Hf계 프리세라믹 합성과 열처리 환경이 HfC세라믹 전환에 미치는 영향 = The Synthesis of Hf-Based Preceramics and the Effect of Heat treatment Conditions on the Conversion Characteristics of HfC

다국어 초록 (Multilingual Abstract)

Ultra-high temperature ceramics (UHTCs) are materials with excellent mechanical
properties and chemical stability, capable of withstanding melting points above 3000°C, longterm use at 1600°C, and temperatures exceeding 2000°C. Among these, hafnium carbide (HfC),
which has the highest melting point, is difficult to densify and process using conventional
powder sintering methods. Therefore, the polymer-derived ceramic (PDC) process, which
utilizes polymers that are easier to mold than powders, has been adopted. In this study, a
preceramic polymer (PCP) was first synthesized. To evaluate its ceramic conversion behavior,
the PCP was subsequently heat-treated to confirm its transformation into HfC. In addition,
considering the high oxidation sensitivity of PCP, oxidized PCP was deliberately subjected to
heat treatment to investigate the possibility of HfC formation under such conditions.
Furthermore, to assess the effect of a high-pressure, closed environment on the formation of
HfC, heat treatment was carried out using the spark plasma sintering (SPS) process. The
synthesis of PCP was confirmed by proton nuclear magnetic resonance (1H-NMR). The heattreated samples were analyzed by X-ray diffractometer (XRD) to confirm their conversion to
HfC. To further verify that oxidized samples were also converted to HfC through the
carbothermal reduction reaction, both XRD and Raman spectroscopy analyses were performed.
The samples subjected to SPS were also analyzed by XRD and Raman spectroscopy,
confirming that conversion to HfC is possible even under high-pressure conditions, although
such conditions are not optimal for the carbothermal reduction reaction.

목차 (Table of Contents)

• 제 1 장 서론 1
• 제 2 장 문헌 조사 5
• 2.1 UHTC와 PDC의 정의 및 특성 5
• 2.1.1 UHTC의 정의 및 특성 5
• 2.1.2 PDC의 정의 및 특성 8
• 2.2 PDC의 반응 메커니즘 10
• 제 3 장 실험 방법 13
• 3.1 Hf-N 고분자 제조 13
• 3.1.1 원료 물질 13
• 3.1.2 원료 합성 15
• 3.2 HfC 세라믹 전환 실험 17
• 3.3 합성물과 성형물 분석 19
• 제 4 장 결과 및 고찰 20
• 4.1 Hf-N 고분자 합성 조건확보 및 제어 20
• 4.2 Hf-N 고분자의 열처리 후 HfC 전환 23
• 4.3 고압환경의 Hf-N 고분자 열처리 27
• 4.4 산화된 Hf-N 고분자의 HfC 전환 32
• 제 5 장 결론 36
• 참고 문헌 38