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PCD Development

The PCD compacts used in our bearings are subjected to rigorous testing to ensure that they meet the needs of our customers.  Impact and tensile strength, abrasion resistance, and thermal stability are evaluated in our state-of-the-art testing facility.  Field tests are also conducted to validate laboratory data.

PCD Development

Diamond as a Bearing Material

Polycrystalline diamond is known for its high thermal conductivity, low coefficient of friction, high toughness and other preferred physical and mechanical properties. Having a bearing material with high thermal conductivity reduces localized temperature extremes that lead to bearing degradation. During starting and stopping, a high thermal conductivity will reduce the likelihood of causing localized welding of the surfaces, which in turn leads to scoring and galling of the bearing surface. In sliding bearings, low coefficients of friction are desired in order to decrease heat generation and reduce power loses. A bearing material exhibiting a large fracture toughness will decrease the likelihood of race damage during extreme operation conditions. Because of its extreme hardness, polycrystalline diamond is very resistant to wear from abrasive particles in lubricants or process fluids.

Physical and Mechanical Properties of Bearing Materials


Properties Polycrystalline Diamond (PCD) Tungsten Carbide Steel (4140) Silicon Nitride Silicon Carbide
 
Coefficient of Friction 0.05-0.08** 0.2-0.25† 0.42‡ -- --
Thermal Conductivity (W/m*K) 543 70 42.6 30 85
Fracture Toughness (MPa√m) 13-15 10-25 50 4 3.5-4
Hardness (GPa, Knoop) 49.8 1.8 0.2 1.8 2.4
Compressive Strength (GPa) 6.9-7.6 2.68 -- -- 2.5
Young’s Modulus (GPa) 841 669-696 205 296 434
Tensile Strength (MPa) 1,300-1,600 334 415 520 500

*ASI 4140 Steel, annealed at 815°C (1500°F) furnace cooled 11°C (20°F)/hour to 665°C (1230°F), air cooled, 25 mm (1 in.) roun(1100°F) temper)
** PCD on PCD in H2O, dynamic, dynamic
†Tungsten Carbide on Tungsten Carbide, static
‡Steel (Hard) on Steel (Hard), dynamic
YAt 100˚C
Sources: Bertagnolli, US Synthetic; Roberts et al., De Beers; Cooley, US Synthetic; Jiang Qian, US Synthetic; Glowka, SNL; Sexton, US Synthetic; Lin, UC Berkeley, MatWeb.com, Cerco

Coefficient of Friction

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Thermal Conductivity

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Hardness

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Fracture Toughness

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