I'm looking for advice on how to attach a thermocouple to a metal surface in a fashion that's relatively temperature resistant (more-so than) glue.
I've got some very fine gauge wire on hand to make the thermocouples and specialized spot welder that will join them to form a bead. My goal is to attach them to a 3-7 mm thick sheet some kind of metal. Could be steel, aluminum, copper etc. I don't have a strong preference on either the metal used or the exact thickness. I have access most commonplace metalworking equipment and can purchase basic tools and materials but can't justify the expense of a purpose-built welder for this kind of thing.
So far I've tried two things (unsuccessfully):
Soldering: I used a gas torch to heat copper plate enough to get a nice puddle of solder on it and then tried to dip the (already welded) TC. The wire simply would not wet, it would just push the solder out of the way and couldn't make a connection.
TIG welding: I tried to weld a both TC and bare TC wire to an aluminum plate by forming a small puddle on the plate and then attempting to dip the wire into the puddle while quickly extinguishing the arc. Mostly the wire just melted and "ran away" from the arc. Other times it just didn't fuse to the surface. I also tried putting the wire in contact with the surface in advance and starting the arc on it.
I know that I've heard mention of doing this, but haven't been able to find any good information about how to actually do it. I could use anything from a definitive answer to comments on how to improve the techniques that I've attempted already.
p.s. I weld semi-regularly but have very little experience soldering (esp. with a torch), so don't assume a lot of skill or knowledge in that department.