Silicon nitride (Si₃N₄)

Silicon nitride (Si₃N₄) is an advanced engineering ceramic renowned for its exceptional combination of mechanical, thermal, and electrical properties. This silicon nitride material has become a critical solution in industries demanding high strength, wear resistance, thermal stability, and reliability under extreme conditions. Composed of silicon and nitrogen atoms forming a strong covalent bond structure, silicon nitride ceramic offers performance characteristics far superior to traditional metals and other ceramics, making it indispensable in aerospace, automotive, semiconductor, and medical applications.

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Key Advantages of Silicon Nitride Material

Silicon nitride has a lower coefficient of thermal expansion than other technical ceramics, resulting in excellent thermal shock resistance. Its exceptional hardness exceeds the high-temperature resistance of most metals, and it also exhibits excellent oxidation resistance. This allows it to withstand the rigors of the most demanding high-temperature, high-load applications.

With a hardness that far surpasses steel, silicon nitride is incredibly resistant to abrasion and wear, making it ideal for friction-heavy applications. This also answers the question, "Is silicon nitride harder than steel?" – Yes, it is significantly harder.

Silicon nitride ceramic can withstand extreme temperature changes without cracking or degradation, making it suitable for high-temperature environments.

It maintains its mechanical strength and toughness at elevated temperatures, unlike many metals.

This silicon nitride material is highly resistant to a wide range of corrosive chemicals, including acids and molten metals.

Silicon nitride thermal conductivity is low, making it an excellent thermal insulator in various applications.

Its lightweight nature is a significant advantage in applications where weight reduction is crucial.

Industrial Applications of Silicon Nitride

Silicon nitride (Si₃N₄) ceramics are widely used across multiple industries thanks to their high strength, excellent wear resistance, outstanding thermal shock resistance, and reliable electrical insulation. Below is a summary of the key application fields:

  • Engine Components: Applied in turbocharger rotors, valve seats, and piston rings to improve wear resistance and extend service life.

  • Bearings and Balls: Silicon nitride balls are used in high-speed, high-load bearings, reducing weight and enhancing reliability.

  • High-Temperature Structural Parts: Utilized in gas turbine blades, sealing rings, and hot-section components, maintaining stability under extreme thermal and mechanical conditions.

  • Lightweight Components: Its low density makes it an ideal replacement for metals, contributing to overall weight reduction.

  • Insulating Layers and Thin Films: With a stable refractive index of silicon nitride, it is used as an insulating, protective, and optical coating material.

  • Substrates and Carriers: Silicon nitride substrates provide high reliability in power electronics and microelectronic devices.

  • Cutting Tools and Mechanical Seals: Its high hardness and wear resistance make it suitable for high-speed cutting, sealing rings, and pump components.

  • Heat Treatment and Metallurgy: Employed in high-temperature fixtures, crucibles, and supporting parts, thanks to its excellent thermal shock resistance.

  • Igniters: Silicon nitride igniters are used in gas furnaces, gas turbines, and power generation equipment for reliable ignition.

  • New Energy Applications: Shows potential in hydrogen energy, fuel cells, and nuclear energy technologies.

  • Applications of Advanced Ceramics in the Chemical, Plastics & Rubber 2
  • Applications of Advanced Ceramics in the Chemical, Plastics & Rubber
  • Applications of Advanced Ceramics in General Manufacturing
  • Applications of Advanced Ceramics in the Industrial Machinery
  • Applications of Advanced Ceramics in the Semiconductor & Electronic

Available Grades of Silicon Nitride

At Great Ceramic, china silicon nitride ceramics are offered in several grades to match different engineering needs:

Gas Pressure Sintered Silicon Nitride Ceramics (GPSN)

Great Ceramic's gas pressure sintered silicon nitride ceramics (GPSN) are high-performance silicon nitride materials produced under high-temperature nitrogen atmosphere and pressure. Compared to hot-pressed silicon nitride (HPSN), the gas pressure sintering process enables near-net-shape sintering and the production of large, complex-shaped parts while maintaining excellent mechanical and thermal properties, making it more widely applicable in industrial applications. Known for its balanced performance, affordable cost, and wide range of applications, GPSN is currently one of the most widely used types of silicon nitride ceramics.

Material Characteristics

  • High Strength and Toughness: Flexural strength typically reaches 600–900 MPa, fracture toughness is approximately 6–8 MPa·m², and exhibits good impact resistance and mechanical fatigue resistance.
  • Excellent Heat Resistance and Thermal Stability: It can be used stably up to 1000–1200°C in air and 1400–1600°C in an inert atmosphere. Its low coefficient of thermal expansion (~3×10⁻⁶/K) and high thermal shock resistance enable it to withstand rapid thermal cycling.
  • Wear and Corrosion Resistance: It exhibits excellent corrosion resistance against most molten metals and chemical media. Its high hardness (~15–20 GPa) makes it suitable for use in wear-resistant components.
  • Electrical Insulation: Its volume resistivity can reach 10¹³–10¹⁴ Ω·cm at room temperature, maintaining stable insulation properties even at high temperatures.
  • Cost-Effectiveness: Compared to hot-pressed silicon nitride, the gas pressure sintering process offers lower costs and higher production efficiency, enabling mass production and the manufacture of complex-shaped parts, while avoiding the shape and size limitations of hot pressing.

Typical Applications

  • Mechanical Engineering: High-speed bearings, gears, turbine rotors, mechanical seals, and other high-load friction components;
  • Automotive: Diesel engine turbocharger rotors, exhaust valves, and spark plug insulators;
  • Energy & Power: Gas turbine hot-end components and heat-resistant insulating supports;
  • Metallurgy & Chemical Engineering: Molten metal contact components (such as aluminum nozzles) and corrosion-resistant linings;
  • Electronics: Insulating substrates, heat sinks, and high-frequency component supports.

Great Ceramic boasts comprehensive silicon nitride ceramic processing capabilities, offering a wide range of standardized silicon nitride ceramic rods and plates. Great Ceramic also provides a full suite of custom processing services tailored to customer needs, from complex part molding to precision grinding and polishing. This ensures our products meet demanding industrial application requirements for strength, wear resistance, and reliability. These products are widely used in bearings, pistons, seals, engine components, and other high-performance structural parts.

Hot-pressed Silicon Nitride Ceramics (HPSN)

Hot-pressed silicon nitride (HPSN) ceramics offered by Great Ceramic are high-density structural ceramics produced through the simultaneous application of high temperature and uniaxial pressure. They are characterized by a dense microstructure, few defects, and properties approaching theoretical limits, resulting in the highest mechanical and thermal properties of all silicon nitride ceramics. Due to the complex preparation process and high cost, hot-pressed silicon nitride is primarily used in high-end and specialized applications.

Material Characteristics

  • Ultra-high mechanical properties

    • Flexural strength reaches 800–1000 MPa, significantly higher than conventional sintered silicon nitride.
    • Fracture toughness is 7–9 MPa·m¹ᐟ², providing excellent impact resistance.
    • High hardness (~20 GPa) and excellent wear resistance.

  • Excellent thermal properties

    • Thermal conductivity reaches 60–90 W/m·K, significantly higher than that of gas-pressure-sintered silicon nitride (20–30 W/m·K).
    • Low thermal expansion coefficient (~3×10⁻⁶/K) and excellent thermal shock stability.
    • Sustainable for extended periods of use at temperatures exceeding 1400°C in an inert atmosphere.

  • Dense microstructure

    • The hot pressing process ensures minimal glass phase at the grain boundaries, near-zero porosity, and uniform and stable overall material properties.

  • Disadvantages and Limitations

    • Forming is limited by molds and pressing directions, making it difficult to produce large or complex-shaped parts.
    • High production costs make it unsuitable for large-scale adoption.

Application Areas

  • Aerospace: Turbine blades, nozzles, and guide components;
  • Military: High-temperature protection components and armor composites;
  • Nuclear and Energy: High-temperature heat exchangers and gas turbine components;
  • Precision Industry: High-precision bearings, cutting tools, and measuring tools;
  • Electronics: Select high-power insulation and heat dissipation substrates.

Hot-pressed silicon nitride ceramics, with their exceptional mechanical and thermal properties, represent the "performance ceiling" of the silicon nitride system, making them suitable for critical core components under extremely demanding conditions. However, due to limited processing dimensions and high costs, they are primarily used in applications requiring the highest performance.

Key Properties of silicon nitride material

Great Ceramic offers a variety of silicon nitride material for customers to choose from. The following values are typical material properties and may vary depending on product configuration and manufacturing process. For more details, please feel free to contact us.

Mechanical Properties

Properties Unit GPSN HPSN HTCSNS
Colour —— Gray or black Gray or black Gray or black
Density g/cm³ 3.2 3.3 3.25
Hardness GPa 15 16 15
Compressive Strength MPa 2500 3000 2500
Flexural Strength MPa 700 900 600~800
Fracture Toughness MPa・m1/2 5~7 6~8 6~7
Modulus of Elasticity GPa 300 300 300~320
Poissons Ratio —— 0.25 0.28 0.25

Thermal Properties

Properties Unit GPSN HPSN HTCSNS
Maximum Use Temperature ℃(No load) 1100 1300 1100
Thermal Conductivity @ 25°C W/(m・K) 15~20 20~25 80~100
Thermal Expansion a at 40–400°C 1 x 10-6/°C 3 3.1 3
Specific Heat J/(kg・K) 660 650 680
Thermal Shock Resistance ℃(Put in water) 550 800 ——

Electrical Properties

Properties Unit GPSN HPSN HTCSNS
Dielectric Constant 1MHz 6~8 8 7.8
Dielectric Strength(6.35mm) ac-kV/mm 15 17 ——
Volume Resistivity @ 25°C Ω・cm ＞1014 ＞1014 ＞1014
Volume Resistivity @ 500°C Ω・cm ＞1010 ＞1010 ＞1010

*At not too high temperature, Si3N4 has high strength and impact resistance, but it will be damaged with the increase of use time above 1200℃, reducing its strength, and it is more prone to fatigue damage above 1450℃, so Si3N4 The operating temperature generally does not exceed 1300 ℃.

Silicon nitride parts case

Silicon nitride ceramic (Si₃N₄) is valued for its exceptional mechanical strength, superior fracture toughness, low density, excellent thermal shock resistance, and outstanding wear performance, making it one of the most reliable materials for demanding engineering applications. Below are some of the most common and impactful use cases of silicon nitride ceramic parts across multiple industries:

  • Precision bearing balls
  • Rolling elements and bearing races
  • Turbine blades and engine components
  • Cutting tools and wear-resistant inserts
  • Nozzles for molten metal and chemical processing
  • Pump plungers and valve components
  • Rotors and shafts for high-speed machinery
  • Semiconductor processing fixtures and substrates
  • Heat exchanger and thermal management components
  • Igniters and heating elements
  • Custom mechanical seals and bushings
Precision bearing balls
Premium Silicon Nitride Bearings
Hot-Pressed Silicon Nitride Substrates
Silicon Nitride Ceramic Nozzle
Custom Silicon Nitride Parts
Silicon nitride ceramic guide rollers
Silicon nitride ceramic wear-resistant bushing
High temperature resistant silicon nitride ceramic protection tube

Silicon Nitride Ceramic Machining

Silicon nitride (Si₃N₄) ceramics are among the hardest technical ceramics, requiring advanced machining techniques to achieve precise geometries. Great Ceramic offers industry-leading silicon nitride machining capabilities, delivering accuracy, durability, and consistency for mission-critical applications.

We use diamond grinding, multi-axis CNC machining, precision lapping, and ultra-fine polishing to achieve micron-level tolerances and exceptional surface finishes. Our capabilities support high-performance components, including silicon nitride ceramic rods, precision bearing balls, substrates, and turbine parts.

Additionally, we provide metallization, brazing, assembly services, and surface treatments, enabling seamless integration of silicon nitride material into advanced systems. As a leading China silicon nitride ceramics manufacturer, we combine cutting-edge technology and deep expertise to deliver high-quality, customized ceramic solutions for global markets.

Precision Ceramic CNC Machining

CNC Grinding & Milling

CNC milling, turning, and grinding to micron-level tolerances.

Ceramic Grinding & Polishing

Lapping & Polishing

Surface polishing for smooth finishes and optical-grade surfaces.

Technical Ceramic Laser Cutting

Ceramic Laser Cutting

Laser drilling and cutting for complex geometries.

Ceramic and Metal Brazed Assemblies

Metallization & Welding

Metallization (Mo/Mn, W) for ceramic-to-metal brazing.

Frequently Asked Questions

Yes, silicon nitride is an advanced technical ceramic composed of silicon and nitrogen atoms (Si₃N₄) with a strong covalent bond structure that gives it exceptional mechanical and thermal properties.

No, silicon nitride is a ceramic material, not a metal. It does not contain metallic bonds though it may contain trace metal elements as sintering aids.

Silicon nitride is an excellent electrical insulator with volume resistivity >10¹⁴ Ω·cm, even at elevated temperatures.

Silicon nitride balls are primarily used in precision bearings for high-speed applications such as machine tool spindles, dental handpieces, aerospace systems, and high-performance automotive applications. They offer superior wear resistance, low density, and electrical insulation compared to steel balls.

Silicon nitride (Si₃N₄) is an advanced engineering ceramic material renowned for its exceptional combination of high strength, fracture toughness, thermal shock resistance, and wear resistance in demanding applications.

Silicon nitride is used in a wide range of applications including bearings, cutting tools, semiconductor processing components, automotive engine parts, medical implants, and electronic substrates.

Silicon nitride balls are typically manufactured through processes including powder preparation, forming, high-temperature sintering (often with sintering aids), and precision grinding and polishing to achieve sphericity and surface finish.

While this article focuses on structural components, silicon nitride igniters utilize the material's excellent thermal shock resistance and electrical insulation properties to withstand repeated heating and cooling cycles.

No, silicon nitride is primarily used as an insulator in electronic applications, though its material properties make it valuable as a dielectric layer in semiconductor devices.

Silicon nitride features primarily covalent bonding between silicon and nitrogen atoms, which contributes to its high strength, hardness, and thermal stability.

The Vickers hardness of silicon nitride ceramics is typically in the range of 14-18 GPa (approximately 1500-1800 HV), depending on the manufacturing process and additive composition.

Yes, silicon nitride is much harder than steel. The Vickers hardness of silicon nitride is 14-18 GPa, while the hardness of steel is usually only 2-3 GPa, which means that silicon nitride is much harder than steel.

Despite its many advantages, silicon nitride also has some limitations: it is somewhat brittle and needs to avoid sharp impact or stress concentration; the processing cost is high and diamond tools are required for precision processing; connection with metal parts requires special welding technology or mechanical interlocking.

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Why Choose Great Ceramic's Silicon Nitride

  • High Performance: Engineered Si₃N₄ ceramics with unmatched toughness, strength, and thermal shock resistance.
  • Custom Solutions: From standard silicon nitride balls to complex, precision-engineered components.
  • Advanced Machining: Multi-axis CNC grinding and diamond tooling for micron-level accuracy.
  • Strict Quality Assurance: Comprehensive testing ensures every batch meets international standards.
  • Full-Service Support: From material design and selection to metallization, brazing, and assembly.

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