Thoughts on DLC Coating...

Natlek said:
DLC has no corrosion resistance properties ? Who told you that ?? I have a bike with DLC coated front fork tube ...quess what ? No rust after several years ? I do not have a knife with DLC but I have HSS knive with TiN coating ....no way that will ever rust ...
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I read that information on Bladeforums (the hyperlinked thread in my post) and then read some company product descriptions of their DLC coatings to verify. I have not found any information indicating that DLC provides corrosion resistance. If you find different info, I'd be glad to know about it.

In contrast to your fork example, I own many things which are not rusty and do not have a DLC coating. Correlation does not necessarily indicate causation.

The point of my post was that I purchased a knife once thinking that it had a protective coating and it turned out that it had a decorative coating. I posted because I was disappointed when I discovered that, and maybe by mentioning it, the information could save somebody else confusion or disappointment in the future.
 
jazub said:
I read that information on Bladeforums (the hyperlinked thread in my post) and then read some company product descriptions of their DLC coatings to verify. I have not found any information indicating that DLC provides corrosion resistance. If you find different info, I'd be glad to know about it.

In contrast to your fork example, I own many things which are not rusty and do not have a DLC coating. Correlation does not necessarily indicate causation.

The point of my post was that I purchased a knife once thinking that it had a protective coating and it turned out that it had a decorative coating. I posted because I was disappointed when I discovered that, and maybe by mentioning it, the information could save somebody else confusion or disappointment in the future.
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Decorative coating is one thing ... :) DLC coating depends of the thickness of coating above all / it s not the same 3µm and 30µm thickness / and underlayers can be deposited to improve the coating’s performance in certain applications. ... It is not cheap to do it right .
 
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This ZT0180 has been batoned through the better part of a face cord of fireplace-length logs, mostly oak. The coating has not been touched, and the knife looks great after I cleaned it up.

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This ZT0770CFM4 has seen quite a bit of cardboard cutting, I use it to cut down cardboard for target backers, and also used it to make a pile of cardboard backers for posters.

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The coating has held up very well, and the steel on both of these knives is outstanding.

ZT does it right.

best

mqqn
 
DLC is very durable as others examples have shown, hence the name "diamond-like carbon".. true DLC finishes are as hard or in some cases harder than diamond.. As for corrosion resistance they were not developed nor applied for corrosion resistance, but they are typically non reactive. They do however have the side effect of protecting the substrate material from exposure to corrosive envirmental factors especially as most are non porous.
 
I am just using educated guessing here(not a professional by any means) But I would think if there was any kind of reaction/corrosion taking place beneath the DLC coating, you would see it by the coating bubbling or even peeling off, since there is no adhesion to the steel anymore.
That is why I opt'd for the DLC coating on my K390 and the knives other less corrosion resistant parts. It has worked great so far!
 
ATJ999 said:
I am just using educated guessing here(not a professional by any means) But I would think if there was any kind of reaction/corrosion taking place beneath the DLC coating, you would see it by the coating bubbling or even peeling off, since there is no adhesion to the steel anymore.
That is why I opt'd for the DLC coating on my K390 and the knives other less corrosion resistant parts. It has worked great so far!
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Unfortunately, it will still rust. DLC is not a "full" coating, and is porous. The coating won't "chip" or "bubble".

Here's a pic (not mine) of a DLC coated YXR7 Rockstead that had corrosion through the coating:

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My son has a black mora with DLC. It doesn't protect from rust, so what was the point of it again? Coated blade is coated, so I guess you have to like a black on black knife color to appreciate it.
 
Boats said:
My son has a black mora with DLC. It doesn't protect from rust, so what was the point of it again? Coated blade is coated, so I guess you have to like a black on black knife color to appreciate it.
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It's has more use in industrial applications, but on knives, it reduces reflectivity (maybe important for military?) and increases wear resistance to the coated surface. Some like the cosmetics too.
 
Blues Bender said:
It's has more use in industrial applications, but on knives, it reduces reflectivity (maybe important for military?) and increases wear resistance to the coated surface. Some like the cosmetics too.
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I'll take that as "DLC is next to practically useless on knives." It's okay to like the aesthetics. Any other supposed benefit strikes ME as marketing BS. All DLC does for a mora bushcraft black is prevent a proper patina from forming.
 
Boats said:
I'll take that as "DLC is next to practically useless on knives." It's okay to like the aesthetics. Any other supposed benefit strikes ME as marketing BS. All DLC does for a mora bushcraft black is prevent a proper patina from forming.
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In some instances, yes. In the case of a DLC coated mirror finish, increased wear resistance helps keep the finish pristine without scratching easily. Not really marketing BS, just fact.
 
Rust protection can involve a coating that is more reactive than steel or less reactive. The former is called are sacrificial coating (like Zinc plating or Galvanized steel) where the coating corrodes in preference to the substrate. This sets up a galvanic competition in which no red rust appears until the Zinc is gone.
In the latter case, a barrier coat is applied to prevent the corrosive agent (H20?) from getting to the steel. In automotive Chrome plating, almost 2 Mils (thousanths of an inch) of Copper, Nickel, and Chrome are applied over a steel or die cast Zinc part to hide the corrodee from the corrodor. These coatings are good for about 5 years (in Michigan) where roads are salted.
A barrier coat can be a metal like Gold or a ceramic coat like TiN (Titanium Nitride). The effectiveness of the coat is dependent on its thickness, its uniformity, and smoothness of the substrate. A rough surface needs a much thicker barrier coat than a smooth one. A highly polished Carbon steel knife is less prone to rust because little pits in the surface are eliminated. Rust can show through a barrier coat that is too thin or porous.
PVD (Particle Vapor Deposition) coatings of ceramics are not very thick. So the smoother the finish, the less inclined to corrosion the substrate will be.
Ceramic coatings are much harder than organic coatings like Parkerize, baked paint, or Teflon. DLC, also known as TDLC (Tungsten Diamond Like Carbon) is basically a Tungsten Carbide coating. It has an HRC (hardness Rockwell C scale) of 72. Most good knives are around 60 HRC. Diamonds are 100 HRC. Tungsten Carbide does not approximate the hardness of diamonds. TiN (Titaniun Nitride) is 82 HRC same as the Vanadium Carbide dissolved in some blades (S-30-V). ZrN (Zirconium Nitride) is often seen on drill bits and has an HRC of 86. TiAlN ( Titanium Aluminum Nitride) is charcoal gray and has an HRC of 92.
I like TDLC, but I like TiAlN better because it is harder and thus more wear resistant. I use the sides of my coated blades and ceramic knives as finishing steels for my metal knives.
 
Blues Bender said:
Unfortunately, it will still rust.
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The possibility of corrosion is dependent on many variables on any knife... Two of which, steel choice & your own attention/maintenance after use. I've never had a problem with rust on any of my knives (both coated/uncoated), I seriously doubt I'd have an issue with DLC'ed S90V.

Boats said:
My son has a black mora with DLC. It doesn't protect from rust, so what was the point of it again? Coated blade is coated, so I guess you have to like a black on black knife color to appreciate it.
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Aesthetic preference for me personally.. And since I'm not too worried about rust (since I prefer high end stainless steels), I'd like to have a coating that has better wear resistance over some of the other coatings used specifically to aid in corrosion resistance.. One of which, cerakote.
 
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