In ultrasonic testing, what does the term 'couplant' refer to?

In ultrasonic testing, the term 'couplant' refers to a medium for sound wave transmission. It is essential because ultrasonic waves do not travel effectively through air; therefore, a couplant, which is typically a liquid or gel, is applied to the surface of the material being tested. This medium facilitates the proper transfer of ultrasonic energy from the transducer into the test material, allowing accurate detection of reflections and any internal flaws.

Using the appropriate couplant ensures that sound waves can penetrate the material effectively, which is crucial for obtaining reliable test results. If there is insufficient coupling or an inappropriate medium is used, it can lead to weak or missed signals, negatively impacting the testing process and the accuracy of the results.