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.

scholarly journals An Optimum Application of Austenitic Nodular Iron for Gas Turbine Components

1968 ◽  
Author(s):  
J. T. Hageboeck ◽  
W. S. Roberts
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Stress Rupture ◽  
Intermediate Temperature ◽  
Cost Information ◽  
Temperature Range ◽  
Nodular Iron ◽  
Intermediate Temperature Range ◽  
Temperature Levels ◽  
Optimum Application

A new modification of an economical casting material is presented for use in the intermediate temperature range, which is considered to be 800 to 1300 F. An illustration is given of two large castings actually produced for the 1500-hp ATAC regenerative gas turbines engine. Comparisons are made with other materials, giving information stress-rupture at various temperature levels and some cost information. Also included are design suggestions for better utilization of foundry techniques.

Effect of volume fraction of dispersed SiO2 particles on intermediate-temperature embrittlement in Cu–SiO2 polycrystals

1998 ◽  
Vol 13 (11) ◽  
pp. 3100-3105 ◽  
Author(s):  
Hiromi Miura ◽  
Taku Sakai ◽  
Günter Gottstein
Keyword(s):  
Stress Concentration ◽  
Stress Relaxation ◽  
Grain Boundary ◽  
Fracture Strain ◽  
Volume Fraction ◽  
Grain Boundary Sliding ◽  
Intermediate Temperature ◽  
Interfacial Diffusion ◽  
Fixed Temperature ◽  
Boundary Sliding

Several kinds of Cu polycrystals with dispersed SiO2 particles of different volume fractions were tensile tested at high temperatures from 473 K to 1023 K. All of the alloys showed clear intermediate-temperature embrittlement (ITE). Although the temperature of minimum elongation was almost the same in all the alloys, temperature dependence of fracture strain depended strongly on the SiO2 volume fraction: (1) At a fixed temperature, the fracture strain tended to first decrease with increase in SiO2 volume fraction, showed minimum in an alloy with certain volume fraction, and increased again with increase in volume fraction. (2) With increase in SiO2 volume fraction, the temperature range of ITE became narrower and sharper. These results were reasonably understood by considering the occurrence of stress concentration at grain-boundary particles induced by grain-boundary sliding (GBS) and occurrence of dynamic recrystallization and stress relaxation by Cu/SiO2 interfacial diffusion.

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