Metals and Alloys Flashcards Preview

BDS2 CLINICAL Dental Materials > Metals and Alloys > Flashcards

Flashcards in Metals and Alloys Deck (70)
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1

What are metals and alloys used for in dentistry

RPD framework
crowns
denture base
orthodontic appliance
restorations

2

What metal/alloy is used in partial denture framework

cobalt chrome
type IV gold

3

What metal/alloy is used in crowns

stainless steel

4

What metal/alloy is used in denture base

stainless steel

5

What metal/alloy is used in orthodontic appliance

NiTi

6

What metal/alloy is used in restorations

amalgam

7

Why do we use metals

They have superior mechanical properties

8

What are the superior mechanical properties of metals

strength
rigidity
elastic limit
ductility
hardness

9

What are the disadvantages of metals

poor aesthetics

10

What is the definition of a metal

aggregate of atoms in a crystalline structure

11

What is an alloy

combination of metal atoms in a crystalline structure

12

What are the building blocks of alloys

metals

13

What is ductility

Ductility is a measure of a metal's ability to withstand tensile stress—any force that pulls the two ends of an object away from each other

14

What is malleability

Malleability is a substance's ability to deform under compressive stress

15

What is the elastic limit

maximum stress without plastic deformation

16

What is the UTS

ultimate tensile strength

17

What is ductility defined as

amount of PLASTIC DEFORMATION prior to fracture

18

What do mechanical properties depend on

choice of metal
crystalline structure

19

What does the crystalline structure depend on

history - method of production
shaping - crucial for dental applications

20

What are the factors that affect mechanical properties

crystalline structure
grain size
grain imperfections

21

What is a grain

a single crystal

22

What is a crystal

a lattice arrangement

23

What are different crystal/lattice structures

cubic
face centre cubic
body centre cubic

24

In the cooling curve of a pure metal what is the straight line

plateau phase

25

What does the plateau phase mean in a pure metal

the melting point
changes from liquid to solid

26

Describe the process crystal growth

1. atoms act as nuclei of crystallization
2. crystals grow to form dendrites
3. crystals (or GRAINS) grow until they impinge on other crystals

27

What is the nuclei of crystallization

the centre of around which other atoms will crystallite

28

What are dendrites

3D branched lattice network

29

What is the region where grains make contact called

the GRAIN BOUNDARY

30

What parameters can effect the size and shape of grains

how you process it
which container you use to cool it