Microstructural Characteristics and Performances of C2O3 and Cr2O3-15%TiO2 S-HVOF-Coatings Obtained from Water-Based Suspensions

Abstract

Abstract Cr2O3 coatings and Cr2O3-based binary coatings offer high hardness, excellent sliding wear performance and corrosion resistance. Therefore, they are widely applied in the paper and textile industry, as well as for pumps and mechanical sealing systems. Compared to the conventional spray processes, the technology of Suspension-HVOF (high velocity oxy-fuel flame spraying of suspensions, S-HVOF) using submicron-scaled raw materials allows the production of dense, finely-structured coatings with smooth surfaces and improved mechanical properties. This work investigates the microstructure and performance of Cr2O3 and Cr2O3-15wt.%TiO2 coatings obtained by SHVOF with water-based suspensions. For the development of the binary composition two routes were used to produce ready-to-spray suspensions: i) dispersion of an appropriate alloyed material in the solvent and ii) mixture of two stable suspensions in the desired ratio. In order to evaluate the potential of suspension spraying over the conventional APS and HVOF processes, the mechanical properties and the corrosion resistance of the S-HVOF Cr2O3 and 85Cr2O3/15TiO2 coatings were compared with the coatings produced from spray powders. From the experimental results it was observed that the suspension sprayed coatings showed in most of cases denser microstructure, good mechanical properties and superior corrosion performances.