Blues skies for copper cladding with 450nm

Today, high performance components rely on a controlled heat dissipation by copper layers, which can be applied by laser cladding with lasers in the near-infrared (NIR) wavelength. However, current cladding processes are restricted to copper alloys with reduced heat conduction in order to achieve a sufficient melting of the material. The challenge of pure copper is the high reflectivity in the NIR wavelength range and the variation of the heat dissipation during the melting of the copper material. This leads conventionally to an undefined energy coupling into the substrate and process instabilities, which can cause a variation in the melting depth and pores in the layers. With the application of a laser wavelength of 450nm, the laser absorption in pure copper is highly improved and similar to alloyed copper or even steel, which allows for a reproducible melting even of pure copper material. This processing opportunity is enabled for the first time with the development of a novel high power blue laser source with 1kW output power at 450 nm wavelength in continuous wave mode, which is applied for the cladding of pure copper powder. In this contribution we will demonstrate the performance of a high power blue laser cladding process of pure copper powder on steel and on copper substrate. The assessment of the resulting homogeneity and reproducibility of the resulting copper coatings give new perspectives for conventional applications such as heat pipes or heat dissipation layers but also for new applications such as pure copper components produced by additive manufacturing.