In this work, Al2O3-AlN composite ceramics with high bending strength and thermal conductivity were fabricated by Digital Light Processing (DLP). The influence of AlN content on the rheological and cure behavior of Al2O3-AlN suspensions, as well as the microstructure, thermal conductivity, and bending strength of Al2O3-AlN ceramics, were systematically investigated. The result shows that the viscosity and cure ability of the suspensions were decreased with the increase of AlN content, which are beneficial to the spreading and printing accuracy of the suspensions. Besides, the bending strength of ceramics can be improved due to the residual stress by the introduction of AlN. Approaches were employed to minimize the formation of AlON in Al2O3-AlN ceramics by optimizing the amount of AlN and the sintering temperature. The thermal conductivity and bending strength of Al2O3-AlN ceramics were 31.72 ± 0.45 W/(m·K) and 572.73 ± 59.40 MPa, respectively, which are much higher than those of Al2O3ceramics fabricated under the same condition. Finally, complex-shaped Al2O3-AlN ceramics components have been successfully fabricated by DLP, which may provide an opportunity to broaden the application of Al2O3-AlN composite ceramics in heat dissipation components.Keywords:Al2O3-AlN composite ceramics;Digital Light Processing;mechanical properties;thermal conductivity
To improve the thermal and mechanical properties of Al 2 O 3 /AlN composite ceramics, a novel heterogeneous precipitation coating (HPC) approach was introduced into the fabrication of Al 2 O 3 /AlN ceramics. For this approach, Al 2 O 3 and AlN powders were coated with a layer of amorphous Y 2 O 3 , with the coated Al 2 O 3 and AlN powders found to favor the formation of an interconnected YAG second phase along the grain boundaries. The interconnected YAG phase was designed to act as a diffusion barrier layer to minimize the detrimental interdiffusion between Al 2 O 3 and AlN particles. Compared with samples prepared by a conventional ball-milling method, the HPC Al 2 O 3 /AlN composites exhibited less AlON formation, a higher relative density, a smaller grain size and a more homogeneous microstructure. The thermal conductivity , bending strength , fracture toughness and Weibull modulus of the HPC Al 2 O 3 /AlN composite ceramics were found to reach 34.21 ± 0.34 W m −1 K −1 , 475.61 ± 21.56 MPa, 5.53 ± 0.29 MPa m 1/2 and 25.61, respectively, which are much higher than those for the Al 2 O 3 and Al 2 O 3 /AlN samples prepared by the conventional ball-milling method. These results suggest that HPC is a more effective technique for preparing Al 2 O 3 /AlN composites with enhanced thermal and mechanical properties, and is probably applicable to other composite material systems as well.
危险品化学品经营许可证（带存储）