Cerium oxide is a significant rare earth oxide, mainly used for smelting metallic cerium and as an additive in various materials.
Since 1940, cerium-rich rare earth polishing powders have gradually replaced iron oxide (red iron) for glass polishing, becoming a critical material in the glass polishing process.
Compared to traditional polishing powders like iron oxide, rare earth polishing powders offer advantages such as faster polishing speed, higher surface finish, and longer lifespan. They also improve polishing quality and working conditions. For example, using cerium oxide polishing powder to polish lenses can take one minute, whereas iron oxide would take 30 to 60 minutes.
The excellent performance of cerium oxide in glass polishing is attributed to the multivalent nature of cerium and its ease of transformation. The Ce(+3)/Ce(+5) redox reaction disrupts the silicate lattice and, through chemical adsorption, removes the surface material by oxidizing it or forming complexes, making it suitable for polishing silica-based glass, crystals, and fluoride crystals like calcium fluoride.
Ⅰ. Classification of Cerium Oxide Polishing Powder
Due to its excellent performance on silica-based glass and crystals, cerium oxide polishing liquid is classified based on the cerium oxide content and the fineness of the particles.
1. Low-Cerium Polishing Powder
Low-cerium polishing powders typically contain around 50% CeO2, with the remaining 50% comprising La2O3, Nd2O3, Pr6O11, or alkaline fluorides such as LaOF, NdOF, and PrOF. Due to the presence of praseodymium (Pr), these powders appear red or reddish-brown, with deeper colors indicating higher praseodymium content. Technological advancements and the utilization of praseodymium have led to the development of white low-cerium polishing powders. While these powders are less expensive, their initial polishing ability is similar to high-cerium powders, making them popular for polishing flat glass, CRT glass, and lenses in low-end products, although they have a shorter lifespan compared to high-cerium powders.
