Combustion synthesized AlN powders were investigated for use as starting material for obtaining high thermal conductivity specimens by microwave sintering and reheating. Microwave sintering and reheating were carried out in a TE 103 single mode cavity with an adjustable microwave power in the range 0-3 kW at 2.45 GHz. Densification was found to be a primary requirement to obtain a high thermal conductivity AlN. AlN powders with good sinterability are required to achieve a high densification. AlN powder with D 50 of ∼6 μm was found to have a poor sinterability that with D 50 of ∼3 μm or finer, a good sinterability. Oxygen content was found to be another important factor determining the thermal conductivity. The thermal conductivity can be enhanced from ∼130 to ∼155 W/m K when the oxygen content is reduced from 2.3 to 1.4 wt %. The thermal conductivity can be significantly improved by microwave reheating of the sintered specimen under a reducing atmosphere. This is considered to be due to enhanced removal of the second phases by the reducing atmosphere.
|Number of pages||6|
|Journal||International Journal of Self-Propagating High-Temperature Synthesis|
|Publication status||Published - 2012 Mar|
All Science Journal Classification (ASJC) codes
- Materials Science(all)
- Process Chemistry and Technology