• Journal of the Speleological Society of Korea
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• no.78
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• pp.9-15
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• 2007

The materials showing high structure dispersion with functional properties were developed on the quartz base and those were obtained by mechano-chemical reaction technology. Depending on the processing conditions and subsequent applications the materials produced by mechano-chemical reaction show concurrently magnetic, dielectric and electrical properties. The obtained magnetic-electrical powders classified by aggregate complex of their features as segnetomagnetics, containing a dielectric material as a carrying nucleus, particularly the quartz on that surface one or more layers of different compounds were synthesized having thickness up to 1050nm showing magnetic, electrical properties and others. The similarity of the structure of surface layers of quartz particles subjected to mechano-chemical processing and nano-structure cluspol (clusters in a polymer matrics) material was alsoconfirmed by the fact that the characteristics of ferromagnetic quartz of insulating nano-composite powder were changed with time, after its preparing process was completed.

• Transactions on Electrical and Electronic Materials
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• v.5 no.1
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• pp.29-33
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• 2004

The materials showing high structure dispersity have been developed on the quartz base by mechano-chemical technology. Depending on the processing conditions and subsequent applications, the materials produced by mechano-chemical reaction (MCR) showed concurrently magnetic, dielectric and electrical properties. The obtained magnetic-electrical powders classified by aggregate complex of their features as segneto-magnetics, contained a dielectric material as a carrying nucleus, particularly the quartz on that surface one or more layers of different compounds was synthesized having thickness up to 10∼50 nm and showing magnetic properties and etc.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07b
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• pp.1241-1244
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• 2003

The materials showing high structure dispersity are developed on the natural quartz base and they are obtained by mechano-chemical technology. Depending on the processing conditions and subsequent applications the materials produced by mechano-chemical reaction (MCR) show concurrently magnetic, dielectric and electrical properties. The obtained magnetic-electrical powders classified by aggregate complex of their features as segnetomagnetics, contain a dielectric material as a carrying nucleus, particularly the quartz on that surface one or more layers of different compounds are synthesized having thickness up to $10{\sim}50nm$ and showing magnetic, electrical and other properties.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.11a
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• pp.585-587
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• 2002

The materials showing high structure dispersity are developed on the quartz base and they are obtained by mechano-chemical technology. Depending on the processing conditions and subsequent applications the materials produced by mechano-chemical reaction show concurrently magnetic, dielectric and electrical properties. The obtained magnetic-electrical powders classified by aggregate complex of their features as segnetomagnetics, contain a dielectric material as a canγing nucleus, particularly the quartz on that surface one or more layers of different compounds are synthesized having thickness up to 10~50 nm and showing magnetic, electrical and other properties.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2004.05a
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• pp.113-116
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• 2004

The materials showing high structure dispersion with functional properties were developed on the quartz base and those were obtained by mechano-chemical reaction technology. Depending on the processing conditions and subsequent applications the materials produced by mechano-chemical reaction show concurrently magnetic, dielectric and electrical properties. The obtained magnetic-electrical powders classified by aggregate complex of their features as segnetomagnetics, containing a dielectric material as a carrying nucleus, particularly the quartz on that surface one or more layers of different compounds were synthesized having thickness up to 10~50 nm showing magnetic, electrical properties and others. The similarity of the structure of surface layers of quartz particles subjected to mechano-chemical processing and nano-structure cluspol (clusters in a polymer matrics) material was also confirmed by the fact that the characteristics of ferromagnetic quartz of insulating nano-composite powder were changed with time, after its preparing process was completed. The magnetic permeability of the sample was decreasing within first two months down by 15~20 %. Then, the magnetic characteristics were almost stabilized steadily and continuously. The observed changes were related with defective structure of the particles, elastic stress relief, and changes of electron density and magnetic moment in deformation zones. This process of stabilization of the investigated properties could be intensified by the thermal annealing heat treatment in short time period of the nano-composite quartz powders at the temperature ranges of 100~15$0^{\circ}C$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.11a
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• pp.99-102
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• 2002

The BSCCO superconductor materials of using Self-propagating High-temperature Synthesis (SHS) were studied. Mechano-chemical activation - as a pre-treatment of the reactants mixture - strongly influences the kinetic parameters, the reaction mechanism, and the composition and structure of the final product. In this paper as an effort for fabricating the SHSed BSCCO superconductor powder SHS method was considered to application in the synthesis of superconducting materials.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2004.05a
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• pp.96-99
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• 2004

The combination of mechano-chemical activation and Self-propagating High-temperature Synthesis (SHS) has widened the possibilities for both methods. For YBCO systems the investigation showed that a short-term mechano-chemical activation of initial powders before SHS leads to single-phase and ultra-fine products. A new technique for preparation ultra-fine high-temperature superconductors of YBCO composition with a grain size d ＜1 ${\mu}{\textrm}{m}$ is developed. The specific feature of the technique is formation of the YBa$_2$Cu$_3$O$_{7-{\delta}}$ crystalline lattice directly from an X-ray amorphous state arising as a result of mechanical activation of the original oxide mixture. The technique allows the stage of formation of any intermediate reaction products to be ruled out. X-ray and magnetic studies of ultra-fine high temperature superconductors (HTS) are carried out. Dimension effects associated with the microstructure peculiarities are revealed. A considerable enhancement of inter-grain critical currents is found to take place in the ultra-fine samples.fine samples.

• Journal of the korean Society of Automotive Engineers
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• v.5 no.1
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• pp.32-44
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• 1983

In case of $K_{Imax}$ < $K_{Iscc}$, the corrosion fatigue of high strength steel in 0.1N $H_{2}$S $O_{4}$ solution and 3.5% salt water is as follows. 1. The fatigue life shortens in order of 3.5% salt water and 0.1N $H_{2}$S $o_{4}$ solution. 2. The fatigue crack growth rate in air is obtained as the following equation. (dc/dN)$_{atr}$=7.23*10$^{-6}$ (.DELTA. K)$^{2.23}$ 3. The corrosion fatigue crack growth rate in environment is divided into three regions, that is, First Region, Second Region and Third Region from the small cyclic stress intensity. 4. The formation rate of the active surface on metal is slower than the mechano-chemical reaction rate in First Region. The crack growth rate depends on time and the cyclic stress intensity and is expressed as the following equation. (dc/dN)$_{I}$=C(/DELTA. K)$^{\delta}$ 5. The formation rate of the active surface is faster than the mechano-chemical reaction rate in Second Region and the synergistic effect by stress and corrosion becomes slow. In case the fatigue load is large, we have the critical crack growth rate which is not related to the cyclic stress intensity. 6. The corrosion crack growth rate by the mechano-chemical reaction is the same in $H_{2}$S $O_{4}$ solution and salt water, so Hydrogen accelerates the crack growth. 7. The environment has no effect on the corrosion fatigue crack growth rate in Third Region. 8. In First Region and Second Region, dimple is observed on the fatigue fracture surface in 0.1N $H_{2}$S $O_{4}$ solution. 9. The striation is observed in any environment as in air in Third Region and its interval approximately coincide with the crack growth rate.ate.e.e.

• Journal of the Korean Society for Heat Treatment
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• v.25 no.3
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• pp.138-145
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• 2012

An ${\alpha}$-Ferrite (Fe) powder dispersed with 4 vol.% of $Al_2O_3$ was successfully produced by a simple miling at 210 K with a mixture of $Fe_2O_3$, Fe and Al ingredient powders, followed by 2 step high temperature consolidation: Hot Pressing (HP) at 1323 K and then Hot Isostatic Pressing at 1423 K. The microstructure of the consolidated material was characterized by standard metallographic techniques such as XRD (X-ray Diffraction), TEM and STEM-EDS. The results of STEM-EDS analysis showed that the HIPed materials comprised a mixture of pure Fe matrix with a grain size of ~20 nm and $Al_2O_3$ with a bimodal size distribution of extremely fine (~5 nm) and medium size dispersoids (~20 nm). The mechanical properties of the consolidated materials were characterized by compressive test and micro Vickers hardness test at room temperature. The results showed that the yield strength of the ODS (Oxide Dispersion Strengthened) Fe alloy are as much as $674{\pm}39$ MPa and the improvement of the yield strength is attributed to the presence of the fine $Al_2O_3$ dispersoid.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07b
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• pp.1270-1273
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• 2004

The combination of methane-chemical activation and Self-propagating High-temperature synthesis (SHS) has widened the possibilities for both methods. For YBCO systems the investigation showed that a short-term mechano-chemical activation of initial powders before SHS leads to single-phase and ultra-fine products. A new technique for preparation ultra-fine high-temperature superconductors of YBCO composition with a grain size d < $1{\mu}m$ is developed. The specific feature of the technique is formation of the $YBa_2Cu_3O_{7-x}$ crystalline lattice directly from an X-ray amorphous state arising as a result of mechanical activation of the original oxide mixture. The technique allows the stage of formation of any intermediate reaction products to be ruled out. X-ray and magnetic studies of ultra-fine high temperature superconductors (HTS) are carried out. Dimension effects associated with the microstructure peculiarities are revealed. A considerable enhancement of inter-grain critical currents is found to take place in the ultra-fine samples investigated.