Introduction
Silicon nitride ceramics (Si₃N₄) are advanced non-oxide ceramics valued for their mechanical toughness, thermal stability, and chemical resistance. Available in grades like Gas Pressure Sintered (GPS) Si₃N₄ and Hot-Pressed Silicon Nitride (HPSN Si₃N₄), these materials provide a spectrum of properties for material science research. This article examines the key properties of silicon nitride ceramics, supported by a comparative table, to highlight their significance in research applications.
Properties of Silicon Nitride Ceramics
Silicon nitride ceramics exhibit various properties that make them ideal for material science studies. Below are their key characteristics:
- High Toughness: Fracture toughness ranges from 6.5 MPa m¹/² (GPS Si₃N₄) to 7 MPa m¹/² (HPSN Si₃N₄), suitable for studying crack resistance.
- Thermal Stability: Thermal conductivity from 25 W/mK (GPS Si₃N₄) to 30 W/mK (HPSN Si₃N₄), ideal for heat transfer research.
- Electrical Insulation: Volume resistivity exceeds 10¹⁴ ohm-cm, supporting studies in electrical insulation.
- Chemical Stability: Minimal weight loss in chemicals (e.g., 0.1 mg/cm² in H₂SO₄), perfect for corrosion studies.
- Low Thermal Expansion: CTE of 3.2 × 10⁻⁶/K ensures dimensional stability under thermal stress.
Detailed Properties Table
The table below compares the properties of silicon nitride ceramics across GPS Si₃N₄ and HPSN Si₃N₄ grades.
Property | GPS Si₃N₄ | HPSN Si₃N₄ |
Main Characteristics |
|
|
Color | Black | Black |
Main Applications | Wear resistance, corrosion resistance | Wear resistance, corrosion resistance |
Characteristics | High toughness, insulation, corrosion resistance | High toughness, insulation, corrosion resistance |
Mechanical Properties | ||
Bulk Density (g/cm³) | 3.2 | 3.25 |
Water Absorption (%) | 0 | 0 |
Vickers Hardness (GPa) | 15 | 16 |
Flexural Strength (MPa) | 800 | 900 |
Compressive Strength (MPa) | 3000 | 3500 |
Young’s Modulus (GPa) | 300 | 320 |
Poisson’s Ratio | 0.27 | 0.27 |
Fracture Toughness (MPa m¹/²) | 6.5 | 7 |
Thermal Properties | ||
Thermal Conductivity (W/mK) | 25 | 30 |
Thermal Shock Resistance (ΔT°C) | 700 | 800 |
Coefficient of Thermal Expansion (10⁻⁶/K) | 3.2 | 3.2 |
Electrical Properties | ||
Volume Resistivity (ohm-cm) | >10¹⁴ | >10¹⁴ |
Dielectric Constant (1 MHz) | 8 | 8 |
Dielectric Strength (kV/mm) | 18 | 18 |
Chemical Properties | ||
Weight Loss in H₂SO₄ (mg/cm²) | 0.1 | 0.1 |
Weight Loss in NaOH (mg/cm²) | 0.2 | 0.2 |
Table Notes:
- Mechanical Properties: HPSN Si₃N₄’s higher toughness (7 MPa m¹/²) and hardness (16 GPa) offer insights into processing effects.
- Thermal Properties: HPSN Si₃N₄’s superior thermal shock resistance (800°C) supports thermal behavior studies.
- Chemical Stability: Both grades provide a benchmark for corrosion resistance research.
Conclusion
Silicon nitride ceramics, with their diverse properties across GPS Si₃N₄ and HPSN Si₃N₄ grades, are ideal for material science research. Their toughness, thermal stability, and chemical resistance provide valuable insights into the effects of processing on ceramic performance.
Heeger Materials is a leading manufacturer and supplier of high-quality silicon nitride ceramic products in forms of plates, sheets, rods, tubes, crucibles, substrates, and customized parts, offering customized solutions for various industrial and research applications.