Thermal Conductivity of Al₂O₃/Glass/C_f Composite Substrates Prepared by Low Temperature Sintering

Abstract

Carbon fiber (C_f) with high thermal conductivity was introduced into the alumina based composites. To avoid oriented alignment of carbon fibers and carbothermal reactions during the sintering process, the Al₂O₃/glass/C_f substrate was hot pressed under a segmental pressure procedure at 1123 K. Experimental results showed that the thermal conductivity of Al₂O₃/glass/C_f increased with the contents of C_f when the volume of C_f was below 30%. The thermal conductivity of Al₂O₃/30% glass/30% C_f was as high as 28.98 W.(mK)^–1, which was 4.56 times and 2.23 times higher than that of Al₂O₃/30% glass and AlN/30% glass, respectively. However, the thermal conductivity of Al₂O₃/glass/C_f decreased with the contents of C_f when the volume of C_f was over 30%. In the Al₂O₃/30% glass/30% C_f composite, carbon fibers lapped with each other and formed a three dimensional network in the matrix. The three dimensional network of carbon fibers brought excellent heat conducting performance to the Al₂O₃/30% glass/30% C_f composite.

Keywords:

• Carbon fiber
• Thermal conductivity
• Ceramic substrate
• Low temperature sintering