Analysis of adhesion strength and residual stresses developed by the EDC process

ABSTRACT This paper reports the effect of coating thickness on adhesive properties, and residual stresses by the electric discharge coating (EDC) process on Mg alloy with copper (Cu) nickel (Ni) powder metallurgical (P/M) electrodes. The composite coating layer thickness was measured by optical microscope and it ranges from 10.2 to 102.4 µm. The coating layer was characterized by a Field emission scanning microscope (FESEM) and Energy-dispersive spectroscopy (EDS). X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) analyses were made to identify the chemical composition and functional group. Residual stresses were evaluated by an ETA diffractometer and it revealed that compressive residual stress increases with a range of −458 ± 118 MPa to −1078 ± 125 MPa and tensile residual stresses decrease from 656 ± 113 MPa to 27 ± 11 MPa. The critical load is measured by scratch test. The result shows the adhesive strength of the coated surface was improved with an increase in layer thickness.