Composite material used for manufacturing heat exchanger fins with high thermal conductivity

12) Method for producing a multi-layer material based on expanded graphite reinforced by a metal comprising at least one recompressed expanded graphite inner layer and two outer metal layers wherein:

• a) a recompressed expanded graphite sheet with a density lower than 1.2 g/cm3, typically a sheet of flexible graphite with a density between 0.8 and 1.2 g/cm3 is inserted between two metal sheets and then co-rolled with them,
• b) the composite structure thus co-rolled is then compressed, the reduction of thicknesses being defined such that the said inner layer of recompressed expanded graphite reaches a density greater than 1.6 g/cm3 and preferably more than 1.7 g/cm3.

17) Flat product, such as a plate or strip, composed of a multi-layer material, comprising at least one inner layer of recompressed expanded graphite and two outer metal layers, the recompressed expanded graphite having a density greater than 1.6 g/cm3, or even better greater than 1.7 g/cm3, wherein each outer metal layer has a thickness less than one tenth of the total thickness of the product.

19) Cooling fin, made of a multi-layer material, comprising at least one recompressed expanded graphite inner layer and two outer metal layers, that cover the surfaces and at least two edges of the said fin.