The development of nickel mold materials that softened at high temperatures was investigated, and their use in the fabrication of replica nickel molds by thermal nanoimprinting was demonstrated. Ni-based carbon nanotube (CNT) composite coatings were formed by ultrasonic assisted electroplating using a horn sonicator. 1.6 g/L CNTs, which were 9.5 nm in diameter and 1.5 μm in average length, were added to a nickel sulfamate plating bath. The Vickers hardness of the Ni-based CNT composite coatings was over 500 HV at room temperature and under 50 HV at high temperatures over the range of 400 to 600 °C. After heat treatment at 500 °C, the grain size of the Ni-based CNT coatings became larger than that of normal Ni coatings. Ni-based CNT composite coatings had random crystals, instead of the columnar crystals in pure nickel coatings. It is thought that the softening of the Ni-based CNT composite was based on containing CNTs in grain boundaries, as well as a crystal structure transformation. To fabricate the Ni-based replica mold, a Ni-based CNT composite coating was directly imprinted at 3 MPa and 500 °C; higher than the softening temperature of the coatings. 5 μm square dot patterns from a mother silicon mold was successfully replicated by thermal nanoimprinting on the Ni-based CNT composite coating. The fabrication method of replica nickel molds was based on the high-temperature softening property of Ni-based CNT composite coatings.
CITATION STYLE
Suzuki, T., Kato, M., Matsuda, T., & Kobayashi, S. (2014). High-temperature softening of nickel-based carbon nanotube composite coatings for the fabrication of nickel-based nanoimprint molds by thermal imprinting. Journal of Advanced Mechanical Design, Systems and Manufacturing, 8(4). https://doi.org/10.1299/jamdsm.2014jamdsm0055
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