Ultrasonic method offers fast, high quality cleaning process and washes hard to reach areas. This ensures the replacement of highly toxic and expensive flammable solvents with plain water. With the help of high frequency ultrasonic vibrations you can clean an automobile carburetor or injectors within as little as a couple of minutes.
The reason for the acceleration in the treatment of cavitation lies phenomenon of emergence of tiny gas bubbles in liquid. These bubbles implode (explode) and create powerful hydrostreams that wash away all the dirt. With this principle in mind, large manufacturers, like UK-based Hilsonic, produce industrial ultrasonic cleaners (washing machines), baths and small cleaning devices. Ultrasound cleans metals from polishing pastes and precious stones from polishing places, it can easily clean the pipes of complex shapes. In addition to cleaning, ultrasound is capable of producing small burr removal and offer polishing of considerable quality.
Medicine & microbiology
Sonication in liquid media kills microorganisms and therefore it is widely used in medicine and microbiology. There is another implementation of the ultrasonic cleaning – the purification of smoke particles in the air. It will also use ultrasound effect on fog and smoke. The particles in the ultrasonic field are beginning to move, collide and stick together, then they are deposited on the walls. This phenomenon is called ultrasonic coagulation and is used to fight with fog on the ground, on the roads and seaports.
The process under the microscope
Destruction of surface films in liquid under the action of ultrasound takes place due to cavitation and acoustic streaming. In some cases, when ultrasonic vibrations are excited in the erasable product, alternating voltage occurring in the film may play a crucial role during decontamination, facilitating peeling of the film, if its strength is low. Intensity, cavitation speed flow and acoustic nature, the value of the pressure of radiation, the amplitude of oscillation of the parts depend on the frequency and intensity of the vibrations, the physical properties of the fluid depend on its temperature. Destruction, separation and dissolution of the film contamination during ultrasonic cleaning is due to the combined action of chemically active environment and factors arising from the imposition of the acoustic field.
There are three possible mechanisms for the destruction of surface films with the help of cavitation bubbles: exfoliation, blasting and emulsification. In the first case the pulsating bubble sticks to the material surface and the film of inner surface. Under intensive fluctuations of the bubble on the film forces start to act, breaking away from the surface of the material. If the strength of adhesion of the film to the surface exceeds the strength of the film itself, the free slice will be cut off. Otherwise the film is peeled. In the second case pulsating cavitation bubble, moving on the surface being cleaned, leaves contaminants in the film cleared, the direction of which coincides with the trajectory of the bubble. In this case, the damaging effects of cavitation can be explained by blows jets of liquid at the surface of the material In the third case, the gas bubbles, which had a thicker film, pulsating under the influence of the sound field and acoustic currents, carries with it some of the surrounding material of the film contamination.