Scientists redefine production of world’s third hardest material

Posted on 8 May 2014 by Callum Bentley

University of Birmingham researchers have reshaped the production process of one of the hardest materials known to man.

  • New method is cheaper and more efficient
  • Commercialisation of the technology currently being sort
  • Material third hardest known behind diamond and boron nitride

Scientists at the University of Birmingham have developed a new method of producing boron carbide powder which uses lower temperatures and introduces fewer contaminants than current processing methods. The cheaper and more efficient way of processing what is known to be one of the hardest materials on the planet, could lead to the production of lighter, stronger and more hard-wearing machinery used for manufacturing.

Boron carbide is important for many kinds of machinery used to make tools and other kinds of hard wearing equipment. Abrasive jets, for example, which are used to cut hard or heat sensitive material, need to be manufactured from hard materials to minimise wear. In addition, boron carbide is very effective at absorbing neutrons, which means it has potential for use in the nuclear industry to protect against radiation.

Licensing partners are currently being sought by the University’s commercialisation arm, Alta Innovations, to commercialise the technology.

Currently, boron carbide is produced in the form of large ingots, produced by mixing petroleum coke – the carbon element of the compound – with boron oxide at temperatures of up to 2000 °C. These ingots then have to be ground into fine grains before being manufactured into the required shape. This method uses a lot of energy and time, making boron carbide products up to 10 times more expensive than other, less hard wearing ceramic materials which currently dominate the market.

Boron carbide is rated the third hardest material in the world behind diamond and boron nitride (video below).

Isaac Chang, of the School of Metallurgy and Materials at the University of Birmingham, has been working on a project, funded by the Defence Science and Technology Laboratory, to look at reducing the costs of producing the material.

His team has devised a method which substitutes a simple carbohydrate-based compound for the petroleum coke. The boron oxide and carbohydrate are mixed in water to form a solution which mixes the carbon and boron sources at a molecular level. The solution is then atomised into fine droplets which convert into a powder on cooling. When this powder is heated – at a temperature below 1500 °C – fine boron carbide particles are produced, ready for processing into final products.

“The raw materials we are using are very cheap,” explains Dr Chang. “They are also highly active ingredients, which means we can use much lower temperatures to produce the chemical reaction that we need, making the process less energy intensive. Also, because our end product is a powder, rather than an ingot, there is no need for grinding, which removes a costly and inefficient step from the process.”

Because boron carbide is one of the lightest materials on the market, relative to its strength, it is also very important in the development of new ceramic armours for the protection of dismounted soldiers as well as military vehicles and aircrafts against ballistic threats.

The team have just completed a series of tests to demonstrate how this process can be scaled up to produce larger yields and are now working further refine the process.