Synergistic enhancement of thermal conductivity and flexural strength in AlN ceramics via the novel ErH2-Y2O3 composite additive system

Aluminum nitride (AlN) ceramics with superior thermal conductivity and flexural strength are crucial for advanced thermal management applications. However, the simultaneous achievement of these properties continues to pose significant challenges. In this study, novel ErH 2 -Y 2 O 3 composite additives were introduced to fabricate AlN ceramics, resulting in a synergistic enhancement of thermal conductivity and flexural strength. The effects of varying ErH 2 content in the composite additives on the phase composition, densification, microstructure, thermal conductivity, and flexural strength of hot-press sintered AlN ceramics were systematically evaluated and compared with pure AlN. The results revealed that the inclusion of ErH 2 facilitated an in-situ reduction reaction with oxygen-containing impurities (e.g., Al 2 O 3 ), thereby generating Er 2 O 3 . Compared to using Y 2 O 3 alone, this ErH 2 -mediated reaction further reduced the lattice oxygen content in AlN. Moreover, ErH 2 significantly enhanced the homogeneity of the AlN grains and purified the grain boundary. Optimal addition of additives effectively reduced the lattice oxygen content and promoted the formation of isolated fine secondary phases. When the composite additives contained 2 wt% ErH 2 and 2 wt% Y 2 O 3 , the thermal conductivity and flexural strength of the AlN ceramics reached the peak value of 188.07 ± 7.37 W·m -1 ·K -1 and 378.22 ± 11.49 MPa, respectively. The enhancement of thermal conductivity by 22.65 % and flexural strength by 16.62 % relative to the sample with only Y 2 O 3 added.