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