Oxidation of Additively Manufactured ZrB2–SiC in Air and in CO2 at 700–1000 °C

Abstract

Oxidation behavior of additively manufactured ZrB₂–SiC in air and in CO₂ is reported in the temperature range of 700–1000 °C. Observed scale morphologies in air and in CO₂ were similar, featuring an outer borosilicate layer and an inner porous zirconia layer containing partially oxidized silicon carbide particles and remnant borosilicate products. Oxide scale thicknesses and parabolic scaling constants in air were approximately twice those observed in CO₂ across all studied temperatures. Activation energies for oxidation of 140 ± 20 kJ/mol in air and 110 ± 20 kJ/mol in CO₂ were determined, indicating similar diffusion processes that appear to be rate-limiting. The formation of protective scales across wide temperature ranges both in air and in CO₂ makes additively manufactured ZrB₂–SiC an attractive candidate for high-temperature industrial process applications featuring varied oxidants such as heat exchangers.