Laser cladding also has several advantages over plasma cladding processes. The substrate of laser clads are free of the micro-cracks and pores typical with the plasma clad process. Other advantages of the HPDDL over plasma processes include the uniformity of the HPDDL coating, the manual requirement of plasma processes, cracks and pores in a plasma clad. The sharp boundary of the plasma clad layer with the substrate also often leads to pores and cracking9. The interface between the clad and substrate of a HPDDL clad is smooth with minimal dilution.

Multiple pass samples were prepared which demonstrated uniform cladding thickness [Figure 3]. Recent research has been performed on 100% overlapping clad passes that indicate that this significantly increase the cladded surface properties10. Corrosion testing indicated that the overlapping passes could withstand prolonged salt spray exposure. Surface roughness and uniformity of the clad are two important properties that are influenced by overlapping clads4. Overlapping passes result in a decrease in surface roughness and are typically dense and well bonded.

Materials Selection

The properties of the clad material alone will not determine the properties of the clad on the substrate. The solubility of the clad, which determines the amount of intermixing of the clad and substrate, i.e. dilution, is important. The resulting microstructure of the clad, the dilution layer and heat-affected zone are all important areas in determining the quality of the clad. Finally, solubility and wetting issues that lead to pits and pores. All of the above influence the wear and corrosion resistance of the clad.