Sitall CO-115MMany optical applications require a substrate material with a near-zero coefficient of thermal expansion and/or excellent thermal shock resistance. Astrosital, equivalent to Zerodur™ (registered trademark of Schott Glass Technologies)   is a glass-ceramic material with ultra low thermal expansion.  
Astronomical and x-ray telescope mirrors are prime examples of application. Another well known application is production of mirror substrates for microlithography.
Maximum available size: 2,000 mm Dia (or 1,000 mm Square) x 300 mm thick.

 

 

 

 

Main Properties

  Astrosital Zerodur
Coefficient of linear thermal expansion, 1/K
from 213K to 333K
from 293K to 573K


0.0 (+/-0.6) x 10-7
2.8 (+/-1.0) x 10-7

 

0.5 (+/-1) x 10-7

Density, g/cm3 at 293 K

2.46

2.53

Young's Modulus, GPa

90.2

91

Poisson's Ratio

0.28

0.24

Bending Strength, GPa

166

 
Relative to BK-7 abrasion hardness

1.78

 
Specific Heat, kJ/(kg K)

0.92

 
Thermal Conductivity, W/(m K)

1.71

 
Heat Resistance, K 823  
Refractive Index, nd 1.536 +/- 0.004  
Mean Dispersion, n- nc 0.0102 +/- 0.0003  

 

THERMAL PROPERTIES
mean linear coefficient of thermal expansion (CTE) within temperature range
-60 to 60 oС
10-7 oC-1 0±1.5
CTE homogeneity 10-7 oC-1 <= 0.2
specific heat capacity kilocalorie kg-1 oC-1 0.22
heat conductivity kilocalorie h-1 m-1 oC-1 1.71
thermal resistance oC 550
MECHANICAL PROPERTIES
density g cm-3 2.46
micro hardness 10-7Pa 860
lapping relative hardness (with reference to glass, K-8 type) - 1.78
modulus of elasticity (Young’s) GPa 92
bending strength 10-7Pa 16.6
Poisson’s coefficient - 0.28
OPTICAL PROPERTIES
refractive index ne - 1.538
refractive index nd - 1.536
average variance nF - nC - 0.0102
quality - as per requirements
bubbles and striae - as per requirements
stress birefringence nm/cm up to 15
分类:零膨胀材料

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