Effect of oxygen pressure on the microstructure and mechanical properties of Mo coating deposited on steel 42CD4 by thermal flame spraying

Surface treatments and coatings are a practical approach used to extend the life of components and structures, especially the most stressed surfaces of the technical component under consideration. The objective of this work is to study the effect of oxygen pressure on the microstructure and the mechanical properties of the Mo coating deposited on 42CD4 steel by flame thermal spraying. The effect of the oxygen flow is controlled by the oxygen pressure. The coatings were characterized by scanning electron microscopy (SEM), energy dispersion spectrometry, X-ray diffraction, Vickers hardness measurement and four-point bending tests. The results show that oxygen pressure in the oxidant is a critical parameter, as our results revealed that increasing oxygen pressure has a positive effect on microstructure and on mechanical properties of the coating. The increase in oxygen pressure generates a better microstructure, with a denser, more compact coating and a low porosity.