• Proceedings of the Korean Society For Composite Materials Conference
• /
• 2003.10a
• /
• pp.217-220
• /
• 2003

The effective thermoelastic properties of porous metals are discussed herein after each material forming process such as hot pressing or extrusion. The voids in metal matrix are assumed to be initially spherical in shape and to be distributed randomly. Once the porous material deforms plastically due to each material forming process, the voids change their shape from a sphere to an ellipsoid and align in one direction. Since the voids are compressible in nature, the void volume fraction is assumed to be decreasing during each material forming process.

• Proceedings of the Materials Research Society of Korea Conference
• /
• 2005.05a
• /
• pp.228-228
• /
• 2005

• Proceedings of the Materials Research Society of Korea Conference
• /
• 2001.11a
• /
• pp.44-44
• /
• 2001

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 1994.03a
• /
• pp.159-166
• /
• 1994

A constitutive model was proposed to analyze creep densification and grain growth of alumina powder compacts during high temperature processing. Theoretical results from the constitutive model were compared with various experimental data of alumina powder compacts in the literature including pressureless sintering, sinter forging and hot pressing. The proposed constitutive equations were implemented into finite element analysis program (ABAQUS) to simulate densification for more complicated geometry and loading conditions. High temperature forming processing of alumina compact with complicated shape was simulated. Processing of Alumina Powder Compacts

• Proceedings of the Korean Institute of Surface Engineering Conference
• /
• 2007.11a
• /
• pp.147-148
• /
• 2007

The compound, Ti3(Al,Si)C2, was synthesized by hot pressing a powder mixture of TiCX, Al and Si. Its oxidation at 900 and 1000 oC in air for up to 50 h resulted in the formation of rutile-TiO2, -Al2O3 and amorphous SiO2. During oxidation, Ti diffused outwards to form the outer TiO2 layer, and oxygen was transported inwards to form the inner mixed layer.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
• /
• 2001.06a
• /
• pp.354-359
• /
• 2001

CNTs were added to Ultra-high molecular weight polyethylene (UHMWPE) to improve the tribological properties of UHMWPE. CNTs which have a diameter of about 10-50nm, while their length is about 3-5nm were produced by the catalytic decomposition of tile C$_2$H$_2$ using a tube furnace. UHMWPE/CNTs composites were fabricated by hot pressing method. It is shown that friction coefficient was increased and wear resistance was improved as CNTs were added to UHMWPE because of excellent mechanical properties of CNTs located on UHMWPE surface.

• Tribology and Lubricants
• /
• v.13 no.3
• /
• pp.102-107
• /
• 1997

Diamond grit was coated with Ti by RF Sputtering to investigate the effect of coated diamond particles on performance of diamond impregnated saw. Coated and uncoated powders were separately mixed with 70Co-30W powders by conventional milling technique. Hot pressing was carried out to make specimens. The wear test were carried out with these two types of diamond impregnated specimens. It was demonstrated that Ti coating was effective in improving the ability of grit retention and thus enhanced the tribological performance of diamond tool.

• Journal of the Microelectronics and Packaging Society
• /
• v.17 no.3
• /
• pp.51-57
• /
• 2010

Thermoelectric properties of the p-type $(Bi,Sb)_2Te_3$, hot-pressed with the $(Bi,Sb)_2Te_3$ powders fabricated by melting/grinding method, were characterized with variation of the hot-pressing conditions. Thermoelectric characteristics of the hot-pressed $(Bi,Sb)_2Te_3$ were also analyzed with addition of $ZrO_2$ as nano inclusions. With increasing the hotpressing temperature from $350^{\circ}C$ to $550^{\circ}C$, Seebeck coefficient and electrical resistivity decreased from 275 ${\mu}V$/K to 230 ${\mu}V$/K and 6.68 $m{\Omega}$-cm to 1.86 $m{\Omega}$-cm, respectively. The power factor decreased with addition of $ZrO_2$ nano powders more than 1 vol%, implying that the optimum amount of $ZrO_2$ nano inclusions to get a maximum power factor would be less than 1 vol%.

• Korean Journal of Materials Research
• /
• v.8 no.5
• /
• pp.408-412
• /
• 1998

Thermoelectric properties of Bi$_{2}$(Te$_{1-x}$Se$_{ x}$)$_{3}$(0.05$\leq$x$\leq$0.25) prepared by mechanical alloying and hot pressing, were investigated. Contrary to the p-type behavior of single crystals, the hot-pressed Bi$_{2}$(Te$_{1-x}$Se$_{ x}$)$_{3}$ exhibited ntype conduction without addition of donor dopant. When $Bi_2(Te_{0.85}Se_{0.15})_3$powders were annealed in (50% $H_2$ + 50% Ar) atmosphere, the hot-pressed specimen exhibited a positive Seebeck coefficient due to the reduction of the electron concentration by removal of the oxide layer on the powder surface and annealing-out of the excess Te vacancies. Among the Bi$_{2}$(Te$_{1-x}$Se$_{ x}$)$_{3}$fabricated by mechanical alloying and hot pressing, $Bi_2(Te_{0.85}Se_{0.15})_3$ exhibited a maximum figure-of-merit of 1.92 $\times$ $lO^{-3}$/K.

• Journal of the Microelectronics and Packaging Society
• /
• v.20 no.1
• /
• pp.15-19
• /
• 2013

The n-type $Bi_2(Te_{0.9}Se_{0.1})_3$ powders, which were fabricated by melting/grinding method and dispersed with 0.5 vol% $TiO_2$ nanopowders, were hot-pressed in order to investigate the effects of $TiO_2$ dispersion on the thermoelectric properties of the hot-pressed $Bi_2(Te_{0.9}Se_{0.1})_3$. Excellent thermoelectric properties such as a maximum figure-of-merit of $2.93{\times}10^{-3}/K$ and a maximum dimensionless figure-of-merit of 1.02 were obtained for the hot-pressed $Bi_2(Te_{0.9}Se_{0.1})_3$. With dispersion of 0.5 vol% $TiO_2$ nanopowders, the maximum figure-of-merit and the maximum dimensionless figure-of-merit decreased to $2.09{\times}10^{-3}/K$ and 0.68, respectively.