Metallic biomaterials
This presentation is the property of its rightful owner.
Sponsored Links
1 / 16

Metallic Biomaterials PowerPoint PPT Presentation


  • 79 Views
  • Uploaded on
  • Presentation posted in: General

Metallic Biomaterials. Metals Are Crystalline. Body-Centered Cubic.

Download Presentation

Metallic Biomaterials

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


Metallic biomaterials

Metallic Biomaterials

CHEE 340


Metals are crystalline

Metals Are Crystalline

Body-Centered Cubic

The body-centered cubic (bcc) crystal structure: (a) hard-ball model; (b) unit cell; and (c) single crystal with many unit cells. Source: W. G. Moffatt, et al., The Structure and Properties of Materials, Vol. 1, John Wiley & Sons, 1976.

CHEE 340


Metal bonding

Metal Bonding

  • The electrons in metals are mobile and surround a core of cations. This gives rise to their high electrical conductivity.

CHEE 340


Crystals and grain formation

Crystals

Grain Boundary

Grain or Crystalline Structure

Crystals and Grain Formation

CHEE 340


Product manufacture

Product Manufacture

  • There are 4 main methods of metal product manufacture:

  • machining

  • melt casting

  • forming

  • hot isostatic pressing (sintering)

CHEE 340


Influence of manufacturing process

Influence of Manufacturing Process

Casting Defect

Polished-etched view of a cast ASTM F75 femoral hip stem. Note dendrites and large grains

In vivo fracture initiated from an inclusion formed during the casting process

From : H. Alexander et al., Chapter 2, Biomaterials Science, BD Ratner et al., Academic Press, 1996.

CHEE 340


Metallic biomaterials1

Metallic Biomaterials

  • There are 3 main groups of metals used as biomaterials:

    • stainless steels

    • Co-based alloys

    • titanium-based alloys

CHEE 340


Design considerations

Design Considerations

  • typically want to match mechanical properties of tissue with mechanical properties of metal

  • have to consider how the metal may fail in vivo

    • corrosion

    • wear

    • fatigue

  • need to consider cost

CHEE 340


Mechanical properties

Mechanical Properties

CHEE 340


Corrosion

Corrosion

  • The extra-cellular environment is a chemically aggressive space. Metallic biomaterials are good conductors in an electrolyte solution, leading to galvanic corrosion.

CHEE 340


Corrosion1

Corrosion

CHEE 340


Mechanisms of corrosion

Mechanisms of Corrosion

  • Crevice Corrosion

  • Pitting Corrosion

  • Intergranular Corrosion

CHEE 340


Mechanisms of corrosion1

Mechanisms of Corrosion

  • Fretting CorrosionStress Corrosion Cracking

CHEE 340


Mechanisms of corrosion2

Mechanisms of Corrosion

Contribution of biological environment

From : S.H. Teoh, International Journal of Fatigue 22 (2000) 825–837

CHEE 340


Metallic biomaterials

Wear

  • The effects of wear are most predominant in joint prostheses.

  • There are two types of wear :

  • Interfacial Wear: Occurs when bearing surfaces come into contact with no lubricant fluid between them.

  • Fatigue Wear:Progressive failure due to application of cyclical stresses.

CHEE 340


Fatigue

Fatigue

CHEE 340


  • Login