Significant improvement of thermal conductivity for AlN/LAS composite with low thermal expansion

Abstract Lithium aluminosilicate (LAS), as a ceramic material with ultra-low thermal expansion, has a wide application in the field of precision instruments. But the effective integration of multiple thermal functions, including low thermal expansion and high thermal conductivity, into one material remains a huge challenge. To obtain LAS composites with high thermal conductivity, AlN was added as the reinforcing phase in LAS matrix, which can form a perfect heat conduction network and act as bridges for transferring heat. The thermal conductivity of the composite reaches 12.8 W/(m K) when the AlN content increased to 40 wt%, which is more than 5 times higher than that of bulk LAS. At the same time, the composite still maintains a low coefficient of thermal expansion of less than 3.2 × 10-6/K which matching that of silicon. Therefore, the proper combination between the components of composites is beneficial to the preparation of AlN/LAS composites with both low thermal expansion and excellent thermal conductivity.