Adhesion Strength and Ductility Evaluation of Cold Sprayed Copper Coatings for the Long-term Disposal of Nuclear Fuel

Copper coatings prepared by cold spray are being used for corrosion protection on steel containers that are designed for the long-term disposal of nuclear fuel. Knowledge of the mechanical properties, namely adhesion strength and ductility, are essential for assuring the integrity and performance of the coating. The current standard method for the measurement of coating adhesion (ASTM C633) relies on the application of a bonding agent (epoxy). However, the adhesion strength of the cold sprayed copper usually surpasses that of the epoxy (typically 60-90 MPa). In the case of ductility measurement, the use of tensile tests (ASTM E8) usually requires lengthy machining time and a quicker method for coating qualification is required. In this work, a tension configuration was tested for adhesion strength measurement, including an alternative approach that allows overcoming the glue limitation. In this alternative approach, adhesion strength values as high as 350 MPa can be measured with minimal changes to equipment fixtures. Other methods for testing in shear and bending configurations were also reviewed and performed. The results are shown with cold sprayed copper on mild steel substrates and where applicable, compared with finite element simulations.