Physical Properties*
Al2O3-content % 99.7 76 60 99.5 73-75 73-75 70 99.5 — — — —- 99.5
Alkali
content		 % 0.05 0.5 3.0 0.05 — — — — — 0.5 <0.1 — <0.1
Type acc. to DIN VDE 0335 — 799 — 610 — — 530 — — — — — — —-
***Water absorption % £0.2 — £0.2 3 5 12 12 7 10 18 3 6 62
Leakage rate at 20°C (Helium) mbar.l.s-1 10-10 — 10-10 — — — — — — — — — —
***Density g.cm-3 3.80-3.93 3.10 2.60 3.30 2.65 2.35 2.35 3.00 2.40 1.65 3.10 1.95 1.05
Flexural strength MPa 300 150 120 80 50 35 35 50 30 15 20 35 <10
Hardness (Mohs scale) — 9 8 8 — — — — — — — — — —
Thermal expansion
20 - 700°C 		10-6.K-1 7.8 5.6 5.4 7.8 5.2 5.3 5.3 7.6 5.0 2.0 — — 7.6
Thermal expansion
20 - 1000°C 		10-6.K-1 8.6 6.0 6.0 8.6 5.7 5.7 5.7 7.9 5.0 1.7 1.0 0.9 7.9
Thermal conductivity
20 - 100°C 		W.m-1.k-1 26.0 3.5 2.0 — — 1.4 1.4 15.0 34.0 — 2.0 — —
**Maximum working temperature °C 1700 1600 1400 1700 1650 1350 1350 1700 1400 1150 1300-1650 1100 1700
Permissible permanent temperature for temperature measurement °C 1600†/
1800††		 — 1500†/
1500††		 — — 1600† — — 1400† — — — —
Dielectric strength related to 1.5mm wall thickness kV.mm-1 17 15 17 — — — — — — — — — —
Volume resistivity DC at 20°C W.cm 1014 1013 1013 — — — — — — — — — —
Thermal shock resistance — good very good good good good very good very good good very good very good very good very good very good
***pore size/avr µm — — — 1.5 8-9 2 2 50 6 — — — —


*The physical properties stated above result from special test specimens. These values can only be used as a reference to technical products and other forms and dimensions. In practice, Alsint 99.7 samples have a flexural strength between 160 and 300 MPa, depending on wall thickness, geometry, manufacturing process and surface finish. **Depending on the applied load. ***Depending on the design and materials processing. †For thermocouple protection tubes according to DIN 43 724. ††For insulators according to DIN 43 723