DEVELOPMENT OF A NEW COST-EFFECTIVE CERAMIC COMPOSITE FOR REENTRY HEAT SHIELD APPLICATIONS

Within the Manned Space Transportation Programme ESA have launched stu dy projects to assess an advanced heat shield concept for re-entry cap sules relying on a C/SiC ceramic matrix composite for the hot structur e. MAN Technologie has developed a C/SiC composite with a polymer deri ved SiC matrix and carbon fibre woven fabrics as reinforcement which i s being tested in this technology study. It is manufactured by a liqui d polymer impregnation (LPI) process. Repeated impregnation and pyroly sis cycles are employed to reach the proper density of 1.75 g/cm(3). T he main mechanical properties of the fabric reinforced LPI-C/SiC, dete rmined with test pieces taken from complex parts, are a tensile streng th of 270 MPa along with a strain to failure of 1.2%, a compressive st rength of 440 MPa, and an interlaminar shear strength of 30 MPa. A str ength retention of 80% was found after 30 min exposure to air at 1870 K and in LCF tests with a peak stress of 200 MPa a million cycles were achieved without rupture. Integrally laminated panel segments have su ccessfully been tested up to 1800 K in air of 20 hPa with high tempera ture gradients (>1000 K) and transients (30 K/sec) without damage. the se results demonstrate that the LPI-C/SiC with fabric reinforcement pr ovides a proper performance and reliability to open up the option for a CMC heat shield application in advanced crew transfer vehicles. (C) 1998 Published by Elsevier Science Ltd. All rights reserved.