Properties and Types of Composite Materials
Composite Materials: Properties and Applications
1. Composition and Resistance
Key components: Glass, calcium, paste, alumina, silicon carbide, boron carbide.
These ceramics exhibit superior mechanical resistance compared to other ceramic materials. Their low thermal expansion coefficients provide excellent resistance to thermal shock and impact.
2. Early Compounds and Applications
Question: What were the first compounds? What were they used for?
Answer: The initial compounds were combined with fiberglass, polyester, and phenolic matrices. They found primary use in electrical installations and related applications.
3. Types of Composites
Question: What types of composites exist?
Answer:
- Dispersion-strengthened: Particles formed are truly stable (resistant to gravity and centrifugation).
4. Structural Composites and Sandwich Panels
Question: What are structural composites and sandwich panels? Briefly explain them.
Answer:
- Structural Composites: These are formed by combining multiple simple materials, such as other composites. Their properties are heavily dependent on design and geometry.
- Sandwich Panels: These consist of two outer plates separated by a harder material with a softer, specific geometry (like a honeycomb structure).
Polymer Characteristics and Recycling
1. Three Types of Polymers
Brief explanation:
- Thermoplastics: Characterized by long chains of carbon atoms, they behave like plastics when heated.
- Thermosets: Featuring crossed carbon chains, they are more resilient yet fragile and cannot be recycled.
- Elastomers: These polymers can deform under pressure and return to their initial state when the pressure decreases.
2. Polymer Definition and Origin
Question: What is a polymer, and how is it obtained?
Answer: Polymers are of organic origin, primarily composed of carbon and hydrogen. They form long chains with high molecular weight. They are created by joining hundreds of thousands of monomer molecules.
3. Plastic Recycling Process
- Primary Recycling: The material is processed from the initial production, having never been recycled before.
- Secondary Recycling: Products are processed for reuse.
- Tertiary Recycling: Materials are broken down into their basic chemical compounds.
Physical Characteristics of Iron
Key Properties:
- Ductility
- Strength
- Malleability
- Cold and hot plasticity
- Elasticity
- Extensibility
- Magnetism