Exhaust buzz

My exhaust buzzs like crazy when decelerating. I found the source, where the cat connects to a pipe the flange is not actually attached to the cat so the pipe is floating free and buzzing. I intend the weld the flange to the pipe stopping the problem but until I can get it welded is there something I can use the wedge in the gap to stop it from buzzing or a way to secure it? It's really embarrassing when I cone to a stop.