Changing the Resistivity of Bakelite

In summary, the conversation discusses the issue of non-uniform surface resistivity in bakelite plates, which are used in particle detectors. The use of linseed oil has been found to improve the uniformity and charge restoration, but the speaker is seeking other methods to achieve these results. Suggestions include using different types of oils, incorporating conductive particles, or using a plasma treatment. These methods may also allow for controlled changes in resistivity.
  • #1
Afunk
8
0
Hey PFers,

So basically, we have these plates of bakelite that have on the order of 10^10 Ohms surface resistivity, but it is not uniform enough. Part of the reason may be that although these sheets may have some non-trivial non-uniform structure at a small enough scale.

These sheets of bakelite are used in particle detectors that require a rather large uniform surface charge on these sheets, and the ability to quickly replenish charge when charge is lost on the surface due to electron "avalanches" that occur in close proximity to them via high potential connections.

So far, linseed oil has been tested and it does a good job of making the surface more uniform and also helps with the rate of charge restoration. One thing that would be great though would be to be able to change the resistivity of this bakelite in a controlled manner. One such possibility is to put a net charge on some metallic salts, and then drop them on the linseed oil coating while it dries on the bakelite, thus spreading it out in a uniform manner.

So you experts on materials and such tell me, are there other methods to:

1. Make a more uniform coating on the bakelite with maybe another coating than linseed oil. (tung oil, etc)
2. Some way to control the resistivity of the surface of the baklite in a uniform manner.

Thanks for any ideas!

This is NOT for any commercial interests but purely for research.
 
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  • #2


Hi there,

Thank you for sharing your research and asking for input from the community. It sounds like you are facing a challenging issue with the surface resistivity of your bakelite plates. I am not an expert in materials, but I have some ideas that may be helpful for your research.

1. In addition to linseed oil and tung oil, you could also consider using other types of oils such as mineral oil or silicone oil. These oils have different properties and may provide a more uniform coating on the bakelite. It would be worth testing them to see if they improve the surface resistivity.

2. To control the resistivity of the bakelite surface, you could try incorporating conductive particles or fibers into the coating. This could be achieved by mixing them into the oil before applying it to the bakelite, or by spraying a conductive coating on top of the oil. This method would allow you to adjust the resistivity to a desired level.

3. Another approach could be to use a plasma treatment on the bakelite surface. This can modify the surface properties and potentially improve the uniformity of the coating. You could also try different plasma gases and treatment times to see which combination works best for your application.

I hope these suggestions are helpful and wish you all the best in your research. Keep us updated on your progress!
 

1. How does temperature affect the resistivity of Bakelite?

The resistivity of Bakelite decreases with increasing temperature. This is because as temperature increases, the molecules in Bakelite start to vibrate more, making it easier for electrons to move through the material, resulting in a decrease in resistivity.

2. Can the resistivity of Bakelite be changed permanently?

Yes, the resistivity of Bakelite can be permanently changed through a process called doping. This involves introducing impurities into the material, which alters the number of free electrons and therefore changes its resistivity.

3. What is the role of moisture in changing the resistivity of Bakelite?

Moisture can have a significant impact on the resistivity of Bakelite. Exposure to moisture can cause the material to absorb water molecules, which can change the properties of the material and affect its resistivity.

4. Is it possible to change the resistivity of Bakelite without altering its chemical composition?

Yes, it is possible to change the resistivity of Bakelite without altering its chemical composition. This can be achieved through physical processes such as stretching, compressing, or bending the material, which can alter its molecular structure and therefore its resistivity.

5. How does the thickness of Bakelite affect its resistivity?

The thickness of Bakelite has a direct effect on its resistivity. Thicker pieces of Bakelite have a higher resistivity than thinner pieces, as there is a greater distance for electrons to travel through the material. This is known as the thickness-dependent resistivity of Bakelite.

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