In situ tribometry of cold-sprayed Al-Al2O3 composite coatings

An in situ tribometer utilizing a transparent hemispherical counterface was used to conduct sliding wear tests on Al-Al2O3 composite coatings deposited by cold spray. Direct observation of the wear interface via the slider allowed for correlation to be identified between the formation of transfer film and friction changes, wear rates, and the evolution of subsurface structures. It was revealed that the presence of hard particles in the Al-Al2O3 coating stabilized the transfer film, characterized by less plastic flow and fewer instances of hole formation at the interface. This increase in stability correlated with lower wear rates, stable friction, and the formation of a mechanically mixed layer (MML) in the worn subsurface.