What Is Ultrasonic Wet Grinding And Particle Grinding

Ultrasonics is an effective method for wet grinding and particle grinding. In addition to dispersion and deagglomeration, particle grinding is also an important application of ultrasonics.

Ultrasonic wet grinding and particle grinding are methods of grinding in a liquid environment using the vibration effect of ultrasonics. This method typically involves the use of an ultrasonic generator to produce high-frequency vibrations, which are transmitted through a liquid medium to the material being processed. The ultrasonic vibration creates high-intensity pressure waves and shear forces in the liquid, resulting in the fragmentation and grinding of the material. This method is commonly used in applications such as powder preparation, particle refinement, and uniform dispersion.

Ultrasonic particle grinding offers several advantages:

Efficient grinding: Ultrasonic vibrations provide high-intensity energy that promotes particle collision and grinding, enabling a fast and efficient grinding process.

Uniform dispersion: Ultrasonic vibrations effectively disperse particles in a liquid, preventing particle aggregation and agglomeration, resulting in a uniform grinding effect.

Wide applicability: Ultrasonic particle grinding is suitable for various types of particle materials, including granular materials, nanoparticles, and colloidal particles.

Strong controllability: Parameters of ultrasonic particle grinding, such as ultrasonic power, frequency, and grinding time, can be adjusted to achieve precise control over the grinding process.

In particular, for the preparation of ultrafine slurries, ultrasonic grinding has many advantages compared to conventional crushing equipment such as colloid mills (ball mills, bead mills), disc mills, jet mills, rotor-stator mixers, or high-pressure homogenizers. Ultrasonics can handle high concentrations and viscosities of slurries, thereby reducing the volume of subsequent processing equipment. Ultrasonic particle grinding is particularly suitable for processing materials in the micrometer and nanometer size range, such as ceramics, alumina, barium sulfate, calcium carbonate, and metal oxides.

The following micrographs show wet grinding of trihydrate alumina (from 150 micrometers to 10 micrometers), ceramics (from 30 micrometers to 2 micrometers), and sodium carbonate (from 70 micrometers to 3 micrometers).

Microscopic Images of Ultrasonic Wet Grinding of Trihydrate Alumina

Microscopic Images of Ultrasonic Wet Grinding of Dental Ceramics

Microscopic Images of Ultrasonic Wet Grinding of Sodium Carbonate

Ultrasonic equipment is extremely easy to install and operate, with only two components coming into contact with the material during grinding: a titanium alloy tool head and a stainless steel circulation reaction tank. Due to the streamlined design of the ultrasonic circulation tank, it can be quickly cleaned. Ultrasonic grinding requires relatively less energy compared to traditional grinding equipment due to the high efficiency of Hangchao ultrasonic devices in converting electrical energy into mechanical energy.

The effect of ultrasonic particle grinding is based on the high-intensity cavitation of ultrasonic waves. When a liquid is subjected to high-intensity ultrasonic waves, the propagating sound waves in the liquid medium alternate between high pressure (compression) and low pressure (dilution) cycles, with the rate of cycles determined by the ultrasonic frequency. During the low-pressure cycle, the high-intensity ultrasonic waves create small vacuum bubbles or gaps in the liquid. When the bubbles reach a volume where they can no longer absorb energy, they collapse violently during the high-pressure cycle, a phenomenon known as cavitation.

The collapse of cavitation bubbles results in microturbulence and microjets reaching speeds of up to 100 kilometers per hour. The surfaces of larger particles are eroded (due to the collapse of cavitation in the surrounding liquid) or reduced in size (due to collision-induced fragmentation or surface-collapsed cavitation between particles). These changes in particle size and structure lead to a rapid acceleration of diffusion, mass transfer processes, and solid-state reactions.

Ultrasonic particle grinding finds wide applications in materials science, nanotechnology, pharmaceuticals, and other fields, such as particle refinement, preparation of nanomaterials, and uniform dispersion of suspensions.