• Journal of the Korean Ceramic Society
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• v.38 no.11
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• pp.1055-1059
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• 2001

Porous glass ceramics composed of Li$_2$O.-Ti $O_2$-P$_2$ $O_{5}$ -CaO were prepared by melting and 2 step heat treatment for nucleation at 61$0^{\circ}C$ and crystallization at 78$0^{\circ}C$. subsequently $\beta$-Ca$_3$(P $O_4$)$_2$crystal phase was selectively leached out in 1N-HC1 solution for 3 days, leaving Li $Ti_2$(P $O_4$)$_3$crystal phases. prepared porous glass ceramics were immersed in 1M AgN $O_3$solution for ion exchange. Staphylococcus aureus and salmonella typhi were used in this study. It was found taht the resultant porous glas ceramics show excellent bacteriostatic properties.

• Electrical & Electronic Materials
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• v.9 no.2
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• pp.146-151
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• 1996

PZT powders were prepared by the molten salt synthesis method. The porous PZT ceramics were made from a mixture of PZT and polyvinylalcohol(PVA) by BURPS(Bumout Plastic Sphere) technique. The 3-3 type composites were fabricated by impregnating an sintered porous PZT ceramics with various polymer matrices. The relative permittivity of 3-3 type composite specimens was shown 860-1,100 smaller than that of solid PZT ceramics(2,100), and the dissipation factors of composite specimens were about 0.02 to 0.03. The piezoelectric coefficient d$_{33}$ of composite specimens(285-328*10$^{12}$ C/N) was comparable with that of single phase PZT specimens(364*10$^{-12}$ C/N). The thickness mode coupling factor k$_{t}$(O.5-0.6) of composite specimens was comparable with that of single phase PZT specimens(k$_{t}$-0.7), and the mechanical quality factor of composite specimens was smaller than 10, and thus these 3-3 type composite specimens would be believed as a good candidates for broad band transducer applications.ons.

• Journal of the Korean Ceramic Society
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• v.46 no.6
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• pp.609-614
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• 2009

The low-temperature preparation of porous ceramics was carried out using mixtures of alumina-zinc borosilicate (ZBS) glass. The compositions of alumina-ZBS glass mixture with PMMA pore-former were unfortunately densified. Because PMMA was evaporated below the softening point of ZBS glass ($588{^{\circ}C}$), the densification through the pore-filling caused by the capillary force might occur. Howerver, those with carbon possessed pores where carbon was evaporated above the softening point. The porous ceramic having 35% porosity was successively fabricated by the low-temperature sintering process below $900{^{\circ}C}$ using 45 vol% of alumina, 45 vol% ZBS of glass, and 10 vol% of carbon as starting materials.

• Journal of the Korean Ceramic Society
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• v.44 no.6 s.301
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• pp.338-342
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• 2007

Porous silicon nitride ceramics were prepared by SHS (Self-Propagating High Temperature Synthesis) from silicon powder, silicon nitride powder and pore-forming precursor. The microstructure, porosity and the flexural strength of the porous silicon nitride ceramics were varied according to the Si/Si3N4 ratio, size and amount of the pore-forming precursors. Some sample exhibited as high flexural strength as $162{\pm}24\;MPa$. The high strength is considered to result from the fine pore size and the strong bonding amoung the silicon nitride particles.

• Journal of the Korean Ceramic Society
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• v.39 no.10
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• pp.948-954
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• 2002

Porous reaction bonded SiC with high fracture strength was developed using Si melt infiltration method for use of the support layer in high temperature gas filter that is essential to develop the next generation power system such as integrated gasification combined cycle system. The porosity and pore size of porous RBSC developed in this study were in the range of 32∼36% and 37∼90 ${\mu}m$ respectively and the maximum fracture strength of porous RBSC fabricated was 120 MPa. The fracture strength and thermal shock resistance of porous RBSC fabricated by Si melt infiltration were much improved compared to those of commercially available porous clay bonded SiC due to the formation of the strong SiC/Si interface between SiC particles. The characteristics of pore structure of porous RBSC was varied depending on the amounts of residual Si as Well as the size of SiC particle used in green body.

• Korean Chemical Engineering Research
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• v.53 no.4
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• pp.425-430
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• 2015

ZSM-5 crystals grew by hydrothermal synthesis method on the surface of foam type porous silicon carbide ceramics which fabricated by polymer replica method. Oxide layer was developed on the surface of the porous silicon carbide ceramics to induce growth of ZSM-5 from the surface. In this study, hydrothermal synthesis was carried out for 7 h at $150^{\circ}C$ using TEOS, $Al(NO_3){\cdot}9H_2O$ and TPAOH as raw materials in the presence of the porous silicon carbide ceramics. X-ray Powder Diffraction (XRD) and Scanning Electron Microscope (SEM) analyses were confirmed $1{\sim}3{\mu}m$ sized ZSM-5 crystals have grown on the surface of porous silicon carbide ceramics. BET data shows that small pores about $10{\AA}$ size drastically enhanced and surface area increased from $0.83m^2/g$ to $30.75m^2/g$ after ZSM-5 synthesis on the surface of foam type porous silicon carbide ceramics.

• Proceedings of the KIEE Conference
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• 1995.07c
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• pp.1199-1201
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• 1995

PZT powders were prepared by the molten salt synthesis method. The porous PZT was preapred from the mixture of PZT and PVA powders by BURPS(BURnout plastic Sphere) technique. The acoustic properties with various plastic sphere wt.% were studied. The acoustic impedance of porous PZT was smaller than that of single phase PZT ceramics. And the pulse-reponse of porous PZT maded transducer was significantly advanced to that of solid PZT maded transducer.

• Journal of the Korean Ceramic Society
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• v.31 no.11
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• pp.1323-1329
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• 1994

Tape casting and lamination were used to produce heterogeneous laminates with alternating layers of different porosity and homogeneous laminates with component layers of the same porosity. The pore structure was investigated for heterogeneous laminates, and bend strength was measured for comparison with that of homogeneous laminates. For a reference, strength measurement was made for the porous body fabricated by sintering samples dry-pressed at low pressure with spray-dried granules. Strength increase, in the range 50~120 MPa, was achieved in the presence of the surface dense layer, while extensive delamination, presumably responsible for enhanced fracture toughness, took place through the internal porous layer.

• Journal of the Korean Ceramic Society
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• v.36 no.6
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• pp.662-670
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• 1999

Porous alumina was fabricated from pressureless powder packing forming method using powders granulated by spray drying. It was investigated the pore size distribution of fabricated porous alumina. The results of microstructural observation showed that intraganular pore size and intragranular pore size. At 1700$^{\circ}C$ there were no intragranular pores but it showed homogeneous distribution of intergranular pore size. The bending strength and shrinkage increased as porosity decreased. In case of thermal shock resistance sudden decrease of bending strength to $\Delta$T was not shown because intergranular large pore prevented sudden crack propagation.

• Proceedings of the KIEE Conference
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• 1994.07b
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• pp.1475-1477
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• 1994

Porous piezoelectric ceramics of PZT have been newly developed to apply for ultrasonic transducers. The porous PZT was prepared from a mixture of PZT and polyvinylalcohol (PVA) powders by BURPS(Burnout Plastic Sphere) technique. Porous PZT bodies were shown a homogeneous microstructure consisting of 30 - 80 (${\mu}m$) pore size in sintered PZT bodies. The dielectric and piezoelectric properties on various PVA wt.% have investigated.