Formation of Heterogeneous Powder Coatings with a Two-Level Micro-and Nanocomposite Structure under Gas-Dynamic Spraying Conditions

Abstract

Heterogeneous coatings have been deposited by the cold gas-dynamic spraying of mechanically synthesized AMg2/graphite + Al₂O₃ powders. A specific feature of the coatings formed is the existence of a two-level micro-and nanocomposite structure. It has been established that an increase in the content of microsized Al₂O₃ particles in the mixture from 10 to 30 wt % produces a twofold increase in the thickness of the coating deposited for the same time period from 140 to 310 μm. A further growth in the content of microsized Al₂O₃ particles in the mixture up to 50 wt % leads to a decrease in the thickness of the coating formed to 40 μm. The manufactured coatings have a high microhardness ranging from 1.7 to 3.2 GPa depending on their composition. The high microhardness of these coatings is caused by an increase in the hardness of the matrix material due to the creation of a nanocomposite structure, which strengthens the immobilization of microsized Al₂O₃ particles in it, thus improving the properties of the heterogeneous coating as a whole.