Comparison of boiling bubble behavior during laser chemical machining under superatmospheric pressure

Abstract Laser chemical machining (LCM), a non-conventional removal process, is based on the thermal activation of heterogeneous chemical reactions between an electrolyte and a metallic surface. When machining metallic surfaces with LCM, large fluctuations in removal quality can occur due to rising boiling bubbles. To delay electrolyte boiling the approach was to increase the process pressure. For detailed investigation of change in nucleate boiling phenomena during laser chemical machining removal experiments with varying process pressure and laser power on Titanium 3.7024 were performed. These experiments were recorded and analyzed by high-speed videography. With increasing process pressure, the diameter of the boiling bubbles decreases due to the lower temperature difference between wall superheat and saturation temperature of the electrolyte. It could be proven that with increasing process pressures the sizes of the boiling bubbles decrease, whereby the process window of the laser chemical machining could be extended.