Commonly used polishing powders are derived from a mix of rare earths, supplemented with fluoride, quartz, calcium, barium, iron, and a small amount of other impurities. From the 60s to the 70s of the 20th century, the preparation process and production method of polishing powder have achieved relatively concentrated research results. A commonly used preparation process is to chemically change rare earth enrichments in a solid state to convert them into compounds with stable mechanical and chemical properties. The rare earth oxide content is 40~70% (containing 30~65% oxide), and the particle size is 1~4 microns. The polishing powder is relatively cheap, has a high cutting rate, and is widely used. It is mainly used for the polishing of cathode ray tubes, flat glass and lenses. The second type of oxide-based polishing powder is produced by chemical precipitation.
Rare earth precipitation is calcined into a stable oxide and ground into a fine powder. Usually contains 70~100% rare earth oxides (40~100% oxides). The advantage of this product is that the composition is uniform, and the particle size and shape consistency are good, but it is mainly used for optical glass. Special glass is polished using a high level of polishing powder (more than 99% oxide). Its particle shape and hardness are uniform, high purity, uniform surface, no defects, no impurity pollution. It is commonly used in the polishing of precision optical instruments, laser crystals and semiconductor components. The requirements for rare earth polishing powders are different from those of similar rare earth products. In the case of polishing powders, although there are also requirements for chemical purity, it is not the decisive factor, but the decisive factor.
Therefore, the preparation of rare earth polishing powder must be endowed with due physical properties on the basis of a certain chemical content, such as particle size, uniformity, crystal properties, hardness, proportion, etc. These properties must be adjusted during the preparation process, including precipitation and calcination.