|
Copper is expected to have many applications due to its virus inactivation property, high thermal conductivity, high electrical conductivity and so on. The market demand for processing of copper is increasing as electric car expand more prevalent. Besides the copper is expected to be used for handrails, doorknobs etc., which touched by many people to prevent from infectious diseases because of having the excellent properties such as an antibacterial property and a virus inactivation property. Thus, 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 previous systems. There is, however, a problem that the surface is discolored due to the oxidation of copper in the air. Thus, Cu-Zn alloy was developed and tried to coat on the substrate surface with B-LMD system. As a result, Cu-Zn alloy layer was formed on the stainless-steel-plate with no pores at the output power of 40 W. It was found that the cross-sectional-area of layer was increased with increase the output power of laser in the Cu-Zn alloy coating. The addition of zinc to copper improves the energy efficiency for layer formation, and zinc concentration is found to be a factor that increases the energy efficiency. So, in this study, the copper layer was formed using different weight % Cu-Zn powder and investigate of threshold for copper layer formation. And the effect of zinc concentration on the threshold value for copper layer formation was examined. The copper layer was formed on SUS304 stainless steel substrate using pure copper or copper alloy. The effect of copper layer formation due to the difference in the amount of zinc was investigated, using (a) pure copper, (b) 80% Cu-20% Zn, and (c) 70% Zn-30Zn powder. In order to form a pure copper layer, an output equivalent to the threshold, which the substrate start to melt, was required. It was possible to form a copper layer with an output power lower below the threshold by adding zinc. On the other hand, when the amount of zinc added was increased, it became possible to form a copper layer at an even lower output power. It is thought that the absorption rate increases by adding zinc, and heat is transferred to the substrate through the Cu-Zn layer. As the amount of zinc added increases, the absorption rate increases further, and it is thought that a copper layer can be formed at a lower output. So, it is thought that even at power below the threshold, the substrate melted slightly and formed copper layer. It was possible to form a copper layer with low output power by adding zinc. It is thought that processing at low output can contribute to energy savings and carbon neutrality.
|
