Topic4

Topic 4.

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Topic Booklet to Download Material selection is directly related to product performance requirements, cost and user needs. The selection of manufacturing processes and materials are connected. Throughout this unit you will be investigating different materials, their origin/source, how they are produced, their properties, and finally their uses in everyday products.

The following resources are recommended:-
 * **Product Design: Resistant Materials Technology** by L. Cresswell, B. Lambert, A. Goodier. (Second Edition) published by Heinemann
 * **How Everyday Things Are Made** by The Product Realization Network, Stanford University
 * **Process, Material, and Measurements** by Daniel Cuffaro (2006) published by Rockport Publishers
 * **http://info.lu.farmingdale.edu/depts/met/met205/index.html> **

= 1. Classifying Materials = It is important that you have an understanding of the properties of materials and are able to use the correct terminology associated with those properties. It is not appropriate to use the term "hard" when you actually mean "tough". For example:- Glass is hard because it can resist abrasive wear such as scratching, but it is not tough. There are two principle categorize of material properties: In class your teacher should provide you with a range of products and materials, as illustrated above, working in groups your task will be to arrange them in to groups and record your ideas, then rearrange them into different group and once again record your ideas. Here are some discussion points for you to consider:
 * **Physical Properties** - These are the properties associated with the actual chemical or atomic makeup and structure of the material.
 * **Mechanical Properties** - These are the properties associated with how a materials reacts when subjected to external forces. These properties are often of greater concern to the designers.
 * What have you learned about the different ways in which products and materials can be classified?
 * In what circumstances is this useful?
 * When might this be problematic?

= 2. Knowledge & Understanding = An **atom** is the smallest part into which an element can be chemically divided. All atoms have the same basic structure but they vary in size and mass. Each atom has a positively charged **nucleus** at its centre containing positively charged protons and neutrons which together make up 99% of the atom. **Electrons** orbit around the nucleus. The number of electrons defines what element the atom is. For example, hydrogen has one electron and oxygen has eight. When two or more atoms join together, they form a **molecule**. Hydrogen and oxygen combine to make water. Water is a **compound** because it is made up from two elements which are joined.

Check out the periodic table below, identify the metals, are the grouped together? When two or more materials are combined, one of which is a metal, an alloy is formed. The properties of each element are still present in the alloy. For example, solder is an alloy of lead and tin. Lead has a relatively low melting point making it easy to use with electronic circuits. However, lead is very soft so the tin is added to make it harder and more durable. Other metal alloys include brass (copper & zinc), bronze (copper & tin) and steel (iron & carbon)


 * Task 1** - Find more information about the metal alloys mentioned above and summerize their properties and uses into a table.
 * Composites** are made by bonding two or more materials. It is possible to make many composites with enhanced properties. For example, a milk carton is a composite of **card** and **polyethylene** known as tetra pack. The card makes the carton rigid and the polyethylene makes it waterproof.
 * Composites** are combinations of two materials in which one of the materials, called the **reinforcing phase**, is in the form of fibers, sheets, or particles, and is embedded in the other materials called the **matrix phase**. The reinforcing material and the matrix material can be metal, ceramic, or polymer. For example snowboards
 * **@http://www.engr.sjsu.edu/WofMatE/Composites.htm**
 * **@http://composites-by-design.com/**


 * Task 2 -** Each team needs to find out about one of the following composite products: Mud bricks, car tyres, concrete and fiberglass. Spend around 5 minutes on this. Present your information to the rest of the group explaining how the properties of the composite are suited to its use.
 * **@http://www.design-technology.org/comp1.htm**

Atoms become joined or bonded when they are attracted to each other. There are three types of bonding to be aware of: **Ionic**, **Covalent** and **Metallic**. Watch the following presentations: __[|Material Bonding Powerpoint]__ View SlideShare __[|presentation]__ or __[|Upload]__ your own.


 * Task 3** - Add to your notes from this lesson, summarizing ionic, covalent and metallic bonding.
 * Challenge:** Instead of just making notes consider other ways you might record your information follow this link [[image:msc-technology:LinkBtn_copy.jpg width="70" height="21" caption="LinkBtn_copy.jpg"]] to find some examples

= 3. Re-classifying Materials = Re examine the products above, or the group of products your teacher provided. Now classify them according to the following material groups: See if you can sub-divide each group as follows:
 * Timber
 * Metal
 * Plastic
 * Ceramic
 * Composite
 * Food
 * Textiles
 * Natural timber & man-made timber
 * Ferrous metals & non-ferrous metals
 * Thermo plastics & thermosetting plastics
 * Earthenware, porcelain, stoneware, glass
 * Natural fibre, synthetic fibre.

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Uploaded on authorSTREAM by mschongkong

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= 4. Property of Materials = Materials behave in different ways under different conditions. These types of behaviour are called material properties. We need to be very careful to describe material properties accurately. Discuss the following question:
 * Physical properties, mechanical properties and aesthetic properties**
 * Is glass a strong material? (Think about the different functions that glass has, its various applications and different types)


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Have a look at the following link to help: Hopefully, you realize that the word strong does not adequately describe glass; glass can be very brittle (it shatters easily) but it is also very hard (difficult to scratch). Some types of glass like Pyrex® are good thermal conductors (absorb heat well) which makes them good for cooking food in. Other types of glass are poor thermal conductors and will shatter easily if they are heated because they cannot absorb the heat rapidly. We also need to remember that materials have properties that we can’t always observe. For example, concrete and steel have elastic properties just like rubber – it can bend and return to its original shape provided it is not forced beyond its elastic limit. We don’t notice this most of the time but….
 * **@http://www.lenntech.com/glass.htm**

Watch the Tacoma Narrows bridge collapse. Can you work out what factor/s caused the bridge to behave in this way?

In groups, define the following physical properties and identify a design context or situation in which one of the above properties is an important consideration. Present your group’s work as a shared Google presentation.
 * Task 1**
 * Density
 * Electrical resistivity
 * Thermal conductivity
 * Thermal expansion
 * Hardness
 * Tensile strength
 * Stiffness
 * Toughness
 * Ductility

= 5. Aesthetic Properties = ‘**Aesthetics**’ is a hard word to define but put very simply, aesthetics are the properties that products have that make them appealing or unattractive to us. Aesthetic properties depend completely on your own personal point of view – this means they are **subjective**. Your tastes depend as much on your **mood** as they do on your **beliefs** and **values**. For example; you probably have a favourite food, like a particular type of music, enjoy wearing certain styles of clothing which are unique to you. Your aesthetic tastes are personal and no-one can say if they are right or wrong. Sometimes though, large groups of people or ‘**target market**’ like similar things, so a company can design a product to meet the aesthetic demands of that group.

However, our aesthetic demands are constantly changing so products must also adapt to meet those changing demands. Have a look at the following video:

You should also watch the following video:


 * Task 1** - In groups, define the following aesthetic characteristics and identify a design context or situation in which one of the above properties is an important consideration. Present your group’s work as a shared Google presentation.
 * Taste
 * Smell
 * Appearance
 * Texture
 * Colour

= Revision = To access this VoiceThread click on the link below: @http://voicethread.com/share/721247/

[|Click here to make your own Fyrebug game]

= Nano Technology = This is not required for IB, but there are some interesting points and information about materials technology, just ignore the many references to "aliens"

[|Alien NanoEngineering - Supermaterials]