23 Acoustic Emission in Coatings—A Review
277
Infrared imaging technology can be used to study the thermal barrier coating
failure process in thermal cycling experiments, and successfully located defects by
using heat flow distribution and acoustic emission signals [28].
Digital image correlation method which is as a tool can reflect material strain in
real time. When it combined with acoustic emission, it can help study the coating
damage process by displaying the deformation of materials in real time [26].
Since the conditions of use of the acoustic emission probe are limited, in some
cases it is necessary to modify the experimental device. Testing at high temperatures
requires a rod named wave guide, which can conduct AE signals. For ultra-high
temperature conditions, for example during air plasma sprayed (APS), a non-contact
laser AE instrument is needed [29].
23.5 Conclusion
Some progress has been made in mechanical property evaluation and failure process
analysis. However, the current research was still in the preliminary stage, and there
were still some problems to be solved.
1. The study on the failure process of coatings was incomplete and has no theoretical
guidance.
2. Time-sharing sampling was still used to verify the acoustic emission results in
most experiments, and the conclusions obtained from time-sharing sampling
were not reliable.
3. At high temperatures, using a wave guide or laser AE may cause signal distortion.
Although there were still many technical challenges, AE still showed great vitality
in coating research. From the analysis of single feature parameters to frequency
domain analysis and wavelet analysis, with the development of signal processing
technology, technologies such as artificial neural networks have begun to be applied
to acoustic emission signal analysis [30, 31]. Technological innovations have injected
new life into the acoustic emission studies of coatings. The development of coatings
application and development will promote research on it as well.
Acknowledgements This paper was funded by Advanced Space Propulsion Laboratory of BICE
and Beijing Engineering Research Center of Efficient and Green Aerospace Propulsion Technology,
No: LabASP-2018-08.
References
1. N.J. Yang, C.J. Yao, X.J. Yuan, X.H. Long, Material damage monitoring technology based on
acoustic emission, 1st ed., vol. 1 (Beihang University Press, Beijing, pp. 3–6, 2016)
277
Infrared imaging technology can be used to study the thermal barrier coating
failure process in thermal cycling experiments, and successfully located defects by
using heat flow distribution and acoustic emission signals [28].
Digital image correlation method which is as a tool can reflect material strain in
real time. When it combined with acoustic emission, it can help study the coating
damage process by displaying the deformation of materials in real time [26].
Since the conditions of use of the acoustic emission probe are limited, in some
cases it is necessary to modify the experimental device. Testing at high temperatures
requires a rod named wave guide, which can conduct AE signals. For ultra-high
temperature conditions, for example during air plasma sprayed (APS), a non-contact
laser AE instrument is needed [29].
23.5 Conclusion
Some progress has been made in mechanical property evaluation and failure process
analysis. However, the current research was still in the preliminary stage, and there
were still some problems to be solved.
1. The study on the failure process of coatings was incomplete and has no theoretical
guidance.
2. Time-sharing sampling was still used to verify the acoustic emission results in
most experiments, and the conclusions obtained from time-sharing sampling
were not reliable.
3. At high temperatures, using a wave guide or laser AE may cause signal distortion.
Although there were still many technical challenges, AE still showed great vitality
in coating research. From the analysis of single feature parameters to frequency
domain analysis and wavelet analysis, with the development of signal processing
technology, technologies such as artificial neural networks have begun to be applied
to acoustic emission signal analysis [30, 31]. Technological innovations have injected
new life into the acoustic emission studies of coatings. The development of coatings
application and development will promote research on it as well.
Acknowledgements This paper was funded by Advanced Space Propulsion Laboratory of BICE
and Beijing Engineering Research Center of Efficient and Green Aerospace Propulsion Technology,
No: LabASP-2018-08.
References
1. N.J. Yang, C.J. Yao, X.J. Yuan, X.H. Long, Material damage monitoring technology based on
acoustic emission, 1st ed., vol. 1 (Beihang University Press, Beijing, pp. 3–6, 2016)