How Are Synthetic Diamonds Used & Produced?

Synthetic Diamond Basics

Synthetic diamonds are manufactured, diamond-like crystals. The first synthetic diamonds were manufactured in 1953 in Sweden, for industrial use. The manufacturing processes work to duplicate the pressure and temperature of the natural diamond-producing environment. The formation process is initiated by forcing a chemical reaction, through adding a catalyst to carbon, and placing the mixture in high-pressure cells. Then, the mixture is cooled and washed with acid, which results in a synthetic diamond. Quality of synthetic diamonds can vary from inferior to superior to the natural diamond, depending upon the technology and individual manufacturing processes. The methods used in the production of synthetic diamonds are high pressure high temperature (HPHT), chemical vapor deposition (CVD), explosive detonation and ultrasound cavitation. Industry applications, for synthetic diamonds, are in areas of jewelry production, tools, industrial machinery and electronics.

High Pressure High Temperature (HPHT)

HPHT is considered the original method for synthetic diamond production and is still widely used, due to its low cost. It's a process combining high pressures of 5 GPa with high temperatures of 1,500 degrees Celsius (2,732 degrees F) to simulate the natural diamond-producing environment and conditions inside the earth. The two main press designs used to create the HPHT environment are the belt and cubic press. The belt press uses upper and lower carbide anvils to supply pressure and an electric current to reach temperatures of 1,200 to 1,500 degrees Celsius. The cubic press is smaller, with 6 anvils, and can simultaneously provide operating pressure in cube-shaped volumes.

Chemical Vapor Deposition (CVD)

CVD grows synthetic diamonds through creation of a high carbon binding environment. CVD promotes the settling of carbon atoms in a gas onto a diamond substrate, to create a diamond crystalline form. Synthetic diamonds produced through this method are commonly used as electrodes for use in DNA and redox reactions and in industrial applications, such as cutting tools and semiconductors.

Explosive Detonation

Explosive detonation is a more recent process from Russia and China. It is not as widely used as the HTHP or CVD processes for industrial synthetic diamond production. The explosive detonation process creates synthetic diamonds from the detonation of TNT/RDX to form detonation nanodiamonds.

Ultrasound Cavitation

Ultrasound cavitation produces synthetic diamonds from a suspension of graphite in organic liquid, at atmospheric pressure and room temperature. This process usually results in a 10 percent yield of nanodiamonds.

Uses of Synthetic Diamonds

HTHP synthetic diamonds are usually applied as a gemstone alternate to natural diamonds for jewelry decoration and production. CVD manufactured synthetic diamonds are used in other industrial applications, such as machine operating parts, cutting tools, additives or strong reinforcement coatings for cutting tools, semiconductors and electrodes in photochemical and redox reaction methods. Nanodiamonds, manufactured by explosive detonation, are commonly used as reinforcement fillers in plastic and rubber. They are also used as an additive to commercial products such as polishing agents, lubricants for metals and additives for engine oils.

Resources

• Synthetic Diamond Chemistry