Ananya Parida 120CR0649 Scientific Technical writting (1) (1).pptx

A ceramic composite is a material that integrates ceramics with additional reinforcing constituents in the form of fibers, whiskers, particles, or nanotubes to enhance its mechanical, thermal, and electrical properties.

1. TOPIC OF PRESENTATION : CERAMIC COMPOSITES BY: ANANYA PARIDA ROLL NO-120CR0649 B.TECH , CERAMIC ENGG. NIT ROURKELA DEPARTMENT OF CERAMIC ENGINEERING NIT ROURKELA SEMINAR & TECHNICAL WRITING (SPRING 2023-24)

2. Composites: A material system composed of two or more physically distinct phases whose combination produces aggregate properties that are different from its constituent’s properties . Objective : advanced material stronger, lighter. 2 Classification: Why composites? Composites: Definition, Classification

3. Ceramic materials are very hard and brittle. (How is a ceramic known? -- one or more metals combined with a nonmetal such as oxygen, carbon, or nitrogen). They have strong covalent and ionic bonds and very few slip systems available compared to metals. Characteristically, ceramics have low failure strains and low toughness or fracture energies. In ceramics, a lack of uniformity in properties is observed. Ceramics have low thermal and mechanical shock resistance, and have low tensile strength. The Problem and approaches to improve Major disadvantage  extreme brittleness. Even the minutest of surface flaws (scratches or nicks) or internal flaws (inclusions, pores, or microcracks) can have disastrous results. One important approach to toughen ceramics involves fiber reinforcement of brittle ceramics. Ceramic Matrix Composites Ceramic Matrix Composites Ceramic Matrix Composites Ceramic Matrix Composites

4. TYPES OF CMC

5. 5 CERAMIC MATRIX COMPOSITES FABRICATION PROCESS

6. Illustrates the individual mechanical response of a monolithic ceramic compared with a high strength fiber reinforced composite with a lower strength matrix. The fiber/matrix interface plays a significant role in determining the fracture behavior and mechanical properties of ceramic matrix composites. The critical driving force in the development of fiber reinforced ceramic composites: graceful failure and damage tolerance. In contrast to brittle ceramics, ceramic composites can survive local damage and inelastic deformation without catastrophic failure . In simpler terms, they have greater strain capability than monolithic ceramics. Why reinforcement in Ceramic matrix CMC damage-tolerant behavior

7. Typically, the strain-to-fracture value of a ceramic matrix is very low. In MMCs and in thermoplastic PMCs, the matrix failure strain ( ε m ) is considerably greater than that of fibers . An important feature of CMCs is matrix microcracking , no match with MMCs or PMCs. The relative elastic modulus values of fiber , E f and matrix, E m are very important in CMCs. The ratio E f / E m determines the extent of matrix microcracking . Reality with Ceramic Matrix Strain-to-fracture for most of Metals: ε m > 10% Polymers fail between 3 and 5%. Typically, fibers such as boron, carbon, and silicon carbide show failure strain values of ~1–2%. Compare this with the failure strains of less than 0.05% for most ceramic matrix materials. Conclusion: Thus, in both MMCs and PMCs fiber failure strain controls the composite failure strain. A comparison: Toughening in CMCs

8. Toughness improvement Two key issues in fiber reinforced ceramic composites: -- how to deflect matrix cracks around the fiber and how to control the sliding resistance of the fiber in the matrix. Historically, the direct introduction of a ceramic fiber into a ceramic matrix has commonly produced a brittle composite, because there is a strong chemical bond between the fiber and the matrix. With a strong chemical bond, matrix cracks penetrate directly into the fiber with no crack deflection. The roles and requirements for fiber interfaces and coatings The primary role of the fiber interface coating in CMCs is to provide a mechanism for crack deflection through debonding and frictional sliding. A successful fiber coating will stop or deflect microcracks at the fiber matrix interface. Without debonding, the matrix cracks will cut through the ceramic fibers, rather than deflecting around the high-strength reinforcements. As further stress is applied and microcracks begin combining and opening, the weakly bound fibers bridge the cracks and slide in the matrix, dissipating strain energy. Without controlled sliding of the fiber in the matrix, strain energy will not be dissipated and high stresses will form as the crack advances, leading to fiber fracture.