High-speed photographic studies of laser machining of ceramics and ceramic composites

Abstract

The present study is directed at using high-speed photographic techniques to study fundamental phenomena during CO2 laser drilling of ceramics and ceramic composites. The objectives of this study were to identify material removal mechanisms and related plume phenomena such as spattering, particulate debris, liquid droplets, plume shape and size for ceramics and ceramic composites. High-speed photographic (1000 fps) visualization of laser drilling was carried out for two monolithic ceramics, namely, sintered α-silicon carbide (α-SiC) and hot-pressed silicon nitride (Si3N4), and two continuous fiber-ceramic matrix composites, namely, carbon fibers in a silicon carbide matrix (C-SiC) and silicon carbide fibers in a silicon carbide matrix (SiC-SiC). The qualitative information and insights obtained from this study will be used to: (i) optimize the laser shaping process for these materials, (ii) design future experiments to measure particle sizes, distribution and velocities in the plume, and (iii) further improve existing models for laser machining of ceramics. The results of this study indicate that each of these ceramic materials decompose differently during laser heating and that the material removal mechanism for a given material is possibly different at different stages of the process. A key result of this paper is that material removal in sintered α-silicon carbide (α-SiC) is accomplished through ablation while for the composite material, SiC-SiC, material removal is accomplished through high-temperature ejection of particulate material through stress build-up and fracture.The present study is directed at using high-speed photographic techniques to study fundamental phenomena during CO2 laser drilling of ceramics and ceramic composites. The objectives of this study were to identify material removal mechanisms and related plume phenomena such as spattering, particulate debris, liquid droplets, plume shape and size for ceramics and ceramic composites. High-speed photographic (1000 fps) visualization of laser drilling was carried out for two monolithic ceramics, namely, sintered α-silicon carbide (α-SiC) and hot-pressed silicon nitride (Si3N4), and two continuous fiber-ceramic matrix composites, namely, carbon fibers in a silicon carbide matrix (C-SiC) and silicon carbide fibers in a silicon carbide matrix (SiC-SiC). The qualitative information and insights obtained from this study will be used to: (i) optimize the laser shaping process for these materials, (ii) design future experiments to measure particle sizes, distribution and velocities in the plume, and (iii) further imp...