One of the most fascinating materials of our time is polycrystalline cubic boron nitride PCBN - the second hardest material after diamond. At CeramTec, PCBN is used as a cutting material from which indexable inserts are manufactured for machining. PCBN (Polycrystalline Cubic Boron Nitride) blanks for cutting tools are composite ultrahard materials sintered by polycrystalline CBN and carbide alloy under ultra-high pressure and high temperature conditions. They combine the hardness, wear resistance, and thermal stability of CBN with the impact resistance and toughness of carbide alloy. PCBN blanks are highly suitable for cutting ferrous and non-ferrous metals with high hardness. PCBN Composites and Inserts Hans Super Abrasive Diamond Tool Co.,Ltd , https://www.hansuperabrasive.com
PCBN is produced synthetically and is a "composite material" made of cubic boron nitride and a mostly ceramic binder phase. The ratio of cBN to binder content and the cBN grain size determine the application.
PCBN cutting materials are used in the machining of hard and/or highly abrasive workpiece materials. The high hardness and the extremely high hot hardness (up to temperatures above 1,000°C), the edge stability and inertness towards ferrous materials as well as the basically good chemical resistance give CBN cutting materials a high potential for use in machining. On the cutting material side, a distinction is made between high- and low-cBN cutting material grades.
To commemorate the 60th anniversary of Queen Elizabeth II's accession to the throne, Buckingham Palace will present seven special diamonds this summer. They are special in cutting from the same huge rough diamond "Kalinan". This will be the first time these diamonds have met the public together. Because of the size of the head, "Kalinan" was mined in 1905 from the "first" mine near Pretoria, South Africa. The original stone is 10 cm long, 6.35 cm wide, 5.38 cm high and weighs 3106 carats. Named after the company owner Thomas Kalinan. This diamond is not only big, but also has a blue color and a very high clarity. Two years after the "Kalinan" diamond fell asleep, the Prime Minister of Transvaal, South Africa, suggested that his government buy the diamond for the British King Edward VII as a 66th birthday present. After the "Kalinan" was given to the King of England, it was handed over to IJ Asher, a diamond processor in Amsterdam, the Netherlands. Three craftsmen worked 14 hours a day for 8 months, using this stone to polish 9 large diamonds, 96 small diamonds, and 9 carat unpolished broken diamonds. These diamonds total 1055.8 carats. The 9 large diamonds are particularly eye-catching, numbered from 1 to 9 in order of size from big to small. The "Calinan" No. 1 pear-shaped diamond and the No. 2 square diamond are also called "Big African Star" and "Little African Star" and are currently on display at the Tower of London. Diamonds No. 3 to No. 9 will be displayed at Buckingham Palace along with other royal jewels. If you want to estimate a price for these diamonds, it is undoubtedly a huge amount. Based on a market price of 250 carats of diamonds of approximately £500,000 per carat (approximately $800,000), the five pieces of jewellery made with the diamonds of Kellyan No. 3 to No. 9 are valued at £78 million (120 million). US dollars), 9.4 million pounds ($15.04 million), 4.4 million pounds ($7.04 million), 5.7 million pounds ($9.12 million) and 2.2 million pounds ($3.52 million).