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jman785
12/22/2004, 12:01 AM
Does Titanium corrode in saltwater? What about if say 12 volts is applied to it? Thanks Randy
Randy Holmes-Farley
12/22/2004, 08:12 AM
It corrodes slowly. Slow enough that it is often a chosen metal of for salt water appliations.

The voltage will have a huge impact. Depending on whether it is + or - 12 volts (or AC), then it may either rapidly corrode, or be protected.

Can you explain more about why you are asking?
jman785
12/22/2004, 10:51 AM
Well I was just pondering the idea of Titanium and NaCl...but I'll end up using nails...I'm doing a science project with my good friends daughter. Electrolysis of saltwater...but I have to successfully make Iron Oxide (Rust) in the process, by using a nail or something to corrode and rust. The Ti, was just me pondering some ideas. Do you know of any metals that are salt resistant, and could have 12 or so volts running through them as well?
Randy Holmes-Farley
12/22/2004, 10:57 AM
Platinum or gold, maybe. They are certainly salt resistant. The issue is that the voltage can drive the oxidation and dissolution of most any metal, even gold and platinum.

Electrolysis of seawater is also potentially dangerous. You may generate hydrogen (H2), oxygen, and chlorine (Cl2).
jman785
12/22/2004, 11:03 AM
Basically the anode will corrode a lot faster than the cathode correct?
jman785
12/22/2004, 11:04 AM
Randy,

There is a fume hood, nearby, no worries mate.

So should the nail, in order to form Iron Oxide, be on the anode?
Randy Holmes-Farley
12/22/2004, 01:35 PM
To drive Fe to Fe+++, you want to suck electrons out, so it needs to be the positive electrode (the anode). That would be true of all metals corroding. :)
jman785
12/22/2004, 08:12 PM
So does the cathode still have to be in the NaCl solution? Or does it have to be there at all?
Randy Holmes-Farley
12/23/2004, 07:53 AM
To do electrolysis, there needs to be some sort of electrical connection between the anode and the cathode through the water. One could put them in the same solution, or one can have a salt water connection between them, usually called a salt bridge (such as thin tubing filled with salt water).
jman785
12/23/2004, 10:36 AM
Randy,

I know this isn't really reef related and I appreciate the help :)

Can you further explain the salt bridge?
Randy Holmes-Farley
12/23/2004, 01:09 PM
No problem. :)

This web site explains it pretty well (at least it looks like it does at a quick glance):
http://library.kcc.hawaii.edu/external/chemistry/everyday_electro.html