This award provides funding to investigate the feasibility of a combined top-down/bottom-up nanomanufacturing method to synthesize a bio-inspired AlMgB14/Ti micro-tool by mimicking, adapting and implementing the nanoscale morphology and analogous structure of nacre in the abalone shell. A femtosecond pulsed Ti:sapphire laser system in conjunction with molecular beam nozzle and computer generated holographic masking procedure will be used to deposit nanoscale thin films of "brick and mortar" nacre layers with angstrom resolution, pattern hexagonal tiles of nacre at high throughput, and nanotexture dimples and bridges. The effects of hierarchical organization of hard AlMgB14 and soft Ti layers on the types of fracture and energy absorption will be determined through a quantitative understanding of energy dissipation mechanisms such as rotation and deformation of nanograins under various types of loading.
If successful, the laser-based nanomanufacturing approach will become superior to the time-consuming, cumbersome self-assembly methods for engineering the bio-inspired materials. The implementation of this nacre design will offer significant performance improvements in the micro/nano-tools used for micro-machining, micro/nano-EDM, probe-based nanomachining and micro-coining. Research will contribute to the development of more energy-efficient, cleaner and sustainable society by minimizing power consumption, energy losses and component replacement frequency. Educational impact will include: develop a hands-on module for K-12 students and host a workshop for students and industry participants on bio-inspired nanomanufacturing; and promote the recruitment and participation of women and underrepresented groups by leveraging several university programs.
The overarching goal of this bioinspired project is to biomimic the hierarchical micro/nanoscale structures of Nacre, mother of pearl, utilizing a set of laser-based nanomanufacturing processes. Natural Nacres are made of calcium carbonate (CaCO3) and organic glue and exhibit superior mechanical properties that are attributed to the Nacre’s hierarchical configuration of "brick-bridge-mortar". In the proposed Nacre-like nanocomposite, CaCO3 and organic glue are replaced by aluminum magnesium boride (AlMgB14 designated as BAM) and titanium (Ti) respectively to provide even more superior mechanical properties. The proposed system that includes bricks and bridges of BAM and a mortar of Ti was built using a series of laser thin film deposition and micro/nano-machining processes. Research results demonstrate the feasibility of using a series of laser thin film deposition and micro-/nano-manufacturing processes to build the bioinspired material microstructure of BAM/Ti composites. The results also showed some major limitations to creating the small bricks features using the proposed ultra-hard materials; 1) using proximity mask felt short in finding the right material for the mask that can withstand the accumulation of heat on the mask during the process; 2) using direct laser machining require scaling the process up which would affect the enhancing mechanism of the mechanical properties that unique to the Nacre-like structure. The most notable achievement is the identification of laser nanomanufacturing processes to create the nacre configuration in hard materials. The improvement in toughness achieved in the bioinspired material in comparison to monolithic bulk materials is also remarkable.
