Ceramics Flashcards
Two types of ceramics
Technical and non technical
Structure of Ceramic
Crystalline
Cermanics- Ductility
no brittle, high moduli
Ceramics- Strength
Strong in tension
Ceramics- how easy is manufacture
Difficult to design and shape as cannot melt and flow
What is Porosity
Holes in the crystal stucture left behind by evaporating water
When more porosity what happens to strength (E, Flexural strength)
it decreases with volume fraction Porosity
Measuring porosity- what is wd
dry weight
Measuring Porosity- what is ws
weight when suspended in water
Measuring Porosity- what is Ww
weight when removed from water
Measuring Porosity- Equation
ww-wd/ww-ws *100
Apparent porosity- cons
doesn’t include the central pores that water cant get into
True porosity- pros and cons
better then apparent, hard to find B
Cermanics - mechanical properties (strength)
Higher compressive strength then glass, highest tensile strength
Cermanics- price
non technical cheap- technical not cheap
Ceramics- Thermal and electrical conductivity
big range for both
Manufacturing ceramics step 1
combine slurry and water
Manufacturing ceramics step 2 and 3
shape and heat to get rid of water
Cons of manufacturing ceramics by hand
leaves micropores
What would happen to a ceramic with micropores in freezing conditions
cracks would propogate as water exapand
How to fix internal pores through manufacture
Coat in ash and then it will penetrate it and then form a glass inside- porcelain
Modern ceramic manufacturing
Uses powder- shape- then sinter
What is sintering
High temp allows movement of atom at grain boundaries
Powder pressing describe
compact powder into mould and then compress
Slip casting
Slip is water and ceramic- creates hollow thing as it can let the water through the mould
Tape casting
Produces flexible films- like pasta- conveyer belt- heat
Are ceramics chemically inert
yes
