Article

# Thermal conductivity behavior of SPS consolidated AlN/Al composites for thermal management applications

(Impact Factor: 1.01). 04/2011; 30(2):189-194. DOI: 10.1007/s12598-011-0222-8

ABSTRACT

AlN/Al composites are a potentially new kind of thermal management material for electronic packaging and heat sink applications.
The spark plasma sintering (SPS) technique was used for the first time to prepare the AlN/Al composites, and attention was
focused on the effects of sintering parameters on the relative density, microstructure and, in particular, thermal conductivity
behavior of the composites. The results showed that the relative density and thermal conductivity of the composites increased
with increasing sintering temperature and pressure. The composites sintered at 1550°C for 5 min under 70 MPa showed the maximum
relative density and thermal conductivity, corresponding to 99% and 97.5 W·m−1·K−1, respectively. However, the thermal conductivity of present AlN/Al composites is still far below the theoretical value. Possible
reasons for this deviation were discussed.

Keywordsmetallic matrix composites–aluminum nitride–spark plasma sintering–density–thermal conductivity

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• "AlN−Al composites can be produced via various solid or liquid state based fabrication methods such as spark plasma sintering [27], pressureless [13], pressure [12] or vacuum [14] infiltration, squeeze casting [34], mechanical alloying [35], gas bubbling method [15], DC arc-discharge method [36] and directed melt nitridation [16]. Pressureless metal infiltration technique is the most attractive processing technique since it can potentially combine low-cost, production of high volume fraction AlN−Al composites with near-net shape. "
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ABSTRACT: Thermal properties of AlN.Si.Al composites produced by pressureless melt infiltration of Al/Al alloys into porous a-Si3N4 preforms were investigated in a temperature range of 50-300 C. SEM and TEM investigations revealed that the grain size of AlN particles was less than 1 micron meter. In spite of sub-micron grain size, composites showed relatively high thermal conductivity (TC), 55-107 W/(m/K). The thermal expansion coefficient (CTE) of the composite produced with commercial Al source, which has the highest TC of 107 W/(mEK), was 6.5*10-6 1/K. Despite the high CTE of Al (23.6*10-6 1/K), composites revealed significantly low CTE through the formation of Si and AlN phases during the infiltration process. Key words: AlN; ceramic-matrix composites; thermal properties; liquid metal infiltration
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