1 September 1998 Ni-Al2O3 and Ni-Al composite high-aspect-ratio microstructures
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Proceedings Volume 3512, Materials and Device Characterization in Micromachining; (1998) https://doi.org/10.1117/12.324077
Event: Micromachining and Microfabrication, 1998, Santa Clara, CA, United States
High-aspect-ratio microstructures (HARMs) have a variety of potential applications in heat transfer, fluid mechanics, catalysts and other microelectromechanical systems (MEMS). The aim of this work is to demonstrate the feasibility to fabricate high performance particulate metal-matrix composite and intermetallic micromechanical structures using the LIGA process. Well-defined functionally graded Ni-Al2O3 and Ni-Al high-aspect-ratio microposts were electroformed into lithographically patterned PMMA holes from a nickel sulfamate bath containing submicron alumina and a diluted Watts bath containing microsized aluminum particles, respectively. SEM image analysis showed that the volume fraction of the alumina reached up to around 30% in the Ni-Al2O3 deposit. The Vickers microhardness of these composites is in the range of 418 through 545, which is higher than those of nickel microstructures from a similar particle-free bath and other Ni-based electrodeposits. In the work on Ni-Al electroplating, a newly developed diluted Watts bath was used to codeposit micron-sized aluminum particles. The intermetallic compound Ni3Al was formed by the reaction of nickel matrices and aluminum particles through subsequent annealing at 630 degrees Celsius. WDS and XRD analyses confirmed that the annealed coating is a two-phase (Ni-Ni3Al) composite. The maximum aluminum volume fraction reached 19% at a cathode current density of 12 mA cm-2, and the Vickers microhardness of the as-deposited coatings is in the range 392 - 515 depending on the amount of aluminum incorporated.
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Tao Wang, Tao Wang, Melford Sorrell, Melford Sorrell, Kevin W. Kelly, Kevin W. Kelly, Evan Ma, Evan Ma, } "Ni-Al2O3 and Ni-Al composite high-aspect-ratio microstructures", Proc. SPIE 3512, Materials and Device Characterization in Micromachining, (1 September 1998); doi: 10.1117/12.324077; https://doi.org/10.1117/12.324077

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