Journal of Powder Materials

Sung-Soo Kim

4 Articles

Microwave Absorbing Properties of Rubber Composites Containing Soft Magnetic Fe-Alloy Particles: Han-Shin Cho, Sung-Soo Kim; J Korean Powder Metall Inst. 2013;20(2):125-128.; DOI: https://doi.org/10.4150/KPMI.2013.20.2.125

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Magnetic and dielectric properties of rubber composites are controlled by using two kinds of high-permeability metal particles with different electrical conductivity (Sendust, Permalloy), and their effect on microwave absorbance has been investigated, focusing on the quasi-microwave frequency band (0.8-2 GHz). Noise absorbing sheets are composite materials of magnetic flake particles of high aspect ratio dispersed in polymer matrix with various filler amount of 80-90 wt.%. The frequency dispersion and magnitude of complex permeability is almost the same for Sendust and Permalloy composite specimens. However, the complex permittivity of the Permalloy composite (varepsilon_rprimesimeq250, varepsilon_rprimeprimesimeq50) is much greater than that of Sendust composite (varepsilon_rprimesimeq70, varepsilon_rprimeprimesimeq0). Due to the large dielectric permittivity of Permalloy composite, the absorbing band is shifted to lower frequency region. However, the investigation of impedance matching reveals that the magnetic permeability is still small to satisfy the zero-reflected condition at the quasi-microwave frequency band, resulting in a small microwave absorbance lower than 10 dB.

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Thermo-oxidative stability of rubber magnetic composites cured with sulfur, peroxide and mixed curing systems
Ján Kruželák, Andrea Kvasničáková, Rastislav Dosoudil
Plastics, Rubber and Composites.2018; 47(7): 324. CrossRef
Electromagnetic Wave Shielding Effect of Nano-powder Dispersed Epoxy Resin Composite
Jun-Young Han, Chul-Hee Lee, Min-Gyu Choi, Soon-Jik Hong, Joong-Hark Park, Dong-Jin Lee
journal of Korean Powder Metallurgy Institute.1970; 22(4): 234. CrossRef

Sintering and Microwave Dielectric Properties of Bi₁₈(Ca_0.725Zn_0.275)₈Nb₁₂O₆₅ [BCZN] Dielectrics with V₂O₅ Addition: Young-Jong Lee, Sung-Soo Kim; J Korean Powder Metall Inst. 2010;17(4):289-294.; DOI: https://doi.org/10.4150/KPMI.2010.17.4.289

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Abstract PDF: For the aim of low-temperature co-fired ceramic microwave components, sintering behavior and microwave properties (dielectric constant varepsilon_r, quality factor Q, and temperature coefficient of resonant frequency tau_f) are investigated in Bi_18O(Ca_0.725Zn_0.275)_8Nb_12O_65 [BCZN] ceramics with addition of V_2O_5. The specimens are prepared by conventional ceramic processing technique. As the main result, it is demonstrated that the additives (V_2O_5) show the effect of lowering of sintering temperature and improvement of microwave properties at the optimum additive content. The addition of 0.25 wt% V_2O_5 lowers the sintering temperature to 890°C utilizing liquidphase sintering and show the microwave dielectric properties (dielectric constant varepsilon_r = 75, quality factor Qtimesf = 572 GHz, temperature coefficient of resonance frequency tau_f;=;-10;ppm/°C). The estimated microwave dielectric properties with V_2O_5 addition (increase of varepsilon_r, decrease of Qtimesf, shift of tau_f to negative values) can be explained by the observed microstrucure (sintered density, abnormal grain structure) and possibly high-permittivity Bi_18Zn_8Nb_12O_65 (BZN) phase determined by X-ray diffraction.

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; J Korean Powder Metall Inst. 2010;17(2):113-122.; DOI: https://doi.org/10.4150/KPMI.2010.17.2.113

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Abstract PDF: Two kinds of oxide-dispersion-strengthened (ODS) 316L stainless steel were manufactured using a wet mixing process(wet) and a mechanical alloying method (MA). An MA 316L ODS was prepared by a mixing of metal powder and a mechanical alloying process. A wet 316L ODS was manufactured by a wet mixing with 316L stainless steel powder. A solution of yttrium nitrate was dried after being in the wet 316L ODS alloy. The results showed that carbon and oxygen were effectively reduced during the degassing process before the hydroisostatic process (HIP) in both alloys. It appeared that the effect of HIP treatment on increase in impact energy was pronounced in the MA 316L ODS alloy. The MA 316L ODS alloy showed a higher yield strength and a smaller elongation, when compared to the wet 316L ODS alloy. This seemed to be attributed to the enhancement of bonding between oxide and matrix particles from HIP and to the presence of a finer oxide of about 20 nm from the MA process in the MA 316L ODS alloy.

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

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