INVESTIGATION OF RESIDUAL-STRESS GENERATION DURING THERMAL SPRAYING BY CONTINUOUS CURVATURE MEASUREMENT

The latest developments of an in situ curvature-monitoring technique for thermal spray processes, including automated video image analysis, are described. Using this technique, curvature measurements have been made while vacuum plasma spraying molybdenum onto stainless steel and titanium alloy substrates. The effects of plasma jet momentum, residual stress relaxation, environmental stability and non-uniform curvature are all discussed and, where appropriate, methodologies for counteracting their influence are proposed. It is concluded that the technique is potentially a reliable and accurate one, and that none of the possible sources of error cause insurmountable problems.