Alumina Al2O3 Alumina Silicate SiO2 53 / Al2O3 47 Alumina / Silica Al2O3 80 / SiO2 20 Alumina / Silica Al2O3 96 / SiO2 4 - Saffil® Alumina / Silica / Boria Al2O3 62 / SiO2 24 / B2O3 14 Alumina / Silica / Boria Al2O3 70 / SiO2 28 / B2O3 2 Aluminium Nitride - Machineable Shapal-M® Aluminium Nitride AlN Alumino-silicate Glass SiO2 57 / Al2O3 36 / CaO / MgO / BaO Beryllia BeO 99.5 Boron Carbide - Hot-pressed B4C Boron Carbide B4C Boron Nitride BN Leachable Ceramic SiO2 50 / ZrSiO4 40 / Al2O3 10 Machineable Glass Ceramic SiO2 46 / Al2O3 16 / MgO 17 / K2O 10 / B2O3 7 Magnesium oxide MgO Potassium Alumino-silicate Muscovite Mica Quartz - Fused SiO2 Ruby Al2O3 / Cr2O3 / Si2O3 Sapphire Al2O3 99.9 Silica SiO2 96 Silicon Carbide - Hot-pressed SiC Silicon Carbide - Reaction Bonded SiC Silicon Carbide SiC Silicon Nitride - Hot-pressed Si3N4 Silicon Nitride - Reaction Bonded Si3N4 Silicon Nitride Si3N4 Silicon Nitride / Aluminium Nitride / Aluminium Oxide Sialon® Titanium Diboride TiB2 Titanium Dioxide TiO2 99.6% Tungsten Carbide / Cobalt WC 94 / Co 6 Yttrium Oxide Y2O3 Zirconia - stabilised with Magnesia ZrO2 / MgO Zirconia - stabilised with Yttria ZrO2 / Y2O3 Zirconia - unstabilised ZrO2 99
Physical Properties
Apparent Porosity % 0       0   0   45 0 <3   42036 25 0 <1%   0 0 0 0 0 0   0 15-23   0.01   0     0    
Density g cm-3 3.9 2.7 3.1 3.3-3.5 2.7 3.05 2.95 3.25 2.65 2.86 2.45-2.52 2.52 1.9-2.2 2.1 2.52 3.4 2.6-3.2 2.2 3.98 3.985 2.18 3.15 3.1 3.2 3.11 2.4 3.44 3.24 4.5 4.05 14.95 5.03 5.74 5.9 6.1
Refractive Index           1.57 1.62     1.54               1.5-1.6 1.46   1.71-1.79 1.46                            
Useful Optical Transmission range                 500-3000nm                 450-700nm 180-2500nm 150-5500nm 200-5500nm 365-2500nm                            
Water Absorption - saturation % 0       0     0   0.07       14     Very Low 0 0 0 0                       0    
Electrical Properties
Dielectric Constant   9.0-10.1       5.2 at 9.4GHz 5.7 at 9.4GHz 7.3 9.2   6.5-7.5     4.3   5.9   6.0-6.6 3.8 7.5-11.5 7.5-11.5 3.8 40     10 10       80-100          
Dielectric Strength kV mm-1 13058           40 15   41913     40-200   40   40-200 25-40 15-50 15-50                              
Volume Resistivity at 25C Ohm.cm >1014           1.8 x 1013 >1014   >1014 0.1-10   1011-1014   >1014   1012 1018 1014 >1014 1014 103-105 102-103   1012-1015 >107   1012-1017 15 1013-1018 2x10-6        
Thermal Properties
Melting Point C 2100 1790   2000       2200     2450 2450           1715 2050 2050 1715 2650-2950   2650-2950         3000 1850   2400   2700 2650
Specific Heat at 25C J K-1 kg-1 850-900 1050 at 1090C   1000 1100 1000 at 500C   800   1020-1120 950   800-2000   790   50 670-740 750 750 750 670-710 1100   680-800 690   620-710     200-480   400-500 400-500  
Sublimation Point C         1800 1800   2500         2600-2800                       1900   1900                
Thermal Conductivity at 20C W m-1 K-1 26-35           100 180   260-300 30-90   15-50   1.5   0.5-7 1.46 35-40 35-40 1.2-1.4 90-160 150-200   15-43 42644   20 50-70 2.5-5.0 60-80 37598 1.5-2.5 2.5  
Thermal Expansivity, 20-1000C x10-6 K-1 8       3 5 5.2 4.4-5.3 5 8.4-9.0 5.6   1.0-36 1.98 13   13394 0.54 5.8 5.8 0.5-0.75 4.5 4.3-4.6   3.3 3.3   3.3-3.7 37443 37537 4.6-5.0 8.1 37534 10  
Upper Continuous Use Temperature C 1700 1260 1600 1600 1200-1400 1350-1650 1000 - 1900 1000-1800 900 1800-1900 600-800 600-800 950-2500 1050 800-1000 2200 500-600 1100-1400 1800-1950 1800-1950 900-1200 1500-1650 1350   1100-1650 1200-1500   1000 1000-2000       1000 2200 2200
Mechanical Properties
Compressive Strength MPa 2200-2600           1000     1550-1850 1400-3400 200-300 30-120   345   190-280 1100 2100 2100   1000-1700 2000-3500   2000-3500 550-650   >3500   800-1000 5300-7000   1500-2000 2000  
Hardness - Knoop kgf mm-2 2100                   2800-3500   280         820 2000 2000                              
Hardness - Vickers kgf mm-2 1500-1650           560 1100   1100-1300 3200       400   2-3 Mohs 1000 2500-3000 1600-1800 490 2400-2800 2500-3500 2500 1700-2200 800-1000   1650-1800 3000 980 1550   1200 1250  
Poisson's Ratio                                                           0.18-0.20            
Shear Strength MPa 330             450   180-250     45992       215-265 70       210-380     480-960 190-240     300-600       414    
Tensile Modulus GPa 300-400     100-300 140 185 160     340-400 440-470   20-35   67     72-74 350-390 350-390 65-75 200-500 410   280-310 170-220   280-300 520-570 250-300 600   200 200  
Chemical Resistance
Acids - concentrated Good Fair-Good   Good Fair Fair   Poor Fair Poor Fair   Fair Fair Poor   Fair Good Good Good Good Good Good   Fair Fair   Good Fair Fair     Fair    
Acids - dilute Good Good   Good Good Good Fair Fair Good Fair Good   Fair Fair Fair   Good Good Good Good Good Good Good   Good Good   Good Good Good     Good    
Alkalis Good Fair   Good Poor-Fair Poor-Fair Poor Fair Good Fair Fair   Fair Poor Fair   Good Fair Good Good Fair Good-Poor Fair   Good-Poor Fair   Fair Fair Poor     Good-Poor    
Halogens Good     Good           Fair Fair   Poor Fair       Good Good Good Good Good-Poor Fair   Good Good     Good       Fair    
Metals Good     Good Good     Good   Good Fair   Good Good   Good   Fair Good Good Fair Fair Fair   Fair Fair     Good Poor     Good-Fair