need some input on Defiant Encore

Hi
I got this stove the other day good price. It has a cat/c that had holes in it. I also have this stuff further in from the cat/c that needs to be replaced. I believe its called Refractory, was white when new in 1986. I believe its in a shape of a box bottom top sides and hollow center is that correct? Could this stuff be made DIY? Could I buy this stuff?
The model is Defiant Encore 0028. My terminology is not up to most of you so if you have any questions please ask.
I also saw that a Encore could be used with 8" or 6" double c/pipe. But now I see on the the label
it says use 8". I know my mind is starting to play with age but could I have dreamt this up?

What I was thinking about is I believe the same material that is used in / when they make
sugaring equipment (maple syrup). Its used between the pans that are in contact with the fire and then the pan holding maple syrup. It transfer heat but wont burn.
Was just an idea. Plus there is on the market this material that could be found stiff board or soft like wool. I also believe there is a cementing material that is the same but in powder that could be used to hold these materials in place.
No one out there has tried this?

Well thanks for your reply. I still have no idea what the shape is of this refractor parts. If I had a picture I could see how hard it would be.

Thanks

Thank You

will let you know how things are going as I still need to reshearsh this more.

Anyway do you have a answer to 6" or 8" flu?