Diamonds Are a Driver's Best Friend

The transition of summer into fall often means back to school, cooler weather, and in some parts of the United States, the end of road construction. Resurfacing existing concrete roads requires road crews to cut, grind, and drill through cement roadways. Early diamond grinders, known as polycrystalline diamond compacts, had a shear strength greater than 50,000 psi1 and were made commercially available by General Electric in 1976.2 When used in road construction, diamonds can reduce tire/pavement noise and promote safer driving conditions.

Diamond (CAS Registry Number® (RN): 7782-40-3) is one of the hardest organic substances on earth. Its strength lies in its chemical composition, which consists entirely of carbon. Without a single hydrogen atom, the carbon atoms in diamond form strong covalent bonds, making a simple, uniform, and tightly bonded arrangement. This structure yields chemical properties such as resistance to other chemicals and friction, making diamond particularly effective in industrial applications where chemical reactions or sparks might be detrimental (space flight). The structure of diamonds also makes them excellent electrical conductors and refractors of light. Gemstone and jewelry diamonds sparkle intensely by refracting the majority of light.

Naturally occurring diamonds are a finite resource and mostly mined for industrial purposes. They are either crushed to form abrasive powders or embedded into saw blades, drill bits, or grinding wheels. Synthetic diamonds, such as synthesized polycrystalline,3 are produced because they retain chemical properties of hardness and durability, and are a viable and inexpensive industrial option for cutting, grinding, drilling and polishing procedures.4 To date, polycrystalline diamond compacts have drilled one-third of total footage for oil and gas wells worldwide.2  

Diamond grinding of cement roads provide more grooves and lands than regular cement. Below the road surface, grooves increase friction and prevent tire slippage during wet conditions by forming channels that drain water. Lands, areas of uncut concrete in direct contact with the tire, reduce tire/pavement noise by trapping less air between the tire and the road. Reduced road noise increases driver comfort, directly contributing to road safety.

Use SciFinder® and STN® to explore more information about diamonds grinding to be found in the CAS databases.

Contributed by
Kathryn J. Kitzmiller, Ph.D.


References
  1. Bovenkerk, H. P.; Malloy, G. T. Polycrystalline diamond compacts. South Africa Patent 6804901, December 31, 1968.
  2. Gearhart, M.; Rehm, B.; Chenevert, M.; Maurer, B.; Robinson, L. Legends of Drilling Special Section. J. Petrol. Tech. 2008, 60, (12) 41-57.
  3. Kanda, H.; Suzuki, K.; Fukunaga, O.; Setaka, N. Growth of polycrystalline diamond. J. Mater. Sci. Lett. 1976, 11, 2336-2338.
  4. Diamond. Mineral Uses and Properties. http://geology.com/minerals/diamond.shtml (accessed September 3, 2010).

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