• Structural Engineering and Mechanics
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• v.61 no.4
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• pp.519-526
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• 2017

In the present paper, the effects of cutting parameters and coating material on the performances of cutting tools in turning of AISI 52100 steel are discussed experimentally. A comparative study was carried out between uncoated and coated (with TiCN-TiN coating layer) cermet tools. The substrate composition and the geometry of the inserts compared were the same. A mathematical model was developed based on the Response Surface Methodology (RSM). ANOVA method was used to quantify the effect of cutting parameters on the machining surface quality and the cutting forces. The results show that feed rate has the most effect on surface quality. However, cutting depth has the significant effect on the cutting force components. The effect of coating layers on the surface quality was also studied. A lower surface roughness was observed when using PVD (TiCN-TiN) coated insert. A second order regression model was developed and a good accuracy was obtained with correlation coefficients in the range of 95% to 97%.

• Journal of the Korean Electrochemical Society
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• v.6 no.1
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• pp.53-58
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• 2003

It is well known that the anode substrate of anode-supported type SOFC should have high electrical conductivity and high gas permeability to minimize the polarization loss of the cell performance during operation. In this study, we made anode substrates of SOFC with two different methods, which gave different anode microstructures, especially different pore structures with each other. We performed electrical and microstructural characterization of Ni/YSZ cermet anode via extensive measurements of its electrical conductivity and gas permeability combined with adequate image analysis based on quantitative stereological theory

• Korean Journal of Plant Tissue Culture
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• v.26 no.3
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• pp.157-161
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• 1999

This study was performed to enhance the proliferation rate of Gladiolus 'Topaz' callus. The callus was induced from the cermet tissue explants on MS solid medium with 10 mg/L 2,4-D. In the case of liquid shaking culture, proliferation of the callus was effective in MS medium with 0.05 mg/L 2,4-D at 2$0^{\circ}C$ under 16 hours daylength and in a 100 mL Erlenmeyer flask containing 20 mL of the liquid medium and at 75 rpm in rotation speed of the horizontal shaking culture. Furthermore the callus was also able to be subcultured in the same liquid medium.

• Journal of the Korean Ceramic Society
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• v.51 no.4
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• pp.243-247
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• 2014

Spherical NiO-YSZ particles were synthesized by ultrasonic spray pyrolysis (USP). The morphology of the synthesized particles can be modified by controlling parameters such as precursor pH, carrier-gas flow-rate, and temperature of the heating zone. The synthesized spherical NiO-YSZ particles have rough surface morphology at high carrier-gas flow-rates due to rapid gas exhaustion and insufficient particle ordering. The Ni-YSZ cermet anode synthesized by ultrasonic spray pyrolysis at a flow rate of l L/min, with precursor solution at pH4, showed a higher maximum power density of 256 $mW/cm^2$ compared to a conventionally mixed Ni-YSZ anode (185 $mW/cm^2$) at $800^{\circ}C$. While the area-specific resistance of conventionally mixed Ni-YSZ anodes increases gradually with operation time (indicating performance degradation), the Ni-YSZ anode synthesized by USP does not exhibit any performance degradation, even after 500 h.

• Journal of the Korean institute of surface engineering
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• v.39 no.6
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• pp.295-301
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• 2006

Hard chrome plating has been used in surface hard coating over 50 years both for applying hard coating and re-building of worn components. Hard chrome plating solution and mist pollute environment with very toxic $Cr^{6+}$(hex-Cr) known as carcinogen which causes lung cancer, High velocity oxy-fuel (HVOF) thermal spray coatings of WC base cermet and Co-alloy powders are the most promising candidates for the replacement of the traditional hard chrome plating. Surface properties, wear, and friction behaviors of micron size Co-alloy (T800) and micron size WC-l2Co (WC-Co) have been studied for the application as hard coatings. The temperature dependence of wear and friction behaviors of T800 and WC-Co have been investigated at the temperature of $25^{\circ}C$ and $538^{\circ}C$ for the application to high speed spindle.

• Journal of the Korean Ceramic Society
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• v.43 no.12 s.295
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• pp.798-804
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• 2006

Co-planar type single chamber solid oxide fuel cell with patterned electrode on a surface of electrolyte has been fabricated by robo-dispensing method and microfluidic lithography. The cells were composed of NiO-GDC-Pd or NiO-SDC cermet anode, $(La_{0.7}Sr_{0.3})_{0.95}MnO_3$ cathode, and yttria stablized zirconia electrolyte. The cell performance at $900^{\circ}C$ was investigated as a function of electrode geometries, such as anode-to-cathode distance, numbers of electrode pairs. Relationship between OCV and I-V characteristics at the optimized operation condition was also studied by DC source meter under the mixed gas condition of methane, air, and nitrogen. An increase of anode-facing-cathode area leads to lower OCV due to intermixing between product gases of anode and cathode, which in turn decreases the oxygen partial pressure difference.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.11a
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• pp.409-414
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• 1999

The influence of ion beam energy and reactive oxygen partial pressure on the electrical and crystallographic characteristics of transition metal oxide compound(Cr0x) film was studied in this paper. Chromium oxide films were prepared onto the coverglass using Ion Beam Sputter Deposition(1BSD) technique according to the processing conditions of the partial pressure of reactive oxygen gas and ion beam energy. Crystallinity and grain size of as-deposited films were analyzed using XRD analysis. Thickness and Resistivity of the films were measured by $\alpha$-step and 4-point probe measurement. As results, according to the XRD, XPS and resistivity measurement, the deposited films were the cermet type films which has a crystal structure including amorphous oxide(a-oxide) phase and metal Cr phase simultaneously. The increasernent of the ion b m energy during the deposition process happened to decreasernent of metal Cr grain size and the rapid change of resistivity above the critical $O_2$ partial pressure.

• Journal of the Korean Ceramic Society
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• v.52 no.5
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• pp.338-343
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• 2015

To prevent an interfacial reaction between the anode and the electrolyte layer during the conventional high-temperature co-firing process, an anode-supported type cell with a thin-film electrolyte was fabricated by low-temperature ceramic thick film coating process. Ni-GDC cermet composite was used as the anode material and YSZ was used as the electrolyte material. Open circuit voltage and maximum power density were found to strongly depend on the surface uniformity of the anode functional layer. By optimizing the microstructure of the anode functional layer, the open circuit voltage and maximum powder density of the cell increased to 1.11 V and $1.35W/cm^2$, respectively, at $750^{\circ}C$. When a GDC barrier layer was applied between the YSZ electrolyte and the LSCF cathode, the cell showed good stability, with almost no degradation up to 100 h. Anode-supported type SOFCs with high performance and good stability were fabricated using a coating process.

• Ceramist
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• v.23 no.2
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• pp.114-131
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• 2020

Fracture in the titanium carbonitride-metal composites occurs by crack propagation through the carbonitride grains or in the interfaces. Thus, intrinsic properties of the carbonitride need to be enhanced and the interfaces should be also modified to coherent structure to strengthen the composites. Especially, interfacial structure can be the main factor to determine the mechanical properties of titanium carbonitride-metal composites because the interfaces between carbonitride grains and metallic phase are weak parts due to heterogeneous nature of carbonitride and metallic phase. In this paper, methodologies for improving the interfacial structure of titanium carbonitride-metal composites are suggested. Total area of the interfaces can be reduced using solid solution type carbonitrides as raw materials instead of a mixture of various carbonitrides in the composites. Also, synthesis of titanium carbonitride-metal composite powders and the low-temperature sintering of the composite powders for short time can be the way for formation of coherent interfaces. The sintering of the composite powders for short time at low temperature can reduce the potential of formation of interfaces by dissolution and precipitation of carbonitride in the liquid metal. As a result of formation of coherent boundaries due to low-temperature and short-time sintering, interfaces between titanium carbonitride grains and metallic phase have the favorable structure for the enhanced fracture toughness. It is believed that the low-temperature sintering of solid solution type composite powders for short time can be the way to improve the low toughness of the titanium carbonitride-metal composites.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.111-112
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• 2006

Injection molding of corrosive super engineering plastics and engineering plastics with various fillers is conducted under severe conditions and causes corrosion and wear problems. We have developed $Mo_2NiB_2$ boride base cermets, which have excellent corrosion-and wear-resistances, and tried to apply them into plastic molding machine parts. In this paper, the effects of V substitution for Cr on the mechanical properties, corrosion resistance and microstructure of Ni-5.0B-51.0Mo-(17.5-X)Cr-XV (mass%) model cermets were investigated. Both transverse rupture strength (TRS) and hardness increased monotonically with increasing V content and reached 2.94GPa and $87.2R_A$ at 10.0%V, respectively. The improvements of TRS and hardness were attributed to microstructural refinement.