In situ X-ray observations of pure-copper layer formation with blue direct diode lasers

Sato, Yuji*; Tsukamoto, Masahiro*; Shobu, Takahisa  ; Funada, Yoshinori*; Yamashita, Yorihiro*; Hara, Takahiro*; Sengoku, Masanori*; Sakon, Yu*; Okubo, Tomomasa*; Yoshida, Minoru*; Abe, Nobuyuki*

A blue direct diode laser metal deposition system, which uses multiple lasers, was developed to realize a high-quality coating layer with a dense, fine structure and high purity. To clarify the formation mechanism of the pure copper layer, the formation process using a blue direct diode laser system was observed using in situ X-ray observations. The stainless steel 304 substrate melts, generating bubbles in the molten pool at a laser power density of 7.2 10 W/cm and a scanning speed of 3.0 mm/s. At a laser scanning speed of 9.0 mm/s, the bubbles disappear because only a slightly molten pool is formed on the surface of the substrate. The bubble amount and penetration depth depend on the laser input energy with a blue direct diode laser. By controlling the amount of input energy, a copper coating is produced minutely without a weld penetration.