Strukturbildung beim Mikrostrukturieren von Metallen in sauren Ätzmitteln mit dem Laser-Jet-Verfahren

Laser-jet-etching is a technique to cut and microstructure stainless steel in sulphuric and phosphoric acid where a laser induces a thermochemical wet etching reaction. Several dynamical regimes and bifurcations are observed by measurement of the electrochemical potential and the reflected laser light during the process. In dependency on the control parameters feed velocity, laser power, jet velocity and applied potential the reaction exhibits either a fix point or an oscillating behaviour. In the oscillating regime the kerfs show a periodic ripple structure. The electrochemical potential (active, passive) and the topology of the interface in the micrometer and nanometer scale are important order parameters. The formation of the ripples is caused by an interface instability and changes of the roughness in the nanometer range. Both give rise to a feedback of the reaction on the absorption of the laser and results in synchronous oscillations of the potential and the reflected laser.