# Fused Silica vs. SiAlON

Fused silica belongs to the glass and glass-ceramics classification, while SiAlON belongs to the non-oxide engineering ceramics. There are 21 material properties with values for both materials. Properties with values for just one material (7, in this case) are not shown.

For each property being compared, the top bar is fused silica and the bottom bar is SiAlON.

Metric UnitsUS Customary Units

## Mechanical Properties

Compressive (Crushing) Strength, MPa | 1100 | |

2620 |

Elastic (Young's, Tensile) Modulus, GPa | 73 | |

290 |

Flexural Strength, MPa | 67 | |

680 |

Knoop Hardness | 570 | |

1700 |

Poisson's Ratio | 0.17 | |

0.23 |

Shear Modulus, GPa | 31 | |

120 |

Tensile Strength: Ultimate (UTS), MPa | 50 | |

190 |

## Thermal Properties

Maximum Temperature: Mechanical, °C | 1080 | |

1200 |

Specific Heat Capacity, J/kg-K | 720 | |

880 |

Thermal Conductivity, W/m-K | 1.4 | |

19 |

Thermal Expansion, µm/m-K | 0.5 | |

3.6 |

## Electrical Properties

Dielectric Constant (Relative Permittivity) At 1 MHz | 3.8 | |

9.3 |

Dielectric Strength (Breakdown Potential), kV/mm | 30 | |

8.3 |

Electrical Resistivity Order of Magnitude, 10^{x} Ω-m |
14 | |

14 |

## Otherwise Unclassified Properties

Density, g/cm^{3} |
2.2 | |

3.3 |

## Common Calculations

Stiffness to Weight: Axial, points | 18 | |

50 |

Stiffness to Weight: Bending, points | 63 | |

67 |

Strength to Weight: Axial, points | 6.3 | |

16 |

Strength to Weight: Bending, points | 14 | |

22 |

Thermal Diffusivity, mm^{2}/s |
0.85 | |

6.4 |

Thermal Shock Resistance, points | 97 | |

13 |