What are the pros of using 316L stainless steel as a biomaterial?
- Good corrosion and fatigue resistance in short term applications
- low cost
- easy to machine
What are the cons of using 316L stainless steel as a biomaterial?
- Tend to corrode in long term applications
- high modulus which leads to the stress shielding effect
- Nickle and Chromium allergies are common
What are the typical biomaterial applications of 316L stainless steel?
temporary implants such as fixations, screws and plates
What are the pros of using Co-Cr alloys as biomaterials?
- Excellent corrosion resistance
- Excellent fatigue/wear resistance
- biocompatible
What are the cons of using Co-Cr alloys as biomaterials?
- difficult to machine
- Expensive to process
- high modulus - stress shielding effect
- High density
- Co and Cr particles can cause allergies
What is the stress shielding effect?
Reduction in the density for bone due to an implant having a higher modulus to bone and therefore bone is unloaded
Typical biomaterial applications for Cr-Co alloys
- Dental replacements
- Hip replacements
- Heart Valves and Stents
- Permenent implants
Give the crystal structure and important properties for Alpha-Titanium
- HCP crystal structure
- Corrosion resistant
- Biocompatible
What does Biocompatible mean?
When a material is not harmful or toxic to living tissue
Give the crystal structure and important properties for Beta-Titanium
- BCC crystal structure
- Ductile
- Tough
Why would aluminium be added to titanium alloy?
Aluminium is added as an alpha phase stabiliser and hardener, it has a solid solution strengthening effect
Why is vanadium added to a titanium alloy?
vanadium stabilises the beta phase of the alloy and therefore this has ductile properties. This increases the hot workability of the alloy
What are the pros of using a titanium alloy as a biomaterial?
- Lightweight
- Greatest corrosion resistance
- Excellent biocompatibility
- Low youngs modulus
What are the cons of using a titanium alloy as a biomaterial?
- lower shear strength
- low wear resistance
- expensive
what are the typical biomaterial applications for a titanium alloy?
- The stem of knee prostheses
- surface for knee prosthesis
- Dental screws
What is the most exciting property of Titanium-Nickle alloys?
Shape memory effect
What is meant by the shape memory effect? Give two examples
If you deform a material with this quality at a low temperature, when you heat it to a certain temperature it will return to its initial shape
e.g. Stents and staples
