• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.04a
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• pp.31-31
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• 2006

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2004.04a
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• pp.14-15
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• 2004

• Journal of Powder Materials
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• v.8 no.4
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• pp.231-238
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• 2001

We combined Field-Activated Combustion Synthesis(FACS) with mechanical pressure to produce dense WC-20 vol.%Co composite in one step. The hardness, the fracture toughness and the relative density of the dense WC-20 vol.%Co were investigated. Under the application of 60 MPa pressure and 3000A current on the reactants, the relative density of WC-20 vol.%Co composite was 99.4%. The fracture toughness and hardness were $9.4 MPa.m^{1/2}$ and $1672kg\textrm{mm}^2$ respectively. The fracture toughness and hardness of WC-20 vol.%Co composite produced by FAPACS were lower than that of nanostructured composite, but similar to commercial ones. Therefore we concluded that the FAPACS method which can produce WC-20 vol.%Co within several minutes in one step is superior to conventional ones.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 1995.04a
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• pp.35-35
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• 1995

• Journal of Powder Materials
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• v.14 no.5
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• pp.315-319
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• 2007

Pure WC or WC with low Co concentration less than 0.5 wt.% is studied to fabricate high density WC/Co cemented carbide using vacuum sintering and post HIP process. Considering the high melting point of WC, it is difficult to consolidate it without the use of Co as binder. In this study, the effect of lower Co addition on the microstructure and mechanical properties evolution of WC/CO was investigated. By HIP process after vacuum sintering, hardness and density was sharply increased. The hardness values was $2,800kgf/mm^2$ using binderless WC.

• Journal of Powder Materials
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• v.11 no.2
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• pp.111-117
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• 2004

The oxidation behavior of 91 WC-9Co hardmetal in weight percentage has been studied in the present work as a part of the development of recycling process. The morphological and compositional changes of the WC-Co hardmetal with oxidation time at 90$0^{\circ}C$ were analyzed by using surface observation and X-ray diffraction. respective]y. As the oxidation time increased, the WC-Co hardmetal was continuously expanded to form porous oxide mixtures of $CoWO_4$ and $WO_3$. The morphology of porous oxide mixture was basically dependent on initial shape of the WC-Co hardmetal. From thermo-gravimetric (TG) analysis, it was found that the oxidation rate was increased with increasing oxidation temperature and oxygen content in the flowing atmospheric gas. The fraction of oxidation versus time curves showed S-curve relationship at a given of oxidation temperature. These oxidation behaviors of the WC-Co hardmetal were discussed in terms of previously proposed kinetic models.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 1998.10b
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• pp.29-29
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• 1998

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.04a
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• pp.79-80
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• 2006

새로운 급속소결방법인 고주파유도가열 소결법과 펄스전류활성 소결법을 이용하여 습식 볼밀링으로 혼합한 WC-8wt.%Co분말에 60MPa의 압력과 90%의 고주파출력 또는 2800A의 필스전류를 가하여 상대밀도가 98.6% 이상인 초경재료를 2분이내의 짧은 시간에 제조하였다. 초기의 WC분말의 입도가 미세해짐에 따라 고주파유도가열 소결법과 펄스전류활성 소결법 모두 소결시간이 단축되는 경향을 보였으며 그 소결체의 결정립 크기도 감소하였다. 고주파유도가열 소결법으로 제조된 초경합금의 WC 결정립 크기는 초기입도가 증가함에 따라 가각 410, 540, 600, 700 및 850nm으로 측정되었으며. 그 결과를 Fig. 1.에 나타내었다. WC의 초기입도가 $0.5{\mu}m$일 경우 고주파유도가열 소결법과 펄스전류활성 소결법으로 제조된 WC-8wt.%Co 소결체의 경도와 파괴인성은 각각 $1923kg/mm^2$과 $10.5MPa{\cdot}m^{1/2}$ 및 $1947kg/mm^2$과 $10.8MPa{\cdot}m^{1/2}$ 이었다.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 1999.10a
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• pp.18-18
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• 1999

• Journal of Powder Materials
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• v.25 no.3
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• pp.240-245
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• 2018

This study focuses on the fabrication of a WC/Co composite powder from the oxide of WC/Co hardmetal scrap using solid carbon in a hydrogen gas atmosphere for the recycling of WC/Co hardmetal. Mixed powders are manufactured by mechanically milling the oxide powder of WC-13 wt% Co hardmetal scrap and carbon black with varying powder/ball weight ratios. The oxide powder of WC-13 wt% Co hardmetal scrap consists of $WO_3$ and $CoWO_4$. The mixed powder mechanically milled at a lower powder/ball weight ratio (high mechanical milling energy) has a more rapid carbothermal reduction reaction in the formation of WC and Co phases compared with that mechanically milled at a higher powder/ball weight ratio (lower mechanical milling energy). The WC/Co composite powder is fabricated at $900^{\circ}C$ for 6 h from the oxide of WC/Co hardmetal scrap using solid carbon in a hydrogen gas atmosphere. The fabricated WC/Co composite powder has a particle size of approximately $0.25-0.5{\mu}m$.