L Biotech Co. | Date: 2011-10-12

Provided are a dental and medical ultrasonic tip that may enhance a durability and a reliability and may simplify a manufacturing process, and a method of manufacturing the same. The method of manufacturing the dental and medical ultrasonic tip may include: providing a molding mixture including powder; manufacturing an intermediate molded object by injecting the molding mixture so as to integrally form a tip body and a plurality of tip protrusions protruded from the tip body; and sintering the intermediate molded object. The tip body and the plurality of tip protrusions may be formed using the same material, and the plurality of tip protrusions may be closely arranged on a substantially polished portion of the tip body.


Park S.J.,Dong - A University | Johnson J.L.,ATI Firth Sterling | Wu Y.,Tsinghua University | Kwon Y.-S.,Cetatech Inc. | And 2 more authors.
International Journal of Refractory Metals and Hard Materials | Year: 2013

The densification behavior of 88W-8.4Ni-3.6Fe, 88W-8.4Ni-3.6Cu, and W-15Cu during heating is compared using the master sintering curve (MSC) approach. The MSC parameters, such as the work of sintering, activation energy, and densification ratio, are calculated from dilatometry tests, based on which the densification is classified into three regions with different sintering mechanisms. This approach enables contrast and comparison of the densification sensitivity to solubility, temperature, and heating rate. The master sintering curves are combined into a master sintering surface that includes integral work and the solubility of tungsten in the liquid phase. © 2012 Elsevier Ltd. All rights reserved.


Do K.-R.,Gyeongsang National University | Choi S.-H.,Gyeongsang National University | Kwon Y.-S.,Cetatech Inc. | Cho K.-K.,Gyeongsang National University | Ahn I.-S.,Gyeongsang National University
Metals and Materials International | Year: 2011

HSS has high strength, wear resistance, and hardness together with an appreciable toughness and fatigue resistance. PIM has received attention owing to its ability to shape without additional processes. The experimental specimens were manufactured using PIM with T42 powders (59 vol.%) and polymer (41 vol.%). The green parts were solvent debound in n-Hexane at 60 °C for 24 hours and further thermally debound in a N2-H2 mixed gas atmosphere for 18 hours. The specimens were then sintered in a vacuum (10 -5 mtorr), hydrogen and nitrogen gas atmosphere. In the vacuum, the specimen sintered at 1240 °C had the highest hardness at 520 Hv. In this condition, the carbides were well-distributed and located in the grain. The grain size was 10 μm, and the carbide size was 1 μm. When sintering in a vacuum at over 1260 °C, the carbides converted to eutectic carbide and were located at the grain boundary. Grain growth was observed. The specimens sintered in a nitrogen atmosphere had a lower density and hardness than that produced in the vacuum. © KIM and Springer.


Kim Y.,Agency for Defense Development | Song Y.-B.,Agency for Defense Development | Lee S.H.,Agency for Defense Development | Kwon Y.-S.,Cetatech Inc.
Journal of Alloys and Compounds | Year: 2016

The hot deformation behavior of Ti-6Al-4V sintered preforms was investigated by hot compression tests over temperatures from 800 to 1100 °C and strain rates from 0.001 to 10.0 s-1. The flow curves for the α + β regimes exhibited continuous flow softening and broad oscillation after the peak stress under all of the processing conditions. Otherwise, for the β field, steady-state flow stress was obtained or stress oscillation appeared after the peak stress. In the α + β field, the dynamic globularization and platelet buckling/kinking were observed at lower and higher strain rates, respectively. Unlike in the α + β regions, dynamic recrystallization was found at higher strain rates in the β ones. The apparent activation energies for hot deformation in the α + β and β regimes from kinetic modeling technique were estimated to 147.35 and 233.95 kJ mol-1, respectively. The efficiency of power dissipation over all of the deformation conditions was also calculated by using dynamic material models and schematized into a processing map. The highest value was predicted to 46% at a temperature of 945 °C and at a strain rate of 0.001 s-1, and the processing condition seemed to be optimal for hot deformation of the Ti-6Al-4V sintered preforms. © 2016 Elsevier B.V. All rights reserved.

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