Carbon-carbon composite protection against oxidation in supersonic flame stream

Carbon fiber reinforced carbon (C-C) is a composite material, which consist of carbon fiber reinforcement in a matrix of graphite. C-C possess unique ability to retain high tensile strength at temperatures up to 2500 °C comparing to other engineering structural materials, which makes it best material for aerospace vehicles hot sections application.

Major drawback of C-C is an extremely low oxidation resistance and corrosion resistance at high temperature in nitrogen atmosphere. As a result mechanical properties decrease.

Thermal protection systems (TPS) application is a main method for protection of these materials. TPS consists of protecting coating (or several coatings) which prevents direct interaction between gases and C‑C. The difference between CTE of C-C (1÷5) 10^-6 К^-1 and typical TPS (6÷12) 10^-6 К^-1 leads to increasing stress between coating and substrate, which could lead to spallation of TPS. Considering operation conditions TPS must withstand thermal shock without cracking let alone spallation.

There are several reports about TPS based on yttria stabilized zirconia (YSZ). Two mixtures of YSZ and MoSi2 were sprayed directly on C-C substrates using APS.

Supersonic flame stream used for heating samples up to 2050 ˚C. YSZ-MoSi2 coating application proven to be effective protection against oxidation in severe conditions.