DLC For Rust Prone Steels

[Bill1170]

I'd be surprised if some of Spyderco's coated blades (of current production) are not coated at the pivot. If that's the case, which ones?
Even if the coating is worn away in the immediate pivot area, the coating protects the area around the pivot that is inaccessible/invisible without taking the knife apart. And DLC wears very well.

If I remember correctly, the DLC Para 2's I've had didn't have any coating around the pivot.

If you go to the off topic forum and read my knife pilgrimage thread, my DLC Para 2 was clipped IWB for my trip ride up to NGK. 8 hours a day soaked in sweat for over a week, not a speck of rust. Give me a satin finished Para 2 in S30V and it'd have rust within the first four hours.

My Para 2 has a coated pivot, and the coating has not worn off in the pivot despite 5 years of hard use and carry.

Rust is a big issue for me. Primarily due to sweat in the summer. When its constantly 105F and humid, you sweat, period. My sweat seems to be unusually corrosive too for some reason. So for me its less the things I cut that corrode my knives than it is simply carrying them.

In my experience a knife like the DLC Manix XL, with its coated blade AND liners, is very close to a Salt in terms of corrosion resistance and overall convenience. The coating keeps the blade from rust due to sweat, and same with the liners.

Other knives that most folks would never worry about rusting, like my Police 3's, have developed a lot of corrosion for me under the same conditions. The pivot, liners, opening hole, blade surface etc. have all developed a lot of corrosion simply from carrying the knife. The edge received little corrosion, barely enough to perceive. Regular sharpenings more than compensate for any dulling I experience from corrosion.

Even if the blade steel is very corrosion resistant, the hardware is not always up to the same level. I have yet to see any corrosion on my CTS204P Military blade, but I visibly rusted the stop pin surface the first hour I carried it.

Thank you for this post, Vivi. I wasn’t sure if DLC helps prevent corrosion, but your testimony convinced me that properly done DLC helps enormously. This is valuable. My first Apple Watch was type 316 stainless steel with polished DLC and it survived two years of crawling in dirt under houses with nary a scratch. The stuff is amazing! Looks dead sexy, too, in glossy polished jet black. Obviously, light discipline wasn’t a consideration with the watch.

[Michael Janich]

Back when I worked for Blackhawk/Masters of Defense, most of what we made was DLC coated. At that time, it was the duller tungsten DLC rather than the chromium DLC (which has a richer, blacker finish) that is more commonly used on knife blades now. Nevertheless, we had several fixed-blade knives that were A2 tool steel (5% chromium). The exposed steel at the edges would rust very easily, but the DLC did a great job of protecting the overall blade surface. Interestingly, because of the way the coating was bonded to the surface, corrosion at the edge would not "get under" the DLC as you often see with other coatings.

Overall, DLC is very durable and has a higher Rockwell hardness than the blade itself. Usually, what look like scratches in the coating are actually other materials rubbing off on the DLC.

If you like your DLC blades to look really pretty, one trick we used was to use LPS TKX spray lubricant. Spray it on, let it soak in a bit, and then wipe it off.

Spyderco has a number of US-made Exclusives coming out with tool steel blades and DLC coating. I expect these will behave like the A2 blades. Since the blades are coated before assembly, only the sharpened edges will be exposed.

Stay safe,

Mike

[Bill1170]

Back when I worked for Blackhawk/Masters of Defense, most of what we made was DLC coated. At that time, it was the duller tungsten DLC rather than the chromium DLC (which has a richer, blacker finish) that is more commonly used on knife blades now. Nevertheless, we had several fixed-blade knives that were A2 tool steel (5% chromium). The exposed steel at the edges would rust very easily, but the DLC did a great job of protecting the overall blade surface. Interestingly, because of the way the coating was bonded to the surface, corrosion at the edge would not "get under" the DLC as you often see with other coatings.

Overall, DLC is very durable and has a higher Rockwell hardness than the blade itself. Usually, what look like scratches in the coating are actually other materials rubbing off on the DLC.

If you like your DLC blades to look really pretty, one trick we used was to use LPS TKX spray lubricant. Spray it on, let it soak in a bit, and then wipe it off.

Spyderco has a number of US-made Exclusives coming out with tool steel blades and DLC coating. I expect these will behave like the A2 blades. Since the blades are coated before assembly, only the sharpened edges will be exposed.

Stay safe,

Mike

This is so helpful to know. The business about DLC not allowing rust to “get under” the coating is huge. This means that, even if the coating does suffer a scratch, it won’t become a spreading cancer of rust.

[vivi]

thanks for the post Mike, informative stuff.

DLC is very tough stuff. I can echo what was said about scratches usually being other material that's rubbed off. It offers years of longevity unlike some of the black mystery finishes I've seen on very low end knives.

[Wanimator]

DLC is a great coating on wearing parts when used with oil. Some companies coat their engine parts with it for friction and wear reduction.

[JimP]

Thanx Vivi. Good information.

On that top pin that rusted, was it coated?

sal

I think Vivi missed your question but I will add for your engineering teams information, my uncoated new CQI Milli 110V's stop pin rusted on me the first day, the rest of the knife remained fine, this is the only Spydie that I have noticed this happening on.

[vivi]

Thanx Vivi. Good information.

On that top pin that rusted, was it coated?

sal

No it was not. It is the CTS204P run from Knifeworks. Here is a close-up of the CQI style stop pin:








It hasn't spread to any other surfaces so I've left it as is. The rest of the knife is corrosion free so far. CTS204P has me impressed so far.

[DougC-3]

I for one am really looking forward to the upcoming Manix 2 DLC exclusives, natural G-10 with CPM M4 steel from BHQ and Orange FRCP with CPM S90V from CS. I'm not too interested in the tactical aspects and I don't have much trouble with rust, so that probably puts me in a category of people who like DLC mainly because of the way it looks. I think my coyote S90V DLC Yojimbo 2 is one of the best looking knives I have :)

[steelcity16]

I guess I'm with Paul on this.

Eric is planning some coatings on Salt models made in Golden as a test. It seems like the Salts as made have less than 1/10th of 1% return for rust, but Eric would like to lower the percentage.

We analyzed the pieces that came back from the Gulf after extended use. The Gulf seems to also have sulphur in the water which creates sulphuric aced, which also has its issues.

As Paul mentioned, it still won't effect the edge, which is the most vulnerable and the most important.

sal

Wait, wait, wait, is this a bombshell that was overlooked?

Coatings on Salt Models...models...with an S...made in Golden. So maybe we will be getting that PM2 Salt that we have been clamoring for? In DLC coated LC200N??? And maybe a Native 5 DLC Salt to follow the upcoming satin??? oooohhhh snap!

[steelcity16]

I for one am really looking forward to the upcoming Manix 2 DLC exclusives, natural G-10 with CPM M4 steel from BHQ and Orange FRCP with CPM S90V from CS. I'm not too interested in the tactical aspects and I don't have much trouble with rust, so that probably puts me in a category of people who like DLC mainly because of the way it looks. I think my coyote S90V DLC Yojimbo 2 is one of the best looking knives I have :)

They are definitely good looking, especially with the black liners and hardware. I REAAAAALLLY hope to see some DLC coated Cruwear in some sprint runs. I think black on black looks good, so Peel Ply CF is one of my top choices. The Jade looks amazing with the black hardware, so i'd like to see that as well. I also think the Red would look awesome with the black! Day Glow Translucent Neon Yellow G10 with DLC LC200N blade and hardware would be killer in some Golden made Salt versions of the Millie, PM2, Para 3, Manix, and Native!