A NEW PROCESS FOR THE PRODUCTION OF LONG GLASSY POLYMERIC CARBON HOLLOW WARE WITH UNIFORM WALL THICKNESS USING A SPRAY TECHNIQUE

Glassy polymeric carbon is produced in the form of open- and closed-en d tubes of uniform thickness up to 1 m long. Resol precursor is spraye d automatically to form a thin gelled coating on a rotating heated man drel. The process is repeated to produce a sheath of thermoset phenoli c resin of required thickness. This resin sheath is carbonized and hea t-treated between 1270 and 2770 K. Mass loss and contraction are noted . Structure is characterized by X-ray diffraction, which is also used to determine texture. Mechanical properties are measured using a speci ally designed hydraulic system to relate hoop strain to hoop stress. H oop strength lies between 20 and 92 MPa, exhibiting brittle fracture v ariance. The scatter in the hoop strength data masked any heat-treatme nt temperature effect. The measured electrical resistivity is 7 x 10(- 2) and 3 x 10(-2) Ohm-mm for heat-treatments of 1270 and 2770 K, respe ctively. Local induction heating has been used to demonstrate that the carbonized ware can endure sharp temperature gradients without fractu ring. The hollow ware is used as a crucible for a new Bridgman crystal growth technique and for containment of hydrocarbon gases at high tem perature. Copyright (C) 1996 Elsevier Science Ltd