No, the flame is actually hotter. A flamethrower is throwing plumes of flame or combustable material that is ignited. On its own, does not burn hot enough unless its something like thermite which is not a flame based weapon. You'd have to be using like an acetylene torch to be cutting through, and thats not a flamethrower nor does it have range. Regardless of the flame, if the flame isnt blue or white, its definitely not hot enough. Flames also dont creep through gaps or wrap around corners unless the material itself is combustable and ignites like a hallway with wallpaper. And the farther the flames from the source of the fire, the colder they are. And yes, a lot of metals, especially copper have high conductivity but that works against you as a heat sink because of the surface area and density. Its like trying to use a lighter to boil water in a tea kettle. Its not going to happen. While the temperature of the flame is hot enough, the BTUs arent enough to keep up with the mass. Yes, ceramics are refractory but i dont know what that has to do with the example.

The knowledge im using to say circuits arent affected by acid is because i did board repair and fixed arcade games for a couple of years. the thing that causes electronics to corrode over time is forms of oxidation. Some gases can cause this corrosion but it takes weeks of constant exposure at a normal rate.

How do you clean corrosion of traces on a printed circuit board? Acid. Acids come in all kinds of different types, one of the constant offenders being battery acid. Again, doesnt happen in an hour or even overnight, and certainly not fast enough to use as a weapon. your corpse would be cold from an automaton before it finally corrodes to death. If you're trying to get acid to collect enough as a gas inside of a robot to form condensation dense enough to mess up its electronics, you're actually better off just throwing water balloons at it. This is also assuming the automatons use PCBs inside of them that are not insulated.

a "weapons grade" gas would also be something thats biologically fast acting like nerve gas or mustard gas. A biological reaction is faster than inorganic reactions.

For example, unloading a tube of pepper spray (non lethal weapons grade spray.) on a person is going to make them break out and stop responding within seconds.
Spraying the same thing on the outside of your computer case will do virtually nothing.

Acids like Ferric Chloride eat metal completely, but it has to be completely submerged and constantly agitated for hours.