Is a DLC Blade Coating Effective In Stopping Blade Corrosion?

GatorFlash1

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I know DLC will jazz up the blade appearance but how effective is it in protecting non-stainless steel knives from blade corrosion? Would it help knives like the Spyderco Gayle Bradley which has an M4 steel blade?
 
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I think it is porous, so the steel will still rust through it, unless the pores are saturated with oil. Maybe drying oils are the best (linseed or tung).

https://www.sciencedirect.com/science/article/pii/S0257897219301951
https://www.sciencedirect.com/science/article/abs/pii/S0257897214007798

DLC only acts as a physical barrier between the steel and external corrosive substances. It's not porous, but if there are any defects in the coating, you have a pathway for contact between the steel and the corrosive substance. The study shows that defects from 10-60 microns are common, likely the result of dust particles on the steel during the coating process. A water droplet in mist/fog is 8-11 microns, so it is very possible for water or a more potent corrosive to make contact with the underlying steel via such a defect. Once corrosion starts at the bottom of such a defect, it basically creates a sponge which will continue to absorb moisture and propagate the corrosion through the steel.

It's better than nothing, but it's not perfect. Practically speaking, because the cutting edge is uncoated, you should be doing some basic upkeep to protect the edge, so doing the entire blade at the same time shouldn't be a serious imposition.
 

GatorFlash1

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Thanks for all the good info. Didn't realize there were so many different knife blade coatings. What I was really asking about was how good it held up on non-stainless steel knives like one with M4 steel. I'm not sure the testing on YouTube considered using it on non-stainless knives.
 
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from what both sal from spyderco & jimmy from benchmade have said on here, dlc isn’t as good at corrosion resistance as cerakote is, but it definitely holds up better to wear from use
 
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I like the DLC on my Cold Steel knives . Used with some lube / oil / polish it acts like a non-stick pan . Easier to cleanup and maintain .

Much tougher than the older type coatings .

Can't swear it will reduce corrosion all by itself , because I always use with anticorrosives .

Might help to hold the oil in place better than bare steel ?
 
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from what both sal from spyderco & jimmy from benchmade have said on here, dlc isn’t as good at corrosion resistance as cerakote is, but it definitely holds up better to wear from use

Cerakote is a much thicker coating, which probably means the barrier it creates is less likely to have microscopic gaps. The tradeoff is that Cerakote adds drag to the blade while cutting and isn't nearly as hard as DLC, so it shows wear.
 
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CPM-M4 will take a patina, but it's still pretty rust resistant compared to high carbon steels like 52100, 1095, etc. I've noted a few slight patches on my GB2 after several months of use, but hardly enough to notice, and they don't affect its performance in any way.
 

GatorFlash1

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What is the difference between a patina and corrosion? Is "patina" just a nicer name?
 
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What is the difference between a patina and corrosion? Is "patina" just a nicer name?
As I understand it, a patina is a surface reaction to chemicals; it forms when the carbon in the steel reacts with an acidic substance (meat, fruit, etc.) It's not rust and doesn't affect the blade, at least not enough to matter. Most high carbon steels and tool steels will take on a bit of a patina. High carbon steels will react faster than tool steels. Rust is formed when steel oxidizes, usually in wet conditions.
 
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What is the difference between a patina and corrosion? Is "patina" just a nicer name?

Technically, any oxidation of metal is "corrosion." In this context though, corrosion usually refers specifically to rust (red iron oxide). "Patina" is also the result of oxidation, but usually refers to black iron oxide (magnetite), which is stable and protects against less desirable forms of corrosion.
 
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