Microstructure and Tribological Behavior of TiN/ Al2O3 Composite Coatings Produced by High-Velocity Suspension Flame Spraying (HVSFS)

In this study, an aqueous suspension containing fine aluminum oxide and coarser titanium nitride (TiN) powders was prepared and processed using high-velocity suspension flame spraying (HVSFS) to produce thick TiN/ Al2O3 composite coatings (>50 µm). The influence of spraying parameters, such as total gas flow and flame stoichiometry, on the microstructure, phase composition, mechanical, and tribological properties was investigated. The results demonstrate that TiN can be successfully deposited under atmospheric conditions using the HVSFS process, achieving a homogeneous distribution of TiN particles within the alumina matrix. This composite structure led to a significant increase in microhardness. Furthermore, the TiN/ Al2O3 coatings produced with λ = 0.8 exhibited improved wear resistance and a reduced coefficient of friction compared to pure Al2O3 coatings.