It's a superabrasive material, but not as you know it
21 July 2010
Synthetic diamond is stretching its wings and moving outside its use as an abrasive and you would be surprised where you will now find the hardest of all materials. Given the opportunity any diamond producer will wax lyrical on the properties of diamond, that is it an engineering material that can knock the socks off any other material in terms of a range of extreme properties – optical, thermal, chemical, mechanical, electrical and even acoustic and electronic. With the cost of diamond abrasives being driven down by increased pressure of competition, the opportunity to create a high value, high performance material that has a broader industrial appeal is driving many of the developments.
The stumbling block had always been that synthesis processes, mainly high pressure, high temperature processes, used to create diamond were geared mainly to producing grains more suited to their incorporating in grinding and cutting tools. Along came a new commercial process for diamond, chemical vapour deposition,CVD, in the late 1980s which allowed films of both single crystal and polycrystalline diamond to be produced.
It has taken more than 20 years of continual development but now chemical vapour deposition alongside developments in processing is proving to offer a manufacturing process that has reached the level of maturity where the material properties can be controlled with consistent results. This is creating a high purity, low defect grades optimised for different applications
As a consequence, these material improvements have finally opened up a raft of new high technology applications and it seems that developments are accelerating. Many new applications are already in commercial development and new ventures are being built on the back of developments in CVD diamond. Companies such as Element Six, Diamond Materials, Advanced Diamond Solutions, Diamonex , Kobe Steel, Iljin Diamond are just a few of the companies actively involved in CVD diamond production and development.
One strong application area for synthetic diamond has been in lasers. For many years, diamond has been used in carbon dioxide lasers used for industrial cutting applications and the power output of these has been trebled by using the power handling capability of diamond in this application. More recently, the potential of diamond in new lasers that operate in different wavelengths have been explored.
And if can afford to buy high end loudspeakers from Bowers & Wilkins you will find that the tweeter is made from polycrystalline diamond. The company has extolled the virtual of the performance of the high frequency component for diamond in its 800 Series Diamond which they say is the ‘ultimate’ tweeter material.
New companies have sprung up to use diamond electrodes in electrochemical sensing, wastewater treatment, ozone generating equipment, diamond detectors for medical X-ray dosimetry, radiation monitoring in the nuclear and defence industries, data logging in oil well exploration and UV photolithography for semiconductor manufacturing.
Companies such as Diamond Microwave Devices is trying to make the breakthrough with active electronic devices built with diamond at their core. The company is aiming to develop an electronic component that can be used for the development of high power, microwave devices for use in amplifiers and transmitters. Set up in 2006, the company has made steady progress in moving towards a practical device and other groups around the world are also interested in this technology.
The New Applications
Powerful and tunable lasers that can work in the long wavelength and extending to the terahertz spectrum could open upp the development of powerful miniature lasers for use in medical imaging, ophthalmology, cancer therapy and a variety of defence applications. Single crystal diamond is seen as a key material because it not only has high optical quality, exceptional thermal properties and broad transmission capabilities but also has high Raman gain, which is a frequency shifting property.
These diamond-based raman lasers are under development at a number of universities. Australian scientists at the Macquarie University and the Defence Science Technology organisation have already announced significant progress in developing a working laser. In the UK, work on these type of lasers are under development at the Institute of Photonics at the University of Strathclyde.
Chemical vapour deposition diamond grades with high isotopic purity as well as high chemical purity is under development for quantum optical applications and could lead the way to faster, more power computers and new solutions for both cryptography and cryptanalysis. A group of universities and companies within Europe and Australia under a major project called EQUIND, Engineered Quantum Information in Nanostructured Diamond, have been collaborating on developing suitable technology to create practical quantum systems. The EU-funded project ended in December 2009 having cost 2.13 m euros and the researchers made significant progress in developing single photon sources in diamond which form the basis of logic elements needed in computing.
So thanks to the advances in chemical vapour deposition, diamond is moving beyond the abrasives industry and is firmly establishing itself in the realms of where its extreme properties can make a real difference.