Santovac 5GB Ultra High Vacuum Grease

Santovac 5GB is a non-melting, ultra-high vacuum grease with exceptional resistance to high temperatures, oxidation, radiation, chemical attack and moisture. The base fluid is Santovac 5 Polyphenyl Ether, which has been used successfully for many years in numerous vacuum applications. This unique grease is intended for applications where exposure to these conditions is likely, especially where silicones and halogens are to be avoided. The resistance to radiation breakdown puts Santovac 5GB grease in a class of its own.

Santovac 5GB Grease has an extremely high surface tension of 50 dynes/cm and as a result, it tends to not want to leave the site where it was originally applied and migrate, a problem with many other greases. That is why Santovac 5GB Grease is known as the best of the "non-migrating" greases. And in addition to this non-migrating property, Santovac 5GB grease will usually last significantly longer since the film that is applied will maintain its thickness at the point of application.

Santovac 5GB vacuum grease is especially advantageous for use on "O" rings being used in systems that are using a diffusion pump charged with Santovac 5, as a diffusion pump fluid, such as in many older electron microscopes, both SEMs and TEMs. The same would be true for many of the world's installed base of GC Mass Specs. This is going to result in the ultimate in compatibility between the grease and the diffusion pump fluid since the base oil used in the grease is the same as that being used as a diffusion pump fluid. For other o ring applications, Santovac 5 fluid might be the product of choice. With regard to overall compatibility with the elastomers typically used for "o" rings, we are not aware of any for which the use of Santovac 5 fluid or grease would be a problem. Under certain circumstances, there can be some nominal swelling of the elastomer with the polyphenyl ethers, but in some instances, such swelling phenomena are actually desirable. In most instances, the polyphenyl ethers will cause less problems with o rings than will hydrocarbon greases generally (e.g. those from petroleum distillates).

Space Applications:
The Santovac 5 polyphenyl ether based products are used in many different space applications, in both lubricant and grease form.

High temperature applications:
Santovac 5GB vacuum grease is thermally stable to 450°C and for short time intervals, up to the range of 500°C. We know of no other vacuum grease that comes close in having this high of a service temperature. For higher temperatures one must resort to solid lubricants of one type or another.

Low temperature applications:
Considering that there are a lot of questions about low temperature applications for vacuum greases, we are ourselves surprised that there is not more information available relative to low temperature performance. We do know that at -80° C (-112° F), Santovac 5GB, will become a glassy solid, but will not crystallize. It is a monomolecular material rather than a polymer, such as the perfluoropolyethers and, therefore, the polyphenyl ether structure will definitely perform differently. Unfortunately we have no hard data available under these low temperature conditions.

As a result, we recommend that some tests be run to confirm that the Santovac 5GB performance will indeed live up to or exceed expectations before incorporating it into some production application or introduction into a complex system.

Electrical contacts and circuit breaker applications:
The electrical contacts and circuit breaker applications require longer duration oils that can sustain oxidation and thermal breakdown due to arching and extreme heat. Also the grease must stay where applied. PPE based grease Santovac 5 GB has the natural ability to stay put where applied because of its high surface tension of 50 dynes/cm. Other greases tend to have surface tensions of less than 30 Dynes.cm. This is a clear advantage which is estimated to increase grease life by at least two fold.

Other major advantages of Santovac 5GB vs. other greases are

1. Much higher temperatures are possible
2. More stable in high radiation environments
3. Higher surface tension results in Santovac 5GB being less mobile and therefore they have a longer life
4. Non-toxic and safer if breakdown does occur
5. Proven over 50 years of use in these kinds of applications.

Outgassing characteristics:
There is no question more important than this one for someone with responsibility for an ultra-clean vacuum system. But in all of our years of experience, especially when it comes to hydrocarbon based greases, we have never come across any grease or fluid that has demonstrated a better outgassing performance than Santovac 5 Lubricant/Fluid or Santovac 5GB Grease. In addition, both Santovac products are very safe and non-toxic and leave no residues. The components that comprise the grease are already quite widely used in cleanroom and semiconductor environments. Santovac 5 is 100% pure polyphenyl ether. 

But remember, nothing is forever, and with the passing of time, and abuse, the fluid could begin to deteriorate, so one must still monitor vacuum system performance, age of the fluid, history of abuse of the fluid (being exposed to air when hot, for example). 

Optical properties:
We do not have data for the refractive index of the grease, only the base fluid. The refractive index of the fluid is 1.63 at 25°C. The grease itself, in the bulk, is opaque. One normally does not talk about the refractive index of an opaque material.

Specifications
Thermal/Oxidation Stability
The base fluid in Santovac 5GB vacuum grease is thermally stable to approximately 466°C (870° F).