The objective of this project is to develop an accurate and high throughput process for machining deep micro holes in ceramics and ceramic matrix composites, such as silicon carbide, silicon nitride and silicon carbide-silicon carbide ceramic matrix composite. The approach to achieve this goal will include i) establishment of an experimental set-up for high aspect ratio micro hole drilling using a state-of-the-art pico-second laser, ii) development of analytical and numerical models for the pico-second laser and material interaction, iii) experimental studies to determine the effects of parameters on micro drilling of ceramic and ceramic matrix composite sheets using the pico-second laser system and iv) demonstration of micro hole drilling capabilities for these materials.
Advanced materials such as ceramics and ceramic matrix composites are strategically important for the defense, medical, aerospace and commercial industries due to their superior mechanical and thermal properties. Many parts made of these materials require precision micro holes for cooling and other purposes. However, these materials are not amenable to conventional micro fabrication processes such as etching or electric discharge machining, while the major shortcoming of laser hole drilling by commonly used nanosecond lasers has been the surface thermal damage caused during laser ablation. This laser machining technique will overcome the current barriers in producing these micro holes, since it can remove the material with virtually no thermal damage by directly transforming solid to plasma and thus creating so called "cold ablation" due to the extremely short pulse duration. It should be possible to produce a clean hole on a curved surface in an oblique angle. Since the project seeks to develop a systematic and scientific model of the pico-second drilling process through combined analytical and experimental investigations, the research will generate critical scientific knowledge on ultra short laser-matter interaction. An improved understanding of ultra short pulse laser-material interaction will contribute to the overall advancement of the laser processing field. Once developed, this process can bring a significant cost reduction in producing micro holes on many difficult-to-machine advanced materials and increased utilization of those materials in commercial and military products.
