Study by X-ray diffraction and mechanical analysis of the residual stress generation during thermal spraying

Abstract

Thermally sprayed coatings are formed by the deposition of molten or partially molten particles, propelled onto a substrate where they impact, spread and solidify rapidly. Residual stresses are expected within the sprayed deposit as a consequence of the release of thermal and kinetic energies. A wide range of materials and two spraying techniques are considered in this study, namely atmospheric plasma spraying (APS) and high-velocity oxygen fuel. Stresses were determined by the X-ray diffraction (XRD) method. The results were compared with those calculated by mechanical analysis of stress relief in coatings detached from the substrate. Comparison of the results for adherent and free-standing coatings shows that the residual stress state can be resolved in terms of the components suggested by models that propose two stages of stress generation: quenching stresses and secondarycooling stresses. The in-depth distribution of residual stresses, through the coating thickness, is discussed in terms of the nature of the coating system. #

Effect of WC on the residual stress in the laser treated HVOF coating

“…In cooling period, quenching stresses are developed because of the contraction of different constituted molten particles during the solidification. These stresses are mainly tensile and contribute to the total residual stress in the region where the cooling rates are high, particularly in the surface region and in the interfacial region of the coating base substrate (Pina et al, 2003). Moreover, the mismatched in thermal contraction between coating and substrate material contributes the residual stress in this region.…”

Residual Strain and Fracture Response of Al2O3 Coatings Deposited via APS and HVOF Techniques

“…Measurement of residual strains in these thermal spray coatings is critical for modeling and designing improved components. The influence of coating powder characteristics, spraying process, and spraying process parameters on the residual stress field of Al 2 O 3 coatings has also been the topic of recent investigations (Ref [10][11][12][13][14][15][16][17][18].…”

Microstructure and mechanical properties of nickel-chrome-bor-silicon layers produced by the atmospheric plasma spray process

“…These features are primarily related to the adhesion and the cohesive strength of the lamellae in coating layers. Voltages can occur as a result of cooling and shrinkage of particles during the process as well as different thermal expansion coefficients between the coating and substrate surfaces [2][3][4][5]. Self -fluxing NiCrBSi alloy powder was developed to produce coatings successfully used for the production and maintenance of equipment in all industries.…”