Surface densification of porous ZrC by a laser process

Thin films of 100%-dense zirconium carbide, ZrC, on top of ca. 30%-porous ZrC are obtained by using an ytterbium-doped fibre laser under argon atmosphere. It is shown experimentally and theoretically that oxidation into zirconia or oxycarbide is completely avoided at the working temperature of at least 3420 °C. This type of highly refractory materials – dense at the surface and porous in the bulk – could be used in high temperature applications where both diffusion and thermal barrier properties are needed. This process could also be used to purify from oxygen the surface of carbides obtained by thermal carboreduction of oxides.