High temperature furnace muffle

A high temperature furnace comprising:

• a first furnace section operative at a predetermined temperature and having a metal muffle;
• a second furnace section operative at a predetermined temperature and having a quartz muffle disposed adjacent said first section;
• a barrier between said first and second furance sections operative to isolate the environments in each of said sections;
• sealing means surrounding an end of said quartz muffle confronting the barrier and defining a peripheral chamber and including porous gasket means sealing said peripheral chamber to the quartz muffle and to the barrier;
• and
• means coupled to said peripheral chamber and operative to introduce sealing gas at predetermined pressure into the peripheral chamber to cause controlled leakage of the sealing gas from the peripheral chamber through the porous gasket means to prevent leakage of gas in the quartz muffle.

For use in a high temperature furnace having a muffle defining a furnace chamber and being of a material having a thermal coefficient of expansion different that that of metal, means for effectively sealing said muffle to an adjacent metal structure of said furance comprising:

• a peripheral chamber surrounding an end of said muffle;
• porous gasket means disposed between an end of said muffle and a confronting surface of said metal structure;
• and
• means coupled to said peripheral chamber and operative to introduce sealing gas therein at predetermined pressure to cause controlled leakage of the sealing gas from the peripheral chamber through the porous gasket means.