242
G. Bai et al.
Fig. 21.3 AE acquisition
system
Table 21.2 The characteristic parameters
Feature
ID. Feature
Parameters
1. Time, 2. channel, 3. threshold, 4. extrinsic parameters
Time domain
5. Rise time, 6. number of counts, 7. energy, 8. duration time, 9. amplitude,
10. signal intensity, 11. absolute energy
Frequency domain 12. Average frequency, 13. peak frequency, 14. weighted frequency, 15.,
back-calculation frequency, 16. center frequency, 17. frequency band 1
(100–175 Hz), 18. frequency band 3 (175–250 Hz), 19. frequency band
2 (250–325 Hz), 20. frequency band 4 (325–400 Hz)
Table 21.3 Results and details of creep
Number Temperature/°C Stress/MPa Specimens describe
Lifetime/min
1
1300
75
Tensile fracture, normal fracture 139
2
1300
140
Tensile fracture, normal fracture 62
3
1300
150
Tensile fracture, normal fracture 35
4
1300
160
Tensile fracture, normal fracture 15
5
1300
140
Tensile fracture, normal fracture 121
6
1300
140
Tensile fracture, normal fracture 90
7
700
140
Tensile fracture, normal fracture 622
information. The specimen lifetimes showed a large difference, and this variability
may largely be due to C/SiC defects caused by the variations in the preparation
process.