• Proceedings of the Korean Vacuum Society Conference
• /
• 2016.02a
• /
• pp.172-172
• /
• 2016

Dual-beam experiments (Focused ion beam - Orientation mapping microstructure, FIB-OIM) is a widely used experimental tool because this experiments tool available alternates between automated serial sectioning and EBSD with the help of dual beams. We investigated the reconstruction procedure for analysis tool which three-dimensional internal microstructure using Ni superalloy(IN100) and ZrO2. As a results, we observed annealing twin boundary each layer in Ni superalloy(IN100) and fairly isotropic internal microstructure in ZrO2 using marching cubes algorithm. According to these results, this procedure is reconstructed well and we gained ability to arrange the EBSD map and internal microstructure.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2000.10a
• /
• pp.21-24
• /
• 2000

Ultra-fine grains were produced in pure Al using an Accumulative Rolling-Bonding (ARB) process. After several cycles of the ARB process, pure Al sheets were filled with the ultra-fine grains whose diameters were several hundred nano-meters. With ARB cycles, the nature of grain boundaries of the ultra-fine grains changed from diffusive sub-boundaries to well-defined high angle boundaries. After 7 cycles, ultra-fine polycrystals with large misorientations between neighboring grains were obtained. Sliding wear tests using a pin-on-disk type wear tester were co ducted on the ultra-fine grained pure Al. Wear rates of pure Al increased with the increase of ARB cycle numbers in spite of the increase in hardness. Worn surfaces and cross-sections were examined with optical microscopy (OM) and scanning electron microscopy (SEM) In investigate the wear mechanism of the ultra-fine grained pure Al.

• Journal of the Korean Ceramic Society
• /
• v.28 no.7
• /
• pp.541-548
• /
• 1991

Sinterability and stability of TZP ceramics co-stabilized by 12 mol% CeO2 and divalent or trivalent oxides less than 1 mol% were investigated. Divalent and trivalent oxides increased stability of tetragonal ZrO2. 100% tetragonal ZrO2 phase was obtained by doping 12 mol% CeO2 and 0.2 mol% CaO and MgO respectively when sintering was carried out at 1500$^{\circ}C$ for 2 hours. Divalent and trivalent oxides improved sinterability and inhibit grain growth of ZrO2. And it was found that CaO was the most effective sintering aid and grain growth inhibitor for ZrO2 in this study. Incorporation of divalent and trivalent oxides into 12Ce-TZP increased the strength of 12Ce-TZP and particulary 12Ce, 0.4Ca-TZP exhibited a flexural strength of about twofold greater than 12Ce-TZP.

• The Korean Journal of Ceramics
• /
• v.5 no.4
• /
• pp.331-335
• /
• 1999

Mechanical propeties of $Y_2O_3$-containing tetragonal $ZrO_2$ polycrystals(Y-TZP) were investigated. Several additives were used to modify the hardness fracture toughness of Y-TZP. The effects of these individual additives were discussed and their interactions were also analyzed. Each additive, such as CoO, $Fe2O3, MnO_2$ was found to deteriorate the mechanical propeties of Y-TZP when it was used singly. But the fracture toughness of Y-TZP was singnificantly improved when these additives and $Al_2O_3$ were added in combination at a certain ratio.

• Journal of the Korean Ceramic Society
• /
• v.34 no.2
• /
• pp.171-174
• /
• 1997

It was experimentally identified, for the first time, that oxygen phonons play an important role in the low temperature degradation(tetragonallongrightarrowmonoclinic phase transformation) of yttria stabilized tetragonal zir-conia polycrystals (Y-TZP). The degradation accompanied by immersing the samples in the boiling water were markedly reduced by substituting of 18O for 16O in Y-TZP. This was attributed to the heavier mass of 18O which leads to the smaller probability to find oxygen atoms beyond certain critical displacements.

• Bulletin of the Korean Chemical Society
• /
• v.26 no.2
• /
• pp.248-252
• /
• 2005

Synthetic layered double hydroxides (LDHs), [$Mg_4Al_2(OH)_{12}]CO_3{\cdot}nH_2O$, were prepared in the submicron size of plate-like polycrystals. Anion-exchange reactions with various linear dicarboxylic acids were performed to produce LDH/organic hybrid materials by solvothermal treatment in toluene. X-ray powder diffraction spectra for the products indicated that the interlayer spacings of LDHs remarkably changed, up to 20 $\AA$ when 1,10-decanedicarboxylic acid anions were intercalated as an organic guest. Dicarboxylates-LDHs samples could be also re-exchanged consecutively with other dicarboxylic acids or carbonate without serious destruction of layer structure under the scanning electron microscopic observation.

• Applied Science and Convergence Technology
• /
• v.23 no.6
• /
• pp.371-375
• /
• 2014

Diffusion coefficient of Fe in polycrystalline host ZnSe as a mid-IR gain medium has been measured in the annealing temperature ranges of 850 to $950^{\circ}C$. The synthesis of the samples was carried out in quartz ampoule in which the Fe thin film deposited by physical vapor evaporation method on the ZnSe. One can realize that the diffusion coefficient strongly depends on the surface active surfactants through the cleaning process and the substrate temperature during the thin film deposition leading to $2.04{\times}10^{-9}cm^2/s$ for $Fe^{2+}:ZnSe$. The Annealing temperature dependence of the Fe ions diffusion in ZnSe was used to evaluate the activation energy, $E_a$=1.39 eV for diffusion and the pre-exponential factor $D_0$ of $13.5cm^2/s$.

• Journal of the Korean Ceramic Society
• /
• v.41 no.7
• /
• pp.497-502
• /
• 2004

A hybrid coextrusion and lamination process has been developed to fabricate macrochanneled bioceramic scaffolds. This process was mainly composed of three steps (i.e., coextrusion of thermoplastic compound, lamination, and thermal treatment), forming unique pore channels in dense bioceramic body. Pore channels were formed by removing carbon black material, while calcium phosphate or Tetragonal Zirconia Polycrystals (TZP) with a calcium phosphate coating layer were used as dense body. Two kinds of pore structures were fabricated; that is, the pore channels were formed in uni- or three-directional array. Such macrochanneled bioceramic scaffolds exhibited the precisely controlled pore structure (pore size, porosity, and interconnection), offering excellent mechanical properties and cellular responses.

• Journal of the Korean Ceramic Society
• /
• v.26 no.6
• /
• pp.789-794
• /
• 1989

The high-temperature strength of Ce-TZP was measured at 200, 650 and 100$0^{\circ}C$ by 4-point bending test. And its fracture behavior was observed by SEM. Below $650^{\circ}C$ of the temperature, where monoclinic fraction was almost zero, the decreasing rate of bending strength was relatively slow, but above this temperature, high temperature strength was largely decreased as a result of the decrease of stress-induced transformation of zirconia. The observation of fracture surface bended at 100$0^{\circ}C$ indicated that the fracture mode changed from intergranular-into transgranular-form with regardless of ceria contents.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.3 no.1
• /
• pp.37-44
• /
• 1993

Calcia stabilized zirconia polycrystal (Ca-TZP) powders synthesized by hydrothermal treatment was sintered at a temperature range of $1200^{\circ}C~1400^{\circ}C$ and investigated the properties of sintered body and the behaviors of isothermal phase transformation. The sintered bodies of Ca-TZP were shown the density of about 97% and the average mean tetragonal grain size of about $0.1~0.25{\mu}m$. Also, Ca-TZP specimen was more stable during aging at $250^{\circ}C$ than that of Y-TZP ceramics.