Mechanical Performance of Metal-Ceramic Interfaces Produced by Laser Processing

This paper concentrates on the mechanical performance of various ceramic coatings of Cr2O3 on steel (SAF2205), as produced by CO2 laser processing. The thickness of the coating that can be applied by laser coating is limited to about 200 µm setting a limit to the maximum strain energy release rate that can be measured in a 4 point flexure test before severe yielding occurs. In addition, a network of cracks with spacings of the order of 200 µm was always present in the laser applied coating preventing steady state crack growth along the interface. It is concluded that a firmly bonded coating of Cr2O3 on steel could be produced by high power laser processing. The actual interface strength of a (Fe, Cr)-spinel applied to stainless steel by laser coating depends strongly on the composition of the substrate and coating materials. The energy release rate was extremely high and delamination occurred by fracture through the coating and partially along the interface, indicating that the interface strength is similar to or higher than the fracture strength of (Fe, Cr)-spinel.