In this study, we performed thermal safety design of the electric module of a heat-loaded equipment with consideration of its heat dissipation performance. Initially, we calculated the heat dissipation of natural convection to choose a cooling method. Based on this, we found that some modules required forced convection and selected an air-cooling method with an outdoor temperature of 43 degrees Celsius, which is the maximum temperature in Korea. Prior to module production, we performed thermal analysis of each module and proceeded with a design to increase the thermal conductivity of the module as a primary step, and subsequently proceeded with Heat Sink design to maximize the heat dissipation performance. After considering various constraints according to the system requirements and designing the cooling path, we experimentally and analytically secured thermal safety at the operating temperature of the equipment.

Ti0.5Al0.5N/CrN nano-multilayers, which are known to exhibit excellent wear resistances, were prepared using the unbalanced magnetron sputter for various periods of 2–7 nm. Ti0.5Al0.5N and CrN comprised a cubic structure in a single layer with different lattice parameters; however, Ti0.5Al0.5N/CrN exhibited a cubic structure with the same lattice parameters that formed the superlattice in the nano-multilayers. The Ti0.5Al0.5/CrN multilayer with a period of 5.0 nm exceeded the hardness of the Ti0.5Al0.5N/CrN single layer, attaining a value of 36 GPa. According to the low-angle X-ray diffraction, the Ti0.5Al0.5N/CrN multilayer maintained its as-coated structure up to 700oC and exhibited a hardness of 32 GPa. The thickness of the oxidation layer of the Ti0.5Al0.5N/CrN multilayered coating was less than 25% of that of the single layers. Thus, the Ti0.5Al0.5N/CrN multilayered coating was superior in terms of hardness and oxidation resistance as compared to its constituent single layers.

As automation systems become more common, there is growing interest in functional labeling systems using organic and inorganic hybrid materials. Especially, the demand for thermally and chemically stable labeling paper that can be used in a high temperature environment above 300 oC and a strong acid and base atmosphere is increasing. In this study, a composite coating solution for the development of labeling paper with excellent thermal and chemical stability is prepared by mixing a silica inorganic binder and titanium dioxide. The silica inorganic binder is synthesized using a sol-gel process and mixed with titanium dioxide to improve whiteness at high-temperature. Adhesion between the polyimide substrate and the coating layer is secured and the surface properties of the coating layer, including the thermal and chemical stability, are investigated in detail. The effects of the coating solution dispersion on the surface properties of the coating layer are also analyzed. Finally, it is confirmed that the developed functional labeling paper showed excellent printability.

Mechanical alloying using high-energy ball mill and subsequent spark plasma sintering (SPS) process was applied to understand mechanical alloying processing of Al-Fe alloy system. The thermal stability of mechanically alloyed Al-Fe alloy was intended to be enhanced by SPS process. Various analytical techniques including particle size analysis, density measurement, micro-Vickers hardness test, SEM, TEM, and X-ray diffractometry were adopted to find optimum processing conditions for mechanical alloying and subsequent SPS and to estimate thermal stability of the prepared alloy. It was found from the treatment of mechanically alloyed Al-8wt.%Fe powder mixture that needle-shaped precipitates was formed in the Al-Fe matrix, and the alloy compact showed enhanced densification and reached its full density with little loss of its fine microstructure. After heat treatment at , it was also shown that the thermal stability of Al-8wt.%Fe alloy fabricated in the present study was enhanced, which was due to its fine microstructure developed by fast densification of SPS.

Mechanical alloying using high-energy ball mill and subsequent spark plasma sintering (SPS) process was applied to Al-Fe-Cr and Al-Fe-Mo powder mixture to investigate effects of Cr and Mo addition on thermal stability of Al-Fe, and thereby to enhance its thermal stability up to . Various analytical techniques including micro-Vickers hardness test, SEM, TEM, X-ray diffractometry and corrosion test were carried out. It was found that addition of Cr and Mo to Al-Fe system played a role of grain growth inhibitor of matrix Al and some precipitates such as during SPS and subsequent heat treatment. The inhibition of grain growth resulted in increased Vickers hardness and thermal stability up to comparing to those of Al-Fe alloy system.

고온구조용 재료로의 사용이 기대되는 Al3Ti금속간 화합물의 연성 향상을 위한 목적으로 기계적 합금화를 통한 cubic Ll2구조의 생성거동과 Mn의 첨가 영향을 조사하였다. Al-8Mn-25Ti조성에서 20시간의 기계적 합금화를 통해 약 1.0nm 사이즈의 grain을 갖는 nanocrystalline cubic Ll2Al3Ti 금속간 화합물이 제조되었다. Mn이 첨가된 3원계 cubic Ll2Al3Ti 금속간 화합물은 2원계 cubic Ll2Al3Ti 금속간 화합물에서 보이는 Ll2구조에서 D023구조나 D022구조로의 상변태가 발생하지 않았으며 Mn의 첨가로 인해 Ll2구조는 1200˚C가지 안정함을 보였다.

본 연구에서는 고온용 고강도 Al 합금을 제조하기 위해 Al-Cr-Zr 복합금속분말을 attritor에서 300rpm의 회전속도로 20시간 동안 기계적 합금화방법으로 제조한 후 진공 고온 압축성형하였다. Al-Cr-Zr 합금의 미세구조 및 조직관찰은 XRD, TEM 등을 사용하여 분석하였고, 열적 안정성은 열적 노출시간에 따른 미소경도측정을 통하여 조사하였다. 진공 열간 압축성형 되었을 때 MA Al-Cr-Zr 합금의 이론 밀도의 97%에 이르는 조밀화르 f보였으며, 300˚C에서 100시간 열처리 한 경우에는 경도변화가 거의 없었고, 500˚C에서 100시간 열처리한 경우에도 감소가 6% 이내로 우수한 열적 안정성을 나타내었다. 이와 같은 MA Al-Cr-Zr 합금의 우수한 열적 안정성은 기계적 합금화에 의해 Al 기지 내에 미세하고 균일하게 분산된 Cr과 Zr이 고온 성형과 열처리 과정에 의해 Al3Zr, Al13Cr2의 금속간 화합물들의 형성되었으며, 열처리 후의 이 합금의 최종 결정립 크기는 150mm 크기 이하이었다.

가용성 폴리이마드 주쇄에 Disperse-Red 1 크로모포를 공유결합 시킨 옆사술계 비선형 전기광학 고분자를 합성하였다. 합성된 고분자의 유리전이온도 빛 열분해온도 는 각각 225˚C, 310˚C이었으며 광통신 파장에서 광학적으로 투명하였다. 100 V/μm의 전기장으로 폴링했을 때, 유전상수는 10 kHz에서 3.37이며, 파장 1300 nm에서, 굴절률은 nTE 및 nTM 모두 1.631로같았으며, 전기광학계수는 4.6 ~ 9.2 pm/V이였다. 폴링한 후 180˚C에서 1시간 동안 유지시킨 시편의 전기광학계수의 값은 감소되지 않 았으며, 장기적인 관점에서 90˚C에서 500 시간 동안 유지시킨 시편의 전기광학계수도 변함이 없었다.

Rf 마그네트론 반응성 스퍼터링법으로 RuO2박막을 Si 및 Ru/Si 기판 위에 증착한 뒤 산소 분위기 (1atm)에서 열처리를 하여 RuO2박막의 열적 안정성 및 확산방지 특성을 연구하였다. RuO2박막은 산소 분위기 700˚C에서 10분까지 안정하여, 산소와 실리콘에 대한 우수한 확산방지 특성을 나타내었다 750˚C 열처리시, 우선 성장 방위에 관계없이 RuO2박막 표면 및 내부에서 휘발 반응이 일어남과 동시에 확산방지 특성은 저하되었다. 그러나 800˚C 열처리 시에는 750˚C 열처리와는 다른 미세구조를 나타내었다. 이러한 열처리 온도에 따른 휘발반응에는 RuO2의 표면 결함구조인 RuO3와 증착시 박막내 함유된 과잉산소에 의한 결함 구조가 영향을 주는 것으로 판단된다.