Laser radiation of 3 μm wavelength was generated by frequency conversion of an industrial IR laser and applied in the context of CFRP bonding pre-treatment. Reinforced and non-reinforced epoxy resins were treated with this radiation varying the relevant parameters such as laser power or treatment time. The interaction between laser radiation of 3012 nm and 1064 nm wavelength and matrix resin was analyzed mechanically (e.g. ablation depth), optically (such as fiber exposure) and chemically (e.g. contamination removal). The results gathered show that, even with the small achievable pulse fluences, a sufficient treatment of the specimens and a sensitive removing of the contaminated layers are possible.
Pulsed lasers with spot diameters in the μm range are widely used for the laminar treatment of surfaces. The laminar treatment is achieved by a two-dimensional overlap of the small laser pulses going from lines to a surface. This publication states the numerical description of the average amount of laser pulses per surface increment and its spread considering processing parameters such as line feed, pulse repetition rate and hatch distance. Based on the numerical results an empirical formula was derived and the basic approach of calculating an accumulated energy as a benchmark for comparing pre-treatment parameters was investigated for different laser systems.