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The Role of Nanodispersed nitrides in the Sintering of silicon nitride ceramics

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Plasma Science and Technology 2010年第1期12卷 46-48页

作者： M.GEORGIEVA G.VISSOKOV I.GRANCHAROV R.F.SILVA F.J.OLIVEIRA Department of Technology of Inorganic Substances University of Chemical Technology and Metallurgy Institute of Catalysis Bulgarian Academy of Sciences ceramics and Glass Eng. Department CICECO University of Aveiro

The synthesis of ceramics based on silicon nitride using nanopowders of TiN and Si3N4 as additives was studied. The ceramic compositions were pressurelessly sintered under ni- trogen atmosphere at different temperatures （1550℃, 1650℃ and 1750℃） with a heating rate of 10℃/min and a holding time of 2 h. The nanodispersed nitrides （NDN） were produced by electric-arc plasma synthesis and characterized. The ceramic composites obtained with nanoparticles of 1wt% to 5wt% TiN and 20wt% Si3N4 were characterized by scanning electron microscopy （SEM）, atom force microscopy （AFM） and energy-dispersive spectrometry （EDX）. The effect of the addition of nanodispersed powders on the mechanical properties and microstructure of Si3N4 ceramics was investigated.

关键词： silicon nitride ceramics nanocomposites nanopowders

Microstructure and properties of Si_3N_4 ceramics obtained from addition of β-phase seeds and celsian

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Journal of University of Science and Technology Beijing 2006年第5期13卷 465-468页

作者： Jun Yang Jiqiang Gao Jianfeng Yang Guanjun Qiao Yonghong Luo State Key Laboratory for Mechanical Behavior of Materials Xi＇an Jiaotong University Xi＇an 710049 China Xi＇an University of Architecture and Technology Xi＇an 710055 China

The silicon nitride based ceramics obtained by the addition of β-Si3N4 seeds was fabricated using celsian as the additive and by pressureless sintering. The microstructure of the material was observed and analyzed using XRD, SEM, and TEM and the mechanical response of this array microstructure was characterized for flexural strength and fracture behavior. The result shows that the growth of the larger aspect ratio grains initiate mainly from the seeds through the heterogeneous nucleation mechanism during the process of phase transformation, and the intergranular phase BaAl2Si20s services as good refractory materials. In contrast to conventional processing, a stable bimodal microstructure and complicated component with a lower cost can be achieved using the abovementioned process theoretically and practically.

关键词： silicon nitride ceramics celsian β-silicon nitride seed pressureless sintering microstructure properties

Effect of Nano-Al_2O_3 on Mechanical Properties and Microstructure of Si_3N_4 ceramics

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China's Refractories 2014年第2期23卷 18-22页

作者： WANG Huifang ZHANG Xijun BI Yubao High Temperature Materials Institute Henan University of Science and Technology Sanmenxia Fangyuan Industrial Co. Ltd

Si3N4 ceramics were prepared by pressureless sintering at 1 650 ℃ in nitrogen atmosphere using Si3N4 powder as main starting material and adding nano Al203 powder （3%, 6%, 9%, 12%, and 15% in mass, the same hereinafter）. The bending strength and fracture toughness （KIC） of the specimens were *** microstructure and phase compositions of the specimens were analyzed. The results show that SigN4 ceramics can be prepared by pressureless sintering when adding 9% -12% nano-A1203 as active reactant, which dissolves in Si3N4, in-situ forming non-oxide SiAION. The obtained Si3N4 ceramics have the maximum bending strength of 710. 86 MPa and KIC of 8. 61 MPa · m1/2 The exceUent properties come from many interwoven structures distributed uniformly in the ceramics matrix, u,hich is composed of big and firm plate-like β-Si3N., hexagonal SiAION and sheet Si2N2 0.

关键词： silicon nitride ceramics pressureless sin-tering bending strength fracture toughness

Densification mechanism of stereolithographical dense Si_(3)N_(4) ceramics with CeO_(2) as sintering additive by field assisted sintering

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Journal of Central South University 2021年第4期28卷 1233-1243页

作者： RAO Wei-dong LIU Yao CHENG Li-jing LIU Shao-jun State Key Laboratory for Powder Metallurgy Central South UniversityChangsha 410083China Shenzhen Research Institute Central South UniversityShenzhen 518007China College of Mechanical and Electronic Engineering Pingxiang UniversityPingxiang 337000China School of Mechanical Engineering Hebei University of TechnologyTianjin 300130China

Combining sintering additive with field assisted sintering,stereolithographical dense Si3N4 ceramics was successfully *** to a large amount of polymer during the stereolithography,the green parts have the characteristics of low powder loading and high *** the process parameters such as sintering temperature and soaking time can effectively improve the density of the *** stress exponent n of all specimens is in a range of 1 and 2,which is derived from a modified sintering kinetics *** apparent activation energy Qd of stereolithographic Si_(3)N_(4) ceramics sintered with applied pressures of 30 MPa,40 MPa,and 50 MPa is 384.75,276.61 and 193.95 kJ/mol,respectively,suggesting that the densification dynamic process is strengthened by raising applied *** grain boundary slipping plays a dominating role in the densification of stereolithographic Si3N4 *** Vickers hardness and fracture toughness of stereolithographic Si3N4 ceramics are HV10/10(1347.9±2.4)and(6.57±0.07)MPaAbstract:Combining sintering additive with field assisted sintering,stereolithographical dense Si3N4 ceramics was successfully *** to a large amount of polymer during the stereolithography,the green parts have the characteristics of low powder loading and high *** the process parameters such as sintering temperature and soaking time can effectively improve the density of the *** stress exponent n of all specimens is in a range of 1 and 2,which is derived from a modified sintering kinetics *** apparent activation energy Qd of stereolithographic Si3N4 ceramics sintered with applied pressures of 30 MPa,40 MPa,and 50 MPa is 384.75,276.61 and 193.95 kJ/mol,respectively,suggesting that the densification dynamic process is strengthened by raising applied *** grain boundary slipping plays a dominating role in the densification of stereolithographic Si3N4 *** Vickers hardness and fracture toughn

关键词： stereolithography silicon nitride ceramics sintering mechanism densification field assisted sintering