Abstract
This article examines the effect of working gas temperature during gas-dynamic spraying (GDS) on residual stresses in coatings made of CRO ceramics and NiAlSiCr metal composites. GDS is a promising technology for applying protective and restorative coatings in mechanical engineering, preventing component overheating (the substrate temperature typically does not exceed 100-150 °C). The method involves the solid-phase bonding of powder particles, accelerated to supersonic speeds, with the component surface due to their plastic deformation upon impact. The working gas is typically heated to temperatures between 300°C and 700°C. Experiments were conducted using a DIMET 405 setup on St3 steel samples at three gas stagnation temperature settings: 200°C, 300°C, and 400°C. Residual stresses were measured using an IKN-3M-129 stress concentration meter. It was found that increasing the working gas temperature from 200°C to 400°C sharply reduced compressive residual stresses (to -121.75 MPa for NiAlSiCr and -81.125 MPa for CRO at 200°C), followed by a transition to low tensile stresses (to +3.5 MPa for CRO). This is explained by the fact that higher temperatures increase particle plasticity, facilitating their deformation and adhesion. A spraying temperature of 400°C was found to be optimal for minimizing residual stresses, which is important for ensuring the stability and durability of the coating.