Residual Stress Measurement of Suspension HVOF-Sprayed Alumina Coating via a Hole-Drilling Method

摘要

The nature and magnitude of residual stresses in thermal-sprayed coatings determine their lifetime and failure mechanisms. The residual stresses of suspension high-velocity oxy-fuel (SHVOF) thermal sprayed alumina (Al2O3) coating were measured with hole-drilling and x-ray diffraction. The coating is dense and consists of amorphous and two crystalline phases: alpha and gamma. The residual stresses measured by hole-drilling in the Al2O3 coating was - 162 MPa (compression) in the longitudinal direction and - 104 MPa (compression) in the transverse direction. This is due to the peening stress and the high substrate-coating CTE ratio of similar to 2.1. The nature of the residual stress through the coating is related to the microstructure build-up shown from the cross section and the fracture surfaces of the coating.