Fatigue Lives and Material Properties of Silicon Nitride Balls for Hybrid Bearing Applications

2010 ◽  
pp. 259-271
Author(s):  
Liang Xue ◽  
Gary L. Doll
Keyword(s):  
Silicon Nitride ◽  
Material Properties ◽  
Hybrid Bearing

scholarly journals Dense, Strong, and Precise Silicon Nitride-Based Ceramic Parts by Lithography-Based Ceramic Manufacturing

2020 ◽  
Vol 10 (3) ◽  
pp. 996 ◽  
Author(s):  
Altan Alpay Altun ◽  
Thomas Prochaska ◽  
Thomas Konegger ◽  
Martin Schwentenwein
Keyword(s):  
Surface Roughness ◽  
High Temperature ◽  
Light Scattering ◽  
Silicon Nitride ◽  
Material Properties ◽  
Refractive Indices ◽  
High Relative Density ◽  
Ceramic Manufacturing ◽  
High Level ◽  
First Time

Due to the high level of light absorption and light scattering of dark colored powders connected with the high refractive indices of ceramic particles, the majority of ceramics studied via stereolithography (SLA) have been light in color, including ceramics such as alumina, zirconia and tricalcium phosphate. This article focuses on a lithography-based ceramic manufacturing (LCM) method for β-SiAlON ceramics that are derived from silicon nitride and have excellent material properties for high temperature applications. This study demonstrates the general feasibility of manufacturing of silicon nitride-based ceramic parts by LCM for the first time and combines the advantages of SLA, such as the achievable complexity and low surface roughness (Ra = 0.50 µm), with the typical properties of conventionally manufactured silicon nitride-based ceramics, such as high relative density (99.8%), biaxial strength (σf = 764 MPa), and hardness (HV10 = 1500).

Silicon Nitride Deposited at Very Low Silane Pressures Using Electron Cyclotron Resonance Plasmas

1992 ◽  
Vol 284 ◽  
Author(s):  
J. R. Flemish ◽  
R. Pfeffer ◽  
W. Buchwald ◽  
K. A. Jones
Keyword(s):  
Refractive Index ◽  
Silicon Nitride ◽  
Microwave Power ◽  
Material Properties ◽  
Cyclotron Resonance ◽  
Total Pressure ◽  
Electron Cyclotron Resonance ◽  
High Quality ◽  
Deposition Rates ◽  
Hydrogen Incorporation

ABSTRACTWe report on the material properties of SiNx:H films deposited using a 2% SiH4/N2 mixture with additional N2 in an ECR reactor. Deposition rates, refractive index, and stoichiometry have been characterized using ellipsometry, Rutherford backscattering spectroscopy, and infrared spectroscopy. Reactor conditions of 2m Torr total pressure, 650W microwave power, and substrate temperature of 250°C result in high quality, stoichiometric silicon nitride. With a SiH4/N2 ratio = 0.003, hydrogen incorporation is approximately 1.5% and the refractive index is nr =2.0. Lower microwave power and a higher SiH4/N2 ratio result in slightly N-rich films which is attributable to increased H-incorporation. Higher total pressure results in significantly enhanced deposition rates, but with greatly increased H and O content.

Material Properties Controlling the Performance of Amorphous Silicon Thin Film Transistors

1984 ◽  
Vol 33 ◽  
Author(s):  
M. J. Powell
Keyword(s):  
Thin Film ◽  
Silicon Nitride ◽  
Amorphous Silicon ◽  
Density Of States ◽  
Threshold Voltage ◽  
Material Properties ◽  
Thin Film Transistors ◽  
Gate Insulator ◽  
Dangling Bond ◽  
Silicon Thin Film

ABSTRACTAmorphous silicon thin film transistors have been fabricated with a number of different structures and materials. To date, the best performance is obtained with amorphous silicon - silicon nitride thin film transistors in the inverted staggered electrode structure, where the gate insulator and semiconductor are deposited sequentially by plasma enhanced chemical vapour deposition in the same growth apparatus.Localised electron states in the amorphous silicon are crucial in determining transistor performance. Conduction band states (Si-Si antibonding σ*) are broadened and localised in the amorphous network, and their energy distribution determines the field effect mobility. The silicon dangling bond defect is the most important deep localised state and their density determines the prethreshold current and hence the threshold voltage. The density of states is influenced by the gate insulator interface and there is probably a decreasing density of states away from this interface. The silicon dangling bond defect in the bulk amorphous silicon nitride also leads to a localised gap state, which is responsible for the observed threshold voltage instability.Other key material properties include the fixed charge densities associated with primary passivating layers placed on top of the amorphous silicon. The low value of the bulk density of states in the amorphous silicon layer increases the sensitivity of device characteristics to charge at the top interface.

scholarly journals Hybrid Ceramic Bearing Development for Gas Turbine Engines

1994 ◽  
Author(s):  
Frederick D. Slaney
Keyword(s):  
Silicon Nitride ◽  
Gas Turbine ◽  
High Speed ◽  
Development Program ◽  
Operating Conditions ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Hybrid Bearing ◽  
Engine Testing ◽  
Hybrid Ceramic

Over the past seven years, an extensive hybrid bearing development program has been conducted at Textron Lycoming. This paper will report the details of testing and the extraordinary results which can be obtained with silicon nitride balls as applied in hybrid bearings on gas turbine engines. This paper describes the analytically predicted advantages which low mass silicon nitride balls offer at speeds over 2.0MDN. Rig testing comparing hybrid bearings to standard bearings is reported. Testing included heat generation evaluation which showed that hybrid bearings generate an average of 40% less heat than standard bearings. Rig simulation of the AGT1500 mission duty cycle demonstrated that the hybrid silicon nitride bearing system is robust enough to handle the most severe operating conditions. Testing under severe slipping/skidding conditions demonstrated good resistance to skid failure. Under conditions selected to produce high wear, no wear was induced in a hybrid bearing while severe wear was induced in the M50 steel bearing. These preliminary successes lead to active engine testing on the AGT1500 and a new test program to demonstrate operation at 4.0 MDN. As a result of these programs Textron Lycoming now considers hybrid ceramic bearings as a viable design to be used in high speed development applications. This paper provides design detail and test data covering the work outlined above.

scholarly journals Effect of Silicon Nitride Balls and Rollers on Rolling Bearing Life

2004 ◽  
Author(s):  
Erwin V. Zaretsky ◽  
Brian L. Vlcek ◽  
Robert C. Hendricks
Keyword(s):  
Silicon Nitride ◽  
Rolling Bearing ◽  
Rolling Element Bearing ◽  
Steel Rolling ◽  
Bearing Life ◽  
Deep Groove ◽  
Rolling Element ◽  
Hybrid Bearing ◽  
Conventional Rolling ◽  
Cylindrical Roller

Three decades have passed since the introduction of silicon nitride rollers and balls into conventional rolling-element bearings. For a given applied load, the contact (Hertz) stress in a hybrid bearing will be higher than an all-steel rolling-element bearing. The silicon nitride rolling-element life as well as the lives of the steel races were used to determine the resultant bearing life of both hybrid and all-steel bearings. Life factors were determined and reported for hybrid bearings. Under nominal operating speeds, the resultant calculated lives for deep-groove, angular-contact, and cylindrical-roller hybrid bearings are respectively, 3.8, 3.3, and 5.5 times that using the Lundberg-Palmgren equations. An all-steel bearing under the same load and nominal operating speeds will always have higher life than the equivalent hybrid bearing operating under the same conditions. Under these conditions, hybrid bearings are predicted to have a lower fatigue life than the all-steel bearings by 58 percent for deep-groove bearings, 41 percent for angular-contact bearings and 28 percent for cylindrical roller bearings.

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