Ch 6 - Biomaterial Processing

Question 1

How do we strengthen materials?

Answer 1

Reduce dislocation (slip/slide) motion ∴ more energy necessary for plastic deformation

Question 2

Strengthening bulk prop’s: Metals

Answer 2

• \alloying = point defects (cancel lattice strain)
• \strain hardening = linear defects (↑ # dislocations)
• \grain size = planar defects (↓ size = misalignment)
• \precipitation hardening = volume defects (precipitates → local lattice strain → prevents dislocation)
• \annealing = heating to ↑ ductility (↑ grain size)

Question 3

Strain hardening

Answer 3

• Metal becomes stronger as it is plastically deformed
• During plastic defor., con’t ↑ # of dislocations → increasing force to overcome
* aka \cold working b/c carried out at low T (w.r.t T_m)
** Concomitant ↓ ductility and ↓ corrosion resistance

Question 4

Strengthening bulk prop’s: Ceramics

Answer 4

Dislocation mvmt already difficult b/c ionic bonds

Question 5

Strengthening bulk prop’s: Polymers

Answer 5

Can improve strength by:
• ↑ % X-talinity (slow cooling → more alignment)
• ↑ Crosslinking (reduces chain sliding)