• 한국세라믹학회지
• /
• 제35권10호
• /
• pp.1049-1054
• /
• 1998

In order to fabricate ideal powders new processing is necessary in which the solute atoms in solution ra-pidly move to mix each other to the degree of molecular level the viscosity of solution should be low not to effect the moving of solute atoms and the powders could be directly obtained as crystalline. Supercritical fluid is defined as condensed gas sated up to its critical pressure and temperature. In this paper su-percritical fluid methods were studied as a new ceramic processing of powder preparation. The crystalline powders of TiO2 which are useful for electronic ceramic materials were fabricated by hydrolysis of titanium (IV) ethoxide using ethanol as a supercritical fluid at the condition of 270$\pm$3$^{\circ}C$, 7.3 MPa for 2hr. The cry stalline anatase powders could be directly obtained and its primary particle size was 20 min.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
• /
• pp.457-457
• /
• 2012

We presented plasma processing using a DC Arc Plasmatron for diamond deposition on Al2O3 ceramic substrates. Plasma surface treatments were conducted to improve deposition condition before processing for diamond deposition. The Al2O3 ceramic substrates deposited, $5{\times}15mm^2$, were investigated by Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR) and X-ray Diffraction (XRD). Properties of diamond (111), (220) and (311) peaks were shown in XRD. We identified nanocrystalline diamond films on substrates. The results showed that deposition rate was approximately $2.2{\mu}m/h$ after plasma surface treatments. Comparing the above result with a common processing, deposition rate was improved. Also, the surface condition was improved more than a common processing for diamond deposition on Al2O3 ceramic substrates.

• 한국기계가공학회지
• /
• 제19권10호
• /
• pp.81-86
• /
• 2020

A ceramic vacuum chamber feedthrough ceramic insulator is made of Al2O3; the manufacturing process involves filling alumina powder into a urethane mold and pressing it with a rubber press to produce a molded body. Thereafter, manufacturing is completed through primary shape processing, sintering, and secondary shape processing in the green body, which is a pressurized molding body, This work is intended to prevent defects in the first shape processing by improving the ceramic insulator in the green body, and to improve the productivity of the ceramic insulator by determining the optimal processing conditions.

• 한국세라믹학회지
• /
• 제39권2호
• /
• pp.126-134
• /
• 2002

Mechanochemical Processing(MP)을 거친 Cement(MPC) 또는 Fly Ash(MPFA)를 사용하여 fly ash 다량 혼화 고강도 mortar의 제조를 위한 연구를 수행하였다. 단순 ball milling processing를 거친 cement(Ball-mill Processed Cement, BPC)와 채취 그대로의 처리하지 않은 fly ash(As Received Fly Ash, ARFA) 혼화시의 공시체와 비교하여 동일한 fly ash의 혼화량(10, 20, 30 wt%), 동일한 재령(7일 및 28일)의 압축강도 및 미세구조의 관점에서 고찰하였다. MPC와 ARFA 및 BPC와 MPFA를 사용한 mortar 공시체가 BPC와 ARFA를 사용한 것보다 각각 5-11% 및 10-20% 상승한 압축강도 값을 나타내었다. 더욱이 MPC와 MPFA의 동시 혼화 mortar 공시체의 압축강도가 fly ash 혼화량 20 wt% 공시체에서 강도 상승률 24%를 나타내었는데 이 값은 MPC 사용에 의한 강도 향상 비율(8%)과 MPFA 혼화에 의한 강도 향상 비율(12%)의 합을 상회하는 synergy 효과를 나다내는 강도 향상율을 나타냈다. 상기의 강도 증진은 MP에 있어서 fly ash와 cement 입자가 혼합되면서 기계적 에너지가 공급되므로 각 입자의 서로에 대한 친화성이 증대되며, 이로 인하여 수화물 생성시 cement와 fly ash 입자간의 결합력이 더욱 증가하게 되어 압축강도가 증가하는 것으로 고려된다.

• 한국전자현미경학회:학술대회논문집
• /
• 한국현미경학회 1995년도 제26회 춘계학술대회 연제초록
• /
• pp.48-49
• /
• 1995

• 한국대기환경학회지
• /
• 제20권2호
• /
• pp.185-193
• /
• 2004

A catalyst with CuO ceramic filter for simultaneous treatment of dust and HAP was prepared and characterized. Catalytic ceramic filter can not only potentially achieve the substantial savings in energy but provide with effective optimization and integration of process for simultaneous removal of SO$_2$, NO$_{x}$ and particulates from flue gases. Catalytic ceramic filters remove simultaneously particulates on exterior surface of filters and reduce NO to $N_2$ and $H_2O$ by SCR (Selective Catalytic Reduction) process. Preparation of catalyst impregnated ceramic filter with disk shape (Ψ 50) follow the processing of alumino-silicate ceramic filter, support impregnation and catalyst impregnation (copper oxide). Preparation routes of alumino-silicate catalyst carrier suitable for production of catalytic filters practically were studied and developed using the sol-gel and colloidal processing, homogeneous precipitation and impregnation method. Characterization of the catalyst, catalyst carrier catalytic filter materials have been performed the using various techniques such as BET, XRD, TGA, SEM. Combination of the sol-gel and colloidal processing and impregnation method is recommended to prepare catalyst carriers economically for catalytic filter applications.s.

• 한국재료학회지
• /
• 제11권2호
• /
• pp.137-145
• /
• 2001

수용액 매체에서 젤케스팅을 이용하여 복잡한 형상의 세라믹스를 제조하기 위한 새로운 공정을 연구하였다 용융실리카 분말과 첨가제로서 지르콘과 코디어라이트 조성으로 혼합된 현탁액을 electrosteric 방법으로 안정화시켰다. 슬립은 다성분계 세라믹 현탁액에 단량체, 이량체 그러고 분산제를 혼합하고, 볼밀하여 준비하였다. 슬립의 유동학적 특성을 평가하기 위해 점도를 측정하였으며 , 낮은 점도를 갖는 50vo1%의 고농도 다성분계 세라믹 슬립의 제조가 가능하였다. 슬립의 점도는 고분자 분산제의 함량과 단량체 및 이량체의 혼합비에 크게 의존하였다. 성형체는 안정화시킨 슬립을 몰드에 부어 상온에서 젤화시킨 후 $25^{\circ}C$, 80~85% 상대습도 분위기 하에서 48시간동안 건조시켜 제조하였으며 건조된 성형체에는 균열이 발생하지 않았다.

• 한국세라믹학회지
• /
• 제50권2호
• /
• pp.93-102
• /
• 2013

Macro porous ceramics possessing controlled microstructures and chemical compositions have increasingly proven useful in the industrial sphere. Their sintered structures have found application in both established and emerging, areas such as thermal insulation in buildings, filtration of liquids and molten materials, refractory insulation, bone scaffolds and tissue engineering. Stable ceramic foams can be formed by wet chemical methods using inorganic particles(e.g., $Al_2O_3$ or $SiO_2$). The wet foams are dried and sintered with improved porosity and mechanical properties. This review examines the different techniques used to prepare porous ceramics from ceramic foams, focusing on the explanation of this versatile method of direct foaming from the past to the present. Comparisons of the processes and the processing parameters are explained with the produced microstructures.

• 한국기계가공학회지
• /
• 제11권3호
• /
• pp.7-12
• /
• 2012

Ceramic core processing technology using 5-axis high-speed cutting machine is applied to make the glass molds for aspherical ophthalmic lenses. In the technology, optimum processing conditions for aspherical ceramic molds are based on minimal experimental data of surface roughness. Such surface roughness is influenced by fabricating tools, cutting speed, feed rate, and depth of cut, respectively. In this paper, we present that surface roughness and shape accuracy of aspheric ceramic mold obtained by optimum processing conditions are Pa $0.6184{\mu}m$ and Pt $5.0301{\mu}m$, respectively, and propose that these values are sufficiently possible to apply to making the glass molds for aspherical ophthalmic lenses.

• 한국세라믹학회지
• /
• 제46권4호
• /
• pp.385-391
• /
• 2009

Need for plasma resistant ceramic materials has been continuously increased in semiconductor and display industry requiring plasma processing to realize ultra fine circuit process. Among promising candidates, alumina ceramics have still some advantages with respect to its economic aspect. In this study, fabrication of plasma resistant alumina ceramics was tried, and its processing optimization was also aimed. Careful processing control and thereby uniform microstructure of $Al_2O_3$ gave rise to enhanced plasma resistance, even comparable to market-governing commercial $Al_2O_3$. A further study is needed concerning ${\beta}-Al_2O_3$ materials system, presumably playing a decisive role in decreasing plasma resistance of $Al_2O_3$ ceramics.