Microstructure and Mechanical Properties of Thermal Sprayed Aluminum Coatings
Abstract:The thermal spraying process is widely used to the metalizing of electronic ceramic for forming the electric conductor and/or the underlayer for bonding. However, mechanical properties of thermal sprayed coatings, which have an important effect on the adherent strength, have not always been clarified. Two kinds of free-standing aluminum specimens, which were formed by an atmospheric plasma spraying (APS) process and an electric arc spraying GAS) process, were machined from the thick coatings and were used for experiments. The Young's modulus, Poisson's ratio, four-point bending strength and bending angle were measured at room temperature in comparison with a rolled aluminum plate. The experimental results suggested that the crack length and crack density in aluminum coatings, which were composed of pores and aluminum oxide, had an important effect on the mechanical properties. Namely, low strength, high ductility, high thermal conductivity and low electric resistivity could be obtained from the aluminum coatings sprayed by APS process, because of low pore volume and low oxide content. Key Words:Atmospheric plasma spraying, Electric arc spraying, Aluminum coating, Mechanical properties, Young's modulus, Poisson's ratio, Pore size, Pore volume, Thermal conductivity, Electric resistivity