Several Effects Of Ultrasonic Welding Machine Propagation

When the ultrasonic wave propagates in the medium, due to the interaction between the ultrasonic wave and the medium, the medium undergoes physical and chemical changes, resulting in a series of mechanical, thermal, electromagnetic, and chemical ultrasonic effects, including the following 4 effects:

mechanical effect

The mechanical action of ultrasound can promote the emulsification of liquids, the liquefaction of gels, and the dispersion of solids. When a standing wave is formed in an ultrasonic fluid medium, the tiny particles suspended in the fluid condense at the node due to the action of mechanical force, forming a periodic accumulation in space. Induced electrical polarization and induced magnetization due to the mechanical action of ultrasonic waves when propagating in piezoelectric and magnetostrictive materials (see Dielectric Physics and Magnetostriction).

Cavitation

When the ultrasonic wave acts on the liquid, it can produce a large number of small bubbles. One reason is that there is local tensile stress in the liquid to form a negative pressure. The reduction of the pressure makes the gas originally dissolved in the liquid supersaturated, and escapes from the liquid as small bubbles. Another reason is that the strong tensile stress "rips" the liquid apart into a cavity called cavitation. Inside the cavity is a liquid-vapor or another gas dissolved in a liquid, possibly even a vacuum. The small bubbles formed by cavitation will continuously move, grow or burst suddenly with the vibration of the surrounding medium. When it bursts, the surrounding liquid suddenly rushes into the bubble to generate high temperature, high pressure, and shock wave. The internal friction accompanied by cavitation can form an electric charge, and the phenomenon of luminescence is generated in the bubble due to the discharge. Most of the techniques for sonication in liquids are related to cavitation.

  Thermal effect

Due to the high frequency and high energy of ultrasonic waves, it can produce significant thermal effects when absorbed by the medium.

chemical effect

The action of ultrasound can induce or accelerate certain chemical reactions. For example, pure distilled water is sonicated to produce hydrogen peroxide; nitrogen-dissolved water is sonicated to produce nitrous acid; aqueous solutions of dyes will change color or fade after sonication. The occurrence of these phenomena is always accompanied by cavitation. Ultrasound also accelerates the hydrolysis, decomposition, and polymerization processes of many chemicals. Ultrasound also has significant effects on photochemical and electrochemical processes. After ultrasonic treatment of aqueous solutions of various amino acids and other organic substances, the characteristic absorption spectral bands disappeared and showed uniform general absorption, which indicated that the molecular structure was changed by cavitation.