I have been been working on some recipes to make a homemade refractory fire brick.
Initially I was building them with sand and clay and they would just crack when I fired them. Then I discovered sodium silicate.
Sodium silicate is easily made from common household chemicals (drain cleaner and kitty litter!), and is essentially a high temperature glue.
So the first bricks I made were a mix of sand and perlite bonded with sodium silicate. They work really well and most importantly withstand high heat.
I have also experimented with calcium hydroxide (lime) as the melting point of calcium oxide is over 2700 Celsius. The mix was lime and perlite bonded with sodium silicate which set so quickly i could barely mould it.
The photo below shows the result of a gas burner on the lime brick for about 2 minutes. It seems to hold up to a high temperature very well. I am ordering some aluminium oxide to make bricks from as well.
