Functionally Graded Ceramic Materials for High Temperature Applications for Space Planes

Abstract

Whether it is possible to develop a fully reusable space vehicle essentially depends, according to the current point of view, on the success of developing appropriate thermal protection materials. Functionally graded materials are being developed for this purpose. This paper presents first results of the manufacturing of graded coatings and their investigation under high enthalpy flow conditions. The materials were manufactured by atmospheric plasma spraying (APS) at the Institute for Manufacturing Technologies of Ceramic Components and Composites (IFKB). The TPS is made up of principally three layers: a substrate, an intermediate layer and the appropriate thermal protection layer. The substrate is the high melting alloy Inconel 625. In addition to the improvement of the adhesive power between the top layer and the substrate the intermediate layer acts as an oxygen barrier. Cr 3 C 2 -NiCr, NiCrAlY and Mo-MoSi 2 are investigated as intermediate layer materials. ZrO 2 and TiO 2 are used for the TPS surface. First investigations of the selection of surface and intermediate layers were carried out. The investigation of the erosion behaviour was performed within a plasma wind tunnel at the Institute for Space Systems (IRS). The circular samples are loaded by a high enthalpy flow produced by a magnetoplasmadynamic generator (MPG). The test conditions were determined by measurements of the heat flux and the Pitot pressure. The surface temperature of the test sample is measured by pyrometers. The effects of thermal and chemical loads on the sample are presented.