Thermal Properties of Mirror Materials

Material,

Near Room Temperature

Density,
r
gm.cm-3

Young's Modulus,
E
GPa

Stiffness Factor

E1/2/r3/2

Coefficient of Thermal Expansion,
a
10-6.K-1

Thermal Conductivity,
k
W.m-1.K-1

Specific Heat,
Cp
W.s.g-1.K-1

Thermal Diffusivity,
D
10-6.m2.s-1

Steady State Distortion,
a.k-1
mm.W-1

Transient Distortion,
a
.D-1
s.m-2.K-1

Preferred Value >>

Small

Large

Large

Small

Large

Large

Large

Small

Small

Aluminum

2.7-2.8

68-75

18-20

22-24

165-220

0.9-1.0

55-85

0.10-0.17

0.25-0.41

Beryllium

1.85

280-305

67-70

11-11.5

190-220

1.8-2.0

49-61

0.05-0.07

0.18-0.25

Silicon Carbide RB

2.88-2.92

300-340

35-37

2.4-2.6

155-165

0.7-1.8

30-80

0.015-0.016

0.03-0.08

Silicon Carbide CVD

2.33-3.21

455-470

33.5-40.5

2.2-2.7

100-330

0.64-0.73

80-240

0.008-0.012

0.018-0.028

SiC - SSG - HP

3.35

450

34.6

2.2

120

0.6

60

0.018

0.037