Effect of the detonation-spraying mode on the tribological properties of NiCr-Al2O3 coatings

Abstract

The article presents the study results of detonation spraying parameters on the phase composition and tribological properties of NiCr-Al2O3 powder coatings. The spraying was carried out at a ratio of the acetylene-oxygen mixture O2 /C2H2=1.856. The detonation barrel filling volume with an explosive gas mixture varied from 30% to 68%. It is determined that the phase composition of the NiCr-Al2O3 coatings varies depending on the degree of detonation barrel filling. With an increase in the detonation barrel’s filling volume, the intensity of the NiCr diffraction peaks is decreased, and the intensity of the a-Al2O3 reflexes is increased, which indicates an increase in the content of the Al2O3 phase. When low filling volume, there is determined a low coating density and uneven roughness. The tribological test results showed that with an increase in the detonation barrel filling volume, there is a decrease in the wear volume, which confirms the increase in the coatings wear resistance. Determined that the lowest friction coefficient was recorded in the sample obtained at the barrel filling volume 68%. The coatings’ high wear resistance is associated with an increase in the alpha phase volume fraction of a-Al2O3 and coatings density.

Preparation and Characterization of NiCr/NiCr-Al2O3/Al2O3 Multilayer Gradient Coatings by Gas Detonation Spraying

“…Such coatings were successfully obtained by detonation spraying, High-Velocity Oxygen Fuel (HVOF), etc. Among them, detonation spraying has several advantageous connections with the peculiarities of the spraying process: pulse spraying, the use of several dispensers and guns, which ensures the high speed of the spraying process [9][10][11].…”