What material can be used as scraper in a chemical reactor?

I am having a 10L reactor built using SS316 for Plastic Pyrolysis.


TEMPERATURE : 550C


I would like a scraper to clean the char that forms on the reactor's inner layer.


[![Picture showing reactor with teflon scraper  ](https://i.stack.imgur.com/hDEP9.jpg)](https://i.stack.imgur.com/hDEP9.jpg)


Teflon scraper is available but it will not withstand 550C temperature.


So I am thinking about using flexible expanded graphite (Similar to graphite gland packing ropes) material. What do you think?


[![graphite gland ropes](https://i.stack.imgur.com/t6VeL.jpg)](https://i.stack.imgur.com/t6VeL.jpg)


What other options do you suggest that I look into? 


