Etching of SiC-SiC-composites by a laser-induced plasma in a reactive gas

The precise machining of silicon carbide composite (SiC-SiC) as a high-tech material with extraordinary characteristics is required for different applications in aerospace, light weight construction and car industry. Laser machining enable new approaches for fabrication processes but the regularly applied ablation processes can cause damage to the SiC-SiC material. Here we propose and demonstrate a new approach for gentle SiC-SiC machining making use of a laser-induced plasma for reactive species generation enabling chemical material removal processes. A fs-laser (775 nm, 150 fs, 1 kHz) was focussed to a CF4/O-2 gas mixture igniting a laser induced plasma (LIP) approximately 100 mu m in front of a SiC-SiC sample. This LIP initiate material removal processes of the textured, multiphase SiC-SiC sample without a mechanical damage of the SiC-SiC composite structure. Different surface features such as etching of the cover SiC layer, etching of the SiC matrix and exposure, thinning and sharpen of the SiC fibres, underetching of the fibres has been observed. Across the whole etched area, no mechanical damage such as cracks, delamination's, broken fibres were observed so that a gentle machining process can be expected.