Tailoring Toughness and Mechanical Reliability by Controlled Laser-Drilled DefectsThursday (29.09.2016) 11:45 - 12:00 Part of:
Nature is well known for mineral-based composites that are simultaneously strong and tough, a combination hardly achieved in similar man-made materials. Selecting structural elements of sponge spicule and nacre, mother-of-pearl, and substituting the natural constituents by advanced synthetic materials, we prepared multi-layered composites with extreme strength and high toughness. Through systematic laser-perforation of individual ceramic layers and their lamination with epoxy, we guide propagating cracks to deflect strongly, resulting in a toughness of 1.8 kJ/m². However, by keeping structural integrety in lines of these laser-drilled holes, strength and modulus maintain on high levels as well, reaching more than 800 MPa and about 150 GPa, respectively. With these data being high already, the most intriguing characteristic of the laminates is a remarkable reliability, though. Due to active modification of the defect distribution, their Weibull modulus amounts to 31, much higher than that of monolithic ceramics of similar strength. Such nature-inspired laminates can thus be considered serious candidates for future structural materials.