MATERIALS
FIRST QUALITY
At Comercial Cobra we have the technical capacity necessary to satisfy the demands of our clients.
Our products are made with top quality materials: Silicate (SiO2), Alumina (AL2O3) and Aluminum Nitride (AIN), which extends the life of the products.
Comparison of material properties
Values obtained in the laboratory. In normal use, there may be slight variations.
| Properties | Measurement units | Porcelain | Steatite | Steatite | Cordierite | Cordierite | Mullite | Alumina | ||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Equivalent to DIN 40685 – CEI 672 – EN 60672 | C-112 | C-220 | C-221 | C-410 | C-511 | C-610 | C-795 | |||||
| Chemical composition | ||||||||||||
| SiO2 | % | 70 | 60-65 | 60 | 60 | 50 | 40 | – | ||||
| AI2O3 | % | 20 | 15-17 | – | 30 | 35 | 50 | 96 | ||||
| MgO | % | – | 18-20 | 25 | 3-5 | 10 | – | – | ||||
| Physical Properties | ||||||||||||
| Colour | White | White | White | White | Brown | White | White | |||||
| Water Absorption | % | Less than 1 | 0’5 | 0 | 0 | 15-20 | 0 | 0 | ||||
| Flexural strength | kg/cm2 | 800 | 1200 | 1400 | 800 | 300 | 1200 | 3000 | ||||
| Compressive Strength | kg/cm2 | 2500 | 4000 | 5000 | 2500 | 2000 | 3500 | 25000 | ||||
| Elasticity | kg/cm2 106 | 0.7 | 0.8 | 1.0 | 0.75 | – | 1.0 | – | ||||
| Hardness | Moh’s | 6-6.5 | 6-7 | 6-7 | 6-6.5 | – | 7 | 12 | ||||
| Thermal Properties | ||||||||||||
| Thermal expansion coefficient 30-600ºC | 10-6/ºC | 6-7 | 6-7 | 6-7 | 6-7 | 4-5 | 5-6 | 8 | ||||
| Thermal shock resistance | ºC | 200 | 250 | 300 | 400 | 750 | 300 | 220 | ||||
| Thermal conductivity | W/M ºK | 1.4-2.5 | 2-3 | 2-3 | 1.2-2.5 | 1.3-1.8 | 2-6 | 25 | ||||
| Maximum operating temperature | ºC | 600 | 1000 | 1050 | 600 | 1000 | 1000 | 1450 | ||||
| Electrical Properties (20ºC) | ||||||||||||
| Dielectric Strength | KV/mm | 8 | 10 | 20 | 10 | – | 10 | 18 | ||||
| Dielectric constant | 5.0 | 5.5 | 6.5 | 6.0 | – | 7.0 | 9.5 | |||||
| Resistivity | Ohm-cm | 1011 | 1011 | 1011 | 1010 | – | 1011 | 1012–1013 | ||||
