Abstract Y2Ti2O7 nanoparticles (0.3 mol%) have been successfully synthesized by the co-precipitation process. The samples, adjusted to pH7 with ammonia solution as catalyst and calcined at 700~900 ℃, exhibit very fine particles with close to spherical shape and average size of 10-30 nm. It was possible to control the size of the synthesized Y2Ti2O7 particles by manipulating the conditions. The Y2Ti2O7 nanoparticles were coated on a glass substrate by a dipping coating process with inorganic binder. The Y2Ti2O7 solution coated on the glass substrate had excellent adhesion of 5B; pencil hardness test results indicated an excellent hardness of 6H. The thickness of the thick film was about 30 μm. Decomposition of MB on the Y2Ti2O7 thin film shows that the photocatalytic properties were excellent.

A thick film of Li7La3Zr2O12 (LLZO) solid-state electrolyte is fabricated using the tape casting process and is compared to a bulk specimen in terms of the density, microstructure, and ion conductivity. The final thickness of LLZO film after sintering is 240 μm which is stacked up with four sheets of LLZO green films including polymeric binders. The relative density of the LLZO film is 83%, which is almost the same as that of the bulk specimen. The ion conductivity of a LLZO thick film is 2.81 × 10−4 S/cm, which is also similar to that of the bulk specimen, 2.54 × 10−4 S/ cm. However, the microstructure shows a large difference in the grain size between the thick film and the bulk specimen. Although the grain boundary area is different between the thick film and the bulk specimen, the fact that both the ion conductivities are very similar means that no secondary phase exists at the grain boundary, which is thought to originate from nonstoichiometry or contamination.

The effects of an addition of CNT on the sensing properties of nano ZnO:CNT-based gas sensors were studied for H2S gas. The nano ZnO sensing materials were grown by a hydrothermal reaction method. The nano ZnO:CNT was prepared by ball-milling method. The weight range of the CNT addition on the ZnO surface was from 0 to 10%. The nano ZnO:CNT gas sensors were fabricated by a screen-printing method on alumina substrates. The structural and morphological properties of the ZnO:CNT sensing materials were investigated by XRD, EDS, and SEM. The XRD patterns revealed that nano ZnO:CNT powders with a wurtzite structure were grown with (1 0 0), (0 0 2), and (1 0 1) dominant peaks. The size of the ZnO was about 210 nm, as confirmed by SEM images. The sensitivity of the nano ZnO:CNT-based sensors was measured for 5 ppm of H2S gas at room temperature by comparing the resistance in air with that in target gases.

The performance of electric boiler using thick-film heater has been investigated experimentally. Electric boilers are using thick film heater is composed of four to a water chamber. In this study, the water flow rate while changing then umber of heaters and heating performance was evaluated. One water chamber, the average heat release is approximately 6.63kW. And average heat release of four water chamber is about 29.08kW. The energy efficiency of the water chamber 4 was 95.4%. Finally, the average heat release and energy-efficiency of electric boiler is increased with increasing water chamber number.

As film products are more frequently used from producing traditional flexible packing products to high-tech electronic products, requested higher level of quality. Most film products are made in the shape of roll-type finished goods, so various quality problems are addressed related with their characteristics of shape. Thickness of film products is one of the most common and important quality problems. Particularly the Degree of thick smoothness is more important than other thickness issues, because it causes many secondary issues of thickness-related quality problems like wrinkles or faulty windings. Thick smoothness must be controlled in both horizontal and vertical direction. In this paper, HOQ (house of quality) was built to interpret VOC (voice of customers) to CTQs (critical to quality). To decide priorities of VOC and CTQs, both techniques are applied. One is AHP (analytic hierarchy process) with pairwise comparison. The other is an absolute weight calculation method with level-up rate. From the result of HOQ, it is certain that the thick smoothness is the most important CTQ in film manufacturing industry. Finally, this paper presents how to monitor and improve repetitive coincidence of microscopic deviation of thickness in some special vertical points.

The effects of a Ni coating on the sensing properties of nano ZnO:Ni based gas sensors were studied for CH4 and CH3CH2CH3 gases. Nano ZnO sensing materials were prepared by the hydrothermal reaction method. The Ni coatings on the nano ZnO surface were deposited by the hydrolysis of zinc chloride with NH4OH. The weight % of Ni coating on the ZnO surface ranged from 0 to 10 %. The nano ZnO:Ni gas sensors were fabricated by a screen printing method on alumina substrates. The structural and morphological properties of the nano ZnO : Ni sensing materials were investigated by XRD, EDS, and SEM. The XRD patterns showed that nano ZnO : Ni powders with a wurtzite structure were grown with (1 0 0), (0 0 2), and (1 0 1) dominant peaks. The particle size of nano ZnO powders was about 250 nm. The sensitivity of nano ZnO:Ni based sensors for 5 ppm CH4 gas and CH3CH2CH3 gas was measured at room temperature by comparing the resistance in air with that in target gases. The highest sensitivity of the ZnO:Ni sensor to CH4 gas and CH3CH2CH3 gas was observed at Ni 4 wt%. The response and recovery times of 4 wt% Ni coated ZnO:Ni gas sensors were 14 s and 15 s, respectively.

Thermoelectric-thick films were fabricated by using a screen printing process of n and p-type bismuth-telluride-based pastes. The screen-printed thick films have approximately 30 in thickness and show rough surfaces yielding an empty gap between an electrode and the thick film. The gap might result in an increase of an electrical resistivity of the fabricated thick-film-type thermoelectric module. In this study, we suggest a conductive metal coating onto the surfaces of the screen-printed paste in order to reduce the contact resistance in the module. As a result, the electrical resistivity of the thermoelectric module having a gold coating layer was significantly reduced up to 30% compared to that of a module without any metal coating. This result indicates that an introduction of conductive metal layers is effective to decrease the contact resistivity of a thick-film-typed thermoelectric module processed by screen printing.

Indium doped SnO2 thick films for gas sensors were fabricated by a screen printing method on alumina substrates. The effects of indium concentration on the structural and morphological properties of the SnO2 were investigated by X-ray diffraction and Scanning Electron Microscope. The structural properties of the SnO2:In by X-ray diffraction showed a (110) dominant SnO2 peak. The size of SnO2 particles ranged from 0.05 to 0.1 μm, and SnO2 particles were found to contain many pores, according to the SEM analysis. The thickness of the indium-doped SnO2 thick films for gas sensors was about 20 μm, as confirmed by cross sectional SEM image. Sensitivity of the SnO2:In gas sensor to 2000 ppm of CO2 gas and 50 ppm of H2S gas was investigated for various indium concentrations. The highest sensitivity to CO2 gas and H2S gas of the indium-doped SnO2 thick films was observed at the 8 wt% and 4 wt% indium concentration, respectively. The good sensing performances of indium-doped SnO2 gas sensors to CO2 gas were attributed to the increase of oxygen vacancies and surface area in the SnO2:In. The SnO2:In gas sensors showed good selectivity to CO2 gas.

The 21st Century Frontier Program, which is one of the R&D programs funded by Korean government, was launched in 1999 to elevate the status of Korean science and engineering capabilities to the advanced nation in the strategic fields. Currently, 23 different fields of science and engineering programs are carried out by researchers in institutes, universities and industries. Center for Advanced Materials Processing (CAMP) was formulated in 2001 to develop the advanced materials as well as to improve the parts manufacturing process. The main role of CAMP is proposing and forecasting the long term vision in Materials Processing Technology and also supporting the project teams for their best performance in R&D. The CAMP program consists of 5 research areas such as, Multi-layer Ceramic Electronic Parts, Powder Formed Precision Parts, 3 Dimensional Polymer Based Composites, Functional Metal Sheets, Parts Integration Technology. An introduction of R & D activities at CAMP, specially focusing on powder metallurgy, wil be presented.

Thermoelectric thick film was fabricated by screen printing process with using p-type Bi-Te-Sb powders. The powder was synthesized by melting, milling and sintering process and hydrogen reduced to enhance the thermoelectric property. The thick film of Bi-Te-Sb powder was fabricated by screen printing method and baked at the optimized conditions. The thermal conductivity, the electrical resistivity and Seeback coefficient of thick film were measured and the thermoelectric performance was analyzed in terms of film characteristics and its microstructure. Finally, the feasibility of thermoelectric thick film into micro cooling device on CPU chip was discussed in this study.

ZnS:Cu,Cl 형광체를 이용하여 ITO/glaas 기판위에 스크린인쇄법으로 적층형과 혼합형 구조로된 2종류의 교류전계 발광소자를 제작한 후 인가전압과 주파수에 따른 광학적, 전기적 특성을 조사, 비교하였다. 적층헝의 경우 발광휘도는 400Hz, 200V 구동전압에서 약 55 cd/m2를 나타내었다. 인가전압의 주파수를 400Hz에서 30Hz로 증가시킬 경우 휘도는 420 cd/m2로 크게 향상되었다. 혼합형의 경우 400Hz의 주파수에서 문턱전압은 45V이었고, 200V, 30KHz 주파수의 동작조건에서 최대휘도는 670 cd/m2 이었다. 휘도-전압 특성 측정결과 적층형구조 보다 혼합형 소자구조에서 발광강도가 약 1.5배 증가하였다. 주파수에 따른 주발광 파장의 변화는 양쪽시료 모두 유사하게 나타났다. 1KHz이하의 저주파에서는 652 nm의 청녹색 발광과장을 나타내었으며 5KHz이상에서는 452 nm과장의 청색발광을 나타내었다.

분산특성이 다른 두 종류의 Ag 분말과 점도가 다른 두 종류의 유리를 사용하여 Ag 후막 도체를 제조하고 이들이 후막의 미세구조에 어떠한 영향을 미치고 그 미세구조가 전기특성에 미치는 영향을 조사하였다. Ag 분말의 분산특성이 좋을수록 그리고 사용된 유리의 점도가 낮을수록 후막의 미세구조는 잘 발달된 치밀한 조직을 보였으며 면저항값도 감소하였다. 이는 Ag 분말의 분산특성이 좋을수록 용융 유리에 의한 Ag 입자들의 미세 재배치의 속도가 빨라지고, 또한 유리의 점도가 낮을수록 모든 미세구조 발전단계에서 그 속도가 증가하기 때문이며. 이러한 미세조직의 치밀화가 후막의 면저항값을 제어하기 때문이다. 소성시간이 증가하여도 더 이상 전기저항값의 저하가 없는 저항감소의 포화시간이 존재함을 확인하였으며, 이 포화시간 역시 후막의 미세구조에 크게 의존함을 알 수 있었다

HVPE(hydride vapor phase epitaxy)법으로 (111) MgAl2O4기판 위에 10~240μm두께의 GaN를 성장하고, GaN의 두께에 따 광학적 성질을 조사하였다. MgAl2O4기판 위에 성장된 GaN의 PL 특성은 결정성장온도에서 기판으로부터 Mg이 out-diffusion하여 auto-doping 됨으로써 불순물이 첨가된 GaN의 PL 특성을 나타내었다. 10K의 온도데서 측정된 PL 스펙트럼은 자유여기자와 속박여기자의 재결합천이에 의한 피크들과 불순물과 관련된 도너-억셉터 쌍 사이의 재결합 및 이의 포논 복제에 의한 발광으로 구성되었으며, 깊은 준위로부터의 발광은 나타나지 않았다. 중성 도너에 속박된 여기자 발광 에너지와 라만 E2모드 주파수는 GaN의 두께가 증가함에 따라 지수 함수적으로 감소하였으며, GaN 내의 잔류 응력에 대하여 라만 E2 모드 주파수는δΩ=3.93σ(cm-1/GPa)의 관계로 변화하였다.

TiO2가 5-50wt%첨가된 SnO2/TiO2 후막형 감습소자를 스크린 프린팅 법을 이용하여 제조 하였다. 소자의 표면결정구조를 XRD, SEM 그리고 FTIR로 조사하였으며, 전기적 특성에 의한 후막소자의 감습특성을 측정하였다. SnO2/TiO2 후막은 TiO2 결정상 보다 주로(SnO2)·6T 결정상으로 나타났으며, 1300˚C에서 소결된 후막소자의 평균입경은 2.0μm이었다. 또한 1300˚C에서 소결된 10wt% TiO2가 첨가된 SnO2/TiO2 후막소자는 상대습도 20-90%에서 높은 감습특성을 나타내었다.

RuO2와 glass의 비가 20/80과 12/88인 두종류의 후막저항계에 NTCR 특성을 나타내는 여러종류의 산화물을 첨가하였을때 저항체의 TCR과 전기비저항이 어떻게 변화하는가에 대한 실험을 실시하였다. 첨가된 TCR modifier들이 NTCR특성을 갖는다고해서 저항체의 TCR이 창상 감소되지는 않으며 또한 어떠한 modifier가 모든 저항계에 항상 일정 방향으로만 TCR을 변화시키지는 않았다. 그러나 이들 TCR modifier들을 적당량 첨가함으로써 후막저항체의 TCR과 저항값을 원하는 바대로 얻을 수 있다는 가능성을 확인하였다. 두 종류의 이상의 TCR modifier를 동시에 첨가하였을때에 첨가된 TCR modifier들 각각의 TCR변화가 합해져서 결과로 나타남으로써 이들 사용된 TCR modifier들 간에는 상호작용이 없음을 알 수 있었다. TCR modifier의 첨가량은 2~3%내로 억제하는 것이 바람직함을 알 수 있었다.