- Why is a “Direct Contact” style cryogenic process so desirable?
- Why is using LN2 the preferred method of CSF, LLC?
- What makes this “cold phase change” so critical?
- My engine builder has a cryo processor, why shouldn’t I just let him do it?
- What else should I know before I decide to cryo my engine?
- Which is more desirable,”stress relief” or “uniform compressive stress”?
- My engine builder claims that the “extreme contraction” at very low temperatures is what realigns the atoms, is that true?
Why is a “Direct Contact” style cryogenic process so desirable?
With every type of cryogenic processing tank there exists a “constant heat flux” (heat entering the tank). Common to nearly every material, there exists a “cold phase change” temperature state that is close to that of liquid nitrogen (-320F). It is virtually impossible to reach the cold phase change temperature state at the component’s core without that component having direct contact with liquid nitrogen (LN2). If a component does not enter a cold phase change state the free electrons, and lattice structure within the material will not realign, and there will be no “compressive stress” induced. As a result, very little will happen to improve the physical properties of the material, and therefore is a waste of time and money.
Why is using LN2 the preferred method of CSF, LLC?
As a component with significant mass i.e.; crankshaft, engine block, etc. descends in temperature and approaches the “cold phase change” temperature state (near -320F) a condition known as the “barrier phenomena” exists. This is where the heat within a component will migrate to the center-core and whose molecules want to stay more excited and not release their latent heat preventing the cold phase change from taking place. Due to the constant heat flux that exists in every type of processor, and the “barrier phenomena”, direct contact with liquid nitrogen is the only way to uniformly reach the “cold phase change” temperature state.
What makes this “cold phase change” so critical?
We are not aware of any other commercial cryogenic processing facility that addresses this phenomena. The “cold phase change” temperature state is a narrow temperature window close to (-320F). This window is common with the vast majority of materials, it is also the key to the science behind the CSF, LLC cryogenic process. The cold phase change temperature state is what allows the free electrons and the lattice structure within a given material to free-up, realign, and tighten thus improving the micro structure and locking in significant “uniform compressive stress”. This all takes place within a few seconds of reaching the cold phase change temperature; most important is how the transition in and out of the cold phase change state is controlled. If this transition is handled improperly as with parts placed in open air to warm-up, or indiscriminately “dunked” into liquid nitrogen etc., the micro-structure within the cryogenic parts material will be severely damaged.
My engine builder has a cryo processor, why shouldn’t I just let him do it?
This would be a big mistake. Unfortunately it is highly unlikely that your engine builder knows how to effectively exploit the power of cryogenic processing. It is virtually impossible to buy a cryo processor, use a pre-programmed generic cycle (which is what most everyone does), and expect world class results. Cryogenic equipment manufacturers may be able to build a processor and sell it to whom ever they will, but they do not understand the true science behind what is required to effect a successful “cold phase change” within a cryogenic engine treatment. It takes years of development and a substantial capital investment to yield a cryogenic stress relief treatment that will actually produce quantifiable results.
What else should I know before I decide to cryo my engine?
There also exists a condition known as the “soft layer phenomena”; this is a situation where certain ferrous metal alloys will exhibit a two to ten micron, or so, thick layer that is somewhat softer than the substrate after being exposed to a cryogenic process that has resulted in a “cold phase change”. For this reason it would be good planning to save all machining operations as well as superfinishing until after the CSF, LLC direct contact cryogenic processing is completed.
I’ve heard that cryo will make things “move around” or change dimensions, is that true?
In certain cases something like this can happen, but not for the reasons most people think. Our proprietary cryogenic process is designed not simply to remove residual uneven stressors, but rather to induce significant “uniform compressive stress” which has proven to equate to that of shot peening. Post-cryo process micro-grain structure analysis has shown that this new compressive stress goes all the way to the core of the component. Things do not really “move around”, what happens is some tool steel alloys common with overhead cam bucket followers may grow in diameter .0005in.-.0015in. This is due to a poor heat treatment performed during manufacture that resulted in a high percentage of retained austenite. However, in the majority of cases this is unlikely to happen.
Which is more desirable,”stress relief” or “uniform compressive stress”?
This is one way to tell whether or not a company is utilizing a scientifically based strategy with their cryogenic treatment process. “Stress relief” should not necessarily be the objective. The CSF, LLC direct contact cryogenic process was designed to remove all uneven stressors, but more importantly to induce a significant “uniform compressive stress” into the cryogenic parts. We are unaware of any other commercial cryogenic treatment facility that is able to put forth their process this way. “Uniform compressive stress” is critical with any high performance engine or drivetrain assembly, and any other type of machine for that matter, as it is the key that unlocks everything; improved microstructure, increased core strength, improved ionic bonding, increasing the heat transfer coefficient, reduced electrical resistivity, improved machinability, improved harmonic resonance, increase in wear resistance, healing of subsurface micro-fissures and increase in fatigue resistance.
My engine builder claims that the “extreme contraction” at very low temperatures is what realigns the atoms, is that true?
This is a widely held misconception, and another example that your engine builder (or anyone else) doesn’t know “squat” with regard to cryogenic processing. To set the record straight, the atoms do not realign, per se, it is the “free electrons” and the “lattice structure” within the material that will realign and tighten when correctly subjected to the critical cold phase change temperature state. Also, there is nearly a 100% transformation of any retained “austenite” into the more desirable “martensite” with carbon steel alloys. It is true that virtually all metals will contract as they get colder, but not infinitely. The vast majority of all metal alloys will stop contracting at approximately (-150F) or so. It is the direct result of the cold phase change temperature state alone (near -320F) that is responsible for all the positive physical changes that will take place within the material of an engine, or any other machine/device cryogenically processed by CSF, LLC.