Expanding silicone core

I have a question,

I've been thinking about it for a long time and it has been on the forum yet, but not with the best results of information.

So I'm planning to make some tests with some silicone as an expanding core to get a nice outer finish with carbonfiber.

I plan to make a testsample of a tube made out of Carbonfiber:

- I plan to use an existing tube of metal

- Cut it in halve

- add some thickness (thickness of the carbonfiber, so not much) on the inside

- Put halves back together

- Fill the tube with silicone

- remove the silicone from the mould and remove thickness added before

- wrap wetted out carbon around the silicone

- Put it in an oven and hope for it to expand.

My question is, which silicone is expanding? mostly they make silicones that DONT expand because you dont want it to expand in most applications.

is it 1K silicone you'd better use or 2K silicone?

anyone has some experience with this?

I know about the blatter technique and so on, and thats not really what i'm looking for.