What are silicon nitride (Si₃N₄) ceramics?

Silicon Nitride (Si₃N₄) is an advanced engineering ceramic known for its excellent mechanical, thermal and electrical properties. This silicon nitride material has become a key solution for industries requiring high strength, wear resistance, thermal stability and reliability under extreme conditions. Silicon nitride ceramics are composed of silicon and nitrogen atoms that form a strong covalent bonding structure that far exceeds the performance of traditional metals and other ceramics, making them indispensable for aerospace, automotive, semiconductor and medical applications.

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Silicon Nitride Ceramics-Advanced Ceramic Materials-Zihao Ceramics

Key Benefits of Silicon Nitride Materials

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

Silicon nitride is much harder than steel and has excellent wear resistance, making it ideal for applications with high friction. This answers the question, “Is silicon nitride harder than steel?” The question - yes, it is much harder.

Silicon nitride ceramics can withstand extreme temperature changes without cracking or degradation and are suitable for high temperature environments.

Unlike many metals, it retains its mechanical strength and toughness at high temperatures.

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

The low thermal conductivity of silicon nitride makes it an excellent thermal insulator for a variety of applications.

Its lightweight nature offers significant advantages in applications where weight reduction is critical.

Industrial Applications of Silicon Nitride

Silicon nitride (Si₃N₄) ceramics are used in a wide range of industries due to their high strength, excellent wear resistance, outstanding thermal shock resistance and reliable electrical insulation. The following is an overview of their main areas of application:

  • Engine components: applied to 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 to reduce weight and increase reliability.

  • High Temperature Structural Parts: Used in gas turbine blades, seal rings and hot section components to maintain stability under extreme thermal and mechanical conditions.

  • Lightweight components: Its low density makes it an ideal alternative to metal, helping to reduce overall weight.

  • Insulation and film:silicon nitrideHas a stable refractive index and can be used as an insulating, protective and optical coating material.

  • Substrates and carriers::Silicon Nitride SubstratesProvides high reliability for power electronics and microelectronic devices.

The

  • Cutting tools and mechanical seals: Their high hardness and wear resistance make them suitable for high-speed cutting, seals and pump components.
  • Heat treatment and metallurgy: due to its excellent thermal shock resistance, it can be used in high-temperature devices, crucibles and support parts.

  • Igniter:Silicon nitride ignitors are used in gas furnaces, gas turbines and power generation equipment for reliable ignition.
  • New energy applications:Demonstrate the potential of hydrogen, fuel cell, and nuclear energy technologies.

Available grades of silicon nitride

To Good Ceramics offers a wide range of grades of Chinese silicon nitride ceramics to meet different engineering needs:

Gas Pressure Sintered Silicon Nitride Ceramics (GPSN)

Great Ceramic's Gas Pressure Sintered Silicon Nitride (GPSN) ceramics are high performance silicon nitride materials produced under high temperature nitrogen atmosphere and high pressure. Compared to hot pressed silicon nitride (HPSN), the pneumatic sintering process allows for 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 price, and wide range of applications, GPSN is one of the most widely used types of silicon nitride ceramics available.

Material Properties

  • High strength and toughness: Flexural strength generally reaches 600-900MPa, fracture toughness is about 6-8MPa-m², with good impact resistance and resistance to mechanical fatigue.
  • Excellent heat resistance and thermal stability: stable in air up to 1000-1200°C and in inert gases up to 1400-1600°C. Its low coefficient of thermal expansion (~3×10-⁶/K) and high resistance to thermal shocks enable it to withstand rapid thermal cycling.
  • Resistance to wear and corrosion: It shows excellent resistance to most molten metals and chemical media. Its high hardness (approx. 15-20 GPa) makes it suitable for the manufacture of wear-resistant components.
  • Electrical insulation: volume resistivity up to 10¹³-10¹⁴Ω-cm at room temperature, even at high temperatures can maintain stable insulation properties.
  • Cost-effectiveness: Compared to hot-pressed silicon nitride, the pneumatic sintering process is less costly and more productive, allowing for high-volume production and the manufacture of parts with complex shapes while avoiding the shape and size constraints of hot pressing.

typical application

  • 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 and Power: Gas turbine hot end components and heat-resistant insulating supports;
  • Metallurgy and chemical industry: molten metal contact parts (e.g. aluminum nozzles) and corrosion-resistant linings;
  • Electronics: insulated substrates, heat sinks and high frequency component supports.

Great Ceramic has comprehensive silicon nitride ceramic machining capabilities, offering a wide range of standardized silicon nitride ceramic rods and plates. great Ceramic also offers a full suite of custom machining services to meet our customers' needs, from molding of complex parts to precision grinding and polishing, to ensure that our products meet the stringent requirements of strength, wear resistance, and reliability in industrial applications. These products are used in bearings, pistons, seals, engine components and other high performance structural parts.

Hot pressed silicon nitride ceramics (HPSN)

Great Ceramic offers Hot Pressed Silicon Nitride (HPSN) ceramics, which are high-density structural ceramics made by simultaneously applying high temperature and uniaxial pressure. They have a dense microstructure, very few defects, and properties close to the theoretical limits, resulting in the highest mechanical and thermal properties of all silicon nitride ceramics. Due to the complex and costly preparation process, hot-pressed silicon nitride is mainly used for high-end and specialized applications.

Material Properties

  • Ultra-high mechanical properties
  • The flexural strength reaches 800 to 1000 MPa, which is significantly higher than that of conventional sintered silicon nitride.
  • Fracture toughness of 7-9 MPa-m¹ᐟ² with excellent impact resistance.
  • High hardness (~20 GPa) and excellent wear resistance.
  • Excellent thermal performance
  • The thermal conductivity reaches 60-90 W/m-K, which is significantly higher than that of air-pressure sintered silicon nitride (20-30 W/m-K).
  • Low coefficient of thermal expansion (~3×10-⁶/K) and excellent thermal shock stability.
  • Can be used continuously for long periods of time at temperatures in excess of 1400°C in an inert atmosphere.
  • Dense microstructure
  • The hot pressing process ensures minimal glass phases at grain boundaries, near-zero porosity, and uniform and stable overall material properties.
  • Disadvantages and limitations
  • Forming is limited by the mold and pressing direction, 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 guiding components;
  • Military: high-temperature protective components and armor composites;
  • Nuclear and energy: high temperature heat exchangers and gas turbine components;
  • Precision industry: high-precision bearings, cutting tools, gauges;
  • Electronics: Selection of high power insulated, heat dissipating substrates.

Hot-pressed silicon nitride ceramics represent the “upper performance limit” of silicon nitride systems due to their excellent mechanical and thermal properties, making them suitable for use in critical core components under extremely harsh conditions. However, due to the limited size and high cost of processing, they are mainly used in applications with very high performance requirements.

Key properties of silicon nitride materials

Zhihao Ceramics offers a wide range of silicon nitride materials for customers to choose from. The values below are typical material properties and may vary depending on product configuration and manufacturing process. Please feel free to contact us for more details.

mechanical property

characterization staircase (for residential buildings) GPSN HPSN HTCSNS
color -- Gray or black Gray or black Gray or black
intensity g/cm3 3.2 3.3 3.25
durometer gigapascal (unit of pressure) 15 16 15
compressive strength megapascal (unit of pressure) 2500 3000 2500
bending strength megapascal (unit of pressure) 700 900 600~800
Fracture toughness megapascal (unit of pressure)1/2 5~7 6~8 6~7
modulus of elasticity gigapascal (unit of pressure) 300 300 300~320
Poisson's ratio -- 0.25 0.28 0.25

thermal performance

characterization staircase (for residential buildings) GPSN HPSN HTCSNS
Maximum operating temperature ℃ (no load) 1100 1300 1100
Thermal conductivity at 25°C W/(M. Kelvin) 15~20 20~25 80~100
Thermal expansion at 40-400°C 1× 10-6 /C 3 3.1 3
specific heat Joule/(kg/Kelvin) 660 650 680
thermal shock resistance ℃ (into the water) 550 800 --

Electrical Performance

characterization staircase (for residential buildings) GPSN HPSN HTCSNS
dielectric constant 1 MHz 6~8 8 7.8
Dielectric strength (6.35mm) AC - kV/mm 15 17 --
Volume resistivity @ 25°C Ω・cm ＞10 14 ＞10 14 ＞10 14
Volume resistivity @ 500°C Ω・cm ＞10 10 ＞10 10 ＞10 10

* At not too high temperatures, Si3N4 has high strength and impact resistance, but above 1200 ℃ with the increase in the use of time will be damaged, reducing its strength, more likely to fatigue damage above 1450 ℃, so the use of Si3N4 temperature is generally not more than 1300 ℃.

Silicon Nitride Parts Box

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

  • Precision Bearing Balls
  • Rolling bodies and housing rings
  • Turbine blades and engine components
  • Cutting tools and wear-resistant inserts
  • Nozzles for molten metal and chemical processing
  • Pump Plunger and Valve Assemblies
  • Rotors and shafts for high-speed machinery
  • Semiconductor Processing Fixtures and Substrates
  • Heat exchangers and thermal management components
  • Ignitors and heating elements
  • Customized mechanical seals and bushings

Silicon Nitride Ceramic Processing

Silicon Nitride (Si₃N₄) ceramics are among the hardest industrial ceramics and require advanced machining techniques to achieve precise geometries. Good Ceramics has industry-leading silicon nitride machining capabilities that provide precise, durable and consistent results for mission-critical applications.

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

In addition, we offer metallization, brazing, assembly and surface treatment services that enable seamless integration of silicon nitride materials into advanced systems. As a leading manufacturer of silicon nitride ceramics in China, we combine cutting-edge technology with in-depth expertise to provide high-quality customized ceramic solutions for the global market.

CNC grinding and milling

CNC milling, turning and grinding to micron tolerances.

Grinding and polishing

Surface polishing results in smooth surfaces and optical grade surfaces.

Laser processing of ceramic substrates

Ceramic Laser Cutting

For laser drilling and cutting of complex geometries.

Metal and Ceramic Brazed Assemblies - 600x600

Metallization and welding

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

common problems

Yes. Silicon nitride is an advanced technical ceramic consisting of silicon and nitrogen atoms (Si₃N₄) with a strong covalent bonding structure that gives it excellent mechanical and thermal properties.

No. Silicon nitride is a ceramic material, not a metal. It does not contain metal bonds, but may contain traces of metal elements as sintering aids.

Silicon nitride is an excellent electrical insulator with a volume resistivity greater than 10¹⁴ Ω-cm, even at high 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. Silicon nitride balls offer superior wear resistance, low density and electrical insulation compared to steel balls.

Silicon Nitride (Si₃N₄) is an advanced engineering ceramic material known for its outstanding 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 usually manufactured through a process of powder preparation, molding, 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 ignitors 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, although its material properties allow it to be used as a dielectric layer in semiconductor devices.

Silicon nitride is characterized primarily by 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 (about 1500-1800 HV), depending on the manufacturing process and additive composition.

Yes, silicon nitride is much harder than steel. Silicon nitride has a Vickers hardness of 14-18 GPa, whereas steel is usually only 2-3 GPa, which means that silicon nitride is much harder than steel.

Despite its many advantages, silicon nitride has some limitations: it is somewhat brittle and sharp impacts or stress concentrations need to be avoided; machining costs are high and precision machining with diamond tools is required; and special welding techniques or mechanical interlocks are needed to connect it to metal parts.

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Why choose Silicon Nitride from Good Ceramics?

  • HIGH PERFORMANCE: Engineered Si₃N₄ ceramics offer unmatched toughness, strength and thermal shock resistance.
  • Customized solutions: from standard silicon nitride balls to complex, precision-designed components.
  • Advanced machining technology: multi-axis CNC grinding and diamond tools for micron-level precision.
  • Strict Quality Assurance: Comprehensive testing ensures that every batch meets international standards.
  • Full-service support: from material design and selection to metallization, brazing and assembly.

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