MEE4019 Lecture 3: Matrix in Composite Materials

Matrix in Composite Materials

• Composites consist of reinforcing fibers and matrix materials.
• Matrix surrounds the fibers, protecting them from chemical and environmental attacks.
• Matrix must have a lower modulus and greater elongation than the reinforcement for fibers to carry maximum load.

Importance of Matrix in Composite Materials

• Holds the reinforcement material in place
• Transfers loads between the reinforcement
• Protects the reinforcement material from environmental factors
• Provides some mechanical properties

Types of Matrix Materials

• Metals
• Polymers (Thermosets and Thermoplastics)
• Ceramics

Matrix Materials: Polymers

• Thermoset Resins: Epoxy, Polyester, Vinylester, Phenolics, Cyanate esters, Bismaleimides, Polyimides
• Thermoplastic Resins: various types

Matrix Materials: Thermoset vs Thermoplastic

• Recycling: Thermoplastics can be recycled, Thermosets cannot
• Mechanical strength: Thermosets have higher mechanical strength
• The use of fillers and reinforcements: Thermoplastics can be used with fillers and reinforcements
• Creep Resistance: Thermoplastics have higher creep resistance
• Susceptible to solvent: Thermoplastics are susceptible to solvents
• Repair: Thermoplastics can be repaired
• Manufacturing: Thermoplastics can be molded

Matrix Materials: Metals

• Examples: Aluminium, Magnesium, Titanium, Copper, Nickel
• Advantages: High strength and stiffness, better thermal stability than polymers, higher transverse stiffness and strength, no moisture absorption
• Disadvantages: Lower ductility and toughness, expensive, heavier than polymers

Matrix Materials: Ceramics

• Examples: Silicon carbide (SiC), Alumina (Al2O3), Zirconia (ZrO2), Mullite (3Al₂O₃2SiO₂ or 2Al₂O₃ SiO₂)
• Advantages: High strength and stiffness, excellent thermal stability, good chemical stability, low thermal expansion
• Disadvantages: Brittle, difficult to process, limited ductility

Selection of Matrix Materials

• Chemical Compatibility
• Thermal Stability
• Electrical Properties
• Flammability
• Environmental Resistance
• Cost
• Performance
• Manufacturing

Current Challenges and Future Directions

• Current challenges: toughness, high-temperature stability, chemical resistance, cost-effectiveness, environmental impact, compatibility with reinforcement materials, manufacturing and processing
• Future directions: development of smart matrix materials, advancements in nanomaterials, sustainable matrix materials, integration of digital technologies, advancements in processing techniques, biocompatible matrix materials