Titanium knives with carbidized edge: What are they, why are you making them, and how are they made?
(Quote Originally Posted by Ban)
Most people think of Titanium knives as novelty items that hold very little practical value unless you are a diver (recreational, professional/commercial, EOD, etc). For the most part it is true. Titanium is soft, relative to steel, and it wont hold an edge like a good heat-treated steel blade will. However, to the average civilian user, titanium offers a high strength-to-weight ratio, superior corrosion resistance, and a tough and ductile edge (so chipping shouldnt be an issue).
Now, add some tungsten carbide to the mix and things start to look even more favorable for the titanium blade. Tungsten carbide is extremely hard; its a 9 in the Moh scale. A measurement of hardness on the Moh scale does not readily convert to the Rockwell C measurement most of us are familiar with, but I think it would be roughly in the mid 80's. If we apply a tungsten carbide edge to a titanium blade, we end up with a very low maintenance (effectively rustproof) piece of cutlery that can hold an edge just as well if not better than most quality steel edges. When a titanium blade is given a decent edge geometry, the carbide allows the titanium to hold a good edge and cut well.
Ive been able to slice slivers of paper easily with a polished carbidized titanium blade. While it could no longer easily and cleanly slice paper after about 25-30 cuts through cardboard, I know it could have kept cutting cardboard for much longer without a problem. I have had a few guys put their carbidized Ti knives through the ringer, and all of them are amazed at how well the edges hold up and how easy they are to maintain. One guy used his knife to cut and lay up a yard full of sod. Needless to say the knife was dull afterwards from all the sand and various other grits in the soil, but it required minimal work to bring the edge back to working order. People have reported their Ti knives functioning well in a variety of tasks, including food prep, working with wood, and taking apart abrasive packaging materials (e.g. cardboard).
I, and others, have noticed that the carbidized edge will still cut very well even when it feels dull. In fact, the carbide edge can almost be considered self-sharpening: since the carbides are only applied to one side of the titanium blade edge, more carbide is exposed as the titanium wears away on the other side. This is similar to the self-sharpening phenomenon observed with the teeth of beavers. Actual sharpening of a carbidized titanium edge is very simple. See the sharpening and maintenance questions further along in this FAQ for more detail.
So why carbidized Ti knives? I think these knives should work well in the kitchen, where they would be cutting relatively soft, non-abrasive, material (veggies, fruit, meat) in a wet and corrosive environment. Titaniums superior corrosion resistance, coupled with the easily maintained carbide edge, makes these knives perfect for every day kitchen duty. I also suspect that carbidized Ti knives will catch on with the ultralight hiking/backpacking crowd. A strong, lightweight, and very low maintenance knife sounds ideal for the ultralight backpacker - someone who typically isnt out there building log cabins or doing things that require a fine edge.
How do I get the tungsten carbide onto the titanium? I currently use The Carbidizer from Travers Tool Co., Inc. Basically, this tungsten carbide applicator electronically embeds the carbides into the titanium. You can sort of think of it as a micro-weld, although no heat is generated. While Im sure its not as fast or as powerful as the Rocklinizer, it does the job for me for now. I am currently looking into more powerful unit, which is supposed to be very close to the Rocklinizer for increased speed.
How do you sharpen carbidized Ti BT knives?
(Quote Originally Posted by Ban)
As I touched upon in the Carbidized Ti knives FAQ question, the tungsten carbide is only applied to one side of the edge on the Ti knives. To sharpen the carbidized knife, you have merely to sharpen or strop the titanium side of the blade/edge to expose more carbides and thereby refresh the cutting edge. Do not sharpen the carbide side of the edge; you will only remove carbides from the titanium substrate.
You should very rarely need to do more than strop the non-carbide side of the blade on a compound-loaded strop. In fact, before you even hit a strop, you should first steel the edge to straighten any rolls and align the edge. Often, a good steeling is all thats really needed to return a carbidized Ti knife to a utility edge. The guy discussed above who sodded an entire yard with the help of a carbidized Ti necker, brought a working edge back to his knife with only a bit of steeling and a couple of passes on a compound-loaded strop. If you have and are adept with a belt grinder, the process is even easier
three seconds on a leather belt and the edge is brand new again.
) and after searching bladeforums this is the best info I found.