Not sure I understand what you are getting at here, but anyway a few suggestions based on what I think you are saying:
I’ve never heard of vacuum heat treatment (but that doesn’t mean anything – I don’t know much about anything!). In respect of heat treatment of steel, may I suggest Workshop Practice Series No. 1 by Tubal Cain. Titled Hardening, Tempering & Heat Treatment it will tell you all you need to know, and possibly more!
Refractory bricks should be available from any good builders merchants although I’m not too sure about what they may be called. The first lot I bought came from Uriah Woodhead in Bradford and worked extremely well. I recently bought some more from there, but I’m not at all sure what I’ve got and I haven’t yet tried them. The invoice describes them as Firebrick.
I did also find a firm, in Nottingham I think, who seemed very knowledgable about them and were prepared to sell them singly and either post them (!) or I could collect. I found them by a roundabout way involving tracing Fossalcil bricks. Apparently the original maker of these had been taken over. Price wise these were about the same as the Woodhead ones.
Anyway, suggest the book first, and then take it from there.
Regards,
Peter G. Shaw