safety concerns of sintered ceramic wicks/coils

[jefx]

A new coil design has emerged using sintered porous ceramic as a wicking material to provide eliquid to the coil, negating the need for fibrous wicks. Currently this design is being used in the vaporesso, and soon to be in the iJoy Reaper Plus.

I have been trying to do some homework on this material as a wick, but there haven't been any studies done in that area (at least that I can find).

There are, however, many studies about thermal degradation of ceramics, including sintered porous ceramics. Most of them (online) require payment to read, so I can't link any of them here.

Here is one that is free to read:
http://www.hindawi.com/journals/isrn/2011/816853/

While it doesn't answer specific questions vapers might have, it does shed some light on a material most of us vapers know very little about.

I am not a material scientist, so if there are any ceramic experts reading this, please feel free to correct me if I am misunderstanding this study, or if you can add any scientific knowledge about the safety of ceramic as a wick/coil.

 

[jefx]

I am not being an alarmist, nor am i trying to dissuade anyone from using ceramic as a coil wick. I'm just sharing my thoughts about what I've read.

In that study, they investigate the thermal degradation of sintered porous ceramic by heating it, then cooling it, and examine the structural changes in the material. They use temperature extremes beyond what most vapers would see.

The study shows that sintered porous ceramic experiences microscopic breaks in the structures surrounding the pores, that can even lead to complete failure of structural strength. Different pore sizes and and ceramic composition can increase or decrease the amount of degradation when heat cycled.

 

[sofarsogood]

After about 50 ml with the DIY I'm making the Ti coil and cotton wick get gunked up enough so that some service improves the taste enough to be worth the work. I doubt that silica or ceramic would change that. If there was a system that would give me months of fresh crisp flavor without service I'd be interested. My best guess is ceramic nor siica coils change risk but that purely a guess by me.

 

[jefx]

So why would structural strength be a concern to vapers in an enclosed coil head?

When the ceramic structure degrades, and tiny breaks are formed, it is possible for small shards of ceramic material to become dislodged from the structure.

Thermal shock adds to this degradation. Ceramic expands and contracts much less than other materials when heated and cooled.

When forming a ceramic coil head (wick) around an internal metal heating coil, thermal shock becomes more pronounced. The metal heating coil will expand and contract at a much higher rate than the surrounding ceramic. This uneven expansion and contraction will lead to increased degradation (breakage) of the ceramic structure, increasing the expulsion of fine ceramic particles.

eliquid also expands and contracts at different rates than either the metal heating coil or the ceramic wicking material, increasing the thermal shock load. As eliquid fills all the pores in the ceramic wick, it will expand when heated applying internal pressure against the structural needles surrounding the pores that maintain the structural strength of the porous ceramic, increasing the thermal shock load of the ceramic.

 

[jefx]

A while back, there was a product called "Vapin Donut" that used ceramic fused with heating wire to be used as a universal coil for atomizers. There are many reports of the product experiencing thermal shock induced catastrophic structural failure which some users described as "exploding".

 

[jefx]

In some of the youtube videos I've seen, reviewers have disassembled the cCell coils of the Vaporesso coil heads. In the unused coils, the ceramic appears to "break" in a manner that we would expect ceramic to "break" and broke down into a gritty powdery "dust".

In pBusardo's review, he also disassembled a cCell coil head which he had been using for a week or so. when he applied pressure to the ceramic with a pair of pliers, the ceramic didn't "break" as much as it did "smoosh" and crumble. To my eyes, that looks like the ceramic had experienced extreme thermal degradation, and it's structural integrity had been vastly compromised.

So if thermal degradation of the cCell's sintered porous ceramic coil wick had reached a visual (non-microscopic) state, it is highly possible that coil wick was also leaching ceramic particulate while being used.

 

[Chuck64]

Doesn't take a rocket scientist to know not to vape anything named "reaper".

 

[jefx]

If you consider the hydrodynamics of the cCell and Reaper Plus ceramic coils, as ejuice flows through the porous ceramic, it is essentially "washing" any ceramic particulate (formed from the thermal degradation) directly into the plenum of the coil head to be exhausted in the vapor produced by the coil.

 

[jacoviii]

yes this is all good and well but even cotton wicks are not bonded together. your bound to get some of those fibers at some point. I for one think the risk is minimal at best. Plus unless you were taking repeated dry hits I can't see the ceramic under normal use every being dry enough to become powdery and inhale it

 

[Troll from behind]

So was there any proof about this slivers possibly breaking off?
How big were this slivers?

 

[gerrymi]

pbusardo's take on cCELL safety:

http://www.tasteyourjuice.com/wordpress/archives/9989

 

[gerrymi]

The safety of the ceramic may become a mute point...if...this coil-less atomizer catches on...

NO ceramic...NO wire...

Altus Tank Atomizer, a Coil-Less tank by Guo Vape

 

[VapingTurtle]

The safety of the ceramic may become a mute point...if...this coil-less atomizer catches on...

NO ceramic...NO wire...

Altus Tank Atomizer, a Coil-Less tank by Guo Vape

Do you know what the heating element's material is?

What makes you say "no ceramic"?

I'd take a guess just based on appearances and say that it is a ceramic heating element. Or possibly sintered ground unicorn horn dust.

Either of my guesses may be wrong. But I'd bet on one of them.

That doesn't mean that there will be anything wrong with using a ceramic heating element in an atty. I'll bet they can be made quite inert and safe for our use. But I could be wrong about that, too.

It's my day for wild guesses.

 

[gerrymi]

Do you know what the heating element's material is?

I'd take a guess just based on appearances and say that it is a ceramic heating element. Or possibly sintered ground unicorn horn dust.

Who knows???

Described as:

Using a cutting-edge silicon valley material that was developed over two years, this tank has a CVU chip, or center vaping unit, that has been granted over a dozen patents in the United States and lasts for years.


This is the cutting edge. It is also a durable and reliable product, with a one-year warranty from the manufacturer.


This material was designed for use in vaping, and is an advanced solid state heater. The CVU is safer than any wire, and within operating temperature it will run forever. The CVU is non-metallic and non-toxic, with a purer and cleaner flavor delivery than any wire currently on the market. There is no need to dry burn it, and dry burning it voids the warranty.


In essence, The CVU chip is the coil head. With far more surface area than a coil, it was engineered to heat up in a perfectly balanced way, unlike regular coils which heat up inside out, and over time, heat less of the perimeter of the coil, and more of the center. This CVU chip lasts for years.

Altus Tank Atomizer, a Coil-Less tank by Guo Vape

Is In Stock here:

Altus Tank by Guo | Worlds First Coil-less Tank

 

[gerrymi]

Do you know what the heating element's material is?

http://www.tasteyourjuice.com/wordpress/archives/10063

 

[WickedWicks]

NO ceramic...NO wire...

What else would it be then?


Big Ego posted some interesting speculation from a reddit discussion in the RTA forum:

A user on reddit is speculating what the heating element is. I will quote him:

I'm almost 100% positive that the "CVU" is just a silicon nitrate heater with tungsten (or some alloy of it) as the resisting heating element. I can understand why they don't want you to dry burn it, it would cause an expansion of the metal which would cause the inner layer of the CVU to turn into liquid-y phase silicon nitride (still a solid, but it expands under high heat) which would then COULD cause the solid-b phase outside to crack under expansive force. Dont worry about dropping it and breaking the CVU though, Silicon Nitride has a Density of 3.2 kg/m3 , nearly the same as diamond.​

 

[BigEgo]

http://www.tasteyourjuice.com/wordpress/archives/10063

So that confirms that it's a tungsten wire inside the ceramic. The question then becomes what is the "ceramic" made of? There's tons of different materials that are called "ceramic." I think that redditor has it right -- it's probably silicon-nitride.