Laser-directed deposition of high-performance Al₂O₃ ceramics enhanced by SiO₂ doping

Abstract

Laser-directed energy deposition (L-DED) has attracted significant attention for its potential to rapidly produce advanced ceramics, which could benefit various industries. Nevertheless, the quality and properties of ceramics manufactured through L-DED still require enhancement to ensure their sustainable application in industry. Here, high-performance Al₂O₃ ceramics were produced using L-DED by adding small amounts of SiO₂. The effects of this doping on the surface bonding quality, microstructure, and mechanical properties of the obtained ceramic materials were thoroughly investigated. The results indicate that SiO₂ doping significantly enhances the surface bonding quality of the deposited cylindrical samples. The complete elimination of intergranular voids between adjacent interlayers, a denser microstructure, and the emergence of small bulges on the sample surfaces evidence this improvement. Additionally, the elliptical pores previously present at the edges of the samples have vanished, resulting in tighter intergranular bonding between the grains and a noteworthy increase in relative density. Remarkably, doping with α-cristobalite produced the highest recorded average flexural strength and fracture toughness of the deposited ceramics, achieving values of (483.47 ± 38.84) MPa and (4.87 ± 0.80) MPa·m^1/2, respectively. These findings establish SiO₂ doping as an effective method for successfully fabricating high-performance Al₂O₃ ceramics through L-DED.

Keywords

additive manufacturing / laser-directed energy deposition / alumina / microstructure / mechanical properties

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