Journal of Powder Materials

[Korean]
Basic Study on the Recycling of Waste Tungsten Scraps by the Oxidation and Reduction Process: Sang-Uk Kim, Ji-seok Yun, Tae-Wook Kim, Bong-Hwi Cho, In-Ho Kim, Sang-Mu Kim, Chang-Bin Song; J Korean Powder Metall Inst. 2017;24(1):34-40. Published online February 1, 2017; DOI: https://doi.org/10.4150/KPMI.2017.24.1.34

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This study is carried out to obtain basic data regarding oxidation and reduction reactions, originated on the recycling of waste tungsten hard scraps by oxidation and reduction processes. First, it is estimated that the theoretical Gibbs free energy for the formation reaction of WO₂ and WO₃ are calculated as ΔG_1,000K= -407.335 kJ/mol and ΔG_1,000K = -585.679 kJ/mol, from the thermodynamics data reported by Ihsan Barin. In the experiments, the oxidation of pure tungsten rod by oxygen is carried out over a temperature range of 700-1,000°C for 1 h, and it is possible to conclude that the oxidation reaction can be represented by a relatively linear relationship. Second, the reduction of WO₂ and WO₃ powder by hydrogen is also calculated from the same thermodynamics data, and it can be found that it was difficult for the reduction reaction to occur at 1,027°C, in the case of WO₂, but it can happen for temperatures higher than 1127°C. On the other hand, WO₃ reduction reaction occurs at the relatively low temperature of 827oC. Based on these results, the reduction experiments are carried out at a temperature range of 500-1,000°C for 15 min to 4 h, in the case of WO₃ powder, and it is possible to conclude that the reduction at 900°C for 2h is needed for a perfect reduction reaction.

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A Basic Study on the Recycling of Wasted Cemented Carbide by the Zn Bath Process(Ⅰ)
Kyung-Sik Kim, In-Ho Kim, Chan-Gi Lee, Chang-Bin Song
Journal of the Korean Institute of Resources Recycling.2020; 29(6): 35. CrossRef

[Korean]
Fabrication and Characterization of ODS 316L Stainless Steels: Min-Ho Kim, Ho-Jin Ryu, Sung-Soo Kim, Chang-Hee Han, Jin-Sung Jang, Oh-Jong Kwon; J Korean Powder Metall Inst. 2009;16(2):122-130.; DOI: https://doi.org/10.4150/KPMI.2009.16.2.122

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Austenitic oxide-dispersion-strengthened (ODS) stainless steel was fabricated using a wet mixing process without a mechanical milling in order to reduce contaminations of impurities during their fabrication process. Solution of yttrium nitrate was dried after a wet mixing with 316L stainless steel powder. Carbon and oxygen contents were effectively reduced by this wet processing. Microstructural analysis showed that coarse yttrium silicates of about 150 nm were formed in austenitic ODS steels with a silicon content of about 0.8 wt%. Wet-processed austenitic ODS steel without silicon showed higher yield strength by the presence of finer oxide of about 20 nm.

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Dispersion Behaviors of Y2O3Particles Into Aisi 316L Stainless Steel by Using Laser Cladding Technology
Eun-Kwang Park, Sung-Mo Hong, Jin-Ju Park, Min-Ku Lee, Chang-Kyu Rhee, Kyeong-Won Seol, Yang-Kyu Lee
Journal of Korean Powder Metallurgy Institute.2013; 20(4): 269. CrossRef
Effects of the Sintering Variable on Impact Energy in MA 316L ODS and Wet 316L ODS Stainless Steels
Sung-Soo Kim, Chang-Hee Han, Jin-Sung Jang
Journal of Korean Powder Metallurgy Institute.2010; 17(2): 113. CrossRef

[Korean]
Preparation and Characteristics of Elongated CdSe nanoparticles: Shin-Ho Kim, Myoung-Guk Park, Yang-Do Kim; J Korean Powder Metall Inst. 2008;15(3):210-213.; DOI: https://doi.org/10.4150/KPMI.2008.15.3.210

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Abstract PDF: Elongated CdSe nanoparticles with a diameter of 3-7nm have been successfully synthesized using two surfactants of trioctylphospine (TOP) and hexadecylamine (HDA) at 160°C. The formation of elongated CdSe nanoparticles is possibly due to the cooperative effects from both the different binding capability of two surfactants (TOP and HDA) and intrinsically anisotropic crystal structure of the CdSe. The electron diffraction pattern of CdSe nanoparticles revealed the formation of wurzite phase. The CdSe samples showed red-shifted wavelength from 560 to 580nm with increasing the refluxing time due to the gradual growth of CdSe nanoparticles. The relatively broad absorption band can be attributed to the surface state of CdSe nanoparticles. The possible formation mechanism of elongated CdSe nanoparticles was proposed and the characteristics of CdSe have been discussed as well.

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