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Improvement of Micro-Hole Processing in SiCf/SiC Ceramic Matrix Composite Using Efficient Two-Step Laser Drilling.
Yue Cao1,2, Bin Wang2,3, Zhehang Li1,2
1College of Mechanical Engineering, Zhejiang University of Technology, Hangzhou 310014, China.
Micromachines
|April 26, 2025
Summary
This study introduces a two-step nanosecond laser drilling method for silicon carbide fiber/silicon carbide ceramic matrix composites (SiCf/SiC CMC). The optimized process achieves efficient and high-quality micro-hole fabrication with a clean sidewall, overcoming previous processing challenges.
Area of Science:
- Materials Science
- Manufacturing Engineering
- Laser Processing
Background:
- Silicon carbide fiber/silicon carbide ceramic matrix composites (SiCf/SiC CMC) are advanced materials known for their high performance but present processing challenges due to their hardness and brittleness.
- Efficient and high-quality fabrication of small-sized features, such as micro-holes, in SiCf/SiC CMC is crucial for their application but remains difficult with conventional methods.
Purpose of the Study:
- To develop and optimize a novel two-step nanosecond laser drilling technique for fabricating micro-holes in SiCf/SiC CMC.
- To investigate the influence of processing parameters on micro-hole quality and efficiency.
- To achieve high-quality micro-hole processing with clean sidewalls and minimal defects.
Main Methods:
- A two-step laser drilling process was employed, involving initial laser pre-drilling in air followed by laser final-drilling with a water jet.
- Single-parameter variation and orthogonal experiments were conducted to identify optimal laser parameters for both drilling steps.
- Key parameters optimized included processing cycles, single-pulse energy, defocus, pulse-repetition frequency, overlap rate, and water jet velocity.
Main Results:
- Optimal parameters for pre-drilling in air (1000 cycles, 0.7 mJ, -4 mm defocus, 15 kHz, 85% overlap) yielded a 343 μm entrance diameter micro-hole in 100 s, but with surface oxidation and recast layers.
- Optimized final-drilling parameters with a water jet (2000 cycles, 0.6 mJ, -4 mm defocus, 10 kHz, 85% overlap, 4.03 m/s water jet velocity) processed the hole in 96 s, resulting in a 423 μm entrance diameter and a 0.36° taper angle.
- The water jet effectively removed spattering slags and oxides, producing a clean sidewall with microgrooves, indicating significantly improved processing quality.
Conclusions:
- The two-step laser drilling method effectively addresses the challenges of processing SiCf/SiC CMC, enabling efficient and high-quality micro-hole fabrication.
- The water jet plays a critical role in the final drilling stage by removing contaminants and improving surface integrity.
- This technique offers a promising approach for the precision manufacturing of micro-features in advanced ceramic matrix composites.
