High speed coating for pure copper by multi-beam laser metal deposition method with high intensity blue diode lasers

Copper is expected to have many applications due to its virus inactivation properties, but it has been difficult to produce a thin layer with high bonding strength. A multi-beam blue diode laser installed laser metal deposition (B-LMD) system was newly developed with a laser intensity of 4.7 × 10⁵ W/cm², which is improved about five times higher than that of conventional systems. Using this system, we demonstrated the high-speed formation of a pure copper layer on a stainless steel type 304 (SS304) circular tube. A pure copper powder and the blue diode lasers were simultaneously supplied to a SS304 circular tube, and the powder was melted and solidified to form a pure copper layer on it. As the result, the laser intensity was increased with increasing layer formation efficiency, and at the laser intensity of 4.7 × 10⁵ W/cm², the maximum value of layer formation efficiency was obtained at the peripheral speed of 400 mm/s. Moreover, it was revealed that the dilution length was decreased with increasing peripheral speed, the minimum value of 3 μm at the peripheral speed of 400 mm/s was obtained.