Materials Science: Composites vs Metals

10 Questions

What is a key advantage of using composite materials in industry applications?

Higher strength-to-weight ratio

What is a major difference between working with composite structures and metallic structures?

Mechanical, thermal, and electrical properties

What manufacturing process is typically used for composites?

Layup

What is a common method used for joining and assembling composite structures?

Bonding using adhesives

What type of testing is commonly used to evaluate composite structures for defects or damage?

Non-destructive testing (NDT)

What is the primary condition for electrolytic corrosion to occur?

Both presence of an electrolyte and contact between two different metals

What is the role of the anode in the corrosion process?

It gives up electrons during the corrosion process

What is uniform etching characterized by?

A generalized dulling of the metal surface

What is the primary cause of pitting corrosion?

Exposure to salt water

What can be a consequence of pitting corrosion?

Disastrous failures of metal components

Study Notes

Composites vs Metals Applications

Composites offer exceptional strength-to-weight ratios compared to metals, making them ideal for applications where weight reduction is critical.
Composites can be as strong as metals but significantly lighter, being preferred in aerospace, automotive, and marine industries.
Composites are inherently resistant to corrosion, unlike metals, which can corrode and degrade over time when exposed to moisture and chemicals.
Composites are well-suited for use in harsh environments, including marine, chemical processing, and infrastructure applications.

Design Flexibility and Fatigue Resistance

Composites can be molded into complex shapes and sizes, allowing for the creation of intricate and lightweight structures.
Composites exhibit superior fatigue resistance compared to metals, making them suitable for high-performance and durable structures in aerospace, sporting goods, and transportation industries.

Thermal and Electrical Insulation Properties

Composites offer excellent thermal and electrical insulation properties, making them suitable for applications requiring thermal stability, electrical insulation, and electromagnetic shielding.
Composites are commonly used in electronics, telecommunications, and energy industries.

Cost and Long-Term Benefits

While the initial cost of composites may be higher than metals, their long-term benefits, such as reduced maintenance, longer lifespan, and improved performance, often outweigh the upfront investment.
Advancements in composite manufacturing technologies have led to cost reductions and increased affordability.

Differences between Composites and Metallic Structures

Fabrication and Manufacturing

Composites and metals have different mechanical, thermal, and electrical properties, requiring specialized knowledge and techniques for handling, fabrication, and testing.
Composite materials may behave differently under loading conditions and may require unique design considerations.
The manufacturing processes for composites differ from those for metals, using techniques such as layup, filament winding, pultrusion, or resin infusion.

Joining and Assembling Composite Structures

Joining and assembling composite structures may require different methods than those used for metallic structures.
Composites are often bonded using adhesives or mechanical fasteners designed for composite materials.
Careful surface preparation and bonding techniques are essential to ensure structural integrity and performance.

Inspecting and Testing Composite Structures

Inspecting and testing composite structures require specific methods and tools tailored to the unique properties of composites.
Non-destructive testing (NDT) techniques such as ultrasonic testing, thermal imaging, and acoustic emission testing are commonly used to evaluate composite structures for defects, delaminations, or damage.