Catalytic Atom Recombination on ZrB2/SiC and HfB2/SiC Ultrahigh-Temperature Ceramic Composites

Results are presented of an experimental investigation into the efficiency of zirconium diboride/silicon carbide and hafnium diboride/silicon carbide ultrahigh-temperature ceramic composites for catalyzing the surface recombination of dissociated oxygen and nitrogen at moderate surface temperatures. Experiments were conducted with a diffusion-tube side-arm reactor, together with laser-induced fluorescence species detection diagnostics. Experiments reveal recombination coefficients in the range between silica glasses and oxidized metals, as well as evidence of environment-induced surface modification.