What is the Use of Ceria Powder in the Glass Manufacturing Industry？

Rare earth elements are often referred to as "industrial vitamins" due to their crucial importance in modern technology. Interestingly, we have discovered that rare earth materials play a significant role in the production of glass.

The most common type of glass is silicate glass. Historically, red powder (iron oxide) was the first polishing material used, but it has a slow polishing speed and the rust-colored contamination cannot be removed. With the development of the rare earth industry in the 1930s, rare earth oxides began to be used as polishing powders for glass, first emerging in Europe. During World War II, an employee at WF and BarnesJ Company in Rockford, Illinois, introduced a rare earth oxide polishing powder called Barnesite in 1943, which quickly found success in polishing precision optical instruments. Due to the high polishing efficiency, quality, and low pollution associated with rare earth polishing powders, countries like the United States began extensive research in this area. As a result, rare earth polishing powders rapidly developed as a replacement for traditional polishing powders.

Basic Requirements for Polishing Powders

Polishing powders should have the following characteristics:

1.Uniform Particle Size: The micro-powder particle size must be consistent and stable within the allowable range.

2.High Purity: There should be no mechanical impurities present to ensure a clean and efficient processing environment.

3.Good Dispersion and Adsorption: These properties are crucial for ensuring uniform and efficient polishing; the suspension rate can be improved by adding the dispersant LBD-1.

4.Specific Crystal Form: Powder particles should have a certain lattice structure that creates sharp edges when broken, enhancing polishing efficiency.

5.Appropriate Hardness and Density: The polishing powder must have suitable hardness and density, ensuring good wettability and suspension in water for ease of use.

Rare earth polishing powders offer advantages such as fast polishing speed, high smoothness, and long service life, with cerium oxide being the primary component used in rare earth glass polishing powders.

Cerium oxide is commonly used in glass polishing due to its high chemical reactivity with silicate glass and similar hardness. It is particularly effective for enhancing polishing speed when combined with fluoride. In mixed rare earth polishing powders with lower cerium content, 3-8% fluoride is typically added; however, pure cerium oxide polishing powders do not contain fluoride, as non-fluoride polishing powders are more suitable for glasses with lower hardness and higher fluoride content, such as ZF or F series glasses.

Applications of Cerium Oxide in the Glass Industry

Cerium oxide polishing powder, as an exceptional material, finds widespread use across various industries, particularly in the glass sector. In a previous article, we highlighted how rare earth polishing powders have revolutionized glass polishing processes. In this article, we explore other applications of cerium oxide powders in the glass industry. We are amazed to find that cerium oxide, this "industrial vitamin," has such extensive applications in the glass industry.

What Compounds Are Used in the Glass Industry?

If we were to identify the compounds commonly used in the glass industry, the first thought would be rare earth elements, particularly cerium oxide. Beyond polishing, cerium oxide can also be used for decolorizing glass.

All glass contains iron oxide, which can be introduced through raw materials, sand, limestone, and crushed glass. There are two forms: ferrous iron, which turns glass a deep blue, and ferric iron, which gives glass a yellow color. Decolorization involves oxidizing ferrous ions into ferric ions, as ferric iron's tint intensity is only one-tenth that of ferrous iron. A color enhancer is then added to neutralize the color to light green. The main rare earth elements used for glass decolorization are cerium oxide and neodymium oxide. Rare earth glass decolorizers have replaced the traditionally used white arsenic decolorizers, not only improving efficiency but also avoiding the pollution associated with arsenic. Cerium oxide is favored for glass decolorization due to its thermal stability, low cost, and lack of visible light absorption.

Interestingly, cerium oxide is not only used for decolorizing glass but also for coloring it.

Rare Earth Colorants for Glass

Different types of glass are used across various fields. In addition to common clear glass, there is a significant demand for colored glass in the market.

 So, how is glass colored?

Rare earth ions exhibit stable and vibrant colors at high temperatures, making them effective colorants when mixed into glass batches. Rare earth oxides such as neodymium, praseodymium, erbium, and cerium are excellent glass colorants. When transparent glass containing rare earth colorants absorbs visible light with wavelengths between 400 and 700 nanometers, it displays beautiful colors.

Such colored glass can be used for aviation, maritime applications, various transportation indicators, and high-end artistic decorations.

Cerium oxide and titanium dioxide are used in combination to give glass a yellow color.

Rare Earth Clarifiers 

Cerium oxide is used as a substitute for traditional arsenic oxide as a glass clarifier, effectively removing bubbles and trace colored elements. This is particularly effective in the production of colorless glass bottles, resulting in a finished product that is crystal clear, with good transparency, and improved strength and heat resistance. Additionally, it eliminates arsenic pollution to the environment and the glass itself.

Moreover, the addition of cerium oxide in everyday glass, such as in construction and automotive glass, as well as crystal glass, can reduce the transmittance of ultraviolet light. This application has been promoted in Japan and the United States. Cerium radiation-shielding glass is used in automotive glass and television casings.