17938709
Descrição
Mapa Mental por Alice Dolman, atualizado more than 1 year ago
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Criado por Alice Dolman
mais de 5 anos atrás
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Describe the process of sintering
during the laboratory fabrication of a
ceramic restoration.
- "Sintering is the process of compacting and forming a solid mass of material by heat or pressure without melting
it to the point of liquefaction. The heating cycle causes the particles in the mix to bind together by a process
called sintering. This is when particles in close proximity to each other are heated to a point where their edges
and corners start to become rounded, and they stick together. "
- 1. Initially, the unfired or "green" porcelain is placed onto a saggar,
and the saggar is placed within the furnace muffle.
- 2. The liquid binder is driven off and the
porcelain becomes brittle and chalky.
- 3. At this stage, the green porcelain is introduced into the hot zone of
the furnace and the temperature is raised to the firing temperature of
the porcelain
- It is best at this stage if the powder is regarded as a glass powder.
- It is best at this stage if the powder is regarded as a glass powder.
- 4. During firing the glass particles soften at their contact points
(grain boundaries) and fuse together.
- This partial fusion is often referred to as sintering.
- This partial fusion is often referred to as sintering.
- 5. As the furnace temperature is raised to the firing temperature of the
porcelain the original air spaces left after condensation of powder escape
via the grain the boundaries of the glass powder by the action of surface
tension.
- 6. As the air is removed from between the powder grains before
sealing of the surface occurs, there is nothing to prevent the porcelain
from shrinking to a pore-free mass.
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