Erosion characteristics of SiC coated C/C materials in arc-heated high enthalpy air flow

SiC coated C/C materials are one of the most promising candidates for application to the highest temperature region of re-usable reentry vehicles. SiC has good high temperature properties but oxidation mechanism and utilization limitation in high temperature range are not clearly understood. In order to prevent oxygen attack through surface micro-cracks, glass sealing is usually applied as a final production procedure. In this investigation, however, SiC coated C/C materials without glass coating are selected as specimens. This would provide advantages in analysis because thermo-chemical behavior on the surface become simpler than glass sealed SiC coating. Two kinds of heating facilities are used in this investigation. One is a xenon lamp facility for obtaining static heating characteristics. Another type of facilities are arc-heated wind tunnels, which are an constrictor-type arc heater facility of NASDA and a magnetoplasmadynamic heating facility of IRS. One of the research objectives is to make comparison of these facilities as a tool of reentry heating simulation. For this purpose, same materials were tested at all of these facilities. Heating conditions were parametrically changed in order to investigate erosion mechanism of the coating materials. The research is particularly focused on the erosion rate dependence on pressure/temperature and active-passive transition characteristics.