Laser Peening Ceramics: Next-Gen Enhancement for Next-Gen Components

Laser shock peening is the next generation of material improvement. This powerful surface enhancement process improves metal fatigue strength up to twenty times – providing invaluable service life extensions for critical components. Though traditionally applied to steels, titanium, and other metals, laser peening is now proving a valuable application for a new class of material: engineered ceramics.

Ceramic engineering involves manufacturing objects from inorganic, non-metallic materials like silicon or zirconia. Ceramic parts offer several key advantages over their metal components in that they are lighter, noncorrosive, and offer superior heat resistance.

Ceramics in Aerospace

Ceramic materials have been used in targeted aerospace applications for years, providing thermal protection and insulation for the Space Shuttle to withstand the extreme temperatures of atmospheric reentry. As ceramic engineering has evolved, these versatile materials have been employed in applications ranging from brake pads to ball bearings to bulletproof vests.
The aerospace industry continues advancing ceramic capabilities as engineers seek to design lighter and more efficient aircraft. The CFM International LEAP engine – a next-generation turbofan engine manufactured via joint venture between GE Aviation and Safran Aircraft Engines – incorporates ceramic matrix composites into the turbine shroud that surrounds the rotating fan blades. These advanced engines offer fifteen percent better fuel efficiency, and the LEAP is one of the fastest-selling engine models in commercial aviation history.

The next leap forward for these engines will involve replacing traditional fan and compressor blades with ceramic composites that are lighter and more heat-resistant. Due to the extreme temperature levels inside a jet engine, metal components are often heated close to their melting point and require constant air-cooling during operation. By transitioning to ceramic blades, engineers can develop engines that are more powerful, more fuel-efficient, and capable of operating at higher temperatures.

Laser Peening – Enhancement and Evaluation

Despite the many benefits offered by ceramic components, these materials also present several drawbacks. Ceramics can be very brittle; they have low ductility and are prone to shatter. Most ceramics have a sizable discrepancy between tensile and compressive strengths – withstanding large compressive forces but comparatively small tensile loads.
To improve the mechanical properties of ceramic components, researchers have investigated the application of laser peening to enhance the material resistance to cracking and fracture. Laser peening utilizes a high-energy pulsed laser to generate a compressive stress wave that plastically deforms the material and produces beneficial compressive residual stresses. Laser peening provides many advantages over shot peening, including greater compressive residual stress depth and more precise application with high process control.
Early experiments in laser peening ceramics have demonstrated improvements in surface hardness, fracture toughness, and crack inhibition,¹ along with significant improvements in bending strength.² Despite the comparatively high yield strength of many ceramic compounds, laser peening can induce plastic deformation and a compressive residual stress layer when appropriate laser peening process parameters are employed.

LSP Technologies has applied laser peening to evaluate the impact resistance of ceramic materials used in body armor and vehicle plating.³ Laser peening is ideal for this type of investigation due to the versatility, precision, and high repeatability of the process. Laser parameters like energy and power density can be manipulated to produce controlled stress waves, and the application ensures ceramic armor tiles are manufactured to requisite standards of performance. Impact evaluation is one of many laser peening research opportunities available through LSP Technologies’ application development program.
Engineers continuously push the boundaries of performance by incorporating new and advanced materials into high-tech designs. Laser shock peening provides a powerful, versatile, and invaluable tool to ensure these innovative components perform safely and reliably. From next-generation turbine blades to state-of-the-art ceramic armor, laser peening transcends material limitations to make the world a safer place.
LSP Technologies is the world’s premiere provider of laser peening services, equipment and technology.
Contact LSPT today.

References:

1. Shukla, G.C. Smith, D.G. Waugh, J. Lawrence, “Development in laser peening of advanced ceramics,” Proc. SPIE 9657 (2015) 77–85.
2. Koichi, A., Yuji, S., Kazuma T., Hirotomo T., Shin I. , “Strengthening of Si3N4 Ceramics by Laser Peening,” Residual Stresses VII, ECRS7, Volumes 524 – 525, 141-146 (2006)
3. Tenaglia, Richard D. Laser Shock Induced Spallation. LSP Technologies, Inc., assignee. U.S. Patent 7,861,573. January 4, 2011.