Can ceramics be thermomechanically processed? and why?
No they cannot because they do not deform plastically.
1 of 20
Name the general steps of powder processing?
1)Powder is shaped into desired geometry.2)A binder is used to make the powder stick together creating a 'green' component'.3) Which is dried and fired at a high temp which is below the T_m of the powder.4) Creating a dense solid.
2 of 20
What production methods are used to create a bulk ceramic?
Die-pressing,injection moulding, slip casting
3 of 20
What production methods are used to create a thick ceramic(10-100μm)?
Tape casting,screen printing,plasma spraying of powder suspension
4 of 20
What production methods are used to create a thin ceramic(0.01-10μm)?
Gel processing or vapour deposition methods.
5 of 20
What production methods are used to create a ceramic fibres?
Spinning from gel solution or suspension.
6 of 20
Describe die-pressing
1)Powder mixed with small amounts of lubricants and binders.2) The mixture is compacted in a steel die at high pressure.
7 of 20
What is plastic forming?
1)Powder is added to liquid additive and a paste is formed ('plastic powder).2) The paste is shaped by 'throwing' or 'turning' a pot (potters wheel)
8 of 20
Explain Extrusion
Creates long components with a constant cross-section. Water and additives are added to ceramic powder and are continuously squeezed through a shape/mould.
9 of 20
Describe Injection mouling
Creates thin-walled compomemeys with complex shapes. Pressure is added to the green components in a single mould.
10 of 20
What is Drain('slip')casting?
Ceramic powder is mixed with water using dispersants (this is the 'slip'). Excess slip is poured out and the components is allowed to dry before removed.[the mould is porous-water leaves mould and the ceramic components are left behind]
11 of 20
What does sintering do?
It transforms a 'green' porous powder compact into a dense solid. It 'fills' in the space between particles.
12 of 20
How does sintering work?
The spaces between particles are filled by mass transfer. Particles coalesce and change shape to provide better packing efficiency. This leads to the reduction of of porosity and thus a denser et smaller product.
13 of 20
Define Mass transport
The transfer of mass form particles to the contact points between them. Causing the contact area between particles to grow.It is driven by solid state diffusion.
14 of 20
Explain in detail how 'liquid phase sintering' works?(mass transporting)
Flux is created when the particles are of different composiions so some melt at low T_m. The flux wets the solid particles and acts like a glue. The liquid phase also lubricate the particles allowing rearrangement.
15 of 20
What does the effectiveness of the sinter detrmine?
The porosity level which determines the properties of the ceramic.
16 of 20
What properties would a reducing the sintering time of a ceramic produce?
It would result in better insulating properties.
17 of 20
What role does the liquid surface tension have in Liquid phase sintering?
It pulls the particles together.
18 of 20
How else can densification occur during liquid phase sintering?
Solid particles can also partially dissolve in the liquid phase, which causes particle re-shaping and densification.
19 of 20
What is tape casting?
A ceramic slip containing polymeric plasticisers and binders is cast onto a moving carrier film (where there is a blade which runs over the ceramic to flatten it)
20 of 20
Other cards in this set
Card 2
Front
Name the general steps of powder processing?
Back
1)Powder is shaped into desired geometry.2)A binder is used to make the powder stick together creating a 'green' component'.3) Which is dried and fired at a high temp which is below the T_m of the powder.4) Creating a dense solid.
Card 3
Front
What production methods are used to create a bulk ceramic?
Back
Card 4
Front
What production methods are used to create a thick ceramic(10-100μm)?
Back
Card 5
Front
What production methods are used to create a thin ceramic(0.01-10μm)?
Comments
No comments have yet been made