Cryogenic Processing

[sketchers356]

Will,

Liquid hydrogen is colder than most any thing with a boiling point of approx 20K but helium has the lowest boiling point at 4K, significantly colder in this domain. Helium will not freeze at 0K, it has to be pressurized to do so (26 atms to freeze at 1K). A couple of years ago the nobel prize went to a team that supercooled helium with lasers so that it was superfluid, it would not stay in a container, instead defying gravity and crawling up the sides!!

[DG624]

Geary, did you measure any additional hardness or see less wear? I think it would be good to reduce wear in the gears and syncros and improve shifing smoothness. Is it a measurable difference (more HP or quicker response)? The finishing process sounds like it should be effective in reducing friction and reduce HP loss.

[Randy Webb]

Just a tidbit since this came up. Many years a go I asked a physics prof. I was working for as a "gravity wave istudent ntern" (as we said in the 70's, it was heavy, man) about the absolute zero thing. He said it was not impossible to get to abs. 0, -- but that no work could be extracted from the system. So, my followup was: Well, does that mean it is unobservable (work is done on a system to measure or look at it). His reply was paraphrased as "Maybe, now go work on the helium vacuum pump."

[unclebilly]

Ah hah! I do have experience with this.

I did some experimentation with this as one of my 4th year mechanical engineering projects. If I dig, I should even be able to find an E-Copy of my report.

Here's what I did:

Got a used brake rotor, and cut in into several specimens.

Specimen 1 was my standard.

The remainder of the specimens were vapour cooled with LN2 (liquid nitrogen) to about -100°C and then were placed into the LN2 (I'm going from memory on the temp there) in an insulated container.

The next morning, the specimens were still below 0°C but the LN2 had all evaporated. I removed one of the samples from the batch (Sample 2).

I then normalized the remaining samples at about 100°C for one hour in air and set one aside (sample 3).

The remaining samples were then heated slowly to 600°C (extreme brake rotor temperature - I developed technology to measure brake rotor surface temperature on a previous project in instrumentation class).

The samples were then cooled (I can't remember if I air cooled them or quenched them - maybe I did both).

I then polished and etched all of the samples with nital. And looked at the grain structure with an optical microscope.

Here's what I found:

Sample 1 (untreated) had graphite all through the sample - nothing special.

Sample 2 was pretty neat - carbide had been precipitated into all of the grain boundaries (hence the long wear characteristics of cryo treated tool bits).

Sample 3 still had the carbides but some had turned back to graphite (very small amount).

The heated samples - these were different from sample 1. The carbides were all gone but the graphite was not randomly scattered throughout the sample - it was only in the grain boundaries (where the carbides had been). The metallic structure was much more regular than sample 1. This can all be clearly seen in the micrographs in the report.

Upon conducting hardness testing on any of the samples, I didn't see any significant difference in any of the samples.

So there's my 2 bits - cryo treatment does change cast iron. Would I pay $650 to have it done? Probably not, you can get LN2 and all you need is a big enough cooler to use as your cold chamber. Be creative.

If anyone want's my report, let me know and I'll try to find it any email it to any intertested parties.

[Geary]

The REM (Isotropic Normalizing) process has measureable and visually obvious benefits, although perhaps not enough to warrant extensive use in Porsche racing transmissions. We had high hopes, and yet couldn't see any obvious oil temperature reduction or discern any increased longevity. Would I do it with my own parts? Probably. But properly masking the areas that shouldn't be made more slippery is very important. You need friction for synchros to work, so this is just one area that you would definitely wish to mask.

I believe that Cryogenic treatment is promise built atop theory, without real merit. Cryogenics has been extensively tested in the automotive industry, with no scientifically measureable benefits.

One example is Brembo, who had the most to gain from the magic promised by Cryogenics, as it supposedly worked exceptionally well on cast iron brake rotors. Brembo spent about $100,000 in testing, and in the end couldn't see ANY benefits to cryo'd rotors over non-cryo'd rotors in any test performed.

The level of austenite transformation is pretty well controlled by knowledgeable heat treaters, without having to rely on the "cryogenics experts" to wave their magic wand at a later date. If there were measureable benefits, the heat treaters would perform this step IN HOUSE, as they have all the equipment to do so. Yet, in recent years, some of the world's finest heat treaters have dropped the cryogenic freezing step (which for decades has been common in the heat treatment of high nickel steels) altogether, and replaced this extremely low temperature treatment with common refrigeration prior to tempering.

The enhanced grain structure of forgings over standard billet (and certainly castings) is quite visible under magnification, while the "realigned grain structure on the invisible molecular level" of cryogenically treated components is just too convenient. Invisible likely = non existent. Enhanced grain stucture can be had for a few dollars more through material selection. Invisibly enhancing the grain structure after-the-fact ? Come on.

However, I must admit that the power of suggestion is powerful. Some very respected mechanics swear by cryogenic treatment, and pay to have this performed on the most unlikely materials, swearing up & down the benefits that they have seen with their own eyes. Rather baffling.

Just my two cents --

[unclebilly]

I'd like to point out that I have nothing to gain from whether cryotreating is for real or not. Like you, I too was unsure if it was for real or not and decided to do more than websearches on the topic, I did some controlled experimentation and found something. So my opinion on this topic is based on something tangible, not just biased articles in trade journals and on websites authored by those with monetary interests at stake.

Here is a link to my report...

http://www.engr.uvic.ca/~ssherman/473%20project.doc


Like I said, this is something the common Joe can do in his garage, provided he can get ahold of some LN2.

[Wil Ferch]

Sketchers356:

Of course you are correct and in my haste failed to notice the normal boiling points of other elements.

Hydrogen is at about 20 degK ( as you say...this is about minus 423 degF)...and helium gets about as close to absolute zero as you get get without external help ( 4.2 degK...or about minus 452.1 degF).

I believe absolute zero is about minus 459 degF ( "0" degK), ..as I remember...

--Wil

[DG624]

unclebilly, I read your report and think there may be something to this for parts that are not heated too high (above 300 F). Transmissions would be a good place. The ability to finish metal to a smoother level may also be important. It would have been good to test other types of steel, stainless steel for example. Brake rotors are constantly being changed due to high heat so treating them may be a waste of money but other engine parts that stay below 300-500 F may be much better. I will ask the manufacturer more questions.

[DG624]

Geary, thank you for the information. I think a transmission treatment would be good when I am having it rebuilt but by then they may have refined the process. WEVO claims to have a rebuilt trans option that perfoms much better with quicker and smoother shifting but the cost is very high.

[wevoid]

DG624,

Our product that claims quicker shifting has eliminated the synchronizers, no magic, just a simple widely accepted (outside Porsche circles) gear selection system that selects gears as quickly as you can move the lever.

It is a race-only system mostly due to noise, harshness issues.

About 60% of the parts in the system come exclusively from Paul (Geary).

Regards

Hayden

[126coupe]

Im no engineer, but I had this process done to my spare race longbox (901). It will go in the car next season for the CA Speedway. I'll let the board no if their is a difference.
I will also take notes on life of the 901 with and without Cyro.
My primary box does not have the process done

Some photos of the process in my spare box

[skilletshot]

I have come to the conclusion that after reading many of the posts in this thread that I may be stupid. lol

[DG624]

Mimkoff, it looks like your gears had the finishing process REM Isotropic Normalizing done also is that true?

[126coupe]

yes but dont ask me any "engineer" questions

Leave that to all the really "smart" guys on this site