found at www.nrcan-rncan.gc.ca
1999
A very popular type of synthetic diamonds is called “Synthetic Diamond Abrasives” (SDA). It is used for sawing, drilling or milling hard stones, concrete aggregate, refractory materials, masonry and asphalt. Industry sources indicate that a plant producing synthetic diamonds using the high-pressure and high temperature method with an annual capacity of10 Mct requires about 60-70 employees, while a plant with an annual capacity of some 50 Mct requires 160-170 employees. One large press of 10 000 t produces about 5-6 Mct of synthetic diamonds
To produce diamond grit with grain sizes up to about 1 mm, the following method is used. High-purity graphite powder, either natural or synthetic, is mixed with a metal (nickel, cobalt or iron) powder alloy that serves as a solvent catalyst. The pressure is applied and then the temperature is raised with an electric current. Liquid metal alloy starts to dissolve the graphite. When the metal alloy becomes saturated, small crystals begin to crystallize out in the form of stable carbon, which is diamond. Synthetic diamonds are allowed to grow to a certain size. Then the temperature is decreased and when the crystals have cooled somewhat, the pressure is removed. The masses of hard material removed from the presses go to a chemical cleaning section where they are crushed and boiled in various acid baths that dissolve non-diamond materials. The diamonds are then cleaned, dried and sent to a sorting department.
Synthetic diamonds that are manufactured using the high-pressure and high-temperature method are produced in some 20 countries.
The two leading producers are De Beers of South Africa and General Electric of the United States. Together these
two companies control approximately 70% of world
production, and both produce a full range of synthetic diamond products. The smaller producers specialize
in certain sizes and types of products. De Beers has plants near Johannesburg in South Africa; at
Robertsfors, Sweden; in Hamburg, Germany; on the
Isle of Man, British Isles; and in Shannon, Ireland. General Electric has plants at Worthington, Ohio,
and in Dublin, Ireland.
In many applications, synthetic diamonds are preferred to natural industrial diamonds because they
can be tailored (size and shape) to the customer’s needs.
synthetic diamonds winnipeg Diamonds
news
