Electromagnetic Acoustic Transducer (EMAT)

Advantages of EMAT

  • No couplant is required
  • Ideal for inspections below the freezing point of couplants
  • Ideal for inspections above the evaporation point of couplants
  • Ideal form situations where couplants are impractical
  • Physical contact with specimen is not required
  • Surface condition is not as critical as with traditional piezoelectric transducers
  • Easier for sensor deployment unlike with traditional piezoelectric transducers where a small
  • variation in sensor deployment may cause a significant change in the refracted angle
  • Easier to generate SH-type waves, providing a convenient means of generating SH bulk wave and SH guided wave

Disadvantages of EMAT

  • Low transduction efficiency, typically EMAT produces raw signal of lower power the piezoelectric transducers
  • More sophisticated signal processing techniques are needed to isolate signal from noise
  • Limited to metallic or magnetic products
  • Examination of plastics and ceramic materials is not suitable or not convenient using EMAT
  • EMAT transducers can be found as small as a penny, commonly used transducers are large in size
  • R&D of low-profile EMAT transducers are still under development
  • EMAT phased array is difficult to made from small elements
  • Caution must be taken when handling magnets around steel products