Enhancing of Tribological, Mechanical and Microstructural Properties of HVOF Coated AISI 316 Steel by Boriding

Abstract

Boriding has been attempted to further improve the wear resistance of high-velocity oxygen fuel (HVOF) coatings, often used for corrosion, oxidation or wear resistant applications. For this purpose, different HVOF coatings containing hard phases such as WC and Cr3C2 were borided at 900 degrees C for 2 h. The samples were examined in terms of microstructure, nanoindentation mechanical properties and tribological behavior. Boride coatings formed very different boride phases depending on the content of the substrate, and their thickness varies between 8 mu m and 20 mu m. Although 5-7 times higher hardness values could be obtained with HVOF than the substrate, these values further increased by an average of two times with boriding. The improvement in the wear resistance of AISI 316 with the HVOF is further enhanced by boriding. HVOF coatings showed wear performance according to their hardness. The wear loss ranking of HVOF coatings changed after boriding. In addition to the hardness, which was provided by the boride phases, fracture toughness and residual stresses were also effective in the wear results.