materials in japan

[Decen]

Hey everyone I am doing the research on my new oven project. And I am currently researching where to find the materials. I just had a couple of questions regarding the specific types of bricks to use.

1. First of all would Refractoriness(S.K.) be the same as the alumina %. considering that it is a rough translation from Japanese.

2. what exactly is the difference between refractory clay and firebricks? or are the same thing

3. Is there anything else i can look at to make sure i am getting the correct bricks currently i am basing my searches on 38% alumina, 138 lb/ft3 density and 2300*F heat threshold

thanks for the help in advance