“ Nanodization ”

1. “Nanodization” Titanium Anodization for various useful applications!

2. Introduction • My name is Ricky • Going into 4A Nanotech Engineering • Currently on co-op with Waterloo Engineering Outreach

3. A bit about WE-Connect • Community and youth engagement through educational and innovative programs • Engineering Science Quest (ESQ) and Catalyst are our two biggest programs

4. What is nanotechnology? • Official definition from the Canadian government: “Nanotechnology is the application of scientific knowledge to manipulate and control matter in the nanoscale to make use of size- and structure-dependent properties and phenomena distinct from those associated with individual atoms or molecules or with bulk materials. The term "nanoscale" is defined as 1 to 100 nanometers (nm) inclusive.” • Very broad definition, because it is broad! Examples of nanotechnology in nature: Setae on a gecko, hydrophobicity of lotus leaves, strength of silk, etc.

5. Why Nano?

6. Titanium • Atomic number 22. Relatively inert, high strength to weight ratio • Uses: aerospace, medical, JEWELLERY

7. Anodization • The electrolytic process of growing oxides on metal surfaces • The metal oxide layer is usually more wear and corrosive-resistant • Oxide layers can be anywhere in the nano to micro meter range • Popular use: anodized aluminum

8. Titanium Anodization • Allows for colorization of titanium without the use of paints or dyes • Titanium oxide that forms is more durable than the metal itself • Useful for: car parts, electronics, etc

9. Mechanism • Titanium metal reacts readily with oxygen at SATP which creates a thin (~2nm) passivating oxide layer. • When the titanium is used as an anode (positive) and a current is passed through, an electric field occurs in the oxide layer. This prevents electrons from flowing into the metal from the electrolyte. • When the voltage is increased, the field strength increases until it is strong enough to push the ions in the oxide to the metal/oxide and oxide/electrolyte interface

10. Mechanism, Continued • Interesting things to note: • Oxide grows from 2 fronts • The oxide thickness is proportional to the voltage applied

11. Where does the colour come from? • Thin-film interference! • Phenomenon where light reflects off the top and bottom surfaces of a transparent thin-film • The difference in path length will cause the light to constructively and destructively interfere and make the film appear to be a certain colour

12. On to the actual activity.. What you need to anodize titanium: 1. A sample of titanium 2. A power source (anything from a variable voltage bench-top power supply to multiple 9V batteries) 3. An electrolyte (we’re using sodium borate, street name: Borax) 4. Wires (alligator clips optional) 5. Counter electrode (scrap piece of titanium, stainless steel, etc) 6. Gloves

13. Procedure • Connect the titanium to be anodized to the positive terminal of the power supply • Connect the counter electrode to the negative terminal of the power supply • Make a solution of borax and distilled water (~4% which is close to saturation) • Submerge both electrodes into electrolyte solution, taking care to make sure that they do not touch each other. • Turn on the power supply (or complete the circuit in the case of 9V batteries) • Wait…. • Done!

14. As a teaching tool… • Titanium anodization can be a valuable teaching tool because: • Low cost • Low safety risk • High impact • Materials are relatively easy to obtain

15. Sources of Titanium • Online! • http://www.apmbodyjewelry.com/ • Titanium manufacturers • Scrap pieces from parts processing • University/college machine shops/labs

16. Thank you!!Questions can be directed to r2tjandr@uwaterloo.ca