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The effect of Sodium Hydroxide on Tungsten Carbide

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Forum topic by Dallas posted 02-23-2012 07:10 PM 5038 views 0 times favorited 26 replies Add to Favorites Watch
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Dallas

3599 posts in 1952 days


02-23-2012 07:10 PM

Big Words.

I keep seeing posts to the effect that Sodium Hydroxide (Lye or Oven Cleaner) will degrade Tungsten Carbide cutters. Usually on saw blades, but we could extend this to anything made with tungsten carbide. This would include most of the carbide tipped band saw blades, drills or moulding and router cutter heads.

My question is this:

Is there any definitive scientific proof that Lye or Oven cleaner, (which isn’t all that strong a concentration of Lye), actually hurts the carbide tips of a saw blade or other tool containing carbide or is this just a tale that is told because someone told you it was true.

We aren’t speaking of anecdotal or empirical proof here, just hard cold scientific facts.

From what I’ve read in a few minutes of Googling around the internet, unless there is a caustic soda (Lye) concentration of over 40%, it can’t actually penetrate the tungsten carbide enough to cause any real measurable harm. I’m not saying that I did any real in-depth research, just a quick half hour of looking at different scientific treatises on the effects.

-- Improvise.... Adapt...... Overcome!


26 replies so far

View knotscott's profile

knotscott

7216 posts in 2841 days


#1 posted 02-23-2012 08:30 PM

Dunno about data on the effect of caustic on the carbide, but I simply found oven cleaner took the lettering off one of my blades and was messier to use than degreaser sprays like 409. I stopped using oven cleaner because other methods were more convenient and as effective.

-- Happiness is like wetting your pants...everyone can see it, but only you can feel the warmth....

View Bill White's profile

Bill White

4456 posts in 3426 days


#2 posted 02-23-2012 08:33 PM

Ya ain’t gonna see me using oven cleaner in my shop. My blades and bits cost too much to be used in a science project.
No scientific proof to be had here, but I’ve been doin’ it my way for years without any degradation of carbide.
Bill

-- bill@magraphics.us

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Dallas

3599 posts in 1952 days


#3 posted 02-23-2012 08:54 PM

Bill, following that logic shouldn’t we still be using asbestos to insulate heating systems and wood stoves?

-- Improvise.... Adapt...... Overcome!

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Danpaddles

554 posts in 1777 days


#4 posted 02-23-2012 09:14 PM

Ummmm….. Dallas- about that asbestos thing…......

I think part of the argument about using Easy Off is that is might degrade the braze that holds the teeth on, not so much that it eats the carbide.

I use it, yes, it will attack some lettering. But it takes the resin off the teeth quickly and easily. Yes, it is messy, I just lean the blade on the inside of the laundry sink and spray away, flip and spray some more. Wait 5 minutes, then brush with an old tooth brush (or, I guess a tooth brush belonging to someone you do not like.). Rinse well, since I have heard of this corrosion thing, I rinse very well, and then inspect closely.

I know I get much nicer cuts for 5 minutes work. Saw cuts faster, and their are no saw marks to be seen, right after a good cleaning. So— don’t stop cleaning your blade!

You know, sometimes teeth come off blades for reasons other than having to do with the cleaner used.

-- Dan V. in Indy

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MrRon

3926 posts in 2709 days


#5 posted 02-23-2012 11:08 PM

I haven’t had any problems using TSP. Ijust soak the blade for up to an hour, brush and rinse clean.

View Viktor's profile

Viktor

456 posts in 2884 days


#6 posted 02-23-2012 11:17 PM

I doubt that lye (NaOH) would affect tungsten carbide cutters subject to occasional cleaning.

There are two things to consider – corrosion of tungsten carbide (WC) itself and corrosion of the binder (usually Co, Ni, or other alloys).
The solution pH determines the process. In neutral and acidic environment the corrosion process of WC-Co consists mainly of Co dissolution. In alkaline conditions dissolution of WC becomes more significant:
- Hochstrasser-Kurz S.; Mueller Y.; Latkoczy C.; et al. 2007. Analytical characterization of the corrosion mechanisms of WC-Co by electrochemical methods and inductively coupled plasma mass spectroscopy. CORROSION SCIENCE 49(4): 2002-2020.

Having said that in practical terms WC-Co and especially WC-Ni cutters should have good resistance to bases and less resistance to acids. Many manufacturers corroborate this too. In fact, some studies suggest that micro-abrasion under alkaline conditions resulted in lowered wear rates possibly due to formation of protective film:
- Thakare M. R.; Wharton J. A.; Wood R. J. K.; et al. 2007. Exposure effects of alkaline drilling fluid on the microscale abrasion-corrosion of WC-based hardmetals. WEAR 263: 125-136
- Thakare M. R.; Wharton J. A.; Wood R. J. K.; et al. 2008. Exposure effects of strong alkaline conditions on the microscale abrasion-corrosion of D-gun sprayed WC-10Co-4Cr coating. TRIBOLOGY INTERNATIONAL 41(7): 629-639

In either case it seems pretty safe to wash the blade in alkaline cleaner for few minutes followed by rinsing. However, oven cleaner may contain other chemicals that could cause harmful effect.

PS. By binder I mean the matrix which holds together WC grains (not the braze). Cutting tips are not solid WC.

View knotscott's profile

knotscott

7216 posts in 2841 days


#7 posted 02-23-2012 11:34 PM

Dallas – My question is what advantage does oven cleaner has over other proven methods that have fewer potential downsides?

-- Happiness is like wetting your pants...everyone can see it, but only you can feel the warmth....

View pons's profile

pons

25 posts in 1780 days


#8 posted 02-23-2012 11:36 PM

Even a dilute sodium hydroxide concentration will have an effect on the carbide over time, but with minimal exposure and thorough rinsing and drying, you shouldn’t see any problems.
If you are looking for a degreaser, a tablespoon of trisodium phosphate(TSP) in a gallon of water will work. That is the stuff the epa took out of laundry detergents a while bacl.

pons

-- Jim in Va

View Dallas's profile

Dallas

3599 posts in 1952 days


#9 posted 02-24-2012 12:04 AM

So far only one response that isn’t anecdotal.

-- Improvise.... Adapt...... Overcome!

View crank49's profile

crank49

3981 posts in 2436 days


#10 posted 02-24-2012 12:47 AM

Look up stress corrosion cracking.
Also related, hydrogen embrittlement.

Sodium Hydroxide is a caustic which can cause stress corrosion cracking, even in mild steel, but specifically in austennitic steels, such as common 18-8 stainless. which can lead to sudden catastrophic failure.
It is the propagation of fractures along the grain boundries of the nickel and chrome and iron molecules where subjected to cyclic loading.
The nickel silver brazing material used to attach the carbide teeth would be easily attacked.

-- Michael: Hillary has a long list of accomplishments, though most DAs would refer to them as felonies.

View JJohnston's profile

JJohnston

1614 posts in 2756 days


#11 posted 02-24-2012 01:05 AM

I don’t see your point here. If you want to clean your blades with oven cleaner, clean your blades with oven cleaner.

Does anybody know why I shouldn’t start popping the clutch on my truck? Honestly – have you ever seen a transmission fall out because somebody popped his clutch?

-- "A man may conduct himself well in both adversity and good fortune, but if you want to test his character, give him power." - Abraham Lincoln

View Dallas's profile

Dallas

3599 posts in 1952 days


#12 posted 02-24-2012 01:16 AM

Whoa, JJohnston, don’t get your panties in a wad. I didn’t say that I was going to clean a blade with oven cleaner, I merely asked if there was any scientific evidence to prove the allegations that oven cleaner would harm a saw blade.

-- Improvise.... Adapt...... Overcome!

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JJohnston

1614 posts in 2756 days


#13 posted 02-24-2012 01:29 AM

But you must have wanted to know for a reason, right?

-- "A man may conduct himself well in both adversity and good fortune, but if you want to test his character, give him power." - Abraham Lincoln

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Dallas

3599 posts in 1952 days


#14 posted 02-24-2012 01:40 AM

Yep, I always like to know stuff.
The point of this question is that I keep reading that using oven cleaner will ruin the carbide teeth of a saw blade but I haven’t seen any evidence to back it up.

I’m just looking for the evidence.

As for the transmission flalling out from popping the clutch I have to answer truthfully, that no I haven’t seen that happen but I have seen transmissions come apart in itty bitty pieces spread all over Sunrise mountain near Las Vegas because a truck with a full load of sheet rock popped the clutch. (Actually, his foot slipped off the clutch).

-- Improvise.... Adapt...... Overcome!

View Viktor's profile

Viktor

456 posts in 2884 days


#15 posted 02-24-2012 07:40 PM

I just reread my first post and I think I obscured the issue quite nicely there.

While WC, being a composite, is a good candidate for corrosion cracking I would be cautious to make broad generalizations as what could cause it in this particular material. Corrosion cracking is notoriously substance specific. It is chlorides for austenitic steel, NaOH for mild steel and so on. In WC-Co hydrogen fluoride (HF) has this effect and I would imagine other halide ions (chloride) might do the same, albeit less potently.

Experimental studies consistently show that the binder (Co, Ni, etc.) leaching is by far the primary corrosion concern for WC. The leaching rate increases as pH decreases (acidic environment). This is in agreement with HF induced corrosion cracking mentioned above. Of course there is more to NaOH solution than high pH, but I can’t think of what else could go on there Na+ related to corrode the substrate.

Perhaps advise not to use oven cleaner (lye) on blades stems from overall caution to avoid household cleaners, many of which do contain chlorine. It is plausible that oven cleaner contains other active corrosive substances, but the original question was specific.

Keep in mind that we are talking about occasional cleaning, not prolonged exposure such as in boiler filled with chlorinated water.

All this was just my humble opinion, but thank you for this interesting and thought provoking question.

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