Self-strengthening and high temperature sintering in binder-free silicon nitride

1993 ◽  
Vol 40 (1) ◽  
pp. 201-208
Author(s):  
M. M. Gasik ◽  
F. R. Sale
Keyword(s):  
High Temperature ◽  
Silicon Nitride ◽  
Free Silicon ◽  
Binder Free

Effects of Silicon Particle Size on the Morphology of Rod-Like Si3N4 Crystals Prepared by SHS Method

2016 ◽  
Vol 680 ◽  
pp. 103-106
Author(s):  
Fei Yang Chen ◽  
Fei Xia Luo ◽  
Ze Hua Zhou ◽  
Chao Du ◽  
Yu Chun Zou ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Particle Size ◽  
High Temperature ◽  
Silicon Nitride ◽  
Silicon Particle ◽  
Nitrogen Gas ◽  
Temperature Performance ◽  
Free Silicon ◽  
Wide Range ◽  
Shs Method

Silicon nitride whiskers or rod-like crystals have a wide range application due to its excellent mechanical properties and high temperature performance. Two different silicon powders with different size (mesh 200 and mesh 300, respectively) were chosen to prepare rod-like Si3N4 crystals by SHS method and the effects of silicon particle size on the morphology of rod-like Si3N4 crystals were investigated. The results indicate that rod-like Si3N4 crystals could be formed with either kind of silicon powders when no more than 9wt% extra Y2O3 was introduced, which could effectively promote the growth of rod-like Si3N4 crystals. The residual free silicon was detected when using coarse silicon powders, while the silicon could be reacted completely with nitrogen gas when using fine silicon powders. The morphology of samples with coarse Si powders as starting materials is more uniform and regular than that of fine Si powders samples. Fine silicon powders are not ideal candidates for forming uniform and regular rod-like Si3N4 crystals.

Lattice Imaging of Grain Boundaries in Ceramics

1977 ◽  
Vol 35 ◽  
pp. 114-115
Author(s):  
D. R. Clarke ◽  
G. Thomas
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Silicon Nitride ◽  
Grain Boundaries ◽  
High Temperature Strength ◽  
Current Interest ◽  
Lattice Imaging ◽  
Special Significance ◽  
Structural Applications ◽  
Refractory Ceramics

Grain boundaries have long held a special significance to ceramicists. In part, this has been because it has been impossible until now to actually observe the boundaries themselves. Just as important, however, is the fact that the grain boundaries and their environs have a determing influence on both the mechanisms by which powder compaction occurs during fabrication, and on the overall mechanical properties of the material. One area where the grain boundary plays a particularly important role is in the high temperature strength of hot-pressed ceramics. This is a subject of current interest as extensive efforts are being made to develop ceramics, such as silicon nitride alloys, for high temperature structural applications. In this presentation we describe how the techniques of lattice fringe imaging have made it possible to study the grain boundaries in a number of refractory ceramics, and illustrate some of the findings.

TEM Studies of Grain Boundary Films in Si3N4 Ceramics

1991 ◽  
Vol 49 ◽  
pp. 930-931
Author(s):  
H.-J. Kleebe ◽  
J.S. Vetrano ◽  
J. Bruley ◽  
M. Rühle
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Silicon Nitride ◽  
Hot Isostatic Pressing ◽  
Amorphous Film ◽  
Liquid Phase Sintering ◽  
Second Phase ◽  
High Temperature Mechanical Properties ◽  
Triple Points ◽  
Boundary Films

It is expected that silicon nitride based ceramics will be used as high-temperature structural components. Though much progress has been made in both processing techniques and microstructural control, the mechanical properties required have not yet been achieved. It is thought that the high-temperature mechanical properties of Si3N4 are limited largely by the secondary glassy phases present at triple points. These are due to various oxide additives used to promote liquid-phase sintering. Therefore, many attempts have been performed to crystallize these second phase glassy pockets in order to improve high temperature properties. In addition to the glassy or crystallized second phases at triple points a thin amorphous film exists at two-grain junctions. This thin film is found even in silicon nitride formed by hot isostatic pressing (HIPing) without additives. It has been proposed by Clarke that an amorphous film can exist at two-grain junctions with an equilibrium thickness.

Electron Microscopy of Silicon Nitride-Based Ceramics

1991 ◽  
Vol 49 ◽  
pp. 926-927
Author(s):  
Gareth Thomas
Keyword(s):  
Electron Microscopy ◽  
High Temperature ◽  
Silicon Nitride ◽  
World Wide ◽  
Sintering Temperature ◽  
Liquid Phase Sintering ◽  
High Temperature Strength ◽  
Sintering Additives ◽  
Glass Forming ◽  
Dense Product

Silicon nitride and silicon nitride based-ceramics are now well known for their potential as hightemperature structural materials, e.g. in engines. However, as is the case for many ceramics, in order to produce a dense product, sintering additives are utilized which allow liquid-phase sintering to occur; but upon cooling from the sintering temperature residual intergranular phases are formed which can be deleterious to high-temperature strength and oxidation resistance, especially if these phases are nonviscous glasses. Many oxide sintering additives have been utilized in processing attempts world-wide to produce dense creep resistant components using Si3N4 but the problem of controlling intergranular phases requires an understanding of the glass forming and subsequent glass-crystalline transformations that can occur at the grain boundaries.

Effect of high temperature cycling on both crack formation in ceramics and delamination of copper layers in silicon nitride active metal brazing substrates

2017 ◽  
Vol 43 (6) ◽  
pp. 5080-5088 ◽  
Author(s):  
Hiroyuki Miyazakia ◽  
Shoji Iwakiri ◽  
Kiyoshi Hirao ◽  
Shinji Fukuda ◽  
Noriya Izu ◽  
...  
Keyword(s):  
High Temperature ◽  
Silicon Nitride ◽  
Crack Formation ◽  
Temperature Cycling ◽  
Active Metal

Polymer-derived silicon nitride aerogels as shape stabilizers for low and high-temperature thermal energy storage

2021 ◽  
Author(s):  
Andrea Zambotti ◽  
Edoardo Caldesi ◽  
Massimo Pelizzari ◽  
Francesco Valentini ◽  
Alessandro Pegoretti ◽  
...  
Keyword(s):  
High Temperature ◽  
Energy Storage ◽  
Silicon Nitride ◽  
Thermal Energy ◽  
Thermal Energy Storage

Mechanical and etching properties of dual ion beam deposited hydrogen-free silicon nitride films

2001 ◽  
Vol 19 (5) ◽  
pp. 2542-2548 ◽  
Author(s):  
M. P. Tsang ◽  
C. W. Ong ◽  
N. Chong ◽  
C. L. Choy ◽  
P. K. Lim ◽  
...  
Keyword(s):  
Silicon Nitride ◽  
Ion Beam ◽  
Silicon Nitride Films ◽  
Free Silicon

Determination of Free Silicon in Sintered Silicon Nitride by Laser Raman Spectrometry

1989 ◽  
Vol 97 (1132) ◽  
pp. 1466-1470
Author(s):  
Atsushi CHINO ◽  
Hideo IWATA ◽  
Sirou TORIZUKA ◽  
Kazuya YABUTA
Keyword(s):  
Silicon Nitride ◽  
Raman Spectrometry ◽  
Laser Raman ◽  
Free Silicon ◽  
Sintered Silicon

Development and Fabrication of Silicon Nitride Components for Ceramic Gas Turbine

1997 ◽  
Author(s):  
Keisuke Makino ◽  
Ken-Ichi Mizuno ◽  
Toru Shimamori
Keyword(s):  
High Temperature ◽  
Silicon Nitride ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Turbine Blades ◽  
High Strength ◽  
Inlet Temperature ◽  
Turbine Inlet Temperature ◽  
Spark Plug ◽  
Power Turbine

NGK Spark Plug Co., Ltd. has been developing various silicon nitride materials, and the technology for fabricating components for ceramic gas turbines (CGT) using theses materials. We are supplying silicon nitride material components for the project to develop 300 kW class CGT for co-generation in Japan. EC-152 was developed for components that require high strength at high temperature, such as turbine blades and turbine nozzles. In order to adapt the increasing of the turbine inlet temperature (TIT) up to 1,350 °C in accordance with the project goals, we developed two silicon nitride materials with further unproved properties: ST-1 and ST-2. ST-1 has a higher strength than EC-152 and is suitable for first stage turbine blades and power turbine blades. ST-2 has higher oxidation resistance than EC-152 and is suitable for power turbine nozzles. In this paper, we report on the properties of these materials, and present the results of evaluations of these materials when they are actually used for CGT components such as first stage turbine blades and power turbine nozzles.

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