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Kawabori, Tatsuru*; Watanabe, Masashi; Imai, Yoshiyuki; Ueta, Shohei; Yan, X.; Mizoshiri, Mizue*
Applied Physics A, 129(7), p.498_1 - 498_9, 2023/07
Times Cited Count：0 Percentile：0(Materials Science, Multidisciplinary)We investigated a potential of femtosecond laser sintering of silicon carbide (SiC) using the nanoparticles in air. A SiC nanoparticle ink including polyvinylpyrrolidone and ethylene glycol exhibited intense absorption by SiC nanoparticles at the wavelength of 780 nm. The whole of the sintered film patterns from the surface to the bottom underwent significant oxidation at a scanning speed of 1 mm/s, suggesting that the excessive energy irradiation generated silicon oxides. In contrast, the patterns fabricated by laser scanning at a raster pitch of 30 
m at which a sintered area was observed at a scanning speed of 5 mm/s, exhibited no significant difference in oxidation of the raw SiC nanoparticles except for the surfaces from 1.72 m. These results indicate that the irradiation of femtosecond laser pulses generated the sintered SiC patterns without additional atmospheric oxidation of the raw materials because of its low heat accumulation. In additions, the dispersant of polyvinylpyrrolidone and ethylene glycol did not affect the sintering by an X-ray photoelectron spectroscopy. This vacuum-free direct printing technique has the potential for additive manufacturing.
Kawabori, Tatsuru*; Watanabe, Masashi; Imai, Yoshiyuki; Yan, X.; Mizoshiri, Mizue*
no journal, ,
In this study, SiC micropatterns were fabricated using near-infrared femtosecond laser sintering in atmosphere. First, a SiC nanoparticle ink was prepared. Then, we investigated the patterning properties of SiC micropatterns fabricated using near-infrared femtosecond laser pulses. 3C-SiC plane patterns were successfully formed even though in air without significant oxidation. Such direct writing technique of SiC patterns is useful for fabrication of microdevices.
Amarsaikhan, K.*; Kawabori, Tatsuru*; Watanabe, Masashi; Imai, Yoshiyuki; Ueta, Shohei; Yan, X.; Mizoshiri, Mizue*
no journal, ,
Femtosecond laser sintering is a promising technique for 2D/3D micro additive manufacturing. In this process, nanoparticles dispersed in binders were coated on substrates, and femtosecond laser pulses were subsequently focused and scanned to write patterns. We also applied this process to fabricating SiC microstructures using SiC nanoparticles of 
100 nm in diameter. In this study, we prepared a SiC nanoparticle ink including finer SiC nanoparticles with the diameter of ~18 nm. First, a SiC nanoparticle ink with the mixture of 100 nm and 18 nm in diameters was prepared. Then, patterning properties by femtosecond laser sintering were evaluated at various laser irradiation conditions. By comparing to the reference ink (SiC nanoparticles of 100 nm in diameter), the SiC nanoparticles with fine nanoparticles (18 nm) decreased the line width. In addition, the ablation width of in the center of the lines decreased by consisting fine particles. These results suggest that the fine nanoparticles increased the surface area in the inks, resulting that the large surface increased the consumption of the irradiated energy, and thermal conductivity of the ink decreased.
Nishisaka, Kairi*; Khaliun, A.*; Watanabe, Masashi; Imai, Yoshiyuki; Ueta, Shohei; Yan, X.; Mizoshiri, Mizue*
no journal, ,
In this study, we investigated the size effect of the SiC nanoparticles using three nanoparticle inks with different size distributions (18 nm, 100 nm, and 18 nm and 100 nm particles mixed 1:1). Then, the dependence of the inks on the direct writing properties using green femtosecond laser pulses was evaluated. The flat and minimum lines without ablation were formed using 18 nm particles. The crystal structures and the chemical bonding states were analyzed by X-ray diffraction and X-ray photoelectron spectroscopy. As a result, all three samples prepared under the minimum line width conditions were 3C-SiC. In addition, the Si-C bond was preserved in the use of 18 nm particles, compared to the other nanoparticles. These results suggest that the small heat capacity and low thermal diffusivity of the finer nanoparticle inks inhibited the excess heating and ablation.
