Non-metallic and structural materials Flashcards
What are the 3 motivations to choosing materials?
– Introduction of a new product
– Need to improve a current product (Product Development)
– A problem situation
What are 4 criteria for choosing materials?
– Function
– Manufacture/Production
– Appearance
– Cost
What are 3 factors of costs?
– Materials Processing Costs
– Manufacturing Costs
– Maintenance Costs
What are 3 economic considerations?
• A product must make economic sense
• To minimize product cost materials engineers
must consider three factors
• Other significant factors include labor & fringe benefits, insurance, and profit
What are 2 things that make a product make economic sense?
- the price must be attractive to customers
- - it must return a sustainable profit to the company
What are 3 factors to consider to minimise product cost materials?
- component design
- material selection
- manufacturing techniques
What are 3 components of green design?
Reduce, reuse, recycle
What does reduce mean? example.
design the product to use less material, less energy
example: PET bottles with thinner walls
What does reuse mean? example.
fabricate the product of a material that can
be reused
example: refillable bottles and shipping containers
What does recycle mean? example.
reprocess the material into a new product example: convert PET bottles to carpet fibers
What are 2 advantages to recycling?
- reduced pollution emissions
- reduced landfill deposits
What are two issues with recycling?
- Product must be disassembled or
shredded to recover materials - Collection and transportation costs are significant factors in recycling economics
Why is better to reprocess metals that refining raw ore? (2)
– is more energy efficient
– produces less waste (pollution)
What is one difficulty to reprocess metals?
• Difficult to recycle metals that are susceptible to Corrosion
How can toxic metals be handled? (3)
• Toxic metals (e.g., Cd and Hg):
– must be handled as hazardous waste
– are difficult to reprocess
– should not be added to landfills
What are 3 things to consider when it comes to recycling glass?
– raw materials inexpensive
– relatively dense - expensive to transport
– must be sorted by
• color – clear, amber, green, brown
• type – plate vs. container
• composition – soda-lime, leaded, borosilicate
How are thermoplastic polymers recycled? (3)
– grind into pellets, melt, and extrude or mold into
new product
– must be sorted by polymer type – polyethylene,
polystrene, PET, etc.
– properties degrade in each reuse
How are thermosetting polymers recycled though they are difficult?
– can be ground up and use as filler
– depolymerize to make monomer
What are some biodegradable polymers?
Current generation based on biorenewable materials such as poly(lactic acid) (PLA)
Why are biodegradable polymers hard to recycle? (3)
- Difficult to recycle because they contain an intimate mixture of materials – difficult to separate
- Some composites are recyclable
- Components must separated by shredding or dissolution
What are composite materials?
Composite Materials effectively form the fourth classification of materials, and are essentially born of the first three classifications, namely metals and alloys, polymers and ceramics and glasses.
What are 3 guidelines for composite materials?
● A composite material is a mixture of two or more distinct constituents or phases, whereby:
- Both constituents are present in reasonable proportions eg >5%.
- Constituent phases must have noticeably different properties.
● In man-made composites, the composite material is produced by intimate mixing and consolidation of the constituents (not by the development of one constituent from another within the process eg phase nucleation in metals and alloys).
● A viable composite material will have properties superior to those of the individual constituents (properties described by the law of mixtures).
What are basic properties of composites? (2)
● Increase stiffness of low modulus material
● Increase toughness of brittle material
What is the law of mixtures?
To describe and develop the properties of composite materials the law of mixtures is used.
In terms of modulus, when two linear elastic solids of a different moduli are combined, composite moduli (in longitudinal direction)
