Influence of hexagonal boron nitride nanosheets on phase transformation,microstructure evolution and mechanical properties of Si3N4 ceramics |
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Authors: | Monika Tatarková Peter Tatarko Alexandra Kovalčíková Ivo Dlouhý Ján Dusza Pavol Šajgalík |
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Affiliation: | 1. Institute of Inorganic Chemistry, Slovak Academy of Sciences, Dúbravská cesta 9, 845 36, Bratislava, Slovakia;2. Institute of Materials Research, Slovak Academy of Sciences, Watsonová 47, 040 01 Ko?ice, Slovakia;3. Institute of Physics of Materials, Czech Academy of Sciences, ?i?kova 22, 616 62, Brno, Czech Republic |
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Abstract: | Fully dense Si3N4 materials with 1 wt.% (~ 1.5 vol.%) and 2 wt.% (~ 3.0 vol.%) h-BN nanosheets were prepared by spark plasma sintering at 1750 °C with the dwell of 7 min under a pressure of 50 MPa in a vacuum. BN nanosheets with different dimensions were prepared by ultrasound-assisted liquid phase exfoliation of h-BN powder, followed by centrifugation at different speeds (1000 rpm and 3000 rpm). The addition of BN nanosheets hindered the particle rearrangement stage of sintering, which resulted in the delayed α→β phase transformation of Si3N4. To study a direct effect of BN nanosheets on the mechanical properties of Si3N4, the results were compared to the monolithic Si3N4 with similar grain size and α/β-Si3N4 ratio. The addition of 2 wt.% h-BN nanosheets (1000 rpm) increased both the fracture toughness (~ 26 %) and the strength (~ 45 %) of Si3N4, when compared to the monolithic Si3N4 with similar microstructure. |
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Keywords: | Silicon nitride Boron nitride nanosheets Microstructure Toughening Mechanical properties |
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