급속소결에 의한 나노구조 Fe-Cr-Al-X 합금의 제조 및 기계적 성질

다국어 초록 (Multilingual Abstract)

Many industrial applications, such as heating elements, high-tensile components in heat exchangers, substrates for catalysts applied in catalytic converters and filter systems in automobiles require long-term resistance to oxidation. Iron-aluminium-chromium alloys are applicable as structural materials and coatings for high-temperature applications. However, the alloy exhibits a low frictional resistance due to its low hardness. One of ways to improve the hardness of the metal by the addition of Al2O3 and Si3N4 is to create composite materials and this structure of the composite material should be made as nanostructure.
Nanostructured materials have been widely investigated, because they have wide functional diversities and enhanced or different properties compared with their bulk counterparts. Particularly, in the case of nanostructured materials, the presence of a large fraction of grain boundaries can lead to better mechanical, electrical, optical, sensing, magnetic, and biomedical properties. Recently, nanocrystalline powders have been developed by co-precipitation method, spray conversion process (SCP), and high energy mechanical milling (HEMM). In the conventional sintering process, the grain size of the sintered materials becomes larger than the powders due to the fast grain growth. Even though the initial particle size is less than 100nm, the grain size increase rapidly to 500nm during the conventional sintering process.
Therefore, controlling grain growth during sintering is the key to the commercial success of nanostructured material. In this regard, the pulsed current activated sintering method (PCAS) and high frequency induction heated sintering (HFIHS) have been adopted, which can make dense materials within 2 minutes. They have been shown to be effective in achieving not only rapid densification to near theoretical density but also the prohibition of grain growth in nanostructured materials.
In this study, we investigated the sintering processes of FeCrAlSi-Al2O3 and FeCrAl-Si3N4 composite from mechanically activated powder by the PCAS and HFIHS method and investigated the structure and mechanical propteries of FeCrAlSi-Al2O3 and FeCrAl-Si3N4 composite

목차 (Table of Contents)

• Abstract i
• 1. 서 론 1
• 2. 이론적 배경 3
• 2.1 나노재료의 구조 3
• 2.2 나노결정립 재료의 물성 4
• 2.3 나노구조 재료의 제조방법 6
• 2.4 나노구조 재료의 응용분야 6
• 2.5 나노구조 재료의 개발현황 7
• 2.6 나노구조 재료 개발에서의 문제점 8
• 2.7 연소합성 9
• 3. 실험방법 15
• 3.1 나노분말의 제조 15
• 3.1.1 FeCrAlSi-Al2O3 나노 혼합분말의 제조 15
• 3.1.2 FeCAl-Si3N4 나노 혼합분말의 제조 17
• 3.2 시편의 제조 17
• 3.3 물리 및 기계적 특성 평가 19
• 4. 결과 및 고찰 24
• 4.1 급속소결에 의한 나노구조 FeCrAlSi-Al2O3 복합재료 합성과 소결 및 기계적 성질 24
• 4.1.1. 고주파유도 가열에 의한 나노구조 FeCrAlSi-Al2O3 복합재료의 합성 및 급속소결 24
• 4.1.2. 펄스전류활성 소결에 의한 나노구조 FeCrAlSi-Al2O3 복합재료의 합성 및 급속소결 36
• 4.2 급속소결에 의한 나노구조 FeCrAl-Si3N4복합재료 합성 과 소결 및 기계적 성질 45
• 4.2.1. 고주파유도 가열에 의한 나노구조 Fe-Si3N4 복합 재료의 합성 및 급속소결 45
• 4.2.2. 고주파 유도가열과 펄스전류활성 소결에 의한 나노결정 17.14Fe0.7Cr0.2Al0.1-Si3N4 복합재료의 합성 및 급속 소결 52
• 4.2.3. 고주파 유도가열과 펄스전류활성 소결에 의한 나노결정 20Fe0.6Cr0.2Al0.2-Si3N4 복합재료의 합성 및 급속 소결 61
• 5. 결 론 71
• 참고문헌 73