scholarly journals HYDROTHERMAL CORROSION RESISTANCE OF SILICON NITRIDE WITH O'-Si Al ON GRAIN BOUNDARY PHASE

2018 ◽  
pp. 382-388
Author(s):  
Michal Vetrecin
Keyword(s):  
Corrosion Resistance ◽  
Silicon Nitride ◽  
Grain Boundary ◽  
Boundary Phase

Examination of Fracture Interfaces in Silicon Nitride

1975 ◽  
Vol 33 ◽  
pp. 60-61
Author(s):  
Nancy J. Tighe
Keyword(s):  
Silicon Nitride ◽  
Grain Boundary ◽  
Crack Growth ◽  
Subcritical Crack Growth ◽  
Slow Crack Growth ◽  
Ceramic Materials ◽  
Grain Boundary Sliding ◽  
Boundary Phase ◽  
Turbine Engines ◽  
Boundary Sliding

Silicon nitride is one of the ceramic materials being considered for the components in gas turbine engines which will be exposed to temperatures of 1000 to 1400°C. Test specimens from hot-pressed billets exhibit flexural strengths of approximately 50 MN/m2 at 1000°C. However, the strength degrades rapidly to less than 20 MN/m2 at 1400°C. The strength degradition is attributed to subcritical crack growth phenomena evidenced by a stress rate dependence of the flexural strength and the stress intensity factor. This phenomena is termed slow crack growth and is associated with the onset of plastic deformation at the crack tip. Lange attributed the subcritical crack growth tb a glassy silicate grain boundary phase which decreased in viscosity with increased temperature and permitted a form of grain boundary sliding to occur.

Glassy grain-boundary phase crystallization of silicon nitride: Kinetics and phase development

1995 ◽  
Vol 14 (19) ◽  
pp. 1362-1365 ◽  
Author(s):  
G. Bernard-Granger ◽  
J. Crampon ◽  
R. Duclos ◽  
B. Cales
Keyword(s):  
Silicon Nitride ◽  
Grain Boundary ◽  
Boundary Phase ◽  
Phase Development

Grain Boundary Phase Analysis of Silicon Nitride by a Newly Developed 300kv Field-Emission Electron Microscope

1994 ◽  
Vol 346 ◽  
Author(s):  
Y. Bando ◽  
H. Suematsu ◽  
M. Mitomo
Keyword(s):  
Electron Microscope ◽  
Silicon Nitride ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Phase Analysis ◽  
Field Emission ◽  
Boundary Phase ◽  
Emission Electron ◽  
Triple Points

ABSTRACTThe grain boundary phase of silicon nitride containing additives Y2O3 and Nd2O3 has been studied by means of a newly developed 300kV field emission ATEM. The composition of the two-grain boundary phase of about 1 nm thick is successfully determined. It is then found that the compositions among the grain boundaries are not the same and the additives of Y2O3-Nd2O3 are poor in the two-grain boundary, while they are rich in the triple points.

Corrosion of Si3N4-Ceramics in Acids and Basics

2006 ◽  
Vol 45 ◽  
pp. 148-155 ◽  
Author(s):  
Jochen Schilm ◽  
Mathias Herrmann ◽  
G. Michael
Keyword(s):  
Silicon Nitride ◽  
Grain Boundary ◽  
Corrosion Behavior ◽  
Aqueous Media ◽  
Structural Features ◽  
Boundary Phase ◽  
The Subject ◽  
Corrosion Mechanisms ◽  
Si3n4 Ceramics ◽  
Made In

The corrosion behavior of silicon nitride materials in aqueous media strongly depends on the composition and amount of the grain boundary. But there exist no systematic investigations of the relation between the corrosion behavior and the composition and amount of the grain-boundary phase. The subject of this study is based on the evaluation of the corrosion mechanisms of Si3N4 ceramics and YSiAlON glasses, both with defined and characterized compositions, in acidic and basic environments with different concentrations. Special effort has been made in describing the compositions of grain boundary phases in the sintered Si3N4 ceramics. A model to describe structural features of YSiAlON-glasses was developed which allows the correlation of the corrosion behavior of the ceramics and the glasses with their compositions. In combination with SEM and TEM investigations it became possible to give structural reasons for the different observed corrosion mechanisms.

Silicon Nitride Ceramics with Sodium Ion Conductive Grain Boundary Phase

2003 ◽  
Vol 18 (12) ◽  
pp. 2752-2755 ◽  
Author(s):  
Hirokazu Kawaoka ◽  
Tohru Sekino ◽  
Takafumi Kusunose ◽  
Koichi Niihara
Keyword(s):  
Electrical Conductivity ◽  
Silicon Nitride ◽  
Ionic Conductivity ◽  
Grain Boundary ◽  
Sodium Ion ◽  
Boundary Phase ◽  
Structural Ceramics ◽  
Silicon Nitride Ceramic ◽  
Nitride Ceramics ◽  
Conductive Particles

Sodium ion-conductive silicon nitride ceramic with Na2O–Al2O3–SiO2 glass as the grain boundary phase was fabricated by adding Na2CO3, Al2O3, and SiO2 as sintering additives. The electrical conductivity was two and four orders of magnitude higher than that of Si3N4 ceramic with Y2O3 and Al2O3 additives at 100 and 1000°C, respectively. This result clearly indicates that ionic conductivity can be provided to insulating structural ceramics by modification of the grain boundary phase without dispersion of conductive particles.

Microstructure and microanalysis of silicon nitride ceramics in the Y-Si-Al-O-N and Y-Si-O-N systems

1990 ◽  
Vol 48 (4) ◽  
pp. 1072-1073
Author(s):  
Michael K. Cinibulk
Keyword(s):  
Silicon Nitride ◽  
Grain Boundary ◽  
Grain Boundary Sliding ◽  
Liquid Phase Sintering ◽  
Boundary Phase ◽  
Full Density ◽  
High Temperature Strength ◽  
Transmission Electron ◽  
Structural Applications ◽  
Nitride Ceramics

Silicon nitride ceramics are among the leading candidate materials for use in structural applications at high temperatures. Due to the highly covalent nature of the Si-N bond and therefore low self-diffusivity, processing Si3N4 to full density requires the use of additives to provide a medium for liquid-phase sintering. When exposed to temperatures above ∼1000°C the resulting amorphous grain-boundary phases soften, leading to grain-boundary sliding and the eventual failure of the ceramic. The objectives of this work were to modify the grain-boundary phase composition and then attempt to devitrify the resulting intergranular phase to a refractory crystalline phase, producing a sintered Si3N4 with improved high-temperature strength and oxidation resistance. Transmission electron microscopy (TEM) and energy-dispersive x-ray spectroscopy (EDS) were used to characterize these materials. This paper describes these results.

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