Stress-Rupture and Stress-Relaxation Behaviors of PIP-SiC/SiC Composites

2008 ◽  
pp. 371-378
Author(s):  
Takashi Nozawa ◽  
Akira Kohyama ◽  
Edgar Lara-Curzio
Keyword(s):  
Stress Relaxation ◽  
Stress Rupture ◽  
Sic Composites

scholarly journals Design, Fabrication, and Testing of Ceramic Joints for High Temperature SiC/SiC Composites

2000 ◽  
Author(s):  
M. Singh ◽  
Edgar Lara-Curzio
Keyword(s):  
Silicon Carbide ◽  
Shear Strength ◽  
Elevated Temperatures ◽  
Stress Rupture ◽  
Ceramic Matrix Composites ◽  
Matrix Composites ◽  
Carbide Matrix ◽  
Sic Composites ◽  
Stress Rupture Testing

Various issues associated with the design and mechanical evaluation of joints of ceramic matrix composites are discussed. The specific case of an affordable, robust ceramic joining technology (ARCJoinT) to join silicon carbide (CG-Nicalon™) fiber-reinforced-chemically vapor infiltrated (CVI) silicon carbide matrix composites is addressed. Experimental results are presented for the time and temperature dependence of the shear strength of these joints in air up to 1200°C. From compression testing of double-notched joint specimens with a notch separation of 4 mm, it was found that the apparent shear strength of the joints decreased from 92 MPa at room temperature to 71 MPa at 1200°C. From shear stress-rupture testing in air at 1200°C it was found that the shear strength of the joints decreased rapidly with time from an initial shear strength of 71 MPa to 17.5 MPa after 14.3 hours. The implications of these results in relation to the expected long-term service life of these joints in applications at elevated temperatures are discussed.

Probabilistic Residual Strength Model for Stress Rupture of SiC/SiC Composites

2001 ◽  
Author(s):  
David J. Thomas
Keyword(s):  
Residual Strength ◽  
Model Calibration ◽  
Composite Structures ◽  
Stress Rupture ◽  
Time To Failure ◽  
Material System ◽  
Degradation Data ◽  
Sic Composites ◽  
Data Requirements ◽  
Rupture Behavior

A probabilistic residual strength (PRS) model for the stress rupture behavior of composites is presented. The material’s initial ultimate strength, time-to-failure, and intermediate residual strength are all considered to be random variables. A Kachonov style rate equation is assumed to model the strength degradation. Data requirements for model calibration are outlined and the calibration process is presented. Model capabilities are demonstrated using experimental data for a SiC/SiC [0/90] 5-harness satin weave material system. The PRS model has the potential to generate design curves and aid in the development of design practices for use with brittle composite structures.

scholarly journals Design, Fabrication, and Testing of Ceramic Joints for High Temperature SiC/SiC Composites

2000 ◽  
Vol 123 (2) ◽  
pp. 288-292 ◽  
Author(s):  
M. Singh ◽  
E. Lara-Curzio
Keyword(s):  
Silicon Carbide ◽  
Shear Strength ◽  
Elevated Temperatures ◽  
Stress Rupture ◽  
Ceramic Matrix Composites ◽  
Matrix Composites ◽  
A Value ◽  
Carbide Matrix ◽  
Sic Composites ◽  
Stress Rupture Testing

Various issues associated with the design and mechanical evaluation of joints of ceramic matrix composites are discussed. The specific case of an affordable, robust ceramic joining technology (ARCJoinT) to join silicon carbide (CG-Nicalon™) fiber-reinforced-chemically vapor infiltrated (CVI) silicon carbide matrix composites is addressed. Experimental results are presented for the time and temperature dependence of the shear strength of these joints in air up to 1200°C. From compression testing of double-notched joint specimens with a notch separation of 4 mm, it was found that the apparent shear strength of the joints decreased from 92 MPa at room temperature to 71 MPa at 1200°C. From shear stress-rupture testing in air at 1200°C it was found that the shear strength of the joints decreased rapidly with time from an initial shear strength of 71 MPa to a value of 17.5 MPa after 14.3 h. The implications of these results in relation to the expected long-term service life of these joints in applications at elevated temperatures are discussed.

Morphology, Distribution and Identification of Micro-Constituents Along Grain Boundaries in Nickel-Base Alloys

1973 ◽  
Vol 31 ◽  
pp. 176-177
Author(s):  
D. E. Fornwalt ◽  
A. R. Geary ◽  
B. H. Kear
Keyword(s):  
Electron Microscope ◽  
Grain Boundaries ◽  
Volume Fraction ◽  
Rupture Life ◽  
Stress Rupture ◽  
High Volume ◽  
Precipitate Morphology ◽  
Stress Rupture Life ◽  
Nickel Base ◽  
Scanning Electron

A systematic study has been made of the effects of various heat treatments on the microstructures of several experimental high volume fraction γ’ precipitation hardened nickel-base alloys, after doping with ∼2 w/o Hf so as to improve the stress rupture life and ductility. The most significant microstructural chan§e brought about by prolonged aging at temperatures in the range 1600°-1900°F was the decoration of grain boundaries with precipitate particles.Precipitation along the grain boundaries was first detected by optical microscopy, but it was necessary to use the scanning electron microscope to reveal the details of the precipitate morphology. Figure 1(a) shows the grain boundary precipitates in relief, after partial dissolution of the surrounding γ + γ’ matrix.

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