Using magnesium in the pivot to prevent corrosion on tool steels

[ImaCutSumSchitt84]

Not sure if it's ever been brought up on here but I've recently seen the results of testing using Magnesium as a sacrificial anode on tool steel blades. The steel was put through various corrosive tests and showed no signs of corrosion, not even a light patina. Now, when you talk about Spydercos not having thumb studs the only place possible would have to be the pivot, on knives with thumb studs thats an easy mount point. Many of my tool steels are fine with patinas and some look better, but for those who love something like k390 but want it to stay pristine, having a pivot bushing made of magnesium could be the answer. I don't think there would be an issue with longevity in the pivot, when I did shower pans, and used a magnesium float, that thing never had any signs of wear. Thoughts?

[yablanowitz]

So you want to keep your blade shiny by putting in a soft metal pivot bushing which will corrode away instead? That's what a sacrificial anode is, a part that is supposed to corrode away. Are you hoping the oxidation products will act as a lubricant rather than an abrasive? The two possibilities I see are:

1) The corrosion products will fill the tiny space between the blade tang and the pivot pin, causing the two to seize, or

2) The corrosion products will wear away, leaving excessive clearance leading to unacceptable blade play.

[Bill1170]

I suppose the anodic magnesium bushing could be replaced at regular service intervals. Seems like work, but an interesting project to do and report back to the forum about the results in a year or two?

[Danke]

I for one totally want my pivot to turn into white dust, vanish, and then the blade can fall out.

Just like my magnesium Oakleys returning to whence they came.

[ImaCutSumSchitt84]

So you want to keep your blade shiny by putting in a soft metal pivot bushing which will corrode away instead? That's what a sacrificial anode is, a part that is supposed to corrode away. Are you hoping the oxidation products will act as a lubricant rather than an abrasive? The two possibilities I see are:

1) The corrosion products will fill the tiny space between the blade tang and the pivot pin, causing the two to seize, or

2) The corrosion products will wear away, leaving excessive clearance leading to unacceptable blade play.

This isn't on an outboard motor,it's a pocket knife, from what I've seen it's not affecting the anode enough to cause damage with regular use and care. As long as you aren't mistreating it you'll likely never know the anode is there. I know any company would want to avoid warranty claims but if you're treating it the same as you would any other knife it may never cause an issue. Like I said about Magnesium, it's not as soft as you're claiming, and may not wear like steel but in a folder I doubt it won't last as long as the rest of the knife. Spyderco may be a bad example because they don't have thumbstuds, which would be a better use case, but Spyderco does have a largest variety of tool steels and would be cool to know how it would hold up.

[Fastidiotus]

NACE Corrosion Engineer here. I'll try to make this a simple read cause it can get out of hand. Just like fire has a triangle of requirements to occur (fuel, oxygen, and heat) corrosion does as well (a material with a polarity imbalance across it's surface, water, and oxygen). When we witness pitting corrosion on steel we're physically able to see which parts of the steel surface are carrying either a positive or negative charge. Corrosion is basically the result of the metals surface acting as a battery. Passive Cathodic protection works by introducing a new metal which will carry a stronger positive charge(the anode) there by turning the metal you wish to save into a negatively charged surface in comparison (the cathode).

While Im unaware of OPs source I would venture to guess the expirement involved a steel being submerged or constantly sprayed with water as a proof of concept and not a knife being edc'd and subjected to humidity. Air is a poor conductor and a great insulator. For cathodic protection to be effective you need the 2 metals to be able to freely exchange ions. Water is great for this especially with an electrolyte like salt, air is terrible for this. That's why you see Passive Cathodic protection used in wet environments like ships and buried pipelines. For this concept to work in a humid environment the entire surface of the steel would need to be coated(galvanized) so that as individual parts of the steel come into contact with moisture particles in the air the anode is there at the point the moisture contacted.

TL/DR: OP's idea would be a great way to have a nonfunctional folding knife that doesn't rust as much in water for a short period of time. OP's idea wouldn't save you from corrosion caused by atmospheric humidity.

[Danke]

If you ever get lost in the woods you'll sure have a handy emergency fire starter.

[Evil D]

Just grease your pivot. Add enough around the pivot that it squishes out from under the washers to make a little ring of grease. This will stop most crud and block water from getting into the pivot. The down side is it'll eventually become contaminated enough to need cleaned out and replaced, but I consider it routine maintenance. I even do this on Salt models because I like the action it provides, I like it way more than other lubes like Nano Lube for example. I've been using the same tube of Phil Wood bearing grease for about 30 years.

[Danke]

Phil Wood is a hidden treasure.

[sal]

Hey ImaCut,

Interesting topic, thanx for the spark. I also appreciate the thoughts shared by professionals like, fastidiotus (I resemble that name) and throw in the many great minds that hang here, gives us all a new file.

At this time, I think that some of our Salts are already a good solution where there is concern. Using exotic hyperformance blade steels that do not have good corrosion resistance do at this time, have to be cared for. I do believe in human-kinds ability to perservere to improve will constantly improve "the cut". Concepts like "MagnaCut" is an example.

But I would like to ask the question, keeping an open mind (drafty brain), is there a place for Magnesium to be easily used in our industry for the purpose of reducing corrosion, like an inlay of magnesium somewhere on the knife?

sal

[Evil D]

Phil Wood is a hidden treasure.

I haven't tried everything but I've tried different greases and oils and Teflon lubes and I find their bearing grease to be a really good viscosity for knife pivots, and obviously it's very good for bearing pivots.

[SpyderEdgeForever]

If you ever get lost in the woods you'll sure have a handy emergency fire starter.

My thoughts exactly.

[Danke]

Phil Wood is a hidden treasure.

I haven't tried everything but I've tried different greases and oils and Teflon lubes and I find their bearing grease to be a really good viscosity for knife pivots, and obviously it's very good for bearing pivots.

They were founded in 71 and have really done of a good job of real world testing.

[Pokey]

Hey ImaCut,

Interesting topic, thanx for the spark. I also appreciate the thoughts shared by professionals like, fastidiotus (I resemble that name) and throw in the many great minds that hang here, gives us all a new file.

At this time, I think that some of our Salts are already a good solution where there is concern. Using exotic hyperformance blade steels that do not have good corrosion resistance do at this time, have to be cared for. I do believe in human-kinds ability to perservere to improve will constantly improve "the cut". Concepts like "MagnaCut" is an example.

But I would like to ask the question, keeping an open mind (drafty brain), is there a place for Magnesium to be easily used in our industry for the purpose of reducing corrosion, like an inlay of magnesium somewhere on the knife?

sal

Hey Sal, what about magnesium washers at the pivot? They'd be touching both the blade and the D-bolt, and they're easy to change if they get sloppy.

As far as attaching an "inlay" on the blade, for knives with flippers, how about a detachable flipper tab made of mag? (a' la the Spymyto)

[yablanowitz]

So you want to keep your blade shiny by putting in a soft metal pivot bushing which will corrode away instead? That's what a sacrificial anode is, a part that is supposed to corrode away. Are you hoping the oxidation products will act as a lubricant rather than an abrasive? The two possibilities I see are:

1) The corrosion products will fill the tiny space between the blade tang and the pivot pin, causing the two to seize, or

2) The corrosion products will wear away, leaving excessive clearance leading to unacceptable blade play.

This isn't on an outboard motor,it's a pocket knife, from what I've seen it's not affecting the anode enough to cause damage with regular use and care. As long as you aren't mistreating it you'll likely never know the anode is there. I know any company would want to avoid warranty claims but if you're treating it the same as you would any other knife it may never cause an issue. Like I said about Magnesium, it's not as soft as you're claiming, and may not wear like steel but in a folder I doubt it won't last as long as the rest of the knife. Spyderco may be a bad example because they don't have thumbstuds, which would be a better use case, but Spyderco does have a largest variety of tool steels and would be cool to know how it would hold up.

According to Wikipedia, magnesium has a Mohs hardness of 1 to 2.5, which is about the same as a human fingernail. That's how soft I'm claiming it is.

[zhyla]

Hey Sal, what about magnesium washers

Since fastidiotus didn’t say it bluntly enough, I will. This is not how cathodic protection works. You need a complete electrical circuit.

There’s a long history of people trying to push cathodic protection products for cars. In the USA it’s actually illegal to sell such a device because too many people get suckered.

[RustyIron]

But I would like to ask the question, keeping an open mind (drafty brain), is there a place for Magnesium to be easily used in our industry for the purpose of reducing corrosion, like an inlay of magnesium somewhere on the knife?

As mentioned previously by others, I'm not convinced that slapping a chunk of magnesium onto a knife blade will prevent corrosion or patination. But if there's any question, it seems simple to add a piece of magnesium to an existing knife blade, for anyone interested in conducting such an experiment.

When I build something, I try to prioritize aspects of the project. Maybe ease of manufacture is a priority. Maybe it's cost of materials. For a knife, the top priorities might be edge retention and ease of sharpening. In that case, maybe I'd choose K390 or Cru-Wear. If the top priority was corrosion resistance, I might choose MagnaCut or LC200N. But if corrosion resistance is of the utmost importance, K390 doesn't make sense.

Think about it in terms of automobiles. Maybe you want to build a car for driving the canyon roads on the weekends. You could get yourself a used 718 Cayman, and you'd have a machine well-suited for the intended task. Or you could be stubborn and insist on getting a Lexus RX350 because you like the added interior space for groceries and the comfortable driving when you're stuck in traffic. You can bolt on all kinds of suspension parts, tires, exhaust, and magnesium pivots, but the Lexus is not going to be as well suited to the primary task as the Porsche.

We can flip the scenario and say that our primary goal is commuting to work and taking the kid to soccer practice. You can do it with the Porsche, but the Lexus is the sensible choice. Whether you're building cars, knives, homes, or toaster ovens, don't lose sight of the primary goal.

[tbdoc4kids]

Hey Sal, what about magnesium washers

There’s a long history of people trying to push catholic protection products for cars. In the USA it’s actually illegal to sell such a device because too many people get suckered.

As a Presbyterian, I am opposed to Catholic protection products. They should be non-sectarian.

Gotta love autocorrect!

[Fastidiotus]

As a Presbyterian, I am opposed to Catholic protection products. They should be non-sectarian.

Gotta love autocorrect!

Hmm Cath-olic Protection, maybe we can't directly communicate with corrosion and that why everything rusts. I'll have to try asking someone else to communicate with corrosion and tell it to stay away from my nice things and not punish me for my impure thoughts.

All joking aside the solution to this problem exists, it's inexpensive(relatively), and joy of joys Spyderco is already using it in their knives. Coatings! Everything man has made in the world around us that isn't slowly crumbling or rotting back to the ground from whence it came is coated. Your house, your place of business, bridges, planes, trains, and automobiles, your fridge, even the inside of the can of soda in your fridge. Coatings prevent moisture and oxygen from reaching the metals surface and completing the corrosion triangle. Coatings aren't perfect though. They experience wear and tear, and most have a service life before they need to be reapplied or touched up. Coated tool steels are the best we're going to get to try and corrosion proof them.

As Sal also said this makes steels like H1/2, lc200n, Vanex, and Magnacut real marvels and we should appreciate just how extreme they are. H1/2 really is just as wild of a steel as 15v/Maxamet/Rex-121 if you're looking at it from a corrosion point of view.

[SpyderEdgeForever]

Infact stainless steel is stain resistant because of the chromium coating from the chromium content, correct?

Imagine if human science reaches the point where we can directly control and re program matter at the quantum wave function level. You could make custom designed atoms that have variable inter atomic forces. You could produce a synthetic metal atom that never rusts because oxygen and other atoms that form oxides or other corrosive compounds cannot chemically bond to it. You could alter it's properties so it has no nucleus but decreased bond length thus making it have stronger bonds. Adamantium Tungsten that has little to no weight and zero rust but that is plastic flexible and 100,000 times stronger and harder than diamond. Imagine a synthetic steel that measures RC 20,000 but cannot shatter.