Ceramic materials possess outstanding physical and engineering properties, such as high melting point, hardness, strength, and good chemical inertness. However, monolithic ceramics tend to be brittle, which limits their use. Many researchers have studied methods for improving the mechanical properties of ceramics, and using added reinforcements to form a more durable composite is one of mostly studied approaches.
As a reinforcement for ceramic matrix composites, graphenes have been investigated due to their outstanding aspect ratio, Young’s modulus, and strength. While several studies have investigated graphene reinforced ceramic matrix composites, the issues of inhomogeneous dispersion of graphene and weak interfacial bonding between graphene and the ceramic matrix remain as unsolved problems.
There have been several studies reported on graphene/ceramic nanocomposites focusing on the mechanical properties. Graphene shows that 2-D nanomaterials can be an appropriate reinforcement for ceramic nanocomposites. Boron nitride nanoplatelet (BNNP) also have unique mechanical properties approaching that of graphene. BNNP is more stable at high temperature and has a white color, which makes it attractive to use in different areas than graphene reinforced nanocomposites, such as high-temperature applications and biomedical areas. However, there has been no research on BNNP reinforced ceramic nanocomposites.
In this research, graphene and BNNP reinforced ceramic nanocomposites were fabricated for various applications. A “Molecular level mixing” process for ceramic matrix composites has been developed, which is a novel fabrication process for 2-D nanomaterials. It solves the issues of inhomogeneous dispersion of 2-D nanomaterial and weak interfacial bonding between the reinforcement and matrix. Furthermore, we firstly produced BNNP reinforced ceramic nanocomposites with enhanced mechanical properties.
Toughening and lubricating mechanisms of 2-D nanomaterial in ceramic matrices were developed. Fiber-reinforcing mechanisms, such as grain refinement, pull out, and crack bridging were then investigated in the 2-D nanomaterial/ceramic matrix composites from the microstructural and formula type analysis.
세라믹 재료는 높은 융점, 경도, 강도 등 높은 기계적 물성을 바탕으로 넓은 분야에 응용되고 있으나, 파괴인성이 낮은 단점으로 강화재 첨가를 통한 복합소재 개발 관련 연구가 진행되고 있다. 강화재로는 우수한 물성을 가지고 있는 그래핀이 최근 주목받고 있다. 그래핀/세라믹 나노복합재료 관련 연구가 2010년 이후 활발히 진행되고 있으나, 그래핀의 기지내 응집 문제와 그래핀-기지 간의 계면 결합이 기계적 물성 향상을 위해 해결해야 할 숙제이다.
본 연구에서는 세라믹 재료의 취성을 보완하기 위해 높은 기계적 물성을 갖는 그래핀 및 육방정 질화붕소 나노플레이트렛으로 강화된 세라믹 나노복합재료를 제조하였다. 그래핀/세라믹 나노복합재료에 ‘분자수준혼합공정’을 개발하여 기존 연구에서 해결하지 못했던 그래핀의 응집과 계면 결합을 해결하고, 기계적 물성을 크게 향상시켰다. 또한, 그래핀의 뒤를 잇는 2차원 나노소재인 육방정 질화붕소 나노플레이트렛으로 강화된 세라믹 나노복합재료를 최초로 개발하였다. 육방정 질화붕소 나노플레이트렛은 그래핀보다 높은 고온안정성과 백색이라는 특징을 가지고 있어 고온소재 및 치과소재 등에 응용이 가능할 것으로 보인다. 마지막으로, 2차원 나노소재의 기계적 물성 향상 기구를 미세조직, 및 수식적 접근을 통해 분석하였다.
