Defect Control of Electro-spark Deposition WC–Co Coatings via Adjusting Pulse Energy and Deposited Layer Number

Electro-spark deposition (ESD) is an effective way to weld non-weldable materials and fabricate coatings. However, severe surface defects such as pores, cracks, and element segregation introduced in the ESD process deteriorate the performance of the material. In this study, WC-10 wt.% Co coatings were prepared with different parameters to investigate the effect of key factors on surface features, which are evaluated by the thickness uniformity of coating, density of pores and cracks, degree of element segregation, and surface roughness. Massive statistical results showed that pulse energy, the number of electro-spark deposition layers, and their interaction mightily affect the coating defects. Quantitative analysis demonstrated that the ultra-low efficiency deposition in the later stage of ESD could effectively repair coating defects. In addition, the evolution of coating defects and the effect of preparation parameters on surface integrity were probed.