What Is a Zirconia Bead?
Zirconia beads are a type of beads used in a device called a bead mill, in which a slurry of material to be ground is stirred together with beads to break the material in the slurry into smaller pieces.
Zirconia beads are characterized by the use of zirconia ceramics as a material.
Uses of Zirconia Beads
Zirconia beads are used in a device called a bead mill. The main components of a bead mill are a feeding section, a stirring section with a stirring device, and a separation section. Zirconia beads and other beads are enclosed in the stirring section. The process is as follows.
- A slurry of finely crushed material to be ground is fed into the liquid.
- The slurry is fed into the stirring section where the beads are enclosed.
- The beads are agitated by rotating at high speed with the slurry.
In process 3, the collision of the beads with the particles or powders of the material to be ground occurs. This collision allows for an even finer grinding of the milled material, surface polishing, or uniform dispersion in the slurry.
Zirconia beads are made of zirconia, which has inherent wear resistance, high strength, and good toughness. They are therefore used for the dispersion and pulverization of electronic materials such as derivatives and piezoelectric materials, dispersion and pulverization of pigments, inks, and paints, and dispersion and pulverization of nanotechnology materials. They are also suitable for the dispersion and pulverization of pharmaceuticals and foodstuffs due to their high strength and safety, as they do not break in the slurry.
Processing Principle Using Zirconia Beads
When zirconia beads are rotated and agitated at high speed in the agitator of a bead mill, centrifugal force is generated, which in turn exerts a force on the zirconia beads and generates pulverization energy. The magnitude of this pulverization energy determines the degree of processing in a single collision, and the number of collisions allows the characteristics of the processing to be controlled.
Large diameter zirconia beads are used when the particles to be ground are large, and smaller diameter zirconia beads are used as the particle size of the material decreases. This is because the larger the particles to be ground, the greater the degree of processing required by a single impact of the zirconia beads.
As the particles become finer, smaller diameter zirconia beads are used to increase the frequency of contact between the zirconia beads and the particles to be ground, thereby increasing the milling effect. Care should be taken when using beads with too small a diameter, as the mass is too light and the milling energy is minimal. In this case, selecting beads made of a material with a higher density and increasing the mass without changing the size will improve the milling energy.
Other Information on Zirconia Beads
1. Material of Zirconia Beads
Zirconia, which makes up zirconia beads, refers to zirconium oxide with the chemical formula ZrO2 and is classified as a ceramic as zirconia ceramics. Zirconia is a material that forms the most stable monoclinic crystal structure at room temperature, which changes sequentially to tetragonal and cubic as the temperature increases.
By reacting zirconia with stabilizers such as yttrium oxide (Y2O3), calcium oxide (CaO), cerium oxide (CeO2), and magnesium oxide (MgO), the cubic crystal structure becomes stable at room temperature. Zirconia with stable cubic crystals at room temperature is called stabilized zirconia or partially stabilized zirconia.
2. Zirconia Beads Production Method
Zirconia beads are manufactured by processing zirconia into microscopic spheres. Among zirconia beads, stabilized zirconia has high strength and high toughness and can be processed into minute sizes.
The rolling and pressing methods for processing into beads include the rolling method and the pressing method, but these methods have the disadvantage that it is difficult to manufacture microscopic beads. For this reason, the use of cross-linked liquids such as water and the liquid granulation method that combines water and a liquid such as alcohol have been proposed as methods for manufacturing even finer beads.