Ultrafast laser micromachining the ultra-low expansion glass-ceramic: Optimization of processing parameters and physical mechanism

• Published in: Journal of the European Ceramic Society Vol. 41; no. 12; pp. 5990 - 5999
• Main Authors: Xiong, Siyi, Wang, Rongping, Tao, Haizheng
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.09.2021
• Subjects: Micro-cracks; Micromachining; Roughness; Ultrafast laser; Ultralow expansion glass ceramics; Ultrafast laser; Micro-cracks; Ultralow expansion glass ceramics; Roughness; Micromachining
• ISSN: 0955-2219; 1873-619X
• DOI: 10.1016/j.jeurceramsoc.2021.05.018

•Photo-darkening, crystalizing, melting, foaming and vaporizing regions are sequentially identified.•Foaming regions are discovered to be very favorable to effectively mediate the thermal stress at the interfaces.•High quality micromachining surfaces are obtained utilizing the merits brought by the foaming region. To fulfill the precise requirements of laser gyroscope for inertial navigation, using the mean surface roughness, taper angle and circularity degree as indicators, we optimize the processing parameters about ultrafast laser micromachining a commercial ultra-low expansion glass-ceramic (ULGC). Furthermore, through careful characterizations, we identify the sequential appearance of photo-darkening, crystalizing, melting, foaming and vaporizing regions during the interactions of ultrafast laser with ULGC. Especially, the foaming region is identified to effectively mediate the thermal stress at the interfaces between different regions. Originated from the Gaussian distribution of energy, poor processing quality by a Gaussian beam is mainly ascribed to the formation of various regions. By using a Bessel beam, higher surface quality could be obtained due to the possibility of the occurrence of only a foaming region in irradiated regions. This discovery gives us an important clue to optimize processing parameters to obtain high-quality ultrafast laser micromachining surface.