Direct Metal Laser Fabrication of Cu slabs from powder precursor: surface depth of melt and furnace temperature issues

摘要

A DMLF processing unit based on a raster-scanned 80 W CO_2 laser beam has beendeveloped to process single layers of metallic powder precursor. The process chamberprovides atmosphere control (high vacuum and inert gas refill) besides temperatureelevation up to 700 °C. In this work, copper powder precursor is confined inside arefractory steel mask surrounded by an aluminum oxide jacket that acts as insulator. Thepowder layers can have thicknesses of 0,5 and 1 mm. An infrared pyrometer measuresin real time the temperature at one location in the surface of the powder bed. Scanspeed, scan step, and furnace temperature have been varied to find combinations of suchparameters that render surface melting and maximum densification. Partially meltedsamples were produced and their mass density was measured. Micro-hardness andsurface roughness were also measured along the resolidified surface, the first renderingan average of 80,6 HV compared to the 90-105 HV of oxygen free copper, while thesecond resulting in an 8 μm R_a value. Maximum melt of depth achieved is ～0,15 mmfollowed by a sintered layer.