Quantitative and Qualitative Nondestructive Evaluation of Cold Spray Manufactured Copper and Aluminum Samples

In this work, nondestructive testing (NDT) methods to quantitatively assess the quality of cold spray deposits is presented. This work also correlates the results obtained through NDT methods with destructive evaluation tests for practical applications. Cold spray is a solid-state process for depositing metal powder, accelerated by a high-velocity gas such that it bonds to the substrate metal through kinetic impact energy. Eddy current, ultrasound, porosity, hardness, and uniaxial tensile strength tests were conducted on copper and aluminum cold spray deposited samples. Ultrasound wave velocity measurements and eddy current electrical conductivity measurements showed good correlation with process conditions that were varied to control particle velocity to intentionally produce samples with varying deposition quality. Influence of process conditions on particle velocity was confirmed via particle image velocimetry. Porosity, hardness, tensile and adhesion strength tests results were further correlated to ultrasound wave velocity and electrical conductivity measurements. Ultrasound phased array was used to qualitatively assess the cold spray coating and substrate interface quality. The results of this work show that nondestructive testing methods can be effectively used to quantitatively assess the cold spray products for quality control purposes.