CARBON-FIBER SPRING FOR HIGH-TEMPERATURE APPLICATION

To avoid both Marangoni convection at the upper edge of the melt durin g crystal growth using the Bridgman technique and the local separation between melt and inner ampoule wall under microgravity conditions, a helical spring of carbon fibre reinforced carbon (C/C) was developed, whose purpose was to press a plunger on the melt's surface. The spring constant was determined to be 0.406 N/mm at room temperature and 0.52 5 N/mm at 1300-degrees-C. It is to be expected that the spring is usab le up to 1800-degrees-C. Its low electrical resistance of 0.826 OMEGA permits Peltier pulsing during crystal growth.