# Polycrystalline CVD Diamond

CVD diamond is a non-oxide engineering ceramic. It has the highest tensile strength among non-oxide engineering ceramics. In addition, it has the highest thermal conductivity and a very low heat capacity. The graph bars on the material properties cards below compare CVD diamond to other non-oxide engineering ceramics (top) and the entire database (bottom). A full bar means this is the highest value in the relevant set. A half-full bar means it's 50% of the highest, and so on.

## Mechanical Properties

Elastic (Young's, Tensile) Modulus

1050 *GPa* 150 *x 10 ^{6} psi*

Fracture Toughness

5.5 *MPa-m ^{1/2}* 5.0

*x 10*

^{3}psi-in^{1/2}Poisson's Ratio

0.1

Tensile Strength: Ultimate (UTS)

750 *MPa* 110 *x 10 ^{3} psi*

## Thermal Properties

Specific Heat Capacity

500 *J/kg-K* 0.12 *BTU/lb-°F*

Thermal Conductivity

1900 *W/m-K* 1100 *BTU/h-ft-°F*

Thermal Expansion

1.0 *µm/m-K*

## Electrical Properties

Dielectric Constant (Relative Permittivity) At 1 MHz

5.7

Electrical Dissipation At 1 MHz

0.00020

Electrical Resistivity Order of Magnitude

13 *10 ^{x} Ω-m*

## Otherwise Unclassified Properties

Density

3.5 *g/cm ^{3}* 220

*lb/ft*

^{3}Light Transmission Range

0.22 to 100 *µm*

Refractive Index

2.4

## Common Calculations

Stiffness to Weight: Axial

170 *points*

Stiffness to Weight: Bending

96 *points*

Strength to Weight: Axial

59 *points*

Strength to Weight: Bending

52 *points*

Thermal Diffusivity

1080 *mm ^{2}/s*

Thermal Shock Resistance

51 *points*

## Followup Questions

## Further Reading

Ceramics and Composites: Processing Methods, Narottam P. Bansal and Aldo R. Boccaccini (editors), 2012

Springer Handbook of Condensed Matter and Materials Data, W. Martienssen and H. Warlimont (editors), 2005