Fabrication and properties of embedded dense coating on direct ink writing Si2N2O porous ceramics.

An embedded dense coating was fabricated on the direct ink writing Si 2 N 2 O porous ceramic by impregnating the SiO 2 -sol and in-situ sintering. The influence of different heat-treatment atmosphere and temperature on the microstructure, phase composition, mechanical properties and water resistance was studied systematically. A relatively flat and dense seal layer was obtained in the air atmosphere. The crystallization of SiO 2 was inhibited by nitrogen atmosphere. The resulting embedded coatings effectively improved the mechanical properties and water resistance of Si 2 N 2 O porous ceramic, and the specimens treated in air exhibited better comprehensive performance due to the higher densification. This strategy provides a reference for in-situ surface reinforced components with complex structures. Unlabelled Image • A strategy for fabricating embedded dense coating on complex structure ceramic was provided. • The samples heat-treated in air exhibits better sealing effect than that in nitrogen. • The crystallization of SiO 2 was inhibited by nitrogen atmosphere. • Mechanical properties and water resistance are improved due to the good sealing effect. [ABSTRACT FROM AUTHOR]