• 한국분말재료학회지
• /
• 제26권3호
• /
• pp.195-200
• /
• 2019

Whisker-type magnesium hydroxide sulfate hydrate ($5Mg(OH)_2{\cdot}MgSO_4{\cdot}3H_2O$, abbreviated 513 MHSH), is used in filler and flame-retardant composites based on its hydrate phase and its ability to undergo endothermic dehydration in fire conditions, respectively. In general, the length of whiskers is determined according to various synthetic conditions in a hydrothermal reaction with high temperature (${\sim}180^{\circ}C$). In this work, high-quality 513 MHSH whiskers are synthesized by controlling the concentration of the raw material in ambient conditions without high pressure. Particularly, the concentration of the starting material is closely related to the length, width, and purity of MHSH. In addition, a ceramic-coating system is adopted to enhance the mechanical properties and thermal stability of the MHSH whiskers. The physical properties of the silica-coated MHSH are characterized by an abrasion test, thermogravimetric analysis, and transmission electron microscopy.

• 한국세라믹학회지
• /
• 제39권11호
• /
• pp.1017-1022
• /
• 2002

$(Ba_{1-x}Ca_x)(Ti_{1-y}Zr_y)O_3(BCTZ)$ powders for the Ni-electrode Multilayer Ceramic Capacitor(MLCC) were synthesized via hydrothermal treatment using mixed aqueous solutions of $BaCl_2{\cdot}2H_2O,\Ca(NO_3)2{\cdot}4H_2O,\ ZrOCl_2{\cdot}8H_2O$ and $TiCl_4$. Two component and three component systems were also extensively studied for basic data. BT, CT and BZ powders were crystalline but CZ was determined to be amorphous under the same synthetic condition. In BTZ system, Zr and Ti were completely soluble and Ca would be substituted for Ba up to ∼6 mol% in BCT. The submicron-sized $(Ba_{0.95}Ca_{0.05})(Ti_{0.80}Zr_{0.20})O_3$ powder of the target composition was successfully synthesized at $150{\circ}$ for 12h.

• 세라미스트
• /
• 제22권4호
• /
• pp.452-463
• /
• 2019

A quartz glass crucible is the essential material for manufacturing silicon ingots such as semiconductors and solar cells. Quartz glass crucibles for semiconductors and solar cells are made similar, but differ in surface purity, structure and durability. Recently, ultra high purity synthetic glass crucibles for semiconductors have become more important due to foreign problems. In Korea, it has succeeded in producing 28-inch quartz glass crucibles through the past 10 years. However, 32-inch synthetic quartz glass for the production of silicon ingots for semiconductors is not up to the level of advanced technology, and the technology gap is expected to be 2 to 3 years. In order to overcome these technological gaps and localize synthetic quartz glass ware, close cooperation between production companies and demand companies and localization of synthetic quartz glass powder must also be made. In addition, if government support can be added, faster results can be expected.

• 한국분말야금학회:학술대회논문집
• /
• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part2
• /
• pp.1009-1010
• /
• 2006

In this study, we attempt to synthesize the cordierite from the reaction of fly-ash, alumina, silicon dioxide, and magnesia powders. For the purpose of air purification, the honeycomb filter with porous cordierite was fabricated from the combination of synthetic cordierite and pore forming agent. Fabricated porous cordierite honeycomb was prepared with high porosity (58%), and good compressive strength (69MPa).

• KSBB Journal
• /
• 제15권6호
• /
• pp.594-599
• /
• 2000

항균성 물질이 함유된 세라믹 포장필름의 제조를 위해 합 성세라믹에 항균성 물질의 홉착 및 내열성올 조사하였다. 메 탄올자화 방선균 MO-16 및 MO-17이 생산하는 천연 항균성 물질은 ethylacetate로 추출하였으며, $121^{\circ}C$, 171압에서 30분간 열처리시 안정하였고 Gram(+)세균 및 Gram(-)세균에 대해 넓은 항균 spe$\xi$trum을 보였다. 항균성 물질을 합성 세라믹 Ce-1에 흡착시켜 열처리한 결과 $105^{\circ}C$ 및 $230^{\circ}C$에서도 항균효과 를 보였다. 또한 열처리 후 methanol로서 홉착된 항균성물질 을 Ce-l으로부터 재추출하여 잔존활성을 검토한 결과 Gram( + ) 세균에 대한 항균활성은 $230^{\circ}C$, 30분 처리시에도 안정하였다. 항균성 물질의 내열성에 대한 산소의 영향은 Ce-1에 흡착시 산소의 유무에 관계없이 효과적인 안정성을 보였다.

• 한국세라믹학회지
• /
• 제22권1호
• /
• pp.19-24
• /
• 1985

The synthetic method was studied on the $SrTiO_3$ powder of pure and homogeneous ultra fine particle of $SrTiO_3$. Pure and ultra fine particle was synthesized from $Sr(OH)_2$.$8H_2O$ and Ti(OH) at 3$0^{\circ}C$~9$0^{\circ}C$ in the $N_2$ gas atmosphere.

• 한국세라믹학회지
• /
• 제11권3호
• /
• pp.14-18
• /
• 1974

Magnesite single crystals up to 250 microns were synthesized from an equi-molar solution of MgCl2 and Na2CO3 in the micro-autoclave at 180-20$0^{\circ}C$. The lattice constant of synthetic magnesite was obtained a=4.6369(7), c=15.0230(10)A.U. by a least squares analysis based on the UNICS Program (Sakurai 1967) was applied to 28 reflections. Results of X-ray powder diffraction and of DTA, TGA, IRA, and EPMA studies indicate that synthesized magnesite has properties to those of natural magnesite.

• 한국세라믹학회지
• /
• 제30권1호
• /
• pp.25-33
• /
• 1993

Formation reaction of Mn-Zn ferrite depending on various synthetic conditions of wet process was investigated using FeCl2.nH2O(n≒4), MnCl2.4H2O, ZnCl2 as starting materials. A stable intermediate precipitate was formed by the addition of H2O2. And the precipitate was hard to transform to spinel phase of Mn-Zn Fe2O4. Single phase of Mn-Zn Fe2O4 spinel was obtained above 8$0^{\circ}C$ reaction temperature. The powder had spherical particle shape and 0.02~0.05${\mu}{\textrm}{m}$ particle size. Fe(OH)2 solid solution, -FeO(OH) solid solution, -FeOOH, Mn-Zn Fe2O4 spinel were formed with air flow rate 180$\ell$/hr. However, single phase of Mn-Zn Fe2O4 spinel with cubic particle shape and 0.1~0.2${\mu}{\textrm}{m}$ particle size was formed with synthetic conditions of 8$0^{\circ}C$ and 90 munutes. The particle shape of the -FeOOH was needle-like.

• 한국세라믹학회지
• /
• 제27권1호
• /
• pp.27-34
• /
• 1990

Single crystals of YBa2Cu3Ox superconductor were grown by means of the flux method. The effectof starting material, cooling rate, melting time, and melting temperjature were evaluated as influencing paraemters. The larger single crystals of YBa2Cu3Ox were obtained with Y2BaCuOy powder as a starting material than with YBa2Cu3Ox powder. The optimum range of synthetic condition for single crystal growth was as follows ; 2-5$^{\circ}C$/hour of cooling rate, 2-5 hour of melting time and melting temperature at 106$0^{\circ}C$. The obtained size of single crystal was 2mm in average and the largest one was 5mm in maximum.

• 한국세라믹학회지
• /
• 제33권7호
• /
• pp.743-754
• /
• 1996

In this study (Ba1-xPbx)TiO3 was synthesized by modified oxalate process in order to prevent vaporization of PbO through low temperature synthesis climinate Cl ion reproducibly substitute Pb for by and uniformly distribute ion (Ba1-xPbx)TiO3 was synthesized by coprecipitation of lead acetate barium acetate and ammonium titanyl oxalate have been used as starting materials. The substitution of Pb for Ba was reproducibly possible synthetic temperature of perovskite structure becomes lowed as the Pb concentration increases and fine partic-les (specific surface are :7.2 cm2/g) were obtained, BaTiO3 powders calcined at 90$0^{\circ}C$ for 3 hours were cubic from in XRD analysis and as Pb content was increases evident split of tetragonal peaks could be observed The optimum conditions to synthesize (Ba,Pb)TiO3 powder are the followings ; synthesis temperature (5$^{\circ}C$)