Fracture toughness anisotropy of a pyrolytic carbon

1986 ◽  
Vol 21 (5) ◽  
pp. 1491-1501 ◽  
Author(s):  
M. Sakai ◽  
R. C. Bradt ◽  
D. B. Fischbach
Keyword(s):  
Fracture Toughness ◽  
Pyrolytic Carbon ◽  
Fracture Toughness Anisotropy

Fracture toughness anisotropy by indentation and SEVNB on tetragonal PZT polycrystals

2001 ◽  
Vol 319-321 ◽  
pp. 692-696 ◽  
Author(s):  
J.M Calderon-Moreno ◽  
Monica Popa
Keyword(s):  
Fracture Toughness ◽  
Fracture Toughness Anisotropy

C/C-ZrB2-ZrC-SiC Composite Derived from Polymeric Precursor Infiltration and Pyrolysis Part 2

2014 ◽  
pp. 447-465
Author(s):  
Weigang Zhang ◽  
Changming Xie ◽  
Xi Wei ◽  
Min Ge
Keyword(s):  
Fracture Toughness ◽  
Wind Tunnel ◽  
Thermal Shock ◽  
Plasma Torch ◽  
Volume Fraction ◽  
Pyrolytic Carbon ◽  
Glass Layer ◽  
Polymeric Precursors ◽  
Long Time ◽  
Sic Composites

Mechanical and ablation properties of the 2D C/C-ZrB2-ZrC-SiC composites with a fiber volume fraction of 17.6%, fabricated by infiltration and co-pyrolysis of blended polymeric precursors, were studied in this Part II. Flexural strength and fracture toughness of the composites were found to be influenced strongly by the thickness of the deposited pyrolytic carbon interphase, a composite with the pyrolytic carbon volume fraction of 22.3% exhibits improved bending strength and fracture toughness of 127.9 MPa and 6.23 MPa·m1/2, respectively. The pseudo-plastic strain to failure of the composite is ascribed to sliding of the interphase and pulling out of carbon fibers from the brittle ceramics matrix. Ablation properties of the composite were investigated with a plasma torch and arc-heated wind tunnel tests at temperatures above 1800~2200°C. The composite exhibits very low ablation rates of 0.18×10-3 mm/s at 1800°C and 0.37×10-3 mm/s at 2000°C in the plasma torch after 1000s testing, as compared to a similar rate of 0.30×10-3 mm/s in the wind tunnel at 1900°C after 600s testing. Ablation rates increase with increasing of temperatures from 1800 to 2200°C. The maximum ablation rate is only 1.67×10-3 mm/s in a plasma torch at 2200°C for 1000s, decreased by 71.0% as compared with the C/C-SiC composite with the same fiber and interphase contents. The 2D C/C-ZrB2-ZrC-SiC composite simultaneously showed excellent thermal shock resistance, on account of no cracks on the surface and breakage of the material being detected after these abrupt temperature increasing and long time ablations. The heating-up rate at the center of the composite specimen was found as high as above 30K/s in the plasma torch tests. Excellent ablation and thermal shock resistances of the composite can be attributed to its architecture of carbon fiber and interphase, as well as its matrix microstructures characterized by nano sized dispersions of ZrB2-Zr-SiC phases inherent formed by co-pyrolysis of three polymeric precursors. These meso- and microstructures make the composites possess very small and steady coefficients of thermal expansion (CTE) around 1.5~2.5×10-6/K and high thermal conductivities around 10~14 W/mK (which increases with increasing of temperature) from room temperature to 1300°C, respectively. Surface products and cross sectional morphologies of the composite after the ablation tests were also investigated using SEM and XRD, it was found that a homogeneous distributed and continuous glass layer composing of ZrO2-SiO2 with zirconia as a skeleton was in-situ formed. These special features of coating benefits from the merits of matrix microstructures, and inhibits the inward diffusion of oxygen and protects the composite from further oxidation and spalled off by strong gas fluid.

The use of compact specimens to determine fracture toughness anisotropy of Ti–6Al–4V additively manufactured for repair

2021 ◽  
pp. 141779
Author(s):  
Sammy A. Ojo ◽  
Sulochana Shrestha ◽  
Joseph El Rassi ◽  
Ragav P. Panakarajupally ◽  
K. Manigandan ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Fracture Toughness Anisotropy ◽  
Determine Fracture Toughness

Fracture toughness anisotropy in a API steel line-pipe

2007 ◽  
Vol 61 (29) ◽  
pp. 5178-5180 ◽  
Author(s):  
Jang-Bog Ju ◽  
Jung-Suk Lee ◽  
Jae-il Jang
Keyword(s):  
Fracture Toughness ◽  
Line Pipe ◽  
Fracture Toughness Anisotropy

Fracture toughness anisotropy of a hot pressed Al2O3/SiCw composite

1990 ◽  
Vol 9 (9) ◽  
pp. 1085-1086 ◽  
Author(s):  
K. Breder ◽  
A. E. Giannakopoulos ◽  
K. Zeng ◽  
D. Rowcliffe
Keyword(s):  
Fracture Toughness ◽  
Fracture Toughness Anisotropy
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