TC beyond Ni200: Nickel Purity, Dicodes; Ti, SS, Resistherm NiFe30; Coefficient of Resistance

[druckle]

The brightness of the hot surface depends on the intensity and color of the ambient light and the radiant emittance of the hot surface. Most of the charts created to show the temp/brightness effects are created in relation to black body conditions because that is the only way that data aren't all over the place. For usability, It would be best if the intensity and spectrum of the ambient light was listed for each color/temp bar but I've never seen this done in a published chart.

I don't think the world will blow up if one exceeds the coil material "max temp" by a little but most folks don't even bother to be in a totally dark room when they do a dry burn so any glow perception and its relation to actual temperature is unreliable at best and almost always the error is that folks think the glowing surface is much cooler than it is. Actually I can't think of a single possibility that the actual temperature is not higher than such a chart would show because we are never in black body radiant conditions with a coil in an atty.

As with all dry burns I think it should be done with great care and attention to the details of what is actually happening.

Dry burning is always an option with any of our materials. It has to be understood in relation to a specific material and the conditions we impose to accomplish it.

In my opinion a blanket condemnation or acceptance of a dry burn because "they say" it can/can't be done is mostly fairy dust.

Duane

 

[druckle]

As an aside I sometimes do a "cold dry burn" as Tchavei and others have described. By that I mean I set the temp to the max available in temp controlled mode, heat the coil and cool it under running water. This can be done multiple times if necessary. The thermal shock involved seems to remove or loosen stubborn deposits that haven't come off by my normal cleaning procedure. More recently I've started heating my coils to the max temp controlled condition with a new coil even after it's been cleaned with water/detergent/alcohol because I almost always see visible vapor coming off the coil even though the wire is "clean". I doubt whatever is being driven off is all that bad but I don't see any reason to assume that it's beneficial either.

Duane

 

[TheBloke]

OK thanks.

I will do some temp probing and/or resistance monitoring when I can to see what temperatures are actually achieved when I do a 'standard' dry burn as I have been doing it - which I now see will probably be very high.

Then I'll see if I can still achieve my goals of dry burning with lesser, lower wattage, slower pulses trying not to exceed 600°C. I am sure I can clean it that way, but maybe also test the coil as well without heating it too much.

And yes I can't imagine the coil is going to drastically change its properties just because it goes to 800°C for 5 seconds. But I suppose nothing can be ruled in or out. With Ni200, I saw a specific reference to what would happen at "prolonged exposure above 600°F" - it talked about graphitization of the material resulting in "severely compromised properties." What 'prolonged' means I have no idea, but it's probably still not what we would ever do.

It would be nice to see similar discussion of NiFe but I can't find much on Google at the moment.

And re the dry burn under TC, I always dry burn it at my current setting and occasionally set TC to max and then do it. But I haven't then washed it in cold water - when doing that kind of cleaning I usually spray it with IPA in-situ, brush it with a toothbrush, then TC dry burn it. Sometimes I pull an IPA-soaked wick through it as well.

And sometimes there's enough IPA left on the deck to catch fire when I do the TC dry burn, which I consider as extended cleaning

 

[TheBloke]

Another factor in the dry burn debate is how long the coil is going to be used for and therefore how many dry burns it gest. It's rare for me to use a single coil for more than two liquids, one liquid change.

That means a total of two or four dry burns - one or two as I first install the coil, one or two more when I change liquid.

Personally I'm fairly comfortable with the thought that I might be taking a NiFe coil above its stated operating temperature for a total of perhaps 20 seconds, in 4 x 5 seconds increments. And I am much more comfortable taking NiFe52 or 70 to, say, 900°C, 50% over its specified temperature, than I would taking Ni200 to 3x its temperature. I never dry burned Ni200 at all.

But I fully admit I have absolutely no idea if there might be problems with doing it.

It does seem like SS should be safer in that regard, with its specified temperature already nearly 900°C. And little to no nickel content (8% in SS304, 0% in SS 430)

 

[druckle]

OK thanks.

I will do some temp probing and/or resistance monitoring when I can to see what temperatures are actually achieved when I do a 'standard' dry burn as I have been doing it - which I now see will probably be very high.

Then I'll see if I can still achieve my goals of dry burning with lesser, lower wattage, slower pulses trying not to exceed 600°C. I am sure I can clean it that way, but maybe also test the coil as well without heating it too much.

And yes I can't imagine the coil is going to drastically change its properties just because it goes to 800°C for 5 seconds. But I suppose nothing can be ruled in or out. With Ni200, I saw a specific reference to what would happen at "prolonged exposure above 600°F" - it talked about graphitization of the material resulting in "severely compromised properties." What 'prolonged' means I have no idea, but it's probably still not what we would ever do.

It would be nice to see similar discussion of NiFe but I can't find much on Google at the moment.

And re the dry burn under TC, I always dry burn it at my current setting and occasionally set TC to max and then do it. But I haven't then washed it in cold water - when doing that kind of cleaning I usually spray it with IPA in-situ, brush it with a toothbrush, then TC dry burn it. Sometimes I pull an IPA-soaked wick through it as well.

And sometimes there's enough IPA left on the deck to catch fire when I do the TC dry burn, which I consider as extended cleaning

The solid state precipitation of carbides in Ni is not a fast thing. The kinetics of the reaction require considerable exposure time in order to get significant growth of carbides. I find dry burning of nickel not attractive because the material is so damned weak in the first place and a dry burn relaxes whatever minimal residual stresses there are such that the coil is not dimensionally stable and sags. (especially since we have to use such fine gauge wire to get decent resistance.

I have not explored NiFe because I haven't been able to get any yet (other than my guitar wires) and I'm waiting for a better ohm meter to arrive before I bother with that. I know folks have said that the wound strings always have steel cores but I checked with the manufacturer again and I'm told that is not true of these strings. I don't trust that yet, but even if the wound strings are steel core they may be good lazy man's claptons for a low price.

I don't see anything about the NiFe alloys we're talking about that is going to make them much different than Ni 200 with respect to dry burning. They will still have the carbide issue but I don't believe that is anything that should concern us. They will likely have a bit higher strength because of solid solution strengthening (which isn't a great strengthening mechanism in alloys) of the Fe-Ni alloy and that will help somewhat with dimensional stability but how much I won't know until I've had a chance to explore. They will still lack the one positive aspect of Kanthal that I see and that is the very protective aluminum oxide surface layer. I'm going to explore the stainless steels because they promise decent vaping, low price and better stability How the NiFe vs. stainless alloys war comes out is a big guess I think. I'd appreciate your thoughts/projections on that Tom since you've had some experience with a few stainless materials and have put a lot of thought into NiFe already.

It would be great if our mythical grad student explored the NiFe system to see what content of aluminum could be added to the alloys so we could achieve a great protective oxide surface. It would also be great to look at the possibility of NiAl strengthening because that's been done for controlled expansion alloys in the turbine engine commmunity with great success. That would give great strength and stability and I judge it is quite possible for us in the vaping community too.

The right material here could have all the benefits of Kanthal and titanium, good dimensional stability, flat pronounced TCR and low price . Being a grad student he or she would want to also put a very small amount of an active element like yttrium in the alloy to increase the oxide adherence even more. This type of project would likely never qualify for a PhD because it's way too simple but a master's student should get high fives from the vaping community for the effort.

As I mentioned earlier I think any of our materials can be dry burned now, as long as it's done with sensitivity and care, but as I see it I don't expect to see any magic about the current NiFe alloys we're discussing with respect to dry burning. They will still form nickel oxides so allergic folks or those sensentive to the negative press on Nickel toxicity. They will good with respect to temperature control but I doubt that they will be dramatically better than titanium.

There's a great material out there for us. I hope someone is motivated and funded to do the few weeks of work it would take to identify it.

Duane

 

[cigatron]

Edit: and the SXKs and Apollo Reliant also have live ohms in VW.

And so does the evic.

 

[cigatron]

In my opinion a blanket condemnation or acceptance of a dry burn because "they say" it can/can't be done is mostly fairy dust.

This I like a lot^^^. Besides, You're just daring me if you say I can't do something.

 

[cigatron]

I have successfully dryburned Ti dozens of times. Ni only a few times and it wasn't easy. I collapsed several coils before I got the hang of it and eventually ruined them all. I'm done with nickel but not because I have trouble winding or setting coils; for all the other reasons @TheBloke has mentioned.

 

[gorman]

Things are actually pretty good now. In the mean time I will be fiddling with wicks and looking at Escribe screens to optimize delivery of liquid to my coils because experience so far says that's the becoming the key issue of the day-week-month for me.

Hi @druckle I lately discovered how important this is too. Care to point in the right direction for these screens you are talking about? Thanks.

 

[druckle]

Hi @gorman

The DNA 200 allows connection by USB with a program called Escribe that lets one see graphs of the actual temperatures of the coil in real time while firing the coil. If the coil temp rises rapidly then becomes flat with temperature (without exceeding the temp control setting) one knows that the wick is keeping up with the vapor production. If the temp goes up very rapidly at first but then continues to rise but at a lower rate than initially we know that the wick is not providing enough liquid to the coil to keep up with the boiling rate.

It becomes easy to know how a wick is performing and to adjust the power applied to the coil such that optimum flavor and vapor are being produced by experimenting with the DNA 200 and Escribe.

One of the nice features of Escribe as one does not have to actually be vaping since there's a fire command button that allows one to select any fire time required. The bad part is without air passing over the coil the vaporization rate is suppressed so the best accuracy for real conditions requires actual vaping. For me this means that the testing has to be done in short sessions to avoid uhhhhh excess inhalation of nicotine (I really need to get some zero nic liquid.

Duane

 

[druckle]

I should have mentioned earlier that our graduate students wire study will clearly be able to manipulate resistance with minimal effect on optimum TCR by minimal additions of minor elements. It may be that aluminum additions can do it by themselves but if not the other possibilities are wide open for the magic resistance increasing element.

Duane

 

[jazzvaper]

I should have mentioned earlier that our graduate students wire study will clearly be able to manipulate resistance with minimal effect on optimum TCR by minimal additions of minor elements. It may be that aluminum additions can do it by themselves but if not the other possibilities are wide open for the magic resistance increasing element.

Duane

I want to update my results with SS 316L but first need to check a nagging question, hinted by druckle's remark, above.

The question (with no ethnic or national insult intended) is how reliable should we consider the FT SS 316L (or any other FT "steel"). Cannot recall at the moment whether it was Deano or Cisco from Avid who mentioned "pig-steel" from China, what I sometimes think of as 'Chineesium'. I am not ready to rely on FT wire, least not until our hypothetical grad student (and resident metallurgist) can say something to confirm the purity of these wires. MIne came through Amazon from "Coppermfg@yahoo.com, PO Box 571837, Tarzana CA 91357". Who knows, they may be getting it from China.

Now, on to last night's results...

After about 1/2 hour of vaping on the DNA 200 with SquapeRs there was a puff of smoke, thereafter little to no vapor. Went poking around ECF to see whether it could be the SquapeRs, finding posts about the 510 and a fix (silicone wire) that I refuse to do since with Ni 200 I have had ZERO issues with the 510.

Switched to the Kayfun 4 with a SS 316L coil. Same thing, after a while a puff of smoke and no vapor.

Sleeping on the question I decided the issue was almost certainly that of a hot leg, or hot legs. Installed a new SS coil in the Kayfun 4, avoiding the question of wonky SquapeR 510, observed the vape using eScribe (thanks for the reminder druckle). By adjusting the 510 I was able to get both Temp and Wattage to acceptable, reliable levels with a more than decent vape.

Did the same with the SquapeRs...same result. What made the difference? Dry-burning, just as we used to do with Kathal A1. For the sake of science I did not use a DNA or other regulated mod. My trusty copper Vanilla sits within arm's reach.

I am in business with SS 316L. Need only to refine such matters as number of wraps/cold ohms, ID of coil (though the SquapeRs and the GEM will not readily take a 3mm ID only 2.5), and lastly to get the best wattage and temp, based on tracking in eScribe.

Oh, Frabjusday!

 

[balazsk]

Which I suppose does raise the question - can I be sure when dry burning it's not exceeding 600°C? And the answer is no, not absolutely certain. I only dry burn the minimum necessary for the task at hand, and in pulses, but this is on my list to verify with temp probing.

Actually it is possible with the accuracy of our mods.
Specific TCR can be calculated to shift the real temperature for dry burning. I have made it for Ti: if you set the TCR to 0.00725 and the temp to 300°C the coil will be about 600°C.
I am sure that it's not perfect, the TC algorythm has been developed for wet coils, but it is good enough to have a rough limit.

 

[tchavei]

Actually it is possible with the accuracy of our mods.
Specific TCR can be calculated to shift the real temperature for dry burning. I have made it for Ti: if you set the TCR to 0.00725 and the temp to 300°C the coil will be about 600°C.
I am sure that it's not perfect, the TC algorythm has been developed for wet coils, but it is good enough to have a rough limit.

Hmm

So I could program a "Cleaning Coil" profile in my dna 200 and whenever I needed to clean my Ti coil, all I would need is to switch into the cleaning program and be done with it...

That's a great idea!

Btw, shouldn't the TCR be half of 0.0035 to trick the mod into thinking 300C = 600C
?

Regards
Tony

Sent from my keyboard through my phone or something like that.

 

[balazsk]

Hmm

So I could program a "Cleaning Coil" profile in my dna 200 and whenever I needed to clean my Ti coil, all I would need is to switch into the cleaning program and be done with it...

That's a great idea!

Btw, shouldn't the TCR be half of 0.0035 to trick the mod into thinking 300C = 600C
?

Regards
Tony

Sent from my keyboard through my phone or something like that.

Yes, it is possible. I do the same for stainless steel.
The important thing is the change of the temperature. What is 280°C in case of 300°C and 580°C in case of 600°C. Therefore we can't just double the original TCR and it has to be calculated for specific temperatures.

 

[druckle]

I want to update my results with SS 316L but first need to check a nagging question, hinted by druckle's remark, above.

The question (with no ethnic or national insult intended) is how reliable should we consider the FT SS 316L (or any other FT "steel"). Cannot recall at the moment whether it was Deano or Cisco from Avid who mentioned "pig-steel" from China, what I sometimes think of as 'Chineesium'. I am not ready to rely on FT wire, least not until our hypothetical grad student (and resident metallurgist) can say something to confirm the purity of these wires. MIne came through Amazon from "Coppermfg@yahoo.com, PO Box 571837, Tarzana CA 91357". Who knows, they may be getting it from China.

Now, on to last night's results...

After about 1/2 hour of vaping on the DNA 200 with SquapeRs there was a puff of smoke, thereafter little to no vapor. Went poking around ECF to see whether it could be the SquapeRs, finding posts about the 510 and a fix (silicone wire) that I refuse to do since with Ni 200 I have had ZERO issues with the 510.

Switched to the Kayfun 4 with a SS 316L coil. Same thing, after a while a puff of smoke and no vapor.

Sleeping on the question I decided the issue was almost certainly that of a hot leg, or hot legs. Installed a new SS coil in the Kayfun 4, avoiding the question of wonky SquapeR 510, observed the vape using eScribe (thanks for the reminder druckle). By adjusting the 510 I was able to get both Temp and Wattage to acceptable, reliable levels with a more than decent vape.

Did the same with the SquapeRs...same result. What made the difference? Dry-burning, just as we used to do with Kathal A1. For the sake of science I did not use a DNA or other regulated mod. My trusty copper Vanilla sits within arm's reach.

I am in business with SS 316L. Need only to refine such matters as number of wraps/cold ohms, ID of coil (though the SquapeRs and the GEM will not readily take a 3mm ID only 2.5), and lastly to get the best wattage and temp, based on tracking in eScribe.

Oh, Frabjusday!

I couldn't bless or disapprove any material based on source other than to say that FT is in the business of buying cheap and selling cheap. I seriously doubt if they have a materials laboratory or care to have someone else analyze the material they sell. China has the capability and does make some of the best materials in the world. They also make some absolutely horrendous materials. In that way they are no different than just about any other country.

The price of wire for vaping is minuscule in the long run if the life of the material is decent so I try to purchase that (and any material I use) from sources I know to be reliable and do not rely on technobabble to sell their product. I probably could save a dollar or two but then who knows?

Duane

 

[balazsk]

I would also have a question to our graduate student. Is it possible that dry burn can slightly modify the TCR of a stainless steel alloy (for example from 0.00105 to 0.0011)?

 

[druckle]

Actually it is possible with the accuracy of our mods.
Specific TCR can be calculated to shift the real temperature for dry burning. I have made it for Ti: if you set the TCR to 0.00725 and the temp to 300°C the coil will be about 600°C.
I am sure that it's not perfect, the TC algorythm has been developed for wet coils, but it is good enough to have a rough limit.

Hey, that really is a great idea. It's one of those "Why didn't I think of that things". Good job @balazsk
Thank for mentioning it.

Duane

 

[druckle]

I would also have a question to our graduate student. Is it possible that dry burn can slightly modify the TCR of a stainless steel alloy (for example from 0.00105 to 0.0011)?

It depends on the stainless steel. There are many that are heat treatable and have solid state reactions which occur at higher temperatures and many that are not heat treatable and would probably not be affected. In short I don't know.

Duane

 

[balazsk]

It depends on the stainless steel. There are many that are heat treatable and have solid state reactions which occur at higher temperatures and many that are not heat treatable and would probably not be affected. In short I don't know.

Duane

Thank you Duane!
I experienced it with SS304. I am not sure that this the real root cause but I don't have better idea.
I should order some silicone oil and do measurements with different wires.