High Conductivity, Low Cost Aluminum Composite for Thermal Management

摘要

In order to produce an inexpensive packaging material that exhibits high thermalconductivity and low CTE, Technical Research Associates, Inc. (TRA) has shown in Phase I the feasibility of incorporating natural flake graphite in an aluminum matrix. TRA has developed a proprietary coating technique where graphite flakes have been coated with a thin layer of molybdenum/molybdenum carbide (approximately 0.2 microns). This barrier coating can protect the graphite flake from chemical reaction and high temperature degradation in molten aluminum silicon alloys. Methods to successfully vacuum infiltrate coated flake with molten aluminum alloys were developed. The resulted metal matrix composites exhibited lower CTE than aluminum metal. The CTE of the composites were significantly lower than aluminum and its alloys. The CTE can potentially be tailored for specific applications. The in plane thermal conductivity was higher than the aluminum matrix alloy. The thermal conductivity and CTE of the composite may be significantly improved by improving the bond strength of the molybdenum coating on the graphite flake. The flake can potentially be incorporated in the molten aluminum and pressure die cast to align the flakes within the aluminum matrix. By preferentially aligning high conductivity graphite flakes within a plane or direction, the thermal conductivity of the resulting composite will be above pure aluminum in the alignment direction.