Fabrication of carbon granules for use in microphones consists of heat treatment of comminuted carbon to give controlled thermal conductivity and high performance

摘要

The fabrication of carbon granules for use in microphones comprises reduction to 100-500 micron of very hard and chemically inert material comprising carbon 99 and ash 1 per cent respectively. After removal of the fines, heat treatment at 800 to 1200 degrees C for 1-10 hours controls the thermal conductivity of the product. The granules give a durable continuous stable microphone signal.