THERMAL-SHOCK OF CARBON BASED MATERIALS AND COATINGS UNDER HIGH HEAT-FLUX

A thermal shock test of carbon based materials and coatings has been performed with a Nd:YAG laser. The carbon based materials used in the experiments were graphite of SMF 650 and G3 and three kinds of 3-dimension carbon fiber reinforced carbon composites (3D-C/C), which were produced with different manufacturing processes. Two kinds of coatings have been tested in the experiments: CVD (chemical vapor deposition) TiC coated on G3 graphite and a MWPCVD (microwave plasma chemical vapor deposition) diamond coating. The duration of laser exposure was 0.1 ms; the laser energy density deposited on specimens in this time was 9.9 kJ/m2 to 1.8 MJ/m2. The corresponding value of phi square-root t was 0.99-18.0 kJ/cm2 s1/2, where phi is the power density of the incident laser (kW/cm2) and t is the duration of the laser pulse (s). Micrographs of radiated specimen surfaces are given in this paper.