TY - JOUR A1 - Yao, Dongxu A1 - Xia, Y. A1 - Zuo, K.-h. A1 - Jiang, D. A1 - Günster, Jens A1 - Zeng, Y.-P. A1 - Heinrich, J.G. T1 - Porous Si3N4 ceramics prepared via partial nitridation and SHS N2 - 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. KW - Si3N4 KW - Strength KW - Porosity PY - 2013 U6 - https://doi.org/10.1016/j.jeurceramsoc.2012.08.033 SN - 0955-2219 SN - 1873-619X VL - 33 IS - 2 SP - 371 EP - 374 PB - Elsevier CY - Oxford AN - OPUS4-31282 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Yao, Dongxu A1 - Xia, Y. A1 - Zuo, K.-h. A1 - Jiang, D. A1 - Günster, Jens A1 - Zeng, Y.-P. A1 - Heinrich, J.G. T1 - The effect of fabrication parameters on the mechanical properties of sintered reaction bonded porous Si3N4 ceramics N2 - 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. KW - Porous ceramics KW - Silicon nitride KW - Reaction bonding KW - Anisotropic grain growth KW - Ceramic PY - 2014 U6 - https://doi.org/10.1016/j.jeurceramsoc.2014.06.018 SN - 0955-2219 SN - 1873-619X VL - 34 IS - 15 SP - 3461 EP - 3467 PB - Elsevier CY - Oxford AN - OPUS4-32542 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Yao, Dongxu A1 - Xia, Y. A1 - Zuo, K.-h. A1 - Zeng, Y.-P. A1 - Jiang, D. A1 - Günster, Jens A1 - Heinrich, J.G. T1 - Gradient porous silicon nitride prepared via vacuum foaming and freeze drying N2 - 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. KW - Silicon nitride KW - Graded PY - 2015 U6 - https://doi.org/10.1016/j.matlet.2014.11.067 SN - 0167-577x SN - 1873-4979 VL - 141 SP - 138 EP - 140 PB - Elsevier B.V. CY - Amsterdam AN - OPUS4-35177 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hu, H.-L. A1 - Zeng, Y.-P. A1 - Zuo, K.-H. A1 - Xia, Y. A1 - Yao, Dongxu A1 - Günster, Jens A1 - Heinrich, J. A1 - Li, S. T1 - Synthesis of porous Si3N4/SiC ceramics with rapid nitridation of silicon N2 - 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. KW - Si3N4 PY - 2015 U6 - https://doi.org/10.1016/j.jeurceramsoc.2015.06.028 SN - 0955-2219 SN - 1873-619X VL - 35 IS - 14 SP - 3781 EP - 3787 PB - Elsevier Ltd. CY - Oxford AN - OPUS4-34956 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hu, H.-L. A1 - Zeng, Y.-P. A1 - Xia, Y. A1 - Yao, Dongxu A1 - Zuo, K.-H. A1 - Günster, Jens A1 - Heinrich, J.G. T1 - Rapid fabrication of porous Si3N4/SiC ceramics via nitridation of silicon powder with ZrO2 as catalyst N2 - 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. KW - D. ZrO2 KW - Rapid nitridation KW - Si3N4/SiC porous ceramics PY - 2014 U6 - https://doi.org/10.1016/j.ceramint.2013.11.098 SN - 0272-8842 SN - 1873-3956 VL - 40 IS - 5 SP - 7579 EP - 7582 PB - Ceramurgia CY - Faenza AN - OPUS4-30295 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Li, M. A1 - Schlaich, C. A1 - Zhang, J. A1 - Donskyi, Ievgen A1 - Schwibbert, Karin A1 - Schreiber, Frank A1 - Xia, Y. A1 - Radnik, Jörg A1 - Schwerdtle, T. A1 - Haag, R. T1 - Mussel-inspired multifunctional coating for bacterial infection prevention and osteogenic induction N2 - Bacterial infection and osteogenic integration are the two main problems that cause severe complications after surgeries. In this study, the antibacterial and osteogenic properties were simultaneously introduced in biomaterials, where copper nanoparticles (CuNPs) were generated by in situ reductions of Cu ions into a mussel-inspired hyperbranched polyglycerol (MI-hPG) coating via a simple dip-coating method. This hyperbranched polyglycerol with 10 % catechol groups’ modification presents excellent antifouling property, which could effectively reduce bacteria adhesion on the surface. In this work, polycaprolactone (PCL) electrospun fiber membrane was selected as the substrate, which is commonly used in biomedical implants in bone regeneration and cardiovascular stents because of its good biocompatibility and easy post-modification. The as-fabricated CuNPs-incorporated PCL membrane [PCL-(MI-hPG)-CuNPs] was confirmed with effective antibacterial performance via in vitro antibacterial tests against Staphylococcus aureus (S. aureus), Escherichia coli (E. coli), and multi-resistant E. coli. In addition, the in vitro results demonstrated that osteogenic property of PCL-(MI-hPG)-CuNPs was realized by upregulating the osteoblast-related gene expressions and protein activity. This study shows that antibacterial and osteogenic properties can be balanced in a surface coating by introducing CuNPs. KW - Mussel-inspired coating KW - CuNPs KW - Multi-resistant bacteria KW - Antibacterial KW - Antifouling KW - Osteogenesis PY - 2021 U6 - https://doi.org/10.1016/j.jmst.2020.08.011 SN - 1005-0302 VL - 68 SP - 160 EP - 171 PB - Elsevier Ltd. AN - OPUS4-51519 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -