Ceramics And Porcelain Fused To Metal Flashcards
From where ceramics word come from? What does it means?
Greek word-keramos
which literally means ‘burnt stuff’
but
which has come to mean more specifi cally a material produced by burning or firing
First ceramics fabricated were ?
Earthenware pots
Characteristics of earthen ware pots
-opaque, relatively weak and porous and would be unsuitable for dental applications
-consisted mainly of
kaolin
How kaolin can be improved for dental appliances?
The blending of this with other minerals such as silica and feldspar produced the translucency and extra strength required for dental restorations
What is porcelain?
Kaolin Material containing these additional important ingredients(silica & feldspar) was given the name
porcelain
Advantages of porcelain?
- esthetics
- excellent biocompatibility
Disadvantages of porcelain?
- Brittle nature
- large shrinkage
Composition of decorative porcelain?
- Clay (Kaolin)-50%
- Silica -25%
- Binder (feldspar) -25%
4 glasses-0%
Composition of high fusing dental
- Clay (Kaolin)-4%
- Silica -15%
- Binder (feldspar) -80%
4 glasses-0%
Composition of low fusing dental?
- Clay (Kaolin)-0%
- Silica -25%
- Binder (feldspar) -60%
4 glasses-15%
Characteristics of dental porcelain?
- contain little or no clay
- increase in the feldspar contain
- therefore improve translucency
- dental glasses
Characteristics of decorative porcelain?
- a mixture of this with silica, bound
together by a fl ux or binder such as feldspar which
is a mixture of potassium and sodium aluminosili-
cates, K2O·Al2O3·6SiO2 and Na2O·Al2O3·6SiO2
What is kaolin?
hydrated aluminosilicate,
Al2O3·2SiO2·2H2O
What is feldspar?
lowest fusing component and it is
this which melts and fl ows during fi ring, uniting
the other components in a solid mass
The high fusing material?
fuse in the range 1300–1400ºC
