Characterization of flame-sprayed and plasma-sprayed pure metallic and alloyed coatings

The composition, structure and properties of thermally sprayed coatings were investigated by a number of methods, including X-ray diffraction, X-ray spectroscopy and scanning electron microscopy. The Vickers hardness and porosity were also investigated. The coatings were plasma-sprayed pure molybdenum, and flame-sprayed copper and nickel alloys. It was found that the alloyed coatings had a different chemical composition than the powders they had been produced from. In addition, all the coatings exhibited a fibre texture which complicated the X-ray method for estimation of residual stresses. However, for the pure molybdenum coating, it was possible to evaluate this parameter, taking into account the effects of the measured porosity and crystallographical anisotropy on the Young's modulus and Poisson's ratio.