BLACK GLASS BALLS

High dimensional stability, these balls are resistant to corrosion and to chemical absorption.
Applications
Medical and chemical flowmeters, aircraft slips, turn indicators. Variety of functions, most common use into precision instruments.
Chemical composition
%SiO2
%Na2O
%CaO
%Al2O3
%B2O3
%K2O
%BaO
%MnO2
-
-
-
-
65.00-75.00
9.50-15.50
3.00-5.00
1.00 max
1.00-3.00
2.00-3.00
3.00-4.00
5.00-7.00
-
-
-
-
Physical / mechanical / thermal / electric / magnetic properties
Property
Symbol
U.o.M.
Type
Notes
Values
Density
δ
[g/cm3]
Physical
Room temp.
2.57
Young's modulus
E
[GPa]
Mechanical
-
66
Refractive index
n
-
Optic
-
1.520
Softening temperature
-
[ºC/ºF]
Thermal
Room temp./P.atm.
650 / 1202
Coefficient of linear thermal expansion
α
[10^-6/ºC]
Thermal
(ΔT=0-100°C)
7.2
Thermal conductivity
λ
[W/(m·K)]
Thermal
Room temp.
0.76
Volume resistivity
ρ
[Ω*m]
Electric
-
> 10^14
Relative magnetic permeability
µ
-
Magnetic
Diamagnetic
<~1
Technical data
Property
Type
U.o.M.
Values
U.o.M.
Values
Hardness
Mechanical
[Knoop]
468 - 530
[Mohs]
6
Ultimate compressive strength
Mechanical
[MPa]
750 - 950
[psix10^3]
109 - 138
Service temperature
Thermal
[ºC]
0 / 300
[ºF]
32 / 572
Range
Diameters (min/max)
U.o.M.
Diameters (min/max)
U.o.M.
Precision grades
1.000 - 100.000
[mm]
3/64 - 4
["]
G25-50-100-200-500-1000-2000
Corrosion Resistance
Good corrosion resistance in contact with most acid and basic compounds.
Revision n.7