High Power Water Jet Guided Laser Cutting of SiC/SiC Ceramic Matrix

Laser processing is widely used in manufacturing metal alloy aerospace components. Over the last few years there has been an increased interest in exploiting silicon carbide (SiC) based ceramic matrix composite (CMC) materials for aero-engine components, as they possess superior thermomechanical properties compared to conventional alloys. However, laser processing of SiC CMCs is difficult due to their high melting temperatures, and differences present between the thermal and physical properties of the matrix and fibre. This paper investigates the basic characteristics of water jet guided laser (WJGL) cutting SiC/SiC, using a high power 532 nm Q-switched pulsed laser with an average power of 400 W. Experimental trials were performed to understand the effect of different process parameters on the cut quality and overall cutting speed. Cutting speed and pulse frequency were found to be key in determining cut quality and overall cutting speed on the WJGL. Average power also affected overall cutting speed. Due to the cooling nature of the water jet, the thermal damage typically associated with conventional laser processing was eliminated. However, heterogeneous removal of the material matrix and fibres was found to occur where fibres aligned parallel to the direction of the cut length, resulting in non-uniform kerf widths.