Industrial Silicon Nitride Rod with High Thermal Conductivity and Compressive Strength for Corrosion Resistant Applications
Silicon Nitride Rod is a premium ceramic material widely used in the metallurgical industry due to its exceptional high-temperature performance. With excellent thermal shock resistance, superior creep and oxidation resistance, low thermal conductivity, and high wear resistance, silicon nitride rods withstand demanding conditions in most industrial applications.
There are five primary production methods for Silicon Nitride Welding Rods: SRBSN, GPSN, HPSN, HIP-SN, and RBSN. Each method results in slightly different application characteristics and working materials. Among these, GPSN is the most commonly used method for producing silicon nitride components.
The use of ceramic rollers in bearings was originally developed to meet stringent operating requirements in advanced gas turbines. This technology has since expanded to machine tool spindles, motors, generators, and various other fields, accelerating the development of ceramic rolling body applications.
Hybrid rolling bearings with ceramic rollers are now used in many challenging applications, including railways and the renewable energy industry, particularly in wind turbines where they are deployed in large numbers.
- High rigidity, strength, and hardness
- Low density (3.26g/cm³) - 60% lighter than steel
- Reduced wear and noise
- High mechanical strength
- High temperature resistance (up to 1000°C)
- Low thermal conductivity
- Low linear expansion coefficient (3.2 × 10⁻⁶/K)
- Excellent thermal shock resistance
- Non-magnetic and electrical insulation
- Strong corrosion resistance
- Self-lubricating properties
- Suitable for vacuum and high-temperature environments
| Property | Item | 99% Alumina | 99.8% Alumina | Zirconia Ceramics | Silicon Nitride | Silicon Carbide | Unit |
|---|---|---|---|---|---|---|---|
| Mechanical Characteristics | Color | light yellow | White | Ivory | Black Grey | Black | |
| Bulk Density | 3.85 | 3.93 | 6.02 | 3.2 | 3.16 | g/cm³ | |
| Water Absorption | 0 | 0 | 0 | 0 | 0 | % | |
| Bending Strength | 310 | 370 | 800 | 750 | 450 | MPa | |
| Compressive Strength | 2,400 | 2500 | 3000 | 3800 | 3900 | MPa | |
| Elastic Modulus | 340 | 390 | 200 | 290 | 420 | GPa | |
| Fracture Toughness | 3~4 | 4 | 8 | 7 | 3.5 | MPa·m¹/² | |
| Vickers Hardness | 1,600 | 1850 | 1200 | 1700 | 2800 | HV 0.5 | |
| Thermal Characteristics | Coefficient of Linear Thermal Expansion | 7~8 | 7~8 | 10 | 2 | 3.7 | 10⁻⁶ K⁻¹ |
| Thermal Conductivity | 29 | 32 | 3 | 20 | 160 | W/m·K | |
| Thermal Shock Resistance | 200 | 280 | 300 | 750 | - | ΔT °C | |
| Max Working Temperature | 1,600 | 1700 | 1000 | 1300 | 1950 | °C |
- Advanced ceramic tubes
- Bearing rollers
- Ceramic cutting materials
- Cryogenic bearing rollers
- Nozzles
- Seal rings
- Tube forming tools
- Mechanical engineering special applications
- Thermal properties: High-temperature refractory substance with no melting point, decomposes at about 1900°C under normal pressure
- Strong creep resistance under high pressure
- Softening point of reaction sintered silicon nitride without binder can reach 1800°C
- Good thermal conductivity
- Small thermal expansion coefficient
- Excellent electrical insulation performance with small dielectric coefficient and high breakdown voltage
- Oxidation resistance: Does not react with oxygen in dry atmosphere below 800°C
- Molten metal corrosion resistance: Resists infiltration and corrosion from elemental metal melts (except copper)
- Resistance to acid, alkali and salt corrosion: Easily soluble in hydrofluoric acid, but resistant to dilute acids
- Excellent high temperature strength with minimal attenuation at 1200°C compared to room temperature strength
- Very low high temperature creep rate due to strong covalent bonds
- High hardness, second only to superhard materials like diamond, cubic BN, and B₄C
- Low friction coefficient with self-lubricating properties similar to oiled metal surfaces
Sintered silicon nitride is primarily used in the automotive industry for engine components. Applications include lower wear rocker pads in spark ignition engines, turbochargers for reduced inertia and engine lag, and waste gas control valves for improved acceleration.
Silicon nitride ceramics offer superior impact resistance compared to other ceramics, making them ideal for performance bearings. NASA's space shuttles utilized silicon nitride bearings in their main engines. These bearings are found in high-end automotive applications, industrial bearings, wind turbines, motorsports, bicycles, roller skates, and skateboards.
Bulk monolithic silicon nitride serves as an excellent material for cutting tools due to its hardness, thermal stability, and wear resistance. It is particularly recommended for high-speed machining of cast iron, hard steel, and nickel-based alloys.
Used as insulators and chemical barriers in integrated circuit manufacturing, silicon nitride provides superior electrical isolation and serves as etch masks in bulk micromachining. As a passivation layer for microchips, it outperforms silicon dioxide as a diffusion barrier against water molecules and sodium ions.
| Properties | Units | Silicon Nitride |
|---|---|---|
| Mechanical Properties | ||
| Density | g/cm³ | 3.2 |
| Porosity | % | 0 |
| Flexural Strength | MPa | 830 |
| Compressive Strength | MPa | 2500 |
| Elastic Modulus | GPa | 310 |
| Poisson's Ratio | / | 0.27 |
| Hardness | kg/mm² | 1580 |
| Fracture Toughness KIC | MPa·m¹/² | 6.1 |
| Thermal Properties | ||
| Heat Conductivity | W/m·K | 30 |
| Coefficient of Thermal Expansion | 10⁻⁶/K | 3.3 |
| Max Use Temperature | °C | 1400 |
| Electrical Properties | ||
| Dielectric Constant | / | 8 |
| Volume Resistivity | Ω·cm | >10¹⁴ |
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