Sintering of silicon nitride ceramics with magnesium silicon nitride and yttrium oxide as sintering aids

2011 ◽  
Vol 18 (20) ◽  
pp. 202017 ◽  
Author(s):  
J Jiang ◽  
J Y Xu ◽  
G H Peng ◽  
H R Zhuang ◽  
W L Li ◽  
...  
Keyword(s):  
Silicon Nitride ◽  
Yttrium Oxide ◽  
Sintering Aids ◽  
Nitride Ceramics

Microstructure, toughness and flexural strength of self-reinforced silicon nitride ceramics doped with yttrium oxide and ytterbium oxide

2001 ◽  
Vol 201 (2) ◽  
pp. 238-249 ◽  
Author(s):  
Y. S. Zheng ◽  
K. M. Knowles ◽  
J. M. Vieira ◽  
A. B. Lopes ◽  
F. J. Oliveira
Keyword(s):  
Silicon Nitride ◽  
Flexural Strength ◽  
Yttrium Oxide ◽  
Ytterbium Oxide ◽  
Nitride Ceramics

Analysis of Internal Friction on Silicon Nitride with Visco-Elastic Model

2006 ◽  
Vol 317-318 ◽  
pp. 429-432 ◽  
Author(s):  
Shuji Sakaguchi
Keyword(s):  
Relaxation Time ◽  
Silicon Nitride ◽  
Internal Friction ◽  
Temperature Dependence ◽  
Creep Deformation ◽  
Maxwell Model ◽  
Elastic Model ◽  
Sintering Aids ◽  
Characteristic Peak ◽  
Nitride Ceramics

Temperature dependence of internal friction on silicon nitride ceramics with yttria and alumina sintering aids was discussed using 4-elements visco-elastic model. It is known that the internal friction of this ceramic material shows a characteristic peak at around 1040 oC and an exponential increase over 1200 oC. This temperature dependence of internal friction was well approximated with using parallel Maxwell model. The parameters for this model and the relaxation time on this model were obtained. The relaxation time was very short, compared to the transient creep deformation of this ceramics. The analyzed results on internal friction could not be related with the creep deformation.

Effects of Sintering Conditions and Additives on Translucent Silicon Nitride Ceramics

2012 ◽  
Vol 724 ◽  
pp. 282-286 ◽  
Author(s):  
Wen Wu Yang ◽  
Miki Inada ◽  
Yumi Tanaka ◽  
Naoya Enomoto ◽  
Junichi Hojo
Keyword(s):  
Silicon Nitride ◽  
Visible Region ◽  
Sintering Aids ◽  
Sintering Aid ◽  
Sintering Additives ◽  
Nitride Ceramics ◽  
Sintering Conditions

Translucent β-Si3N4 sintered ceramics have been fabricated by using AlN-MgO sintering additives. In the present study, the authors employed AlN-MgO as a standard sintering aid, and investigated the effects of sintering conditions on the translucency of Si3N4. Furthermore, various oxides such as HfO2, Sm2O3, Y2O3, Sc2O3, La2O3, Nd2O3, CeO2, CaO, ZrO2 etc. were used as the sintering aids of Si3N4, and the sintered β-Si3N4 ceramics exhibited different transmittances in the visible region. It was found that the transmittance of sintered ceramics was mainly affected by the sintering additives.

Crystallization of Zirconium Nitride in Silicon Nitride Ceramics with Nitrogen Pressures and Sintering Additives

2005 ◽  
Vol 287 ◽  
pp. 253-258 ◽  
Author(s):  
S.M. Lee ◽  
K.H. Park ◽  
Jung Whan Yoo ◽  
Hyung Tae Kim
Keyword(s):  
Mechanical Properties ◽  
Silicon Nitride ◽  
Surface Region ◽  
Nitrogen Atmosphere ◽  
Zirconium Nitride ◽  
Sintering Aids ◽  
Sintering Aid ◽  
Heat Treated ◽  
Nitride Ceramics ◽  
Sintered Silicon

We investigated grain boundary crystallization of gas-pressure-sintered silicon nitride with zirconia and magnesia as sintering aids. Cation compositions were mostly uniform throughout the specimen however, ZrO2 was crystallized in the surface region, while ZrN in the inside. When the specimen was heat-treated at 1 atm nitrogen atmosphere, ZrO2 in the surface region transformed to ZrN. The transformation, however, was suppressed when alumina was incorporated as an additional sintering aid. Based on these results, we propose a model describing the reaction among Si3N4, SiO2, ZrO2, ZrN and N2. Observed microstructures and measured mechanical properties were consistent with the model.

Enhancing Toughness of Silicon Nitrides With Nanoscale Additions

2008 ◽  
Author(s):  
Sridhar Santhanam ◽  
Kei-Peng Jen ◽  
Zachary N. Wing
Keyword(s):  
Silicon Nitride ◽  
Room Temperature ◽  
Crack Path ◽  
Sintering Aids ◽  
Silicon Nitrides ◽  
Multiple Strategies ◽  
High Toughness ◽  
Nano Scale ◽  
Nitride Ceramics ◽  
Path Deviation

Silicon nitride ceramics for applications in demanding environments require high toughness and adequate hardness. A well known route to making tough silicon nitride compositions is to control the grain size distribution. For beta silicon nitrides, the grain shapes in the form of their acicularity is known to be very important too. In this paper, we report on the use of multiple strategies to achieve increased toughness and toughening in silicon nitrides. These strategies include the use of a blend of nano-scale and micron-scale silicon nitride powders, the use of nano-scale sintering aids, and the addition of carbon nanotubes. Microstructures and mechanical properties are determined for these hot-pressed ceramics and are compared with a baseline silicon nitride prepared with conventional micron-scale powders. Hardness and fracture toughness are determined at room temperature using hardness indents produced by a macro Vickers hardness indenter. The toughening ability of these ceramics are compared by R-curve measurements. Grain boundary debonding and crack path deviation are identified as toughening mechanisms.

Erosion Wear Characteristics of Si3N4 Fabricated from Low-Cost Powders

2007 ◽  
Vol 280-283 ◽  
pp. 1331-1334
Author(s):  
Bing Wu ◽  
Long Hao Qi ◽  
Jian Shen
Keyword(s):  
Silicon Nitride ◽  
Low Cost ◽  
Raw Material ◽  
Erosion Wear ◽  
Hot Press ◽  
Sintering Aids ◽  
Nitride Ceramics ◽  
Silicon Nitride Powder ◽  
Worn Surface ◽  
Si3n4 Ceramics

High producing cost is one of the important reasons that silicon nitride ceramics can’t be widely used today. In this paper, one kind of commercial low-cost silicon nitride powder was used as raw material. High density samples were obtained through pressureless sintering with alumina, yttria and magnesia as sintering aids. The Si3N4 material was tested and the erosion wear rate was measured. It was found that the low cost and dense Si3N4 ceramics exhibited a better erosion wear resistance than the hot-press ceramics produced with the UBE Si3N4 powder and much better then the Cr-26 cast iron. The worn surface was observed with the SEM and the erosion wear mechanisms were analyzed.

Fabrication of translucent silicon nitride ceramics with various sintering aids

2013 ◽  
Vol 10 (1/2) ◽  
pp. 119 ◽  
Author(s):  
W.W. Yang ◽  
M. Inada ◽  
Y. Tanaka ◽  
N. Enomoto ◽  
J. Hojo
Keyword(s):  
Silicon Nitride ◽  
Sintering Aids ◽  
Nitride Ceramics

Tensile Creep of Y-Si3N4: II. Cavitation

1991 ◽  
Vol 49 ◽  
pp. 972-973 ◽  
Author(s):  
B. J. Hockey ◽  
S. M. Wiederhorn
Keyword(s):  
Silicon Nitride ◽  
Creep Rupture ◽  
Tensile Creep ◽  
Sintering Aids ◽  
Microstructural Changes

ATEM has been used to characterize three different silicon nitride materials after tensile creep in air at 1200 to 1400° C. In Part I, the microstructures and microstructural changes that occur during testing were described, and consistent with that description the designations and sintering aids for these materials were: W/YAS, a SiC whisker reinforced Si3N4 processed with yttria (6w/o) and alumina (1.5w/o); YAS, Si3N4 processed with yttria (6 w/o) and alumina (1.5w/o); and YS, Si3N4 processed with yttria (4.0 w/o). This paper, Part II, addresses the interfacial cavitation processes that occur in these materials and which are ultimately responsible for creep rupture.

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