The history of the pink fused alumina

In 1877, the French chemist, Fremy took pure alumina powder, potassium carbonate, barium fluoride and a small amount of potassium dichromate as raw materials, then melted them in a crucible at high temperature for about 8 days to obtain small particles of like ruby crystal, which was the beginning of the artificial pink fused alumina.

In 1900, scientists produced 2g~ 4g ruby by adding a small amount of chromium oxide and Cr2O3 to the fused alumina according to a proportion of 0.7%. However, now we can make artificial pink fused alumina as large as 10g.

In Geneva,Switzerlandin 1885, some high-quality synthetic rubies were produced, which were said to be made from fragments of natural rubies and potassium dichromate to enhance the red color, then melting at high temperature. It has the same properties as natural ones. However, it was the French chemist Verneuil who made the artificial ruby and made them into large-scale production.

In 1891, Verneuil invented the flame melting method and used it to trial-produce synthetic gem. After success, he tested it with pure aluminum oxide. That is, in a high temperature muff furnace, he tested it with an inverted oxyhydrogen blowing tube, so that the fine particles of pure aluminum oxide containing a small amount of chromium oxide were slowly melted into the flame and dropped on the base to condense and crystallize.

After ten years of efforts, Verneuil officially produced artificial rubies in 1904. Later, the flame melting method was gradually improved, and the ruby produced by it was almost no different from natural products. This method has been in use until modern times, and is still the main method of producing artificial gems in the world, which known as "verneuil method". But now, as long as several hours, the rough stone of ruby can be made, and the appearance of it is a kind of synthetic corundum crystal with inverted pear-shaped or carrot shape. Moreover, it has pure texture and the transparency even more than natural, as well as the economic benefit is huge. Modern “Verneuil method” can not only produce the ruby from pale pink to deep red, also can produce various colors of sapphire, and can even produce ruby and sapphire with starlight, which are really wonderful artical excelling nature.

Pink fused alumina is mainly made from aluminum oxide powder and then added with appropriate amount of chromium oxide. The hardness of pink fused alumina is similar to that of white fused alumina, and the toughness of pink fused alumina is higher than that of white fused alumina. Moreover, the grinding tools made of Pink fused alumina have good durability and high finish in grinding process. It is suitable for precision grinding of measuring tools, machine tool spindles, instrument parts, thread workpieces and sample mills.