MEASUREMENT OF ACOUSTIC PROPERTIES OF MAGNETIC FLUID AND ITS APPLICATION TO NONDESTRUCTIVE EVALUATION

The ultrasonic velocity in a magnetic fluid (MF) on a base of water is measured under different temperatures, frequencies and magnetic fields. Two Kinds of ultrasonic correlation systems are employed. The maximum velocity is observed at 38-degrees-C without distinction of frequency. In the frequency range of 4 approximately 10 MHz, a weak frequency dependence of ultrasonic velocity of 1 -2 m/s is observed. Dependence of external magnetic field in the magnetic field strength of 0 approximately +/- 0.2 T is on the order of 10(-4). An experiment with a magnetic fluid as an acoustic coupling medium is performed to demonstrate its usefulness in ultrasonic nondestructive evaluation (UNDE).