• Clean Technology
• /
• v.4 no.2
• /
• pp.32-40
• /
• 1998

The polymeric porous materials which consist of polypropylene(PP) and polyethylene(PE) powder were prepared to apply to the air purification systems by extrusion sintering method. SEM analysis showed that a composite polymeric porous structure made up of PP and PE was obtained, where PE was melted and adhered to PP because the melting temperature of PE was lower than that of PP. The filtration characteristics and mechanical properties of polymeric porous materials were investigated by varying the head die temperature of the extruder, extrusion velocity, and the melt index and quantity of PE. The filtration efficiency was proportional to the quantity of PE but inversely proportional to the melt index of PE. The polymeric porous materials composed of PP and PE, which was made by extrusion sintering method, was found to be suitable for the filter element of the air purification system.

• Korean Journal of Materials Research
• /
• v.15 no.12
• /
• pp.765-772
• /
• 2005

PAS(Plasma Activated Sintering) process was tried to apply for the fabrication of BMG(Bulk Metallic Glasses) of $Ni_{57}Zr_{20}Ti_{18}Si_5}\;and\;Ni_{57}Zr_{20}Ti_{18}Si_3Sn_2$ from the as-atomized amorphous powder. Compressive strength for the BMG(bulk Metallic Glasses) of $Ni_{57}Zr_{20}Ti_{18}Si_5$ were lower than those of BMG rods produced by warm extrusion ,or copper mold casting method. Microstructural examination by optical microcope, SEM ana EDS showed that oxidation had occurred during PASintering. In order to prevent the powder from the oxidation during PASintering, Ni coating for $Ni_{57}Zr_{20}Ti_{18}Si_5$ amorphous powder by electroless-plating method was performed. Microstructural examination for Ni coated layers after PASintering indicated that the Ni coating had been so effective to prevent powder from oxidation during PASintering. Sintering behaviors of $Ni_{57}Zr_{20}Ti_{18}Si_3Sn_2$ represent the same as those of $Ni_{57}Zr_{20}Ti_{18}Si_5$.

• Journal of the Korean Ceramic Society
• /
• v.46 no.1
• /
• pp.94-101
• /
• 2009

The physical properties of artificial aggregates made from clay and inorganic wastes with poor plasticity depends largely on forming method. The artificial aggregates composing of coal fly ash, stone sludge and clay were fabricated using 4 different forming methods and those physical properties were comparatively analyzed. The surface of aggregates made through the extrusion forming process was dense and smooth but was rough for the aggregates obtained by crushing a tile-shaped green body. The aggregates made by pelletizing process had a weak green strength and bumpy surface. The shell generated at surface during a high temperature sintering process induced the most aggregates to be bloated due to a dense shell. But the aggregates made through pelletizing process with dense surface layer showed no significant change in bulk density with sintering temperatures. The water absorption of aggregates decreased with sintering temperature, and that of pelletized specimen was standing $1.8{\sim}2.2$ times higher than that of made by other forming methods. It is concluded that the aggregates having various properties could be fabricated from one batch by using different forming methods.

• Membrane and Water Treatment
• /
• v.14 no.1
• /
• pp.11-18
• /
• 2023

This work addresses the development of microfiltration ceramic membrane from alumina using extrusion method. The membranes were sintered at different temperatures ranging between 1000 and 1300℃. The alumina was characterized with thermogravimetric analysis, particle size distribution, X-ray diffraction, Fourier transform infrared spectrometer and scanning electron microscope analysis. Subsequently, the effect of sintering temperature on the membrane properties such as porosity, flexural strength, and pure water permeability was investigated and optimized for the sintering temperature. It is observed that with increasing sintering temperature, the porosity of the membranes decreases and the flexural strength, and pure water permeability of the membranes increase. The uncoated and coated membranes were compared at constant flux mode of filtration. Under the turbidity solution recirculation alone at 100 NTU, trans-membrane pressure (TMP) of uncoated membrane remained constant when the filtration flux was below 121 Lm^-2 h ^-1 , while the coated membrane was 111 Lm_-2 h ^-1 . Although suction pressure increased more rapidly at higher turbidity, coated membrane filtration showed better removal efficiency of the turbidity.

• Proceedings of the Korean Powder Metallurgy Institute Conference
• /
• 2006.09a
• /
• pp.325-326
• /
• 2006

Using $6wt%Y_2O_3-2wt%Al_2O_3$ as sintering additives and Si as a raw powder, the continuously porous in-situ $Si_2N_2O-Si_3N_4$ bodies were fabricated by multi-pass extrusion process and their microstructures were investigated depending on the addition of carbon (0-9wt%) in the mixture powder. The introduction of $Si_2N_2O$ fibers observed in the unidirectional continuous pores as well as in the pore-frame regions of the nitrided bodies can be an effective method in increasing the filtration efficiency. In the case of no carbon addition, the network type $Si_2N_2O$ fibers with high aspect ratio appeared in the continuous pores with diameters of 150-200 nm. However, in the case of 9wt% C addition, the fibers were found without any network type and had diameters of 200-250 nm.

• Applied Chemistry for Engineering
• /
• v.9 no.7
• /
• pp.1011-1017
• /
• 1998

$YBa_2Cu_3O_{6+x}(Y123)-Ag$ high-Tc superconducting wires were fabricated by plastic extrusion technique using pyrophoric synthetic and mechanical mixing powder with and without Ag addition(20 wt.%). This method involves powder preparation, plastic paste making, die extrusion, binder burn-out and the sintering process. In order to fabricate a good-quality superconducting body, it is required to use homogeneous and fine-size power as a starting materials. $Y_2O_3-BaCO_3-CuO$ precursor powders with/without Ag addition were prepared both by pyrophoric synthetic(PS) and mechanical mixing(MM) method of raw powders. The formation kinetics of the powder mixtures into Y123 phase was investigated at various temperatures and times in air atmosphere. The powder prepared by PS method was more easily converted into a Y123 phase than the MM powder. The fine size and good chemical homogeneity of the powder prepared by PS method is attributable to the fast formation into a Y123 phase. The critical current density($J_c$) of the Y123-Ag superconducting wires made by plastic extrusion method were in the range of $150A/cm^2{\sim}230A/cm^2$. depending on the charateristics of starting material powders. $J_c$ of the wire prepared by pyrophoric synthetic powder with 20 wt.% Ag addition was $230A/cm^2$.

• Resources Recycling
• /
• v.19 no.5
• /
• pp.31-43
• /
• 2010

To fabricate porous SiC candle filter for filtration facility of the IGCC system, the candle type filter preforms were fabricated by ramming and vacuum extrusion process. A commercially available ${\alpha}$-SiC powders with various particle size were used as starting raw materials, and $44\;{\mu}m$ mullite, $CaCO_3$ powder were used as non-clay based inorganic sintering additive. The candle typed preforms by ramming process and vacuum extrusion were sintered at $1400^{\circ}C$ for 2h in air atmosphere. The effect of forming method and particle size of filter matrix on porosity, density, strength (flexural and compressive strength) and microstructure of the sintered porous SiC candle tilters were investigated. The sintered porous SiC filters which were fabricated by ramming process have more higher density and strength than extruded filter in same particle size of the matrix, and its maximum density and 3-point bending strength were $2.00\;g/cm^3$ and 45 MPa, respectively. Also, corrosion test of the sintered candle filter specimens by different forming method was performed at $600^{\circ}C$ for 2400h using IGCC syngas atmosphere for estimation of long-term reliability of the candle filter matrix.

• Korean Chemical Engineering Research
• /
• v.50 no.3
• /
• pp.562-566
• /
• 2012

A novel design of tubular segmented-in-series(SIS) solid oxide fuel cell (SOFC) sub module was presented in this paper. The tubular ceramic support was fabricated by the extrusion technique. The NiO-YSZ anode and the yttria-stabilized zirconia (YSZ) electrolyte were deposited onto the ceramic support by dip coating method. After sintering at $1350^{\circ}C$ for 5 h, a dense and crack-free YSZ film was successfully fabricated. Also, the multi-layered cathode composed of LSM-YSZ composite, LSM and LSCF were coated onto the sintered ceramic support by dip coating method and sintered at $1150^{\circ}C$. The performance of the tubular SIS SOFC cell and sub module electrically connected by the Ag-glass interconnect was measured and analysed with different fuel flow and operating temperature.