Lesson 3 - Classification and Properties SAQ
This lesson allows you to test yourself on the material covered in the lesson on Classification and Properties and determine the level to which you have met the learning outcomes.
Self-Assessment Questions
1. *Why is it important to understand what materials of construction are used for the manufacture of beer brewing equipment?
2. *Indicate whether the following statements are true or false. Provide a reason if they are false.
a) Metals are characterised by a crystal lattice structure of negative metallic ions.
b) Iron is an alloy.
c) Aluminium is a ferrous metal.
d) Steel is a noble metal.
e) Tension refers to material under a pulling force.
f) Glass is a crystalline ceramic.
g) Stick welding is suitable for fixing a leak on your beer mains.
h) Copper is widely used as the metal of choice for modern brewing.
i) Thermosets make excellent gaskets.
3. *Match the terms in column 1 to the descriptions in column 2.
|
Column 1: Term |
Column 2: Meaning |
|
Stiffness |
The amount of plastic deformation a material can withstand before breaking. |
|
Young’s Modulus |
Breaking, without first developing cracks or deformation in response to stress. |
|
Elasticity |
The ability to withstand a force without deforming. So, if a material is very stiff there will be a very small change in its length for a comparatively large stress placed on it. |
|
Yield / proof strength |
The maximum stress a material can withstand before it fractures. |
|
Ultimate tensile strength (UTS) |
The slow deformation of a material under low stress. This can happen with metals at higher temperatures and polymers at lower temperatures. |
|
Ductility |
How well a material under stress returns to its original form after the stress is removed; when the stress exceeds the elastic limit the material is permanently deformed. |
|
Brittleness |
Resistance to impact. |
|
Hardness |
The amount of stress needed to produce a permanent deformation. Beyond this point the material cannot return to its original. |
|
Toughness |
The ability to not be damaged by scratching, abrasion, indentation or abrasion its wear and tear resistance. |
|
Creep |
The ratio of stress to strain in the elastic region which is shown by the gradient of the line. If the gradient is steep the material is very stiff and if it is flat then the material is very elastic. |
4. *Differentiate between the following:
a) Thermoplastics, thermosets and elastomers
b) Degradation and corrosion
c) General and localised corrosion
d) Fusion zone and heat affected zone in welding
e) Pitting and crevice corrosion
f) Arc welding and TIG welding
5. **What steps do you need to take to prevent corrosion throughout the brewery?
6. **What are the characteristics of the three main zones in a weld? What impact does this have on the potential for corrosion to occur in the area of the weld?