Ultrasound is used in practice, mainly in the following aspects

Test

Ultrasound has a shorter wavelength than ordinary sound waves, has better anisotropy, and can penetrate opaque materials. This feature has been used in ultrasonic flaw detection and ultrasonic imaging technology. Ultrasound imaging is a technology that uses ultrasound to present the internal image of an opaque object. Focus the ultrasonic wave emitted from the transducer on the opaque sample through the acoustic lens. The ultrasonic wave transmitted from the sample carries the information of the illuminated part (such as the ability to reflect, absorb and scatter mechanical waves), and is converged by the acoustic lens. On the piezoelectric receiver, the obtained electrical signal is input to the amplifier, and the image of the opaque sample can be displayed on the fluorescent screen by the scanning system. The above device is called an ultrasound microscope. Ultrasonic imaging technology has been widely used in medical inspections. It is used to inspect large-scale integrated circuits in the manufacturing of microelectronic devices, and in materials science to show the regions and grain boundaries of different components in alloys. Acoustic holography is an acoustic imaging technology that uses the interference principle of ultrasonic waves to record and reproduce three-dimensional images of opaque objects. Its principle is basically the same as that of light wave holography, but the recording method is different. Use the same short-wave signal source to excite two transducers placed in the liquid, and they respectively emit two coherent ultrasonic waves: one beam becomes an object wave after passing through the object under study, and the other beam is used as a reference wave. The object wave and the reference wave are coherently superimposed on the liquid surface to form an acoustic hologram. The acoustic hologram is irradiated with a laser beam, and the diffraction effect generated when the laser is reflected on the acoustic hologram is used to obtain a reproduced image of the object, usually with a camera and a TV. The machine makes real-time observation.

deal with

Utilizing the mechanical action and cavitation of ultrasound, it can perform ultrasonic welding, drilling, solid crushing, emulsification, degassing, degreasing, descaling, cleaning, sterilization, etc., in various sectors such as industry, mining, agriculture, and medical treatment. Get the application.

Cleaning

The principle of ultrasonic application for cleaning is that the short-wave signal sent by the ultrasonic generator is converted into a short-wave mechanical wave by the transducer and propagated to the medium. The ultrasonic wave in the cleaning solvent radiates forward in the dense and dense phases of the cleaning liquid, causing the liquid to flow and generate data. Tens of thousands of tiny bubbles, tiny bubbles (cavitation nuclei) that exist in the liquid. When the sound intensity reaches a certain value, the bubbles grow rapidly and then suddenly close. When the bubbles close, shock waves are generated, and thousands of bubbles are generated around them. Atmospheric pressure destroys insoluble dirt and disperses them in the cleaning solution. When the group particles are wrapped in oil and adhere to the surface of the cleaning part, the oil is emulsified and the solid particles are separated, so as to achieve the purpose of cleaning the surface of the cleaning part.

humidifier

In the dry winter in northern China, if ultrasonic waves are passed into the water tank, the mechanical waves will break the water in the tank into many small mist droplets, and then use a small fan to blow the mist droplets into the room to increase the indoor air humidity. This is ultrasonic wave The principle of humidifier. For diseases such as pharyngitis and bronchitis, it is difficult to use the blood flow to make the medicine reach the diseased part. The principle of a humidifier is used to atomize the medicine and let the patient inhale it, which can improve the curative effect. In the case of high power, the huge energy of ultrasound can also make the stones in the human body broken under the action of mechanical waves, thereby reducing the pain and achieving the purpose of healing. In medicine, ultrasound can sterilize items.

basic research

After ultrasonic waves act on the medium, an acoustic relaxation process is generated in the medium. The acoustic relaxation process is accompanied by the transport process of energy between the respective electrical degrees of the molecules, and shows the absorption of mechanical waves in a macroscopic view. The properties and structure of substances can be explored through the absorption of ultrasound by substances. Research in this area constitutes the acoustic branch of molecular acoustics. The wavelength of ordinary sound waves is much larger than the distance between atoms in a solid, and the solid can be regarded as a continuous medium under this condition. But for ultra-ultrasound with a wavelength below 300pm, the wavelength can be compared with the distance between atoms in a solid. At this time, the solid must be regarded as a lattice structure with spatial periodicity. The energy of the lattice is quantized, called phonons (see solid state physics). The effect of special ultrasound on solids can be attributed to the interaction of special ultrasound with phonons, electrons, photons and various quasi-particles. The research on the generation, detection and propagation of special ultrasound in solids, as well as the research on acoustic phenomena in quantum liquid-liquid helium constitute a new field of modern acoustics.

The branch of acoustics that studies the generation, propagation, and reception of ultrasonic waves, as well as various ultrasonic effects and applications, is called ultrasonics, which corresponds to sub-acoustics. The devices that generate ultrasonic waves include mechanical ultrasonic generators, electric ultrasonic generators made using the principles of electromagnetic induction and electromagnetic action, and electroacoustics made using the electrostrictive effect of piezoelectric crystals and the magnetostrictive effect of ferromagnetic materials. Transducers, etc.

Degreasing

The degreasing process in which the parts with oil stains are placed in the degreasing fluid and the degreasing process is under the action of an ultrasonic field with a certain wavelength is called ultrasonic degreasing. The introduction of ultrasound can strengthen the degreasing process, shorten the degreasing time, improve the degreasing quality, and reduce the consumption of medicines. Especially for parts with complex shapes, small precision parts, parts with difficult to remove dirt on the surface, and parts made of insulating materials, it has a significant degreasing effect, which can save time-consuming manual labor and prevent parts from being damaged.

The effect of ultrasonic degreasing is related to the shape and size of the parts, the nature of the surface oil, the composition of the solution, and the location of the parts. Therefore, the best ultrasonic degreasing process must be determined through experiments. The wavelength used for ultrasonic degreasing is generally about 1.1 cm. When the part is small, use a shorter wavelength; when the part is large, use a longer wavelength. The ultrasonic wave has a short wavelength, which can only travel in a straight line, and is difficult to diffract. Therefore, it is difficult to reach the shielded part. Therefore, the parts should be rotated or flipped in the oil removal tank so that all parts on the surface can receive the ultrasonic radiation, which is more affected. Good degreasing effect. In addition, the concentration and temperature of the ultrasonic degreasing solution should be lower than that of the corresponding degreasing solution, so as not to affect the propagation of ultrasonic waves and also reduce the corrosion of the metal material surface.