Dokument-ID Dokumenttyp Autoren/innen Persönliche Herausgeber/innen Haupttitel Abstract Auflage Verlagsort Verlag Herausgeber (Institution) Erscheinungsjahr Titel des übergeordneten Werkes Jahrgang/Band ISBN Veranstaltung Veranstaltungsort Beginndatum der Veranstaltung Enddatum der Veranstaltung Ausgabe/Heft Erste Seite Letzte Seite URN DOI Lizenz Datum der Freischaltung OPUS4-31282 Zeitschriftenartikel Yao, Dongxu; Xia, Y.; Zuo, K.-h.; Jiang, D.; Günster, Jens; Zeng, Y.-P.; Heinrich, J.G. Porous Si3N4 ceramics prepared via partial nitridation and SHS Porous Si3N4 ceramics were prepared via partial nitridation and self-propagating high temperature synthesis (SHS) process. Raw Si and additive Y2O3 were mixed and molded under 10 MPa into a compact, the compact was partial nitridation at 1300 °C to form a porous Si/Si3N4, and then it was buried in a Si/Si3N4 bed for SHS to obtain porous Si3N4 with rod-like β-Si3N4 morphology. The processing combined the advantages of the nitridation of Si and SHS with low cost, low shrinkage and time saving. Porous Si3N4 with a porosity of 47%, a strength of 143 MPa were obtained by this method. Oxford Elsevier European Ceramic Society 2013 Journal of the European Ceramic Society 33 2 371 374 10.1016/j.jeurceramsoc.2012.08.033 2016-02-20 OPUS4-32542 Zeitschriftenartikel Yao, Dongxu; Xia, Y.; Zuo, K.-h.; Jiang, D.; Günster, Jens; Zeng, Y.-P.; Heinrich, J.G. The effect of fabrication parameters on the mechanical properties of sintered reaction bonded porous Si3N4 ceramics Porous silicon nitride ceramics were prepared via sintered reaction bonded silicon nitride at 1680 °C. The grain size of nitrided Si3N4 and diameter of post-sintered ß-Si3N4 are controlled by size of raw Si. Porosity of 42.14-46.54% and flexural strength from 141 MPa to 165 MPa were obtained. During post-sintering with nano Y2O3 as sintering additive, nano Y2O3 can promote the formation of small ß-Si3N4 nuclei, but the large amount of ß-Si3N4 (>20%) after nitridation also works as nuclei site for precipitation, in consequence the growth of fine ß-Si3N4 grains is restrained, the length is shortened, and the improvement on flexural strength is minimized. The effect of nano SiC on the refinement of the ß-Si3N4 grains is notable because of the pinning effect, while the effect of nano C on the refinement of the ß-Si3N4 grains is not remarkable due to the carbothermal reaction and increase in viscosity of the liquid phase. Oxford Elsevier European Ceramic Society 2014 Journal of the European Ceramic Society 34 15 3461 3467 10.1016/j.jeurceramsoc.2014.06.018 2016-02-20 OPUS4-35177 Zeitschriftenartikel Yao, Dongxu; Xia, Y.; Zuo, K.-h.; Zeng, Y.-P.; Jiang, D.; Günster, Jens; Heinrich, J.G. Gradient porous silicon nitride prepared via vacuum foaming and freeze drying Gradient porous silicon nitride (Si3N4) was fabricated by a novel vacuum foaming and freeze drying process. Aqueous Si3N4 slurries were foamed at vacuum pressure of 50-90 kPa, the green body was obtained by the freeze drying process, a gradient pore structure with porosities of 72-90% was achieved after pressureless sintering at 1680 °C. The porosity was increased with decreasing vacuum pressure. The pore structure consists of large pores (~100 μm) on top, medium pores (~45 μm) on the wall of the large pores, and small pores (~0.7 μm) in the matrix. Such gradient porous Si3N4 with macro- and micro-pores has potential application as high temperature filters. Amsterdam Elsevier B.V. 2015 Materials letters 141 138 140 10.1016/j.matlet.2014.11.067 2016-02-20 OPUS4-34956 Zeitschriftenartikel Hu, H.-L.; Zeng, Y.-P.; Zuo, K.-H.; Xia, Y.; Yao, Dongxu; Günster, Jens; Heinrich, J.; Li, S. Synthesis of porous Si3N4/SiC ceramics with rapid nitridation of silicon Porous Si3N4/SiC ceramics were prepared with Si and SiC as raw materials, Y2O3 as sintering additive and ZrO2 as nitrided catalyst through a rapid nitration process. The nitriding rate as a function of temperature and duration was investigated. The porous Si3N4/SiC ceramics with 8 wt% monoclinic ZrO2 addition that was nitrided at 1400 °C for 2 h exhibited the highest nitridation degree of 95%. The experimental results also demonstrated that the reciprocal formation of ZrO2 and ZrN can effectively enhance the level of nitridation by suppressing the melting of silicon in micro-regions. The effects of nitriding time on the mechanical properties of the specimens with ZrO2 as a catalyst was also studied. After nitrided at 1400 °C for various durations from 2 to 8 h, the porous Si3N4/SiC ceramics with the properties of a porosity over 39.8%, a flexural strength over 88.9 MPa and a linear shrinkage lower than 0.6% were achieved. The systematic investigation reveals the catalytic mechanism of ZrO2 in the synthesis of Si3N4/SiC ceramics. Oxford Elsevier Ltd. European Ceramic Society 2015 Journal of the European Ceramic Society 35 14 3781 3787 10.1016/j.jeurceramsoc.2015.06.028 2016-02-20 OPUS4-30295 Zeitschriftenartikel Hu, H.-L.; Zeng, Y.-P.; Xia, Y.; Yao, Dongxu; Zuo, K.-H.; Günster, Jens; Heinrich, J.G. Rapid fabrication of porous Si3N4/SiC ceramics via nitridation of silicon powder with ZrO2 as catalyst Porous Si3N4/SiC ceramics were rapidly prepared with Y2O3 as sintering additive and ZrO2 as nitrided catalyst, using Si and SiC as starting powders. Porous Si3N4/SiC ceramics with 5 wt% ZrO2 addition showed a complete nitridation and good mechanical properties (with a high porosity of 34.96%, flexural strength of 150±4.2 MPa, linear shrinkage of 0.02%). It was revealed that the reciprocal formation of ZrO2 and ZrN effectively enhanced nitridation by inhibiting the melting of silicon in micro-regions. Faenza Ceramurgia 2014 Ceramics international 40 5 7579 7582 10.1016/j.ceramint.2013.11.098 2016-02-20