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Research Article

Waveform characteristics of ultrasonic wave generated from CNT/PDMS composite

CNT/PDMS 복합체로부터 방사된 초음파의 파형 특성

Gisuk Kim1
,
Moojoon Kim1
,
Kanglyeol Ha1∗
,
Jooho Lee2
,
Dong-Guk Paeng2
,
Min Joo Choi2
김 기석1
,
김 무준1
,
하 강렬1∗
,
이 주호2
,
팽 동국2
,
최 민주2
1부경대학교 물리학과
2제주대학교 대학원 의공학협동과정
∗Corresponding Author
31 July 2019. pp. 459-466
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Abstract

When a laser pulse is irradiated on a CNT (Carbon Nanotube) and PDMS (Poly dimethylsiloxane) composite coated on a transparent PMMA (Poly methyl methacrylate) substrate, a strong ultrasonic wave is generated due to the thermoelastic effect. In this paper, the thermoacoustic theory related to the wave generation by the CNT/PDMS composite was established. The waveforms of ultrasonic waves when a laser pulse having a Gaussian waveform is irradiated on the composite with a thickness of 20 μm were numerically simulated. From the results, it was confirmed that ultrasonic shock waves can be generated from the CNT/PDMS composite and the waveforms are changed little even if the physical properties of the composite are changed by ±20 %. It was found that the peak positive and negative pressures increase as the thermal expansion coefficient increases, or as density, heat capacity and sound speed decreased. However, those changes were not so sensitive with thermal conductivity. In addition, the physical properties of the CNT/PDMS composite fabricated in this study were estimated from the comparison of the measurement and simulation results.

Keywords
Ultrasonic transducer
Thermoelastic effect
Shock wave
CNT (Carbon Nanotube)
PDMS (Poly dimethylsiloxane) elastomer

투명한 PMMA (Poly methyl methacrylate) 기판 위에 탄소나노튜브(Carbon Nanotube, CNT)와 PDMS (Poly dimethylsiloxane)를 코팅한 복합체에 레이저 펄스를 조사하면 열탄성효과에 의해 수중에 강한 초음파가 발생한다. 본 논문에서는 그 초음파 발생과 관련한 열음향 이론을 정립하고, 가우시안 파형을 갖는 레이저 펄스를 두께가 20 μm인 CNT/PDMS 복합체에 조사했을 때 어떤 파형의 초음파가 발생하는지를 시뮬레이션을 통해 파악하였다. 그 결과로부터 CNT/PDMS 복합체에서는 충격 초음파가 발생하며, 그 파의 형상은 복합체의 각종 물성 값이 ±20 % 변하여도 크게 변하지 않는 것을 확인하였다. 그러나 정(+), 부(-)의 피크 값은 열팽창계수가 증가하거나 밀도, 열용량, 음속이 감소하면 증가하며, 열전도도에 대해서는 민감하게 변하지 않음을 알았다. 나아가, 직접 제작한 CNT/PDMS 복합체에서 방사되는 초음파의 측정 결과와 시뮬레이션 결과의 비교로부터 그 물성 값을 추정할 수 있었다.

키워드
초음파 트랜스듀서
열탄성효과
충격파
탄소나노튜브(Carbon Nanotube, CNT)
PDMS (Poly dimethylsiloxane) 탄성중합체
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Information
  • Publisher :The Acoustical Society of Korea
  • Publisher(Ko) :한국음향학회
  • Journal Title :The Journal of the Acoustical Society of Korea
  • Journal Title(Ko) :한국음향학회지
  • Volume : 38
  • No :4
  • Pages :459-466
  • Received Date : 2019-05-14
  • Revised Date : 2019-06-28
  • Accepted Date : 2019-07-12
  • DOI :https://doi.org/0.7776/ASK.2019.38.4.459
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