Material Science

Question 1

According to Miodownik, why did steel sword making acquire magic-like legend to it?

Answer 1

The process for incorporating the exact correct amount of steel was often complicated and not well understood, which was likened to magic

Question 2

According to Miodownik, how did samurai swords incorporate different types of steel?

Answer 2

They used low carbon steel for the core to make them tough and high carbon steel for the edges to make them easy to sharpen.

Question 3

What is polyester made out of?

Answer 3

Extruded petroleum

Question 4

What is bronze made out of? Why was it so useful in early human development?

Answer 4

Bronze is a copper-tin alloy that is much harder than other available metals. It is easier to make than iron, which has a higher melting point

Question 5

What is steel made out of?

Answer 5

Iron and carbon

Question 6

What is stainless steel made out of?

Answer 6

Iron, carbon, and >10.5% chromium

Question 7

How do you soften metal?

Answer 7

Warm it up

Question 8

Why does metal make for better tools than bone, wood, or flint?

Answer 8

It is malleable and can be shaped without splintering, cracking, or breaking.

Question 9

How do you make metal harder? What is that doing to the structure of the metal?

Answer 9

Hammering the metal. It creates a crystal structure between the atoms.

Question 10

What property of the crystalline structure of metals allows them to be shaped and bent?

Answer 10

Dislocations are defects in the perfect crystal where atoms can move between parts of the crystal when bent

Question 11

How did copper tools enable the Pyramids to be built?

Answer 11

They allowed the workers to carve and work on the blocks

Question 12

Why do alloys tend to be stronger than pure metals?

Answer 12

The atoms are different sizes and disrupt the crystal structure. This makes it harder for dislocations to move.

Question 13

What are the series of metal ages that humans went through?

Answer 13

Copper age, Bronze Age, Iron Age

Question 14

What was the Bessemer process for making liquid steel? Why didn’t it work? How did they fix it?

Answer 14

Blow oxygen through the steel to take out carbon as carbon dioxide. It didn’t work because they couldn’t calibrate the amount of carbon. They fixed it by taking out all the carbon and adding back carbon

Question 15

How does the chromium in stainless steel prevent rusting?

Answer 15

It reacts with the oxygen to form chromium oxide, which becomes a protective film over the steel

Question 16

What is the name of the organic polymer that binds together cellulose in tree bark?

Answer 16

Lignin

Question 17

What are some advantages of the book (codex) over the scroll?

Answer 17

1. Faster to create and copy one page at a time
2. Easier to search and index into as a reader

Question 18

What do we add to paper to make it glossier, smoother, whiter, more water resistant, etc.?

Answer 18

Powder additives like calcium carbonate

Question 19

How does concrete technically not dry out?

Answer 19

The water is actually locked up within the structure of the concrete. It forms a gel within the silicate hydrate fibrils.

Question 20

What problem does reinforced concrete solve about concrete?

Answer 20

Concrete does well under compression but is susceptible to cracks and bending. The steel skeleton takes the stress there

Question 21

How does self-healing concrete work?

Answer 21

They added bacteria found in alkali environments along with starch. When there’s a crack, the bacteria is exposed, rats, and produces calcite as waste to fill in.

Question 22

What two properties make cocoa butter a good lotion?

Answer 22

Its low melting point makes it solid at room temperature but melt at body temperature. It has natural antioxidants for a long shelf life.

Question 23

What about the structure of cocoa fat creates different types? How many types are there?

Answer 23

Cocoa butter is made of triglycerides, crystals that can pack in different ways to give different melting points and temperatures. There are 5 different types.

Question 24

What is an aerogel?

Answer 24

A gel where the liquid component has been replaced by gas yet the gel structure remains

Question 25

How were the first aerogels made?

Answer 25

Using an autoclave, they heated and maintained pressure so the liquid was at the same state as gas while maintaining the structure. Then they slowly let the gas out

Question 26

Why is glass transparent I.e. how does visible light pass through glass but not most other materials?

Answer 26

The energy required to move electrons to a higher orbit in glass is much higher than what visible light provides so it passes through.

Other materials provide more opportunities to absorb visible light.

Question 27

How is graphite harder than diamond but also soft enough as pencils?

Answer 27

It has very strong bonds within a layer but no extra electrons for bonds between layers. As such, each layer is very strong but easily pulled from other layers.

Question 28

How is carbon fiber composite made? What was the first application?

Answer 28

Roll up layers of graphite into fibers and stick the layers with epoxy glue

Made for airplanes to be light and tough, but first adopted in sports.

Question 29

What is graphene? How can you make it?

Answer 29

A single 2d layer of graphite. Make it using scotch tape

Question 30

How did potters fix the problem of holes in terra cotta making the ceramic brittle?

Answer 30

Glazing it by melting ash onto the outside

Question 31

How is porcelain different from other pottery?

Answer 31

It includes kaolin and is fired to 1200C. This creates a strong, smooth, and translucent product

Question 32

What metal do we use for body part replacements?

Answer 32

Titanium

Question 33

How does a hip replacement work?

Answer 33

The surgeon saws off the top of your femur, drills in a new ball, and replaces the socket on your hip with titanium lined with polyurethane