The end of microcoils?

[druckle]

Dear friends:

I am posting this on behalf of Pedro Carvalho; he asked me to do so, so as to shed some light on this discussion. Thank you for taking the time to read this.

-----------

I'm Pedro Miguel Carvalho the material scientist that wrote a post together with Dr Farsalinos.

In that text, there are some less-than accurate statements. I assume the responsibility (and I apologize) because Dr. Farsalinos sent me the text to participate on it, and I didn't read the whole thing with the proper care.

IMO we could move forward and have a great discussion about this theme. Obviously the bulk of resistive wire will change with a heat treatment, increase of grain size, solid solution, crystallization or re-crystallization, etc. In any case, this IMO does not present any concern. What could represent a problem is the formation of oxides layer in the surface of the metal/alloy. The thickness and composition of this layer will depend on the temperature and duration of the heat treatment and type of resistive wire. In some cases like kanthal, a "light" heat treatment can be beneficial, but a longer heat treatment can eliminate the oxide protection layer. This frontier is very narrow, so it is difficult to recommend a specific "light " heat treatment.

Alloys that contain Al or Ti present a oxide layer that protects against deeper oxidation. In the case of nickel chromium wire, the benefits of a cleaning heat treatment should be compared with the possibility of formation of hexavalent chromium. In principle, hexavalent chromium formation requires a higher temperature than 1000 Celsius degrees, but without scientific data, we cannot exclude this possibility.

Any heat treatment that causes the coil to turn red can easily exceed 900 Celsius degrees; this promotes the formation of an oxide layer (inclusively destroying the protective layer as aluminum oxide or titanium oxide). Since we have no scientific data regarding composition/adhesion, or the possible reactions of this oxide layer with the high variety of juices, IMO if its use could be avoided, in general, it would be beneficial.

Soon I will start a start a study to determine the dependence of temperature/duration of the heat treatment on the composition, thickness and adhesion of these oxide layers. I have always believed that is better to be safe than sorry, and given in the lack of scientific data, I would recommend minimizing all heat treatment to any resistive wire, and avoiding extended and repetitive heat treatment. It will be a pleasure to further discuss this theme. Here is my contact: pmcbfcarvalho@gmail.com. Kind regards to all.

Pedro

What follows is an email I have sent to Dr. Carvalho with respect to the posting quoted above.


Dear Dr. Carvalho
I have exchanged some emails with Dr. Farsalinos. I provided him my name and invited him to do a do an internet search for my published papers/patents etc. so that he would know my technical background. I invite you to do the same so that we can establish a basis for technical discussion.


As to my work background I have been involved with alloy and process development for iron, nickel and titanium alloys for over 40 years. My work history began in the nuclear industry with Aeroet General Nucleonics followed by many years with Pratt and Whitney division of United Technologies Corporation and finally by sixteen years with Garrett AirResearch/Allied Signal/Honeywell. My later two employers were both producers of gas turbine engines for aircraft.


As you will see from my published papers and patents a large portion of my work was specifically directed to development and evaluation of FeCrAlY, NiCrAlY, NiCoCrAly and vapor deposited and plasma sprayed ceramic thermal barrier coatings for gas turbine engine turbine blades.


I appreciate your posting on the ECF forum however I would appreciate it if you would review and clarify your comment quoted below.


Your quoted text >>>
“ In some cases like kanthal, a "light" heat treatment can be beneficial, but a longer heat treatment can eliminate the oxide protection layer. This frontier is very narrow, so it is difficult to recommend a specific "light " heat treatment.”


Specifically the statement that the “frontier is very narrow” is of interest. My own work and a very large body of international work directed at long term evaluation of the adherence of protective oxides on FeCrAlY system alloys and Kanthal indicates that initial spalling of protective oxides does not occur for times of the order of hundreds of hours at temperatures between 1500F and 1700F. As you no doubt know the exposure of e cigarette coils by so-called dry burning is typically a matter of seconds in this temperature range.


If you have information which indicates that the “frontier is indeed very narrow”as you say, it is critical that it be supplied to the international gas turbine industry for the sake of aircraft safety as of course for the much lesser and less serious issues of e cigarette user safety.


I look forward to your reply. Issues of safety for both aircraft engines and the vaping public must indeed be taken seriously and I am sure you agree.

 

[Cacique]

I assure you that the letter is from the real Pedro; he is a long time friend. The new account was him but it would not allow him to post (new member regulations) - this is why he asked me to post it for him. He is not a registered supplier on ECF and no longer has the account he had here years ago.

Thanks for clarifying this. That was one of the thoughts that I had, could be him if he didn't have the old account.

 

[druckle]

Double posting deleted. I apologize for typos. (I'm concerned if I try to correct them again I will end up posting the same material a third time

 

[druckle]

Sorry for the double posting I was trying to edit to correct some typos and somehow the posting was entered a second time.
My apologies!!!

 

[MacTechVpr]

This issue actually interests me enormously. Our ejuices are not that innocent--some flavorings, like cinnamon, citrus and banana, for example, are known to crack, fog up and even completely melt polycarbonate tanks. I can provide pictures upon request.

I have no idea what they can do to the stable oxide, if anything, especially at elevated temperatures, but it is most certainly worth investigating.

Why exactly the anti-corrosive characteristics of the alumina formed by Kanthal is an asset. Methods to achieve it beneficial.

While I believe cinnamon and banana have anti-corrosive properties contaminants from human handling can be more damaging.

Good luck all.

 

[Mactavish]

@druckle
Now that's a resume!

 

[zoiDman]

Double posting deleted. I apologize for typos. (I'm concerned if I try to correct them again I will end up posting the same material a third time

Sorry for the double posting I was trying to edit to correct some typos and somehow the posting was entered a second time.
My apologies!!!

Don't Feel Bad.

I think I have Kacked more Quotes since the New Software was rolled-out than the Entire time I have been a Member here.

 

[Alien Traveler]

This is not my field so I might be totally wrong but my guess is that he's more concerned about the oxide layer starting to flake off (if thick enough) than with the oxidation by itself?

A1 Kanthal is designed for continuous work at 2550 F (1400 C). Well above temperatures of dry burning.

Somehow I assume Pedro Carvalho should know it.

Iron-chromium-aluminium (FeCrAl) wire — Kanthal

 

[Magaro]

Yeah, you might want to try and keep that in check.

LOL. You have NO idea what that short-lived, misclicked post was referring to. But whatever. It's the interwebs and you can assign any meaning to it that you like. Thanks for your input. I'll be sure to give it the consideration I think it deserves.

 

[Katya]

If you have information which indicates that the “frontier is indeed very narrow”as you say, it is critical that it be supplied to the international gas turbine industry for the sake of aircraft safety as of course for the much lesser and less serious issues of e cigarette user safety.

Thanks again for your efforts, Druckle!

 

[Alien Traveler]

What follows is an email I have sent to Dr. Carvalho with respect to the posting quoted above.


Dear Dr. Carvalho
I have exchanged some emails with Dr. Farsalinos. I provided him my name and invited him to do a do an internet search for my published papers/patents etc. so that he would know my technical background. I invite you to do the same so that we can establish a basis for technical discussion.


As to my work background I have been involved with alloy and process development for iron, nickel and titanium alloys for over 40 years. My work history began in the nuclear industry with Aeroet General Nucleonics followed by many years with Pratt and Whitney division of United Technologies Corporation and finally by sixteen years with Garrett AirResearch/Allied Signal/Honeywell. My later two employers were both producers of gas turbine engines for aircraft.


As you will see from my published papers and patents a large portion of my work was specifically directed to development and evaluation of FeCrAlY, NiCrAlY, NiCoCrAly and vapor deposited and plasma sprayed ceramic thermal barrier coatings for gas turbine engine turbine blades.


I appreciate your posting on the ECF forum however I would appreciate it if you would review and clarify your comment quoted below.


Your quoted text >>>
“ In some cases like kanthal, a "light" heat treatment can be beneficial, but a longer heat treatment can eliminate the oxide protection layer. This frontier is very narrow, so it is difficult to recommend a specific "light " heat treatment.”


Specifically the statement that the “frontier is very narrow” is of interest. My own work and a very large body of international work directed at long term evaluation of the adherence of protective oxides on FeCrAlY system alloys and Kanthal indicates that initial spalling of protective oxides does not occur for times of the order of hundreds of hours at temperatures between 1500F and 1700F. As you no doubt know the exposure of e cigarette coils by so-called dry burning is typically a matter of seconds in this temperature range.


If you have information which indicates that the “frontier is indeed very narrow”as you say, it is critical that it be supplied to the international gas turbine industry for the sake of aircraft safety as of course for the much lesser and less serious issues of e cigarette user safety.


I look forward to your reply. Issues of safety for both aircraft engines and the vaping public must indeed be taken seriously and I am sure you agree.

It definitely looks like you are better qualified to talk about Kanthal than I do (you have a direct involvement in work with similar alloys). Glad our opinions on Kanthal behavior coincide. As for your suggestion to be involved in "technical discussion" with members of e-cig production and/or research community, I have to excuse myself. I do not perform consulting services for free.

 

[Punkndrublic]

Honestly, I see nothing wrong with the questioning of Pedro's theory. This is how the science works. You get questioned by your peers, this is a honest debate. And I find all this information from both sides extremely fascinating. And, you never debate with emotion, always use facts and empirical data.

 

[druckle]

It definitely looks like you are better qualified to talk about Kanthal than I do (you have a direct involvement in work with similar alloys). Glad our opinions on Kanthal behavior coincide. As for your suggestion to be involved in "technical discussion" with members of e-cig production and/or research community, I have to excuse myself. I do not perform consulting services for free.

I am now essentially retired so I am not adverse to some new work....but of course if a corporation were asking for service with respect to a new advanced engine or some such...I would not be so cheap!

 

[Magaro]

What follows is an email I have sent to Dr. Carvalho with respect to the posting quoted above.


Dear Dr. Carvalho
I have exchanged some emails with Dr. Farsalinos. I provided him my name and invited him to do a do an internet search for my published papers/patents etc. so that he would know my technical background. I invite you to do the same so that we can establish a basis for technical discussion.


As to my work background I have been involved with alloy and process development for iron, nickel and titanium alloys for over 40 years. My work history began in the nuclear industry with Aeroet General Nucleonics followed by many years with Pratt and Whitney division of United Technologies Corporation and finally by sixteen years with Garrett AirResearch/Allied Signal/Honeywell. My later two employers were both producers of gas turbine engines for aircraft.


As you will see from my published papers and patents a large portion of my work was specifically directed to development and evaluation of FeCrAlY, NiCrAlY, NiCoCrAly and vapor deposited and plasma sprayed ceramic thermal barrier coatings for gas turbine engine turbine blades.


I appreciate your posting on the ECF forum however I would appreciate it if you would review and clarify your comment quoted below.


Your quoted text >>>
“ In some cases like kanthal, a "light" heat treatment can be beneficial, but a longer heat treatment can eliminate the oxide protection layer. This frontier is very narrow, so it is difficult to recommend a specific "light " heat treatment.”


Specifically the statement that the “frontier is very narrow” is of interest. My own work and a very large body of international work directed at long term evaluation of the adherence of protective oxides on FeCrAlY system alloys and Kanthal indicates that initial spalling of protective oxides does not occur for times of the order of hundreds of hours at temperatures between 1500F and 1700F. As you no doubt know the exposure of e cigarette coils by so-called dry burning is typically a matter of seconds in this temperature range.


If you have information which indicates that the “frontier is indeed very narrow”as you say, it is critical that it be supplied to the international gas turbine industry for the sake of aircraft safety as of course for the much lesser and less serious issues of e cigarette user safety.


I look forward to your reply. Issues of safety for both aircraft engines and the vaping public must indeed be taken seriously and I am sure you agree.

Props for sharing so much personal history in this thread. Because I am a current long-time employee of a major corporation, I am contractually bound not to represent myself as a spokesperson for my employer. Voluntarily disclosing too much about my prior employment history, publications and patents could cause an issue. Ya know? Lawyers...

I understand people's concerns about the emission of vapors or particles from coils, but I am saddened by the unwillingness of some to accept input from people conversant, educated, and experienced in the field (metallurgy) most immediately relevant to this issue.

Anyway, I hope this post buys you credibility with the non-believers following this thread. They need the information to help them make the right choice.

 

[Katya]

Honestly, I see nothing wrong with the questioning of Pedro's theory. This is how the science works. You get questioned by your peers, this is a honest debate. And I find all this information from both sides extremely fascinating. And, you never debate with emotion, always use facts and empirical data.

Absolutely. I find this discussion fascinating also, and I want more of it. Which is why I'm so disappointed with Dr. F's decision to remain silent.

Yes, you do grill your peers in an honest debate--but the debate has to be honest and on topic. In other words, you attack your peer's facts/conclusions/science--you don't attack your peer.

 

[zoiDman]

I am now essentially retired so I am not adverse to some new work....but of course if a corporation were asking for service with respect to a new advanced engine or some such...I would not be so cheap!

I don't have any problems Volunteering my Time or Expertise when the Beneficiary is a Non-Profit entity.

Especially if it Benefits a cause I Believe In.

 

[Punkndrublic]

Absolutely. I find this discussion fascinating also, and I want more of it. Which is why I'm so disappointed with Dr. F's decision to remain silent.

Yes, you do grill your peers in an honest debate--but the debate has to be honest and on topic. In other words, you attack your peer's facts/conclusions/science--you don't attack your peer.

Totally agree.

 

[Alien Traveler]

I am now essentially retired so I am not adverse to some new work....but of course if a corporation were asking for service with respect to a new advanced engine or some such...I would not be so cheap!

Many years ago as a young researcher I had a stint with aircraft industry. We worked on creating of hard TiN coating in glow discharge on turbine blades.

 

[druckle]

Props for sharing so much personal history in this thread. Because I am a current long-time employee of a major corporation, I am contractually bound not to represent myself as a spokesperson for my employer. Voluntarily disclosing too much about my prior employment history, publications and patents could cause an issue. Ya know? Lawyers...

I understand people's concerns about the emission of vapors or particles from coils, but I am saddened by the unwillingness of some to accept input from people conversant, educated, and experienced in the field (metallurgy) most immediately relevant to this issue.

Anyway, I hope this post buys you credibility with the non-believers following this thread. They need the information to help them make the right choice.

I'm essentially retired and don't have the restrictions you have. I also find it interesting that some folks choose to accept myth as fact and are resistant to any introduction of reality. I guess it's a case of a sort of vaping religion being developed and we all know that's a subject best not discussed in polite society. That makes it difficult to converse about much of anything that matters.

 

[Vwls]

From Pedro:

Chromium and nickel came from the coil itself, even when they did not dry-burn the coil. Although we explained in our risk-assessment analysis that the levels found were not a significant health concern, we cannot assure that heat treatment would not increase this concentration. Please refer to this article: http://www.ncbi.nlm.nih.gov/pubmed/23526962