.

Carbide is very brittle and would not hold up in acute edges, you will notice that all of your carbide tools in the tool room have angles at the cutting edge much more obtuse (like 45 degrees in most metal working applications and down to 30 degrees min. in wood working) than what is required for a knife edge, down around 20 degrees, inclusive.
 
+1 on that. I have made tungsten carbide cutters in the machine shop. and anything with an edge more acute than about 40 chipped right away. it is a nice idea though, but i dont think most want to deal with such a wide edge angle. also, sharpening would not be cake either.
 
You'll find tungsten carbide welded onto the edges of knives done in titanium. The Ti won't hold an edge, but it also won't corrode and is lightweight. The tungsten carbide is hard and brittle and give a toothy, micro-serrated edge.
 
RandomAyes said:
I feel that WC would be chip-resistant enough for many normal uses, and at the same time it would far surpass most steels (if not all steels) in terms of edge-holding.

.
Click to expand...

I would expect that it would far surpass most steel in edge holding in abrasive applications when used in light duty cutting or at a more obtuse edge angles than could be done in steel.

There are three primary mechanisms where an edge dulls.

1. Wear such as abrasive wear and adhesive wear (carbide would do well here)
2. Gross edge damage such as chipping, rolling and tearing (carbide would do poorly here)
3. Chemical, where an edge erodes due to corrosion (carbide would do fair here)

Carbide is difficult to sharpen by hand, even on diamond stones, because it is not ductile. So a fine edge tends to crumble away rather than get super sharp.

For these reasons, I think you will find it difficult to find a material that combines hardness, toughness and ease of sharpening better than steel.

I was watching the cutting competition at Blade last weekend and I wondered if tungsten carbide could play a roll in the competition knives. Not as the cutting edge (too brittle), but as the spine. The edges on these knives are very thin, but the spines are very thick, but the same stiffness and weight could be done with carbide in a thinner section and thus perhaps cut better?
 
Nathan the Machinist said:
I would expect that it would far surpass most steel in edge holding in abrasive applications when used in light duty cutting or at a more obtuse edge angles than could be done in steel.

There are three primary mechanisms where an edge dulls.

1. Wear such as abrasive wear and adhesive wear (carbide would do well here)
2. Gross edge damage such as chipping, rolling and tearing (carbide would do poorly here)
3. Chemical, where an edge erodes due to corrosion (carbide would do fair here)

Carbide is difficult to sharpen by hand, even on diamond stones, because it is not ductile. So a fine edge tends to crumble away rather than get super sharp.

For these reasons, I think you will find it difficult to find a material that combines hardness, toughness and ease of sharpening better than steel.

I was watching the cutting competition at Blade last weekend and I wondered if tungsten carbide could play a roll in the competition knives. Not as the cutting edge (too brittle), but as the spine. The edges on these knives are very thin, but the spines are very thick, but the same stiffness and weight could be done with carbide in a thinner section and thus perhaps cut better?
Click to expand...

Actually, a less brittle tungsten alloy might work really well for that.
 
I have tried it on a couple of knives in the past, and they didn't turn out very good, they were chisel ground warnclifs, and I was having all sorts of trouble betting it flat, with an acute enough angle, and sharp. But I got a new piece custom made
20110610175515181.jpg
out of a tougher grade of carbide. its 3" long and 1/32" thick, which seemed allot thicker until I got it in hand. My plan is to laminate it between carbon fiber plates. but I'm kinda scared to grind it it seems so thin. I hope that since it is tougher than the last piece of carbide, and has a nice curve and is thinner, it will be easier to get a sharp durable edge.

Nathan I chose CF because it was so stiff, it is much stiffer than titanium, but less stiff than TC. I really dont want this thing snapping in two it was expensive!
 
Nebulae said:
Nathan I chose CF because it was so stiff, it is much stiffer than titanium, but less stiff than TC.
Click to expand...

I'll be darned. Carbon fiber is actually stiffer than titanium.

I figured you were off your rocker, but I looked it up and you're right, it can be almost as stiff as steel. (Young's modulus in some directions as high as 26,300 KSI, Steel = ~ 30,000 KSI, titanium ~16,000 KSI)

I've always thought of it as just a fancy fiber reinforced plastic and expected it to be literally an order of magnitude lower than that. Neato.
 
its actually really pronounced in real life especially tubes, or other shapes with naturally high flexural strength, (I bet a CF I beam would be incredible) because you are holding this thing that weighs almost nothing, and you can't bend it at all. you expect a heavy piece of steel to be stiff, but not something so light its weird.

EDA: just to stay on topic, anybody know anything about Cryo treating TC? I have seen some research (one paper, and some Cryo providers websites) saying it increases hardness, wear resistance, and toughness, because of some funky stuff (like a phase transition) happening to the cobalt binder. So should I send it out, I'm kinda scared it will get broken somewhere along the line.
 
Last edited:
I have no personal experience with the process or knives made with it, but I have heard of Ti and similar non-ferrous blades being coated with carbide at the very edge. Apparently this is a cool thing to have if you need a non-magnetic knife. (EOD techs and such). Of course it can also be done to regular steel.

Rocklin Carbizer at USA Knifemaker

Tracy just started selling these units and is offering to treat one blade per customer for testing purposes. (Contact him with any questions, I'm not affiliated with USAKnifemaker except as a customer.)

"How does a carbidizer work" thread here on BF; there may be more, I didn't search very hard :o
 
Last edited:
I started two WC blades several years back. It took forever using lapidary diamond equipment to form the bevel on the one.....and was even longer lapping it sharp. I never finished the second one. It was a skinner, and the person who had me make it said it cut like crazy.I don't know if the edge lasted or not. The second one was for me, and still sits in a drawer somewhere ,shaped but not beveled.
 
Tungsten carbide (WC) has a RWC hardness of 72. ZDP-189 is only taken to 67 RWC. Carborundum (SiC) abrasives were developed to sharpen WC tool bits. The Rocklinizing process applies Tungsten carbide to steel blades and Titanium carbide to Titanium blades. Titanium carbide has a RWC hardness of around 80. The carbide coating treatment puts a hard layer over a softer substrate which resuls in a practical working tool such as a Titanium fillet knife (flexible with great wear resistance). If you apply the carbide coat to the flat side of a chisel sharpened blade, the knife becomes self sharpening as the blade material wears away in preference to the coating and exposes more of the coating.
 
tiguy, I've read a little about "normal" steel blades as well as non-ferrous blades C1S* with tungsten carbide, and their reputed long-wearing, self-sharpening properties. I'm very interested if anyone has some sort of test results comparing such blades with knives made in the usual manner. I'm curious if a blade made that way would equal or surpass one made from high-alloy steel like CPM-154, CTS-XHP etc in terms of strength and edge-retention.

*C1S= coated, one side... it's a paper industry term, no idea if it's in use with machinists or knifemakers.
 
Last edited:
I've come across knives that had stellite applied to the blade edge. I suppose you could heat up a stellite rod and drip it onto the edge that has been undercut, much like they used to do with automobile valves. It's very hard and a knife blade coated with it would hold an edge and not be brittle.
 
you'll see some solid carbide edges on knives when I finish... got some chisel edged pieces ready now, bevels are done just some finish work and handle to go...

just carbidized an O-1 blade while at the Blade show on the weekend, it was a bit difficult to resharpen after but testing the edge soon now that I'm home
 
Mete I had already seen that paper after weeks of searching.:p Thanks anyway though, its good to look it over.
 
I had 2 knives carbidized at the Blade show (thanks to Chris Rosener). Both were Kitchen (chef's) knives. Both were chisel sharpened prior to Rocklinizing (carbidizing). The coatings were applied to the flat (non-bevel) side. One knife (an 8" Sabatier chef knife) was coated with Tungsten carbide (RWC 72). The other knife (a 7" Boker beta Titanium chef knife) was coated with Titanium carbide (RWC 80). Since I got home from the Blade Show, I have put both knives in the front row. I am anxious to see how they retain their edges and whether they are self sharpening. This will probably take some time, but if I am favorably impressed, I will post my impressions. If I am unfavorably impressed, I will try to find out if I screwed up, because the theory says that the process should work.
 
You can get blades made out of Stellite 6B and 6K. They are quite expensive because of the wear resistance and the resultant use of many grinding belts in the stock removal process. David Boye gets around the stock removal problem by pouring his blades in ceramic molds. Since the blades are half Cobalt and half Chrome, the base prices are $100 and $265 per pound respectively. A really good steel might fetch $40/ pound. Chisel sharpened ceramic coated blades were marketed by Buck in the late 90's. The 3 coatings offered were Titanium Nitride (TiN), Zirconium Nitride (ZrN), and Titanium Aluminum Nitride (TiAlN). These coatings are also used on drill bits and milling cutters. The colors were gold, champagne, and charcoal respectively, and the hardnesses (RWC) were 82, 86, and 92 respectively. I have used all three of these coated blades and have been very favorably impressed with their performance in terms of edge holding and corrosion resistance. An added bonus, the blades have such a hard finish that they can be used as a finishing steel for other blades. Another bonus, since the blades are chisel sharpened, they are inherently twice as sharp as a double bevelled edge.
 
You must log in or register to reply here.
Back
Top