Ceramics

Question 1

Talk about Feldspar

Answer 1

unhydrated aluminaum silcate=potassium feldspar
when subjceted to high temp.–>crystalline form
crytsalline form is leucite
High strength
High thermal expansion
diff. shades of opacity
forms a glassy phase but dont affect esthetics
main bulk of ceramic as it presents with high %
75-85 %

Question 2

Silica

Answer 2

12-22

act as strengthening & esthetic agent

Question 3

Kaolin

Answer 3

act as binder
form workable mass
increase modulability
increase sever opacity--> decrease eastheics
modern ceramics are free from kaolin
3-5 %

Question 4

what are other ingredients

Answer 4

1

Question 5

talk about fluxes

Answer 5

1

Question 6

talk about glass modifiers

Answer 6

1

Question 7

talk about sugar & starch

Answer 7

1

Question 8

talk about coloring pigments

Answer 8

1

Question 9

talk about lanthamide earth

Answer 9

provide fluroscnece

Question 10

Talk about vitrification

Answer 10

1

Question 11

Talk about devitrification

Answer 11

1

Question 12

What are the things that decrease during devitrfication

Answer 12

1

Question 13

what is the main disadvantage of ceramic

Answer 13

1

Question 14

what are factors of crack propagation

Answer 14

1

Question 15

what is compaction

Answer 15

1

Question 16

what is firing

Answer 16

1

Question 17

what is the alternative step to firing

Answer 17

slip casting technique

Question 18

what is the step of glazing

Answer 18

1

Question 19

what are 2 types of glaze

Answer 19

auto (self) internal glaze

external (added) glaze

Question 20

what are the disadvtanges of external glaze

Answer 20

1

Question 21

what is the cooling

Answer 21

1

Question 22

what are properties of porcelin

Answer 22

shrinkage
porosity
chmecial
biological
inert
mechanical
esthetics

Question 23

why poreclin should be about 13% oversized

Answer 23

to prodce minimum shrinkage & less porosity

Question 24

How to strength ceramic materials or increase fracture toughness

Answer 24

Design components in restoration
Decrease number or size of stress raisers
Usage of diff.phases of diff. materials to X crack prop.

Relie on toughness of crystals : cystalline phases of leucite & lithium disilicate

Relie on transforming toughness of crystalls
Devolpment of compression stresses

Question 25

What are classification of ceramic

Answer 25

1