Thermal conductivity modelling of alumina/Al functionally graded composites

This paper describes a new manufacturing process for producing functionally graded ceramic-metal composites with anisotropic properties for thermal management in automotive engine blocks. These composites are elaborated by producing a porosity gradient within an alumina matrix, subsequently infiltrated by a molten aluminum alloy. The interconnected macro porosity inside the ceramic is controlled by the coalescence of PMMA (PolyMethylMethAcrylate) spherical particles during the elaboration step of an organic frame template in which bridges are created at contact points between the particles. The diameter of the interconnection contact plays a key role because it greatly controls the microstructure of the final composites and consequently the thermal conductivity. A numerical model was developed for simulating the different steps of the elaboration process of the composites. Numerical assessments of the effective thermal conductivity are achieved in order to examine interconnection contact effects. To end up, the developed model is validated by comparing the numerical predictions with experimental measurements.