1. "Bridging the Gap"
Materials

2. Materials

3. Spot the difference

4. 1. The Manner in which atoms are chemically bound changes its properties

5. A) Ionic vs. Covalent

6. B) Chiral Molecules (Mirror Molecules)
E.g Limonene
Carvone (Dill, Spearmint)

7. Ibuprofen + vs. ibuprofen -

8. 2. The way that the atoms are chemically bound together dictates the properties of a material

9. Properties
Characteristics that will help determine how a given material will react to a constraint.

10. Properties
The reaction of a material to constraints depends on its mechanical properties.
Types of Mechanical Properties:
Hardness
Elasticity
Resilience
Ductility
Malleability
Stiffness
Which properties do you believe were considered in the selection of the building material for the Victoria Bridge?

11. Definition of mechanical properties
Hardness
Ability to resist indentation
Elasticity:
Ability to return to their original shape
Resilience:
Ability to resist shocks

12. Definition of mechanical properties
Ductility:
Ability to be stretched without breaking
Malleability:
Ability to be flattened or bent without breaking
Stiffness:
Ability to retain their shape when subjected to many constraints

13. A material can also undergo chemical changes, such as rusting and corrosion.

14. Other properties Resistance to corrosion: Electrical conductivity:
Ability to resist the effects of corrosive substances which cause the formation of rust, for example.
Electrical conductivity:
Ability to carry an electric current
Thermal conductivity:
Ability to transmit heat

15. 3. Material properties dictate how a material will react under specific constraints

16. What external forces are at play?
Constraints
What external forces are at play?

17. Constraints
A constraint is the effect external forces have on a material/object/system.
Examples of constraints:
Pulling an elastic band
Squishing a sponge

18. Types of Constraints There are 5 main types of constraints Compression
Tension
Torsion
Deflection
Shearing
Using the definitions soon to be provided, can you give a common everyday example for each of these constraints?

19. Types of constraints Compression: Tension
When a material is subjected to forces that tend to crush it
Tension
When a material is subjected to forces that tend to stretch it

20. Types of Constraints Torsion Shearing Deflection
When a material is subjected to forces that tend to twist it
Shearing
When a material is subjected to forces that tend to cut it
Deflection
When a material is subject to forces that tend to bend it

21. Types of Constraints
Which constraints would a bridge most likely be subjected? Explain your reasoning.
5 Constraint reminder:
Compression
Tension
Torsion
Shearing
Deflection

22. 4. A material’s properties will also determine how the material will deform (react under specific constraints) and degrade.

23. Ways that materials react to the constraint
Deformation
Ways that materials react to the constraint

24. Deformations
A material deformation is the change in shape of a material based on the constraints that are applied.
There are three main types of deformations
Elastic
Plastic
Fracture
Using the definition soon to be provided, can you give a common everyday example for each of these deformations?

25. Types of material deformation
Elastic:
When the constraint leads to a temporary change in the shape or dimensions of the material.
When the constraint is removed, the material returns to its original form.

26. Types of material deformation
Plastic:
The constraint leads to a permanent change in the shape or dimensions of the material.
Even when the constraint is removed, the material remains deformed

27. Types of Material Deformation
Fracture:
The constraint is so intense that it breaks the material

28. What to consider?
What are the stresses/external forces the material will undergo? (Constraints)
How do we want the material to react to such stresses? (Deformation)
How will the material react? (Material properties)
Will the material last a long time? (Degradation)

29. Degradation
How will a material age?

30. Degradation
The degradation of a material is the decline in some of its properties due to its environment or time

31. Types of Materials

32. 1. Wood
Wood is a ligneous (fibrous) material whose bark has been removed.
The mechanical properties differ depending on the type of wood
Types of wood
Hardwood (deciduous trees)
More resistant to wear and harder than softwood
Softwood (coniferous trees)
Modified Wood (properties usually more constant)

33. Properties: Hardness, elasticity, resilience
Low thermal and electric conductivity
Easily shaped and assembled
Light weight

34. Issues: Protection: It can rot, be subject to disease
Properties depend on water content and conditions of growth
Due to its organic nature, fungus, insects and micro-organisms can infest the wood.
Protection:
By varnishing, heating, painting or treating the wood, we can extend its lifetime.

35. 2. Ceramics
Ceramic is a solid non-metallic material obtained by heating inorganic matter containing various compounds
Types of ceramic
Crystalline
Non-crystalline (glass)

36. Properties Issues Low thermal and electrical conductivity Hardness
Resist corrosion
Durable
Issues
Fragile to shocks and thermal shocks
Wears easily in presence of acids and bases

37. 3. Metals
Metals:
A material extracted from a mineral ore
Metals are not usually used in their pure form, but are combined with other substances to improve their properties.
This mixture is called an alloy (homogeneous mixture of two or more metals)

38. Properties (vary on the metal used)
Usually shiny
Good conductors (heat and electricity)
Ductility and Malleability depend on the materials

39. Degradation Corrosion and Oxidation Protection:
Coat the metal with a less corrosive metal (Zn, Au, Ag, Ni)
Coat the metal with paint, enamel, grease, resin