- Synthesis of Ultrafine TiC-5%Co Powder by Using Co Nitrate and TiO(OH)2 Slurry and Evaluation of Sintered Materials Prepared by Mixing WC-Co
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Seong-Hyeon Hong, Byoung-Kee Kim
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J Korean Powder Metall Inst. 2008;15(2):107-113.
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DOI: https://doi.org/10.4150/KPMI.2008.15.2.107
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- Ultrafine TiC-5%Co powders were synthesized by spray drying of aqueous solution of TiO(OH)_2 slurry and cobalt nitrate, followed by calcination and carbothermal reaction. The oxide powders with carbon powder was reduced and carburized at 900°Csim1250°C under hydrogen atmosphere. During reduction, CO gas was mainly evolved by reducing reaction of oxides. Ultrafine TiC-5%Co powders were easily formed by carbothermal reaction at 1250°C due to using ultrafine powders as raw materials. The ultrafine WC-TiC-Co alloy prepared by sintering of mixed powder of ultrafine WC-13%Co powder and ultrafine TiC-5%Co powder has higher sintered density and mechanical properties than WC-TiC-Co alloy prepared by commercial WC, TiC and Co powders.
- Life and Mechanical Properties of Hot Former Die for Bearing Race using P/M High Speed Steel
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Seong-Hyeon Hong, Jong-Soo Bae
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J Korean Powder Metall Inst. 2007;14(6):367-371.
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DOI: https://doi.org/10.4150/KPMI.2007.14.6.367
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- P/M high speed steel (1.26% C, 4.42% Cr, 6.54% W, 4.92% Mo, 3.21 % V, 8.77% Co, bal. Fe) was applied to hot former die. It showed that the die life became 2.7 times higher than that of cast/wrought SKH 55 tool steel which is commercially used. The increase of die life was corresponding to the improved hardness and transverse rupture strength of PM high speed steel due to the finer grain and carbide as well as the uniform carbide distribution. The P/M high speed steel with the promoted die life could be an alternative to the conventional SKH55.
- Effect of Heat Treatment on the Microstuctures and Mechanical Properties of TiC Dispersed Ni-base Alloy
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Seong-Hyeon Hong, Keum-Chul Hwang, Won-Hyuk Rhee, Eog-Yong Chin
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J Korean Powder Metall Inst. 2002;9(6):455-462.
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DOI: https://doi.org/10.4150/KPMI.2002.9.6.455
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- The microstructures and properties of TiC dispersed nickel-base alloy were studied in this work. The alloy prepared by powder metallurgical processing was solution treated, 1st-aged at 880°C for 16 hours, and then 2nd-aged at 760°C for 4 hours. Microstucture of sintered specimen showed that TiC particles are uniformly dispersed in Ni base alloy. In the specimen aged at 880°C for 8 hours, the fine gammaNi_3(Al,Ti) precipitates with round shape are observed and the very fine gammaNi_3(Al,Ti) particles with round shape are precipitated in the specimen aged at 760°C for 4 hours. The presence of gammaprecipitates in TiC/Ni base alloy increased the hardness and wear resistance of the specimen. The hardness and wear resistance of the Ni-base with TiC are higher than those of conventional Ni-base superalloy X-750 because of dispersion strengthening of TiC particles. The hardness, transverse rupture strength and resistance of the specimen 2nd-aged at 760°C for 4 hours are higher than those of 1st-aged specimen due to ultrafine gammaNi_3(Al,Ti) precipitates.
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