Lesson video

Hello there.

My name is Mrs. Taylor.

And I'm really pleased you can be here to join me for our lesson today.

Our lesson today is Enhancing the Properties of Metals, and this is part of the technical principles unit.

The outcome, I can explain how metal material properties can be enhanced.

There are five key words.

Properties, words used to describe how a material appears, sometimes known as physical properties or characteristics, or behaves when worked and this is known as the working properties or mechanical properties.

Combine, to join two or more things to create something new.

Modify, to change something to make it perform differently.

Reinforce, to make something stronger.

And structural integrity, which is how well something stays together and holds up without breaking.

There are three learning cycles in our lesson today.

Combining materials, modifying materials, and structural integrity.

We begin with combining materials.

Materials don't always have the perfect properties for the job we want them to do.

Sometimes they're too weak, too flexible, not hard-wearing enough, or can't handle heat or moisture.

By enhancing material properties, we can make products stronger and last longer.

Improve safety and performance.

Allow innovation in design and function.

Properties are words used to describe how a material appears.

Its physical properties or characteristics or behaves when worked, this is the working or mechanical properties.

There are three ways that a material's properties can be enhanced.

Combining, which is joining together.

Modifying, which is changing.

Or reinforcing, which is making stronger.

Here we have a check for understanding.

Which three methods are used to enhance material properties? Is it a, compare, model, reinforce? Or b, combine, manufacture, repeat.

Or c, combine, modify, and reinforce.

Or d, compare, modify, and reuse.

Pause the video and have a go.

Wonderful.

Let's check.

That's right.

It's c, combine, modify, and reinforce.

Well done.

Composites are materials made by combining a matrix, also known as a binder.

Reinforcement for strength, to create a material with improved overall properties.

A composite is like a chocolate-chip cookie.

The dough is the matrix, the binder.

And the chips are the reinforcement, added strength.

It can also be like a lava or layer cake, where the reinforcement is encapsulated or layered through the matrix.

This image shows the dome of a building that was once made with steel-reinforced concrete.

Steel-reinforced concrete is made from cement, which is the matrix, and steel bars, which are the reinforcements.

It is commonly used in buildings because it allows for complex shapes that can support their own weight.

The steel frame of this dome was once covered with concrete.

Here we have a check for understanding.

In a composite material, what is the role of the reinforcement? Is it a, to hold the structure together? b, to give strength or other useful properties.

Or c, to act as a decorative layer.

Or d, to make the material more flexible.

Pause video and have a go.

Wonderful.

Let's check.

That's right.

It's b, to give strength or other useful properties.

Well done.

Other examples include, cement is made from hard ceramic particles, which is the reinforcement and a metal such as cobalt, which is the matrix.

It results in a tough, wear-resistant material and can be used for cutting tools.

Aluminium matrix composite is made from silicon carbide particles or fibres, which act as the reinforcement and aluminium, which is the matrix.

It's lightweight but strong, and can be used in aerospace parts.

Titanium matrix composite is silicon carbide fibres, which are the reinforcement and titanium, which is the matrix.

It is used for bone implants because of its strength and resistance to corrosion.

Composite materials can have the matrix and reinforcement laminated, which means layered together.

Or encapsulated, which means enclosed.

Aluminium foil-lined cardboard is used for hot food containers.

Both layered materials insulate and the foil protects against leakage.

Copper is laminated onto a polymer sheet to create printed circuit boards.

This allows conductivity whilst maintaining structure.

Steel mesh is encapsulated within glass to create safety glass.

It keeps the shards of glass intact, if broken, and provides additional strength.

Here we have a check for understanding.

In a composite material, what is the role of the matrix? Is it a, to bind the materials together? Or b, to give strength or other useful properties.

Or c, to act as a decorative layer.

Or d, to make the material more flexible.

Pause the video and have a go.

Wonderful.

Let's check.

That's right.

It's a, to bind the materials together.

Well done.

An alloy is a material made by combining two or more elements, where at least one is a metal.

Alloys combined properties of its constituent elements to create a material with enhanced properties.

Examples of alloys include, brass is an alloy of copper and zinc.

It is corrosion resistant and has good acoustic properties, making it useful for musical instruments and door handles.

Stainless steel is made from iron mixed with chromium, and sometimes nickel.

It is strong and non-porous, so it is used for hygienic applications like cutlery, kitchen equipment, and medical instruments.

Bronze is an alloy of copper and tin.

It is tough and easy to machine and work, which makes it ideal for sculptures and mechanical components.

Here we have another check for understanding.

What is an alloy? a, a material made by combining two or more elements, at least one of which is a metal.

b, a pure metal used for electrical wiring.

c, a mixture of a metal and a non-metal that cannot be separated.

Or d, a coating applied to metal to prevent corrosion.

Pause video and have a go.

Wonderful.

Let's check.

That's right.

It's a, a material made by combining two or more elements, at least one of which is a metal.

Great.

Well done.

We now move to Task A.

Part 1, explain what a metal-based composite is, referring to the terms matrix and reinforcement in your answer.

Part 2, describe two benefits of using composite materials.

Use examples in your answer.

And Part 3, explain why stainless steel might be chosen over aluminium for cooking pans and utensils.

Pause the video and have a go.

Wonderful.

Let's have a look at some of the answers you may have come up with.

For Part 1, you may have said, "Composites are made by combining two or more materials to improve properties.

The matrix binds the structure while the reinforcement adds strength or other benefits." And for Part 2, you may have said, "Aluminium matrix composite uses aluminium with silicon carbide, making it strong and lightweight for aerospace and car parts.

Cement combines ceramic particles with metals like cobalt, creating a hard, wear-resistant material used in cutting tools." And for Part 3, you may have said, "Stainless steel is often chosen over aluminium for kitchenware because it is harder, so it doesn't scratch or dent easily.

While aluminium is lighter and conducts heat well, stainless steel is stronger and more hygienic, making it better for long-lasting kitchen items." Well done.

We now move to the second learning cycle in this lesson, modifying materials.

Modifying a material means changing its structure or composition, which is what it is made from to improve how it performs. The changes usually take place at a molecular level and include heat treatments and chemical treatments.

Metals can be modified with additives, usually through the process of alloying.

Alloys do not have to be made from just metals.

While many alloys are mixtures of metals, an alloy can also be made from a combination of at least one metal and another element.

An element that is commonly used is carbon, which is used to make steel.

Steel is made by adding carbon to iron.

The amount of carbon added changes the properties of the steel and its use.

We can see here mild steel has a low carbon content of less than 0.

3% carbon.

It is soft and easily shaped and used for things like wire mesh.

Spring steel has between 0.

5 and 0.

6% carbon.

It is tough with slight elasticity and is used for springs.

Toll steel has between 0.

5 and 1% carbon.

It is hard and wear-resistant and is used for things like hammers.

High-speed steel has between 0.

7 and 1.

5% carbon and can withstand high temperatures.

This makes it suitable for drill bits.

Here we have a check for understanding.

What is the purpose of adding carbon to steel? Is it a, to make it easier to recycle? Or b, to make it lighter and more flexible.

Or c, to improve its colour and shine.

Or d, to increase its strength and hardness.

Pause video and have a go.

Great.

Let's check.

That's right, to increase its strength and hardness, so d, is the correct answer.

Well done.

Heat treatment is used to alter the molecular structure of metals to change their properties.

This can make metals stronger, harder, and easier to work with.

Common methods to heat treat metals are annealing, and hardening and tempering.

Annealing makes metal softer and easier to work with.

The metal is heated up, held at that temperature, then cooled down slowly, usually in a furnace.

This process makes the metal less brittle.

Improves ductility, which means it can bend without snapping.

Annealing is normally used with metals like copper and aluminium.

Hardening and tempering are usually done together to get the best properties from a metal.

Hardening is where a metal is heated up and then cooled quickly by placing it in water or oil.

This is known as quenching.

This makes it very hard but also brittle, which means it can snap under pressure.

Tempering happens after hardening.

The metal is reheated to a lower temperature and then cooled slowly.

This makes it tough and less brittle while still keeping most of the hardness.

Hardening and tempering is usually done with steel, especially for tools.

We now have a check for understanding.

Why is metal tempered after being hardened? Is it a, to increase its melting point? b, to reduce brittleness and improve toughness.

Or c, to make it more brittle.

Or d, to make it non-magnetic.

Pause the video and have a go.

Great.

Let's check.

That's right.

It's b, to reduce brittleness and improve toughness.

Well done.

Metals can be chemically treated to improve surface properties such as corrosion resistance, appearance, or hardness.

Galvanising involves coating steel with zinc.

The zinc acts as a protective barrier against corrosion such as rust.

Examples of galvanised products include outdoor nails and metal roofing sheets.

Anodizing uses an electric current to create a thick oxide layer on the surface of aluminium to make it more resistant to corrosion.

Examples of anodized products include bike parts, and phone casings.

We now move to Task B.

Part 1, explain how adding different amounts of carbon to iron changes the properties of steel.

Part 2, describe two different heat treatments for metals and what each one does to the metal.

And Part 3, why is it important to treat metal used outdoors? Give an example.

Pause the video and have a go.

Wonderful.

Let's check.

Some of the answers you may have come up with.

For Part 1, you may have said, "Adding small amounts of carbon to iron makes low carbon steel, which is soft and easy to shape.

High carbon steel has more carbon, making it much harder and stronger." For Part 2, you may have said, "Annealing is a heat treatment that softens the metal, making it easier to bend or shape.

It involves heating the metal and letting it cool slowly.

Hardening makes metal very hard by heating and then cooling it quickly.

Tempering follows this to reduce brittleness and make the metal tougher." And for Part 3, you may have said, "Steel used outdoors is exposed to corrosion such as rust, which can damage its surface.

Galvanising the surface coats the steel with a zinc layer, which acts as a protective barrier against corrosion.

Galvanising is used for steel roofing sheets and fencing." Well done.

We now move to the third learning cycle, structural integrity.

Materials can be reinforced to enhance their properties.

Reinforcement involves adding an element or altering the structure of a material to improve its performance under stress.

Reinforcement techniques can be applied to a variety of materials including timbers, polymers, papers and boards, textiles, and metals.

Here we have a check for understanding.

Why might materials need to be reinforced? Is it a, to improve aesthetics? b, to make them stronger and last longer.

c, to reduce costs for the consumer.

Or d, it makes them more environmentally friendly.

Pause the video and have a go.

Wonderful.

Let's check.

That's right.

It's b, to make them stronger and last longer.

Well done.

Reinforcing materials improves their structural integrity.

Structural integrity refers to how well something stays together and holds up without breaking.

For metals, the techniques used to ensure structural integrity are particularly prevalent in the shaping of metal parts and various joining techniques.

Sometimes we don't need to combine or modify a material.

Just changing its shape can make a material much stronger and more resistant to bending.

Corrugation involves forming ridges in sheet metal to increase its rigidity.

They are often used for roofing sheets.

Adding folded edges known as flanges to sheet metal add strength along those edges.

They are used in casings and coupling rings.

Embossing creates raised lines to increase stiffness.

They can be seen in aircraft parts and tread plates.

We now have a check for understanding.

What is the main purpose of corrugating sheep metal? Is it a, to make it easier to join together? b, to improve the appearance of the surface.

c, to make the metal more flexible.

Or d, to increase strength and stiffness without adding weight.

Pause the video and have a go.

Wonderful.

Let's check.

That's right.

It's d, to increase strength and stiffness without adding weight.

Well done.

Welding is a method used to connect metal parts together in products or structures by melting and fusing it together.

Good welds prevent weak points, key to maintaining structural integrity.

Butt welds join two flat pieces, edge to edge.

The edges must be aligned properly to avoid stress concentration.

Fillet welds join parts of an angle.

Extra weld material is added to reinforce the corner.

There are many reinforcement techniques used to strengthen metal frames, especially in engineering and construction.

They don't change the material itself, but improve how it handles loads.

Bracing involves adding diagonal supports between beams to prevent twisting and buckling under a load.

They are common in building frameworks, roller coasters and bridges.

Notice how these beams create triangles, one of the strongest shapes that do not buckle under pressure.

This method of reinforcement is called triangulation.

We now move to Task C.

Part 1, draw a labelled diagram to explain the structure of corrugated sheet metal and how it provides strength.

Part 2, explain how welding can be used to reinforce a metal structure.

Give one example of a type of weld to support your answer.

And Part 3, describe how bracing and triangulation help improve the structural integrity of metal frames.

Pause video and have a go.

Great.

Let's have a look at some of the answers you may have come up with.

For Part 1, you may have drawn some images which look similar to this.

Corrugated sheet metal has either ridges or waves folded into the sheet metal.

The folds spread the load evenly to prevent the sheet from flexing too much.

For Part 2, you may have said, "Welding can reinforce a structure by creating strong joints between metal parts, which helps the structure resist movement and stress.

A fillet weld, for example, joins two metal parts at an angle and adds extra material to the joint.

This increases strength at the corners." And for Part 3, you may have said, "Bracing adds diagonal supports to stop the frame from twisting or bending.

Triangulation strengthens structures by forming triangles, which are very stable shapes that don't deform easily.

Both techniques spread loads more evenly and are often used in bridges and roller coasters to keep them strong and secure." Well done.

We now have a summary of our learning.

Combining materials creates improved properties, compared to the individual materials alone.

Material properties can be modified with the use of heat and/or chemicals.

Reinforcing techniques can improve a material's structural integrity.

I'm so pleased you could join me for this lesson today.

Well done.