Artificial Diamonds
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We all know that natural diamonds are created by geological processes spanning over several thousands of years. Meanwhile, synthetic/artificial diamonds are produced within weeks in laboratories using an artificial process.
Synthetic diamonds are also called HPHT diamonds or CVD diamonds. They are named after two major production methods, high-pressure high-temperature and chemical vapor deposition methods.
Several methods are used for producing synthetic diamonds. High-pressure and high temperature (HPHT) methods are widely used since they are cost effective. Here, three main press designs are used for supplying the pressure and temperature required for producing synthetic diamonds. They are namely the belt press, the cubic press, and the split-sphere (BARS) press.
These presses weigh hundreds of tons, which helps them produce a pressure of 5 GPa at 1500°C (2732°F).
CVD method is used for developing synthetic diamonds from a hydrocarbon gas mixture. It is rather simple and flexible to set up. The advantages of this method include the possibility of growing synthetic diamonds over large areas and exercising precise control over chemical impurities. Compared to the HPHT method, the CVD method does not require much pressure.
With the help of ultrasonic cavitation, micron-sized diamond crystals can be developed from a suspension of graphite in organic liquid at atmospheric pressure and room temperature.
Properties of Synthetic Diamonds
The properties of synthetic diamonds largely rely on the manufacturing processes.
The key properties of artificial diamonds are:
Mechanical properties: Owing to their exceptional hardness and very low coefficient of friction, synthetic diamonds have several mechanical applications. This includes extending tool life, decreasing downtime and reducing operating costs and carbon footprints. Polycrystalline diamond is an example of a very tough synthetic diamond. Synthetic diamonds are produced for having an ultra-fine edge for very high precision.
Optical properties: Synthetic diamond has the widest spectral band.It extends from UV to infrared and wave microwave band.
Thermal properties: They have the highest resistance to thermal shock and also possess the highest thermal conductivity. Four times greater than copper. They are used in thermal management applications which require optimum performance. They have low thermal expansion as well.
Electronic properties: They possess high electrical carrier mobility and have excellent electrical insulator properties. Their low dielectric constant and loss, and wide electronic band ensures that they carry very low current even under high voltages.
Acoustic properties: They have terrific acoustic properties which enables CVD diamond tweeters to achieve frequencies of 70 kHz. Now this creates an unmatched clear and transparent sound reproduction!
Electrochemical properties: Synthetic diamonds can be used in extreme chemical, physical and radioactive environments since they are chemically and biologically inert.Their good electrochemical properties help in efficient oxidation of organic and inorganic compounds. Artificial diamond anodes can facilitate ozone production for homes and hospitals. The method is the best among currently available technology.
Synthetic Diamond Companies
Below is a list of the companies involved in the synthetic diamonds business.
Since 1937, Wonderstone Ltd has been mining the unique pyrophyllite deposit located 300 km west of Johannesburg. They are the ones who supply the material to synthetic diamond manufacturers across the globe.
Element Six is another company which is specialized in providing synthetic diamonds.Scio Diamond Technology Corporation is another example for synthetic diamonds manufacturers. They function in South Carolina, USA.