Influence of deposition conditions and heat treatment on tensile strength of cold spray aluminium coatings on Al_2O_3 and AlN substrates

摘要

A novel process to produce dense, well adherent aluminium coatings on ceramic materials is cold gas spraying (CGS). The mechanical, physical and chemical processes leading to the bonding of cold-sprayed coatings on ceramic substrates have only been described rudimentarily. A survey of the literature on adhesion mechanisms of cold spray coatings is given, where influences on bond strength are discussed and parameters identified. Using the example of coating Al_2O_3 and AlN substrates with pure aluminium via cold gas spraying, a process and substrate parameter variation is presented. A significant raise in tensile coating strength was seen at elevated substrate temperatures and after subsequent annealing. Tensile strength also depended on chemical composition and roughness of the substrate. The results allow the discussion of the bonding mechanisms of cold spray aluminium on ceramic substrates as a function of deposition and annealing parameters.