Correlating Thermal and Mechanical Properties of Al2O3-Ni Composites in the Scope of Percolation Effect

Composite materials are of great interest in many applications for their ability to combine properties of various materials into a single system. In most traditional modes of processing composite materials, properties follow the rule of mixtures principle where properties change with respect to volume fractions of each constituent. In practice, thermally sprayed composites have been shown to deviate from this rule and instead reach a percolation threshold when the conducting filler content increases to a point where the material system undergoes an insulator-to-conductor transition. The complex highly defected microstructures of thermal spray coatings are expected to greatly influence percolation in these systems through complex mechanisms. Plasma sprayed Al2O3-Ni composites of varying composition have been produced and the effects of composition on coating thermal and mechanical properties are investigated through multimodal testing. The influence of process, microstructure and composition on these properties and the percolation threshold is further correlated with preliminary results given in this work.