Apr 16 2003
Chemical Formula
The chemical formula of Ruby is Al2O3/Cr2O3/Si2O3
Background
Ruby exhibits identical properties to those of Sapphire. Small amounts of impurities give Ruby a red colouration.
Key Properties
The key properties of Ruby are tabulated below.
Table 1. Key properties
| Chemical Resistance |
| Acids – concentrated |
Good |
| Acids – dilute |
Good |
| Alkalis |
Good |
| Halogens |
Good |
| Metals |
Good |
| Electrical Properties |
| Dielectric constant |
7.5 - 11.5 |
| Dielectric strength ( kV.mm-1 ) |
15 - 50 |
| Volume resistivity @ 25 °C ( Ohm.cm ) |
1014 |
| Mechanical Properties |
| Compressive strength ( MPa ) |
2100 |
| Hardness - Knoop ( kgf.mm-2 ) |
2000 |
| Hardness - Vickers ( kgf.mm-2 ) |
2500 - 3000 |
| Tensile modulus ( GPa ) |
350 - 390 |
| Tensile strength ( MPa ) |
250 - 400 |
| Physical Properties |
| Apparent porosity ( % ) |
0 |
| Density ( g.cm-3 ) |
3.98 |
| Useful optical transmission range |
150 - 5500 nm |
| Water absorption - saturation ( % ) |
0 |
| Thermal Properties |
| Coefficient of thermal expansion, 20-1000 °C ( x10-6 K-1 ) |
5.8 |
| Melting point (°C ) |
2050 |
| Specific heat @ 25 °C ( J.K-1.kg-1 ) |
750 |
| Thermal conductivity @ 20 °C ( W.m-1.K-1 ) |
35 - 40 |
| Upper continuous use temperature ( °C ) |
1800 - 1950 |
About Goodfellow
Goodfellow supplies metals, ceramics and other materials to meet the research, development and specialist production requirements of science and industry worldwide.
The Goodfellow group consists of four companies. The main administration, research laboratories and workshops are located at the Company's headquarters in Cambridge, England. The subsidiary offices in America, France and Germany provide an additional service.