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Biomaterials 2 > Ceramics > Flashcards

Ceramics Flashcards

1
Q

What are the useful properties of Ceramics? (7 things)

A
  • High melting points
  • good resistance to heat
  • good chemical stability (they don’t oxidise)
  • very high elastic modulus
  • very high hardness
  • light
  • high compressive strength
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2
Q

What are the less useful properties of ceramics? (3 things)

A
  • Brittle
  • Sensitive to microcracks
  • Tensile strength is low
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3
Q

What is Morphological Fixation?

A

Cementing the device into tissue or press fitting into defects

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4
Q

What is biological fixation?

A

Ceramics attach by bone ingrowth

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5
Q

What is Bioactive fixation?

A

Ceramics attach by chemical bonding with bone

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6
Q

What is Resorbable fixation?

A

Ceramics are slowly replaced by bone

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7
Q

What are the 4 different types of ceramics?

A

Non-porous, porous, non-porous bioactive, resorbable

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8
Q

What is sintering?

A

Compacting and forming of a powder by pressure or heat without reaching the melting point

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9
Q

What is hot isostatic pressing

A

using an inert gas (argon) to create high pressure on the material

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10
Q

What are examples of a non-porous ceramic?

A

Aluminium Oxide, Zirconia

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11
Q

Tell me everything you know about aluminium oxide?

A
  • A non-porous ceramic
  • Single crystal alumina
  • Strength increases with grain size
  • Elastic modulus 360 - 380 GPa
  • low friction and wear properties
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12
Q

What are some applications of aluminium oxide?

A
  • Femoral Heat
  • Bone screws and plates
  • Knee prosthesis
  • Dental crowns and bridges
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13
Q

Tell me everything you know about Zirconia?

A
  • Non-porous
  • 2nd hardest material known
  • complex tetragonal crystal structure
  • higher fracture toughness than aluminium oxide
  • Youngs modulus of 250GPa
  • you can make a smooth surface
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14
Q

What have been the historical problems with Zirconia?

A

A change in the processing of the material leads to a slight change in the structure which lead to failure of 400 femoral heads

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15
Q

What is glass?

A

Amorphous solid that lacks detectable crystallinity

an inorganic product of fusion that has cooled to a rigid condition without crystallisation

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16
Q

What are some examples of bioactive ceramics or glasses?

A

Bioactive glass and Calcium hydroxyapatite

17
Q

What is Calcium Hydroxyapatite?

A

The primary structural component of bone

18
Q

what is bioglass?

A

A glass that can bind to bone
it is very sensitive to composition
made of silicon oxide, calcium oxide and sodium oxide

19
Q

Applications of Calcium Hydroxyapatite

A
  • Coatings for metallic implants
  • Bone filler
  • Provides a scaffold and encourages the filling of bone defect by naturally forming bone
20
Q

What is an Example of Resorbable Ceramics?

A

Calcium Phosphate

21
Q

Calcium Phosphate

A
  • Abundant in nature and in living systems
  • The phase depends on the ratio of calcium to phosphate
  • the most stable phase of calcium phosphate is hydroxyapatite
22
Q

How is Calcium Phosphate resorbed

A
  • Physiologic dissolution
  • Physically Disintegration into small particles as a result of preferential chemical attack of grain boundaries
  • Biological factors, phagocytosis causes a decrease in local pH concentration
23
Q

What is an example of a non-porous ceramic

A

Pyrolytic Carbon

24
Q

Tell me everything you know about Pyrolytic Carbon?

A
  • Similar structure to graphite
  • made by heating to very high temps in the absence of oxygen
  • used as a coating material
25
Q

Applications of Pyrolytic Carbon?

A

Very good blood-contacting properties so, therefore, used to coat heart valves and stents

26
Q

Advantages of Ceramics as Biomaterials

A
  • Inert or bioactive
  • High wear resistance
  • High youngs modulus and compressive strength
  • Esthetic or dental applications
27
Q

Disadvantages of Ceramics as biomaterials?

A
  • Brittle
  • Low tensile strength
  • Poor Fatigue resistance

Biomaterials 2 (14 decks)

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