Quest 2 study guide

properties of clay

• plasticity - manipulate at room temp

• cohesive - maintains shape

• poor tension strength

• high compression strength

• opaque

• insulating

• can be chemically transformed when heated

• can be tried

composition of clay

Al, Si, O (plus water)

why use clay

made of the earth’s most abundant elements

clay mineral structure

tetrahedron, octahedron, tetrahedron, water interlayer

octahedron - aluminum 

tetrahedron - silicon

why does clay have so much plasticity 

water interlayers in clay mineral structure

when does clay turn into a ceramic

after firing, induces chemical bonds of layers between Si and O

origins of clay

• weathering of rocks

  • silt is larger than clay

primary clay 

found at site of formation

secondary clay

washed downstream

different types of clay depends on what

minerals in the soil

kaolinite

1:1 tetrahedra/octahedra layer 

low shrink/swell capacity (more stable)

aka China clay 

heat below 1,000 - reversible drying; above 1,000 - stone wear dishes

montmorillonite (smectite)

2:1 tetrahedra/octahedra ratio

large shrink/swell capacity 

temper

added to clay to prevent shrinkage and cracking during drying and firing

examples of temper

bone

charcoal

wood ash

sand/crushes sandstone

crushed limestone

crushed volcanic rock

crushed shells

early uses of clay

clay figures, Japanese pottery (earliest clay pottery), clay bricks, catal huyuk clay society, potters wheel, clay tabelts/ writing, track trade, land ownership, centralized government 

Japanese pottery 

• earliest clay pottery

• pots for cooking

jericho/mesopotamia

• very fertile land, people settled

• sun baked bricks

• crops cultivated and stored in clay

clay inventions for harvesting

sickle, for harvesting wheat efficiently

cuneiform

early form of writing on tablets

epic of gilgamesh 

ancient uses of clay

building materials, construction, writing materials, cooking, storage, sling ammunition, medical (armenian bole), musical instruments (ocarina)

modern uses of clay

oil drilling, wells, land fill liner, odor absorbents, building materials, pottery and porcelain, dams

challenges with phosphate mining

clay waste

why is clay helpful for plants

negative surface charge so good for ion exchange (absorbs NH4+)

helps with soil fertility and organic farming

nuclear waste migitation

switch clay surfaces from neg to pos to attract radioactive waste

how can clay bricks be used to address global warming

carbon capture

Firing of clay  

makes it brittle

Affordances

advantageous properties in a given situation 

Constraints

disadvantageous, limiting, restricting  

thing

an assembly or gathering of components, qualities, and properties

ceramic/glass properties

• inorganic

• nonmetallic

• solid

• brittle

• high melting point

• poor conductor

• chemically resistant

• waterproof

• crystallinity: crystalline, semicrystalline, amorphous

ceramic 

quartz 

glass

obsidian 

structure of ceramics and glass

silicon dioxide network

technical ceramic

oxides, nonoxides, functional cermaics

functional ceramics

materials that can convert energy from one form to another

piezoelectric

force transduced into electricity

what kind of solid is glass

amorphus

most common glasses based on what compound?

SiO2

SiO2 in glass

• glass is amorphous

• unstable so will crystallize over time (devitrification)

earliest forms of glass

obsidian 

• volcanic glass

• didn’t need a fire

faience

ceramic with a coating on it

natron

NaCO3

egyption hsitorical uses of glass

slave sculptures, and king’s scarab

what made glass making possible

• NaCO3 + SiO2 → glass (temp over 1,000)

• faience made with nile sediment containing natron 

• sodium is a network modifier

• lowers melting point of glass

• add too much salt, bad, glass will dissolve in water

• add lime to strengthen network (network former)

  • creation of soda lime glass

key aspects history of glass

glass blowing led to mass production of objects, made glass inexpensive, roman conquest took technology back to rome

roman glass

• added MnO2 to make clear glass

  • made drinking vessels

  • contributed to the appreciation of glass

  • made first windows, mirrors

glass and european hisotry

significant impact on churches and 

developments of glass

• telescopes, microscopes

• revolutionized science and medicine

• 1st export was glass from jamestown to england

• float glass

  • development of fiber optic glass

properties of glass/ceramics that can be changed

mechanical properties

• typically very brittle

• weak under tension, strong under compression

how do we make glass stronger

The Rupert drop, corning ware, gorilla glass (substitude K for Na)

key aspects of the rupert drop

• large coefficient of thermal expansion

• surrounded by glaze with small coefficient of thermal expansion

• inside is a state of tension

• outside is a state of compression

  • lots of stored mechanical energy

using ceramics for superhydrophobic coatings 

Al2O3 nanoparticles

surfaces, clothing, etc

insulating properties of ceramics

make good electrical conductors and thermal insulators (can be improved by increasing porosity)

chaine operatoire

tool used in anthropology to study the step-by-step production, use, and disposal of artifacts

cradle to grave and cradlel to cradle

lifecycle for materials and sustainable materials

what in the chaine operatoire is ignored in lifecycle analysis

social context

modern application of glass

bioglass, flexible glass, foat glass, fiber optics

vitrification

transformation of atomic/molecular structure of ceramics to create glass (excessive heating to make truly amorphous cermaic)

flintknapping

controlled reduction of glass-like rock

steps to flitknapping

1. acquire raw material

2. prepare material for transport

3. prepare core for reduction

4. shape and thin biface

5. remove flutes (many fail)

6. finish edges

7. grind basal margins

   1. attach point to head or shaft

community aspect of flintknapping

communities of practice; learning is social

clovis caching

ritual deposits, occasionally with human burials

early cookware

better at insulating than conducting heat

need to unlock nutritional potential of foods that require prolonged boiling

wild grasses

basis for early farming

problem: require prolonged boiling to maximize nutritional value

what were kilns used for

achieving temperatures of vitrfication

intensification

producing more but at higher per-unit costs (possibly lots of hidden costs and unforeseen consequences)

properties of copper and bronze

• metallic

• malleable

• opaque

• electrically conductive

• thermally conductive

• orange

• shiny 

  • hard

copper

• a pure element

• named after where it came from cyprus

• higher melting point than bronze

bronze

• alloy of copper and an impurity (arsenic or tin)

• named after the italian word bonzo for bell metal

• melting point varies but is generally a little lower than copper

purpose of smelting

provides increased temperatures and the pathway to a specific chemical reaction instrumental in removing metals from their ores

smelting of copper

malachite and carbon → heat → copper will form

smelting

• commonly mixing of ore with charcoal

• incomplete combustion of charcoal produces carbon monoxide

  • carbon monoxide reacts with the ore to produce carbon dioxide and elemental metal 

chalcolithic age

copper

bronze age

bronze

why is bronze harder and stronger

because it is an alloy

strengthening mechanisms 

copper relatively easy to refine but also very soft

key thing is slowing down dislocation and motion

how to slow down a dislocation

work hardening

• add lots of dislocations

• they get tangled, making it difficult for them to move

• cold rolling copper increases tensile strength

ways to strengthen copper

adding impurities

• solid solution hardening

• put atoms on lattice sites to block dislocations

  • use arsenic and tin