I wouldn't suggest it. First, it doesn't add to functionality. Second, if it's a gorgeous older mic you want to look new; it still won't be worth more powder coated than in it's original worn-paint condition. Third, a hammertone paint or wrinkle paint (depending upon what was originally there) should be plenty durable enough to last another decade or two in the sort of careful use a mic should get.
The risks are distortion of the frame; somewhat less likely loss of the joint between the frame and any carbide faces you asked about. Someone who actually worked for a mic maker may be able to chime in on the softening point of the solders used; but I'd expect them to be above 400F.
The female threads, typically with segments for adjusting the fit, can also be quite twitchy. Just the slightest heat-induced change in alignment might greatly affect the "feel."
There's also the question of what happens where a relatively thick powder coat hits such details as the spindle openings, the lock openings, the graduated sleeves, etc. Seems difficult to mask things off so you avoid a build up where you don't want it; while not having a near zero thickness (and thus subject to rust, etc.) edge at the transitions.
There are also special cases depending upon the mic, such as tubular frames, plastic components for locks, etc. What mic are you trying to restore?
