Tribological performance of thermally sprayed NiWCrBSi alloy coating by two different oxyacetylene flame stoichiometries

In the present work, the effects of oxidising and standard flame spray techniques on microstructure and wear performance of Low Velocity Oxygen Fuel NiWCrBSi coatings produced onto mild steel substrate were studied. Results showed that coating microstructure was dependent on the stoichiometry of the reacting gas mixture. Coatings produced in oxidising flame conditions showed higher amounts of semi-molten particles and high quantity of WC phases. Those coatings showed a good behaviour in dry sliding wear test, due to their higher hardness and the formation of compact and adherent oxide tribofilms. The wear behaviour of non-molten particles against friction forces is discussed, with the aim of establishing relationships between the tribological response of the material and its process-induced microstructure defects.