Polishing powder, an indispensable main material in the grinding and polishing process, effectively increases the grinding amount of the product by adding rare earth and metal oxides such as iron, cerium, aluminum, zirconium, titanium, and chromium. The reasonable combination of its performance and process conditions has a profound impact on the processing efficiency and surface quality of parts.
Key factors affecting the performance of polishing powder
When discussing the performance of polishing powder, we need to pay attention to several core indicators. These indicators not only determine the grinding efficiency of polishing powder, but also have a direct impact on its overall performance in part processing.
1. Powder particle size: This is a key factor affecting polishing accuracy and speed. Usually, we measure it by mesh number and average particle size of powder. The mesh number of the sieve can reflect the size of the powder particle size, while the average particle size determines the size of the polishing powder particles as a whole.
2. Mohs hardness of powder: Powders with higher hardness have better cutting effects. At the same time, adding an appropriate amount of grinding aids can further improve the cutting effect. However, it should be noted that the requirements for powder hardness in different application fields may be different, and the processing technology itself will also affect the results.
3. Suspension of powder: High-quality polishing powder should have good suspension. The shape and particle size of the powder have a certain influence on the suspension performance. Generally, flake-shaped and fine-grained polishing powder has better suspension. However, this is not absolute. The suspension performance of polishing powder can also be effectively improved by adding suspension (agent).
4. Crystal form of powder: The crystal form of powder is composed of single crystal particles agglomerated together, which directly affects the cutting, wear resistance and fluidity of the powder. During the polishing process, these single crystal particles will gradually separate (break), resulting in a decrease in their cutting and wear resistance. In contrast, particles with irregular hexagonal crystals show good cutting, wear resistance and fluidity.
5. Appearance color: The appearance color of polishing powder is closely related to factors such as the Pr content in the raw material and the burning temperature. For example, powders with a high praseodymium content are brown-red, while low-cerium polishing powders also appear brown-red due to the large amount of praseodymium (cerium-praseodymium material) contained in them. The color of high-cerium polishing powder varies with the burning temperature. The higher the burning temperature, the more white-pink its color is; when the temperature is low (about 900 degrees), it appears light yellow.
In addition, polishing powders are divided into many types, including rare earth polishing powders, diamond polishing powders (such as polycrystalline diamond micropowders, single crystal diamond micropowders, nano-diamond micropowders), alumina series micropowders, cerium oxide series micropowders, and coated diamond micropowders. Different types of polishing powders have their own unique characteristics and application areas.
Rare earth polishing powders
Rare earth polishing powders, especially cerium oxide polishing powders, exhibit strong cutting force, which can significantly shorten the polishing time while ensuring long service life and high polishing accuracy. According to the different cerium oxide content, rare earth polishing powders can be divided into three categories: low cerium, medium cerium and high cerium, and their cutting force and durability increase in turn. This type of polishing powder is widely used in the polishing process of optical glass devices, TV picture tubes, optical glasses, oscilloscopes, flat glass, semiconductor wafers and metal precision products.
Diamond polishing powder
Diamond polishing powder includes many types, such as polycrystalline diamond powder, single crystal diamond powder, nano diamond and coated diamond powder.
① Polycrystalline diamond powder
Polycrystalline diamond powder is synthesized by explosion method. Its particle crystal structure is similar to natural black diamond. It is connected to each other by unsaturated bonds to form a polycrystalline structure. Compared with single crystal diamond, polycrystalline diamond has more crystal edges and grinding surfaces. Each crystal edge has cutting function, so it shows excellent removal rate. At the same time, it has both toughness and self-sharpening. During the polishing process, large particles will naturally break into small particles, thereby effectively preventing scratches on the workpiece surface, ensuring the high quality of the workpiece surface, and improving the efficiency of grinding and cutting. This makes polycrystalline diamond powder show unique advantages in the processing of high-quality products.
Mainly used for: fine grinding and polishing of sapphire substrates, optical crystals, and hard disk heads.
② Single crystal diamond powder
Single crystal diamond powder uses high-quality diamond as raw material, and undergoes fine ball milling, grading and purification processes to create high-quality products that meet ultra-pure technical indicators. It has a wide range of applications, covering the fine grinding and polishing of precision components in multiple fields such as industry, science, and medicine, as well as the manufacture of resin-bonded tools, metal-bonded tools, and electroplating tools. In addition, single crystal diamond powder is also used as a fine abrasive for the processing and manufacturing of molds, gemstones, and gem bearings, and can exert its unique thermal and electrical functions.
③ Nano diamond
Nano diamond is synthesized by detonation of high-energy explosives in an oxygen-deficient environment. At the moment of detonation, this synthesis method provides the extremely high pressure and temperature required for synthetic diamonds. At the same time, the free carbon atoms produced by the decomposition of explosives gather into nano-scale diamond particles. This nano diamond is different from conventional static pressure synthetic diamonds. Its shape is spherical, and the single crystal grain size is only a few nanometers, without edges and corners.
④ Coated diamond micropowder
Coated diamond micropowder is a layer of metal coated on the surface of diamond using advanced chemical plating and composite plating technology, aiming to enhance its adhesion in cutting and grinding tools, thereby extending the service life of the tools. It has a wide range of applications, covering the production of turning tools, files, saw blades, drill bits, etc. in the field of machining, the cutting and forming of graphite and carbon materials in the electrical and electronic industry, and the manufacturing of cutting and grinding tools for reinforced plastics, silicon wafers, and glass. In addition, it is also used for the carving and grinding of arts and crafts such as gemstones, jade, and ceramics, such as the production of electroplated diamond grinding heads.
Alumina polishing powder
The core component of alumina polishing powder is α-Al2O3 powder calcined at high temperature. This high-purity nano α-alumina polishing powder has an average particle size of 20 to 40 nanometers. It not only has excellent microscopic shape, but also has high purity and uniform particle size distribution. Because of this, it plays a key role in many fields, including the manufacture of tableware, accessories, and automotive accessories, as well as the surface treatment of optical lenses and machine electrical accessories.
Silicon dioxide (SiO2)
SiO2 polishing material is known for its excellent selectivity and dispersibility. It also has good mechanical wear resistance and active chemical properties, making waste liquid treatment in the post-cleaning process relatively easy. However, it also has some shortcomings, such as high hardness, which may cause unevenness on the surface of the polished object during use. In addition, gelation is prone to occur in the polishing slurry, which will have an adverse effect on the stability of the polishing speed and may cause scratches on the surface of the polished object.
SiO2 polishing material is mainly suitable for high-precision polishing of silicon wafers, germanium wafers, compound semiconductor materials such as gallium arsenide and indium phosphide, as well as precision optical devices, sapphire wafers, etc., and is also commonly used for polishing metal mirrors.
Using SiO2 abrasives in combination with abrasive leather for polishing can obtain an excellent mirror effect of the middle frame of the mobile phone.
Nano zirconium dioxide (ZrO2) polishing powder
Nano zirconium dioxide polishing powder, whose particles are spherical, has the characteristics of stable crystal phase, high hardness and uniform distribution. It not only has strong grinding force and fast polishing, but also can produce a high-brightness mirror effect. In addition, the polishing powder has outstanding grinding efficiency, high surface finish, strong cutting force, fast light output, and can complete the polishing task evenly and brightly. It is widely used in the field of precision polishing of metals, gemstones, etc.
