Laser additive manufacturing of typical highly reflective materials-gold, silver and copper

Abstract

Laser additive manufacturing of silver and gold can be used for customised fabrication of artworks, jewellery, watches, etc. Having excellent electrical and thermal conductivity, copper is important material in traditional industry. Additive manufactured copper is widely used in electronic devices, thermal management, transportation, industrial manufacturing, etc. Additive manufacturing of gold, silver and copper has wide application prospects, but also faces significant problem: laser absorptivity of gold, silver and copper is too low. The theoretical analysis shows that the conductivity of material and the wavelength of laser affect laser absorptivity directly. Replacing original powder with alloying powder or surface modified powder, as well as using blue or green laser with shorter wavelength, will enhance the laser absorptivity of powder, thus enable better as-print samples. This paper summaries the current situations of printing and feed stock issue in using laser additive manufacturing to fabricate highly reflectivity material such as copper and gold. Laser additive manufacturing of copper and copper alloys attracts the attention of more researchers in recent several years, and good research results are constantly emerging, which provides new ideas for additive manufacturing of gold and silver. However, there are few suppliers of gold and silver powder for additive manufacturing nowadays. Moreover, the powder producing technique is not mature. Considering laser absorption improvement and the feed stock issue, the future prospect of laser additive manufacturing of highly reflective materials is put forward, including widely applying new 3D printers with high power and short wavelength, replacing powder with wire as raw material to reduce the loss of precious metal during gas atomization, and developing new additive manufacturing powder with high absorptivity.