Ultrasonic energy density

Ultrasonic measurements (5 MHz) made at ambient temperature on amine-crosslinked epoxies (Morel et al., 1989), or styrene-crosslinked vinyl esters (Bellenger et al., 1994), show that K is effectively proportional to the cohesive energy density ... 

Since the unrelaxed bulk modulus, Ku e.g., determined by ultrasonic propagation velocity measurements, is a good measure of the cohesive energy density, CED (Ku 11 CED Chapter 10), and CED gives a good indication of the overall material s polarity, one can expect a correlation between Ku and W. This is shown in Fig. 14.3 for the amine-epoxy and styrene-vinyl ester networks. The following relationship is found ... 

Reisse and co-workers [147-149] were the first to describe a novel device for the production of metal powders using pulsed sonoelectrochemical reduction. This device exposes only the flat circular area at the end of the sonic tip to the electrodeposition solution. The exposed area acts as both cathode and ultrasound emitter, named by Reisse et al. as sonoelectrode . A pulse of electric current produces a high density of fine metal nuclei. This is immediately followed by a burst of ultrasonic energy that removes the metal particles from the cathode, cleans the surface of the cathode, and replenishes the double layer with metal cations by stirring the solution. In [145], a list is given of chemically pure fine crystalline powders, mostly metals or metallic alloys, prepared by this method, with particle sizes varying between 10 and 1000 run depending on deposition conditions. 

Vis coiner tial losses (Fig. lb). As an ultrasonic wave passes through an emulsion it causes the droplets to oscillate backwards and forwards because of the density difference between them and the surrounding liquid. The movement of the droplets leads to the generation of a dipolar pressure wave the energy of the new wave is not detected and hence contributes to measmed attenuation. In addition, the oscillation is damped because of the viscosity of the siuround ing liquid, and so some of the ultrasonic energy is lost as heat. 

Some Fundamentals oT Ultrasonics and the Design of High Energy Density Cravice Reactors... 

---