Dry sliding wear behavior of cold sprayed aluminum amorphous/nanocrystalline alloy coatings

Dry sliding wear behavior of cold sprayed Al amorphous/nanocrystalline alloy coatings in as-sprayed and heat treated conditions is reported. As-sprayed coatings exhibit higher coefficient of friction (COF) and wear volume loss 68% greater than heat treated coatings. Wear mechanism is elucidated in terms of worn surface and sub-surface analysis, splat bonding and tribochemical oxidation layer formation. The micro-abrasion and splat delamination resulted in higher wear loss in as-sprayed coatings. Heat treated coatings exhibit lower wear rate due to dense and partially crystallized structure which results in plastic deformation assisted wear. The tribo-chemical layer formation during the wear is studied by energy dispersive spectroscopy (EDS) elemental analysis and supported by thermodynamic computation and flash temperature estimation. The fracture behavior of the splats is investigated using tensile testing of free standing coatings in as-sprayed and heat treated conditions and correlated with the wear mechanism.