Mechanical and thermal properties of AlN-BN-SiC ceramics

作者：Buchheit Andrew A; Hilmas Greg E^*; Fahrenholtz William G; Deason Douglas M; Wang Hsin

来源：Materials Science and Engineering A-Structural Materials Properties Microstructure and Processing, 2008, 494(1-2): 239-246.

DOI：10.1016/j.msea.2008.05.051

• Aluminum nitride
• Boron nitride
• Silicon carbide
• Mechanical properties
• Thermal properties
• Hot pressing

Mechanical and thermal properties were characterized for two AlN:BN:SiC composite ceramics produced from BN with different particle sizes. The ceramics were hot pressed at temperatures from 1950 to 2100 degrees C to similar to 97% relative density. For both materials, the matrix (90:10 vol% SiC:AlN) had a grain size of similar to 0.4 mu m, and the BN grains (10 vol%) were crystallographically aligned. Microhardness values were between 20 and 22 GPa, while fracture toughness values were between 2.5 and 3.1 MPa m(1/2). Other Properties were found to be dependent on testing direction. Elastic moduli were between 260 and 300 GPa and strengths were similar to 630 MPa for small particle BN additions. Thermal conductivity was calculated to be between 25 and 37W/m K at room temperature and 17 and 25 W/m K at 900 degrees C. The low values compared to traditional SiC ceramics were attributed to AlN-SiC solid solution formation and sub-micron matrix grain sizes.

• 出版日期2008-10-25