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Search Publications by: William E. Luecke (Assoc)

Displaying 76 - 100 of 104

Influence of Grain Size on the Tensile Creep Behavior of Ytterbium-Containing Silicon Nitride

March 1, 2004

Author(s)

Sheldon M. Wiederhorn, A R D Lopez, William E. Luecke, Michael J. Hoffmann, B Hockey, J French, D C. Yoon

The effect of grain size on the tensile creep of silicon nitride is investigated on two materials, one containing 5 % by volume Yb2O3, the other containing 5 % by volume Yb203 and 0.5 % by mass Al2O3. Annealing of the alumina-free silicon nitride increased

Instrumented Indentation and Ultrasonic Velocity Techniques for the Evaluation of Creep Cavitation in Silicon Nitride

January 1, 2003

Author(s)

F Lofaj, Douglas T. Smith, Gerald V. Blessing, William E. Luecke, Sheldon M. Wiederhorn

Instrumented indentation and ultrasonic wave velocity techniques combined with precise density change measurements and transmission electron microscopy (TEM) were used to investigate the changes of elastic moduli in silicon nitride after tensile

Effect of Temperature, Strain Rate, and Grain Size on the Mechanical Response of Ti 3 SiC 2 in Tension

April 1, 2002

Author(s)

M Radovic, M W. Barsoum, T El-Raghy, Sheldon M. Wiederhorn, William E. Luecke

Results of tensile tests at constant cross head displacement rates, relaxation tests and cycling loading-unloading tests indicate that the mechanical response of Ti 3SiC 2 is a strong function of temperature, strain rate and grain size. Loading at low

Creep of Lanthanum Gallate

March 1, 2002

Author(s)

William E. Luecke, T R. Armstrong

Strontium- and magnesium-doped lanthanum gallate (LSGM) was deliberately prepared to give A-site deficient non-stoichiometry with compositions (La 0.9Sr 0.1)z(Ga 0.8Mg 0.2)O 3-delta (z =1.0,0.98, and 0.95). Creep tests in four-point 950 C 75 Mpa in air

Results of an International Round-Robin for Tensile Creep Rupture of Silicon Nitride

February 1, 2002

Author(s)

William E. Luecke

Fourteen laboratories participated in an ubterkabiratirt study to establish the within- and between-laboratory repeatability of tensile creep rupture of silicon nitride. In air at 1375 C at 200 Mpa the times to failure ranged over a factor of 50, and the

Standards for Reliability Testing of Heavy Vehicle

October 1, 2001

Author(s)

S Jahanmir, James F. Kelly, William E. Luecke

The objective of this project is to develop international standard test methods for assessing the reliability of ceramic components used in diesel engines and other heavy vehicle propulsion systems. Advanced ceramics such as silicon nitrides offer unique

Standards for Reliability Testing of Heavy Vehicle Propulsion Materials

January 1, 2001

Author(s)

S Jahanmir, James F. Kelly, William E. Luecke

Comparison of Tensile and Compressive Creep Behavior in Silicon Nitride

January 1, 2000

Author(s)

K J. Yoon, Sheldon M. Wiederhorn, William E. Luecke

The creep behavior of most commercial grade of Si 3N 4 was studied at 1350 and 1400 C. Stresses ranged from 10 to 200 Mpa in tension and from 30 to 300 Mpa in compression. In tension, the creep rate increased linearly with stress at low stresses and

High-Temperature Properties of Liquid-Phase-Sintered A-Sic

November 1, 1999

Author(s)

R P. Jensen, William E. Luecke, N P. Padture, Sheldon M. Wiederhorn

We have characterized the high-temperature subcritical crack growth and oxidation resistance of a liquid-phase-sintered (LPS) SiC with 20% volume fraction yttrium aluminum garnet (YAG) second phase. Constant stress rate testing in air in the temperature

A new model for tensile creep of silicon nitride

October 1, 1999

Author(s)

William E. Luecke, Sheldon M. Wiederhorn

The tensile creep rate of most commercial grades of Si3N4 increases strongly with stress. Although the usual power-law functions can represent the creep data, the data often show curvature and systematic variations of slope with temperature and stress. In

Tensile Creep and Rupture of Silicon Nitride

May 1, 1999

Author(s)

Ralph Krause, William E. Luecke, J French, B Hockey, Sheldon M. Wiederhorn

We have characterized the tensile creep, rupture lifetime, and cavitation behavior of a commercial, gas-pressure-sintered silicon nitride in the temperature range 1150 to 1400 C and stress range 70 to 400 MPa. Individual creep curves generally show primary

A Strain-Based Methodology for High Temperature Lifetime Prediction

September 1, 1998

Author(s)

Sheldon M. Wiederhorn, William E. Luecke, Ralph Krause

In structural materials, lifetime is often strain-determined. Once a part exceeds its allowable strain, its functional integrity is lost. Although most ceramics are designed to a brittle failure criterion, silicon nitride at the temperatures expected in

Interlaboratory verification of silicon nitride tensile creep properties

April 1, 1997

Author(s)

William E. Luecke, Sheldon M. Wiederhorn

Five laboratories tested NIST-supplied, pin-loaded, 76-mm-long tensile creep specimens at 1400 degrees C under a 150 MPa load using flag-based, laser extensometry, The laboratories reported failure time and strain and supplied the individual creep curves