Engineering Materials - Metallurgy

Summary

This script delves into the world of materials, categorizing them into metals, polymers, ceramics, and composites. Metals, being the most versatile, are crucial in constructing everything from cars to space equipment. Polymers, both natural and synthetic, have transformed industries. Ceramics, with their ancient roots, are now pivotal in semiconductor technology. Composites, blending materials for superior properties, include concrete and carbon fiber. The script also explores metal strengthening through alloying and the role of atomic structure in material properties.

Takeaways

• ⚙️ Materials are categorized into four main groups: Metals, Polymers, Ceramics, and Composites, each with distinct properties and applications.
• 🏗️ Metals, especially steel and cast iron, are the most widely used due to their strength and cost-effectiveness, with applications ranging from everyday objects to extreme conditions like space exploration.
• 🔬 Polymers, including plastics, are made from hydrocarbons and have a broad range of properties, making them versatile for various industries from packaging to construction.
• 🏺 Ceramics, such as glass and clay, have been used for thousands of years and are known for their light weight, high strength, and good heat resistance, but can be brittle.
• 🤝 Composites combine two or more materials to achieve unique properties; examples include concrete and carbon fiber, which is both strong and lightweight but expensive.
• 🧬 Ferrous metals contain iron and are used for their strength and affordability, while non-ferrous metals like aluminum, copper, and titanium offer different properties.
• 🔬 The strength of metals is influenced by their crystalline structure, with imperfections like dislocations reducing their theoretical strength.
• 🔩 Metals can be strengthened by alloying, which involves adding other metals or non-metallic elements to alter their atomic structure and properties.
• 🔬 Processing methods for polymers significantly affect their properties, allowing for the creation of materials with varying degrees of strength, toughness, and electrical conductivity.
• 🏗️ The Romans were pioneers in material science, mastering the use of glass, concrete, and composites, which have shaped modern construction and infrastructure.
• 🔬 Recent advancements in material science have led to the development of semi-conductors with high electrical efficiency and carbon fiber composites for high-strength applications.

Q & A

What are the four key areas of materials used in engineering?

The four key areas of materials used in engineering are Metals, Polymers, Ceramics, and Composites.

Why are metals the most widely used materials in engineering?

Metals are the most widely used materials because they are used in the manufacture of everyday objects and extreme applications, and even in materials that are not made of metal.

What are the two subgroups of metals and what are their main constituents?

The two subgroups of metals are Ferrous and Non-ferrous. Ferrous metals have iron as their main constituent, including steels and cast irons, while Non-ferrous metals include other metals such as aluminium, copper, zinc, titanium, and nickel.

How are natural and synthetic polymers different?

Natural polymers are substances like amber, wool, silk, natural rubber, and cellulose, which have been used for centuries. Synthetic polymers, on the other hand, are produced more recently and include materials like synthetic rubber, nylon, PVC, polystyrene, silicone, and many more.

What are the most common types of ceramics and how have they been used historically?

The most common types of ceramics are glass and clay. Historically, clay was the first material transformed using fire, dating back to about 29,000 years ago for decorative figures, and later for functional items like jugs and bowls. The Romans mastered glass production, using it for windows.

What is a composite material and how has its use evolved?

A composite material is a combination of two or more materials, such as concrete, which has been used for centuries and was mastered by the Romans. Modern composites include reinforced concrete, which was developed in the 19th century by adding steel bars to concrete.

What are the properties that make polymers versatile and easily processed?

Polymers are made up of hydrocarbons, which can form long chains. This allows for versatility and easy processing, with properties such as strength, toughness, and electrical conductivity that can be varied during processing.

How do ceramics achieve high electrical conductivity like semiconductors?

Ceramics achieve high electrical conductivity through the development of semiconductors. When cooled, these ceramics can have virtually 100% efficiency in electrical conductivity, significantly reducing energy loss compared to traditional materials.

What is the theoretical strength of metals and what reduces it in reality?

The theoretical strength of metals is much higher than what is seen in reality, which is due to imperfections in the atomic structure known as dislocations. These dislocations allow atoms to move, reducing the material's strength.

How can the properties of metals be manipulated to achieve specific characteristics?

The properties of metals can be manipulated by adding other chemical elements, which distort the atomic structure, making it more difficult for atoms to move around and thus strengthening the material. Elements like carbon, manganese, nickel, copper, molybdenum, boron, chromium, niobium, titanium, and vanadium can be used for this purpose.

What is the significance of the crystalline structure in metals and how does it affect their properties?

The crystalline structure in metals, where atoms are arranged in an orderly manner, is significant as it affects properties like strength and ductility. The arrangement can be in Body Centred Cubic or Face Centred Cubic forms, and the presence of grains and grain boundaries can influence the metal's performance.

Outlines

00:00

🔩 Metals: The Backbone of Engineering

This paragraph introduces metals as the most widely used materials in engineering, highlighting their versatility in everyday objects like cars, buildings, and bridges, as well as in extreme applications such as jet engines and space exploration. It explains that metals are essential in the manufacturing process of many non-metal materials. The text also categorizes metals into ferrous, which primarily consist of iron and include steels and cast irons, and non-ferrous metals like aluminum, copper, zinc, titanium, and nickel. The properties of metals, such as electrical and thermal conductivity, ductility, strength, and toughness, are discussed, emphasizing their importance in various applications.

05:04

📦 Polymers: Versatile Carbon Chains

Polymers, including plastics, are highlighted as materials that have revolutionized modern society. The paragraph distinguishes between natural polymers like amber, wool, silk, natural rubber, and cellulose, which have been used for centuries, and synthetic polymers that have been produced more recently and include materials like synthetic rubber, nylon, PVC, polystyrene, and silicone. The properties of polymers are attributed to their hydrocarbon composition, which makes them abundant and cheap due to their by-product status from the petroleum industry. The paragraph also discusses how processing techniques can vary the properties of polymers, such as strength and electrical conductivity, and how they can be tailored for specific uses.

10:09

🏺 Ceramics: Ancient Materials with Modern Applications

Ceramics, with glass and clay being the most common types, are discussed as materials with a history of use spanning thousands of years. The paragraph details how clay was one of the first materials transformed using fire, dating back to 29,000 years ago for decorative figures and later for functional items like jugs and bowls. Glass, primarily made from sand, is noted for its mastery by the Romans, who were the first to use it for windows. The paragraph also touches on the recent advancements in ceramics, particularly in the development of semiconductors, which have nearly 100% electrical conductivity when cooled, offering significant energy efficiency improvements over traditional materials.

🤖 Composites: A Blend of Strength and Functionality

Composites are described as materials made from a combination of two or more different materials, with a matrix or binder and a reinforcement. The paragraph emphasizes the wide use of concrete, a composite of cement and aggregate, which has been instrumental in shaping the modern world. Other examples include fiberglass, which combines plastic and glass strands. The paragraph also discusses the development of carbon fiber composites in the 1960s, which, despite being expensive, offer unique properties of strength, stiffness, and light weight. The historical use of composites, such as concrete by the Romans, and the addition of steel bars to create reinforced concrete in the 19th century, are mentioned to illustrate the long-standing significance of composites in material science.

🔬 The Science of Material Properties

This paragraph delves into the atomic structure of metals, explaining how understanding metals on an atomic scale has been a relatively recent development. It describes two common atomic arrangements in metals: Body Centred Cubic and Face Centred Cubic. The theoretical strength of metals is contrasted with their actual strength, which is reduced due to imperfections known as dislocations. The paragraph also explains how metals can be formed and shaped due to the movement of atoms under pressure, facilitated by dislocations. The role of grains in metals, which can both enhance ductility and collect impurities at grain boundaries, is discussed. Finally, the paragraph covers how metals can be strengthened by alloying, either with other metals or non-metal elements, and how these additions can distort the atomic structure, affecting the material's properties.

Keywords

💡Materials

Materials are substances used to make things or perform certain functions. In the context of the video, materials are categorized into four key areas: Metals, Polymers, Ceramics, and Composites. They are essential for everyday objects and advanced applications like space exploration. The video aims to uncover the properties and uses of these materials, highlighting their importance in engineering and technology.

💡Metals

Metals are a significant category of materials known for their strength, ductility, and conductivity. They are the most widely used materials, even in the production of non-metal items. The video mentions metals like steel and cast irons, which are ferrous metals, and non-ferrous metals like aluminum, copper, and titanium. Metals are crucial in constructing cars, buildings, and even extreme applications like jet engines.

💡Polymers

Polymers are large molecules composed of repeating subunits. They include both natural polymers like amber, wool, and cellulose, and synthetic polymers like nylon and PVC. Polymers are highlighted in the video as materials that have revolutionized modern society due to their versatility and the ability to tailor their properties through processing.

💡Ceramics

Ceramics are inorganic, non-metallic materials often made by heating materials like clay and glass to high temperatures. The video discusses ceramics' long history of use and their recent advancements, such as semiconductors, which have nearly perfect electrical conductivity when cooled. Ceramics are known for their high strength, hardness, and resistance to heat and wear.

💡Composites

Composites are made from two or more different materials that combine to produce a material with characteristics different from the individual components. The video explains that composites like concrete and reinforced concrete have been used for centuries and are integral to modern construction. The script also mentions high-tech composites like carbon fiber, which is both strong and lightweight but expensive.

💡Ferrous Metals

Ferrous metals are those that contain iron as their main constituent. The video points out that steels and cast irons are examples of ferrous metals. These metals are cost-efficient due to iron's abundance in the Earth's crust and are used in various structural applications because of their strength.

💡Non-Ferrous Metals

Non-ferrous metals are metals that do not contain iron. Examples given in the video include aluminum, copper, zinc, titanium, and nickel. These metals have diverse properties and applications, making them valuable in various industries and technologies.

💡Hydrocarbons

Hydrocarbons are organic compounds consisting of hydrogen and carbon atoms. They are the fundamental building blocks of plastics and are derived from the petroleum industry. The video emphasizes that hydrocarbons' abundance and low cost make them ideal for mass-producing polymers like plastics.

💡Dislocations

Dislocations are imperfections in the orderly arrangement of atoms in a crystal lattice. The video explains that while the theoretical strength of metals is high due to their crystalline structure, dislocations reduce their actual strength. This concept is crucial for understanding how metals deform and can be worked into different shapes.

💡Grain Boundaries

Grain boundaries are the areas where individual grains of a polycrystalline material meet. The video mentions that these boundaries can be both beneficial and detrimental to a metal's properties. They can increase ductility but are also areas where impurities can collect, affecting the metal's overall performance.

💡Alloying Elements

Alloying elements are additional chemical elements added to a metal to alter its properties. The video discusses how elements like carbon, manganese, nickel, and others are used to create steels with specific characteristics for various applications. These elements can either expand or collapse the atomic structure, influencing the material's strength and other attributes.

Highlights

Materials are essential in our everyday life and can be categorized into four key areas: Metals, Polymers, Ceramics, and Composites.

Metals are the most widely used materials, even in the manufacturing of non-metal items.

Metals are crucial in extreme applications like jet engines, mining equipment, and space exploration.

Polymers, including plastics, are used across various industries with both natural and synthetic types.

Natural polymers like amber, wool, and silk have been used for centuries, while synthetic polymers have revolutionized modern society.

Ceramics, with glass and clay as the most common, have been used for thousands of years.

The Romans were pioneers in glass and clay technology, using them for decorative and practical purposes.

Composites are combinations of two or more materials, with concrete being one of the most utilized.

Ferrous metals, primarily iron-based, include steels and cast irons known for their strength and affordability.

Non-ferrous metals consist of various metals like aluminum, copper, and titanium, which are ductile and strong.

Polymers are organic carbon-containing molecular chains with a range of properties influenced by hydrocarbons.

Ceramics are inorganic non-metallic materials with properties like high strength, hardness, and heat resistance.

Composites consist of a matrix and reinforcement, offering unique properties like strength and light weight.

Metals have a crystalline structure with atoms arranged in specific patterns, influencing their properties.

The theoretical strength of metals is much higher than actual due to imperfections called dislocations.

Metal properties can be manipulated by adding other chemical elements, which distort the atomic structure.

The addition of alloying elements to iron can create steels with tailored properties for specific applications.

Carbon fiber, a high-tech composite, is strong, stiff, and lightweight, but its production is costly.

Transcripts

Materials Materials are all around us, we use them is

our everyday life, but what are the most common materials? What do they make? And what properties

do they hold? These are the key insights that we will try to uncover in this module.

For engineering purposes, materials can be divided into 4 key areas:

The first is Metals Metals are the widest used of the four materials.

Even if a material is not made of metal, metal will have been used at some point during it's

manufacture. Metals are used for everyday objects like cars, buildings and bridges,

but also go in to extreme applications like; jet engines, mining equipment and space exploration.

Even the tallest buildings in the world are only possible due to metals.

The second material is polymers, which includes plastics.

Polymers are widely used in many different industries. Natural polymers consist of amber,

wool, silk, natural rubber and cellulose which is the main constituent of wood and paper.

These natural polymers have been used for centuries. More recently Synthetic polymers

have been produced and these have revolutionised modern society. These include synthetic rubber,

nylon, PVC, polystyrene, silicone and many more.

The third is Ceramics

Ceramics have been used for thousands of years and the most common two are glass and clay.

Clay was the first material that we learnt to transform into another state using fire.

This was done about 29000 years ago when clay was formed into decorative figures. Much later

clay was used to form items like jugs and bowls.

Glass which is mainly made from sand, was mastered by the Romans who unlocked the secret

of blown glass by mixing it with minerals. The romans were the first people to use glass

for windows. The fourth material is Composites.

A composite is a combination of two or more materials. Composites have been used for centuries

in the form of concrete. Again it was the Romans who really mastered the process, in

text from 25BC different aggregates are discussed for use in lime mortars. In 1853 steel bars

were first added to concrete making one of our widest used composites: reinforced concrete.

Metals can be divided into two sub groups; ferrous and non-ferrous.

In Ferrous metals the main constituent is iron, and this group consist of steels and

cast irons. For the amount of strength that is achievable

in steel and cast irons, it is a cheap material. This is because iron is one of the most plentiful

elements in the earth's crust. Non-ferrous metals include any other metals,

some examples are aluminium, copper, zinc, titanium, and nickel.

Metals have good electrical and thermal properties. They are ductile, strong, tough and have strength

at temperature. Polymers are organic carbon containing molecular

chains. They have a wonderful array of properties

and are primarily made up from Hydrocarbons these are the building blocks of plastic,

Hydrocarbons are a by-product from petroleum industry and due to this they are an abundant,

and therefore a cheap material. The carbon and hydrogen which make up the

plastics are the key to how they work, because these can form together to produce long chains,

this enables plastics to be versatile and easily processed.

How the material is processed can produce the desired combination of properties; the

strength can be varied, the toughness can be varied, they can be a good conductor of

electricity and are often very good insulators. Again ceramics can have a wide array of properties

and in recent years we have really begun to understand them. Semi-conductors have been

produced which, when cooled, have virtually 100% efficiency in electrical conductivity.

To put this into perspective, current electricity cables lose about 5% of electricity through

resistance. With the loss in the world's electrical energy for one year you would be

able to power over 3 million washing machines constantly for 100 years, meaning that each

person on the earth could run a washing machine constantly for 15days for free.

Ceramics are an inorganic non-metallic material, they are chemically bonded and can have a

structure that is crystalline, non-crystaline or a mixture of both.

Ceramics are known for their light weight, high strength, high hardness, good heat and

wear resistance making them excellent for furnace lining. Although ceramics can be brittle.

Composites consist of a matrix or binder and a reinforcement. Composites affect our everyday

life, probably without our awareness. Concrete is likely to be the most common composites

and has shaped the modern world we live in. Concrete consist of a cement matrix and a

stone or aggregate Reinforcement. Another is fibre glass, with a matrix of plastic and

a reinforcement of fine strands of glass. In the 1960's Scientists set out to make

plastics as strong as metals. Through their research they produced carbon fibre, this

is also known as carbon fibre composite and it is made from fibres of carbon and plastic

(similar to glass fibre). This gives unique properties of strength, stiffness while being

light weight. But carbon fibre is very expensive. Script:

Only over the past 60 years have we really understood metals on an atomic scale.

In metals, atoms are arranged in an orderly manner giving them a crystalline structure.

Metals consist of two common arrangement of atoms. One with an atom at each of the corner

of a cube and one atom at the centre, this is called Body Centred Cubic.

The other has an atom at each corner of a cube and one atom on each face of the cube

this is called Face Centred Cubic. Mild steel arranged in a crystalline manner

should have a strength of approximately 20,000MPa which is equivalent to supporting the weight

of an elephant on a 1mm thick piece of wire, but mild steel has a strength much lower than

this. It has a strength of approximately 1000MPa (or a strength 20x lower) which is equivalent

to supporting the weight of a sheep from a 1mm thick piece of wire.

The reason that steel is reduced in strength is due to the imperfections in the atomic

structure, these are called DISLOCATIONS. Normally when we think of crystals we imagine

that we can smash them under a load like a hammer but the interesting thing about metals

is that when pressure is applied the atoms can move and this is how a they can be formed

and worked into different shapes. The dislocations help this deformation process.

In metal the atoms are arranged in groups, these groups are galled grains, these are

evident when you look at a zinc coated surface or what is known in the industry as a galvanised

surface. These grains can work both in favour and against the steel, they can increase the

ductility of the steel, but where the grains join (the grain boundaries) are areas where

impurities collect. Metals can be strengthened by adding more

than one metal together such as copper and tin to make bronze. In this example the two

combined has far greater strength than each of the individual metals (the sum is greater

than the parts). We can also change the properties of metals by adding non metallic elements

like carbon. If we take steel, there are hundreds of steels

all with slightly different properties, some tough, some strong, other resistant to rust.

These steels are produced by the same principle as bronze, we take one element IRON, which

is the bulk of all steels and add another chemical elements. Often called alloying elements

to it, to name a few we could add Carbon, Manganese, Nickel, Copper, Molybdenum, Boron,

Chromium, Niobium, Titanium, Vanadium. In this way we can tailor a steel to a specific

application. So we take our grains of iron atoms

And our alloying additions, which often have a different atomic size, for example Carbon

is small, Nickel is slightly smaller that iron and Molybdenum is slightly larger than

iron. And add them together

And we get a distorted structure When we add atoms that distort the atomic

structure this makes it more difficult for the atoms to move around and makes the material

stronger. Depending on the type and amount we can make a metal much stronger.

The smallest elements like carbon lay in between the iron atoms, these are call interstitial.

We have the largest atoms which replace an iron atom, like Molybdenum, this is called

substitutional, this type expands the structure. Or we can have smaller substitutional atoms,

like Nickel, that collapse the structure. Script:

So in Summary Engineer materials can be divided in to 4

key areas, Metals, Polymers, Ceramics and Composites.

Composites are as high tech as carbon fibre and as abundant as concrete.

Composites are a combination of two or more materials

Composites consist of a binder and a reinforcement Ceramics were the first material that we learned

to transform from one state to another. Ceramics are inorganic non-metallic materials.

We have really begun understand ceramics in recent years with semi-conductors.

Polymers have revolutionised modern society. Plastics are made from hydrocarbons which

are a by-product of the petroleum industry, this make them abundant and cheap.

How the polymer is processed has a large influence over its properties.

Metals are the widest used of the 4 materials. Metals are divided in to two sub-groups; ferrous

(containing iron) and non-ferrous (not containing iron).

Iron is one of the most plentiful elements in the earth's crust. This is used to make

steel and cast iron, which makes them efficient in terms of cost per the amount of strength

achievable. The atoms in metals are arranged in an orderly

manner, they have a crystalline structure. The theoretical strength of metals is much

higher than reality due to dislocations. The crystals of metals are arranged in grains.

The properties of metals can be manipulated by adding other chemical elements to them.

These elements distort the atomic structure making it more difficult for atoms to move

around.