The film on the inside of the CRT tube is a Phosphor coating. See here: Parts of a Cathode Ray Tube
Then look here on wiki: Phosphor and there is a sections that says what is. Not sure if you can scrap it or not (assume you can), but you would have to vacuum A LOT of tubes in order to get enough to make it worth while. It is a very very thin film!
Hope it helps!
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