For years and years together, the human race has considered diamonds to be the hardest substance on the face of Earth. This common statement however has been proved to be false about sixty years ago. This is all thanks to the increasing curiosity and the extent of research available currently. Even recently, researchers have come across materials that have properties that very closely resemble that of a diamond, one important thing being cubic boron nitride.
What is cubic boron nitride?
Generally, boron nitride is a heat-resistant compound material, both thermally and chemically. It exists in many crystalline forms and is made by combining boron and nitrogen. Among the long list of forms possessed by this material lies the cubic variant, which is said to possess the same crystalline structure as a diamond. The only variation is that in the structure of cubic boron nitride, the carbon atoms are changed out for alternately bonded atoms of boron and nitrogen.
The discovery
- This diamond alternative was first created by Rober H Wentorf Jr and his team of scientists in the year 1955. This was a top-secret project at the General Electric Research Laboratories, where they had been hacking at methods for years together. The team produced this successfully by subjecting graphite in its purest to very high-pressure scenarios.
- Later around the year 2009, UC Riverside geologists along with those from China and Germany found the substances naturally existing at the borders of Tibet along its southern mountains. This discovery was given credit only in late 2013.
- Following this, scientists from China and America teamed up to try and compress c-BN even more into an extremely hardened variation, which was supposedly harder than a diamond. They reorganized the crystals of hexagonal boron nitride into a nanotwinned structure, making the atoms share walls and mirror each other. Through nanotwinned atoms, the size was brought down to 4 Nm, which zero compromises in the stability and strength. As an added perk, the material was also highly temperature resistant.
Manufacturing process
Almost similar to the process of making artificial diamonds, producing crystals of cubic boron nitride is done by a process of sintering.
Sintering is a process where manufacturers make use of added heat to strengthen the component and improve the overall integrity. By being subject to high pressure, heat, and highly stressful conditions, the substance becomes a hardened solid mass once it hits the melting point. At this point, a catalyst substance like lithium is added to bring down the conditions to a more bearable point, making it fit for conversion.
Applications of c-BN
- This substance is being used in the aviation and turbine industries for electroplated precision grinding wheels.
- Many of the important platforms and surfaces which require a high amount of strength and resistance include this component in their making.
- Ceramic manufacturer teams make use of this cubic boron nitride in their cutting tools as an alternative for diamonds.
Conclusion
In spite of all these properties and physical factors which prove the cubic boron nitride to be a valid competitor, it has been clearly stated that diamond is the hardest naturally occurring substance on earth. However, it is now deprived of the privilege of being the hardest natural substance on earth, thanks to stronger materials like c-BN.
