spore: profile id: silicon-nitride spore_version: 0.2 family: carbide-nitride-boride-ceramics name: Silicon nitride abbreviation: Si3N4 role: structural ceramic category: ceramics type: nitrides summary: 'Silicon nitride is a high-strength structural ceramic used in bearing elements and high-temperature components. Its reported properties depend on the forming and densification route: this profile keeps a gas-pressure-sintered grade, several legacy NIST grades, and a manufacturer bearing grade separate. The available sources show good strength and thermal-shock properties, while also documenting oxidation in hot wet oxygen and contact damage in bearing tests.' best_for: Structural parts and bearing elements where low mass, wear resistance, high temperature capability, or thermal shock resistance matter. weakest_at: Grade-sensitive performance and brittle contact damage; select a process and grade, and use its own design data. identity: formula: Si3N4 (trisilicon tetranitride) cas: 12033-89-5 source: pubchem-sin3n4 where: Molecular Formula and CAS sections, CID 3084099 tags: environments: - launch - deep-space stresses: - extreme-heat - thermal-cycling - mechanical-wear applications: - propulsion-and-tanks - mechanisms - structures properties: - benchmark: density label: Bulk density, gas-pressure-sintered SN-GP value: 3.18 value_high: 3.3 bound: range unit: g/cm3 scope: material conditions: form: gas-pressure-sintered silicon nitride grade: SN-GP basis: manufacturer's test samples composition: 85-92 wt% Si3N4 plus 8-15 wt% RE2O3/Al2O3 blend per Qsil datasheet method: Determined according to DIN 623-2, as stated in footnote [1] status: ground source: qsil-sn-gp where: Section 2, General Properties, Bulk Density row - benchmark: residual_porosity label: Residual porosity, gas-pressure-sintered SN-GP value: 1 bound: upper unit: '%' scope: material conditions: form: gas-pressure-sintered silicon nitride grade: SN-GP printed_value: < 1% method: Manufacturer datasheet value; the density and porosity method is identified as DIN 623-2 status: ground source: qsil-sn-gp where: Section 2, General Properties, Residual Porosity row and footnote [1] - benchmark: grain_size label: Grain size, longitudinal direction, gas-pressure-sintered SN-GP value: 1 value_high: 15 bound: range unit: µm scope: material conditions: form: gas-pressure-sintered silicon nitride grade: SN-GP direction: longitudinal method: Manufacturer datasheet range status: ground source: qsil-sn-gp where: Section 2, General Properties, Grain Size (Longitudinal Direction) row - benchmark: hardness label: Hardness, gas-pressure-sintered SN-GP value: 14.5 unit: GPa scope: material conditions: form: gas-pressure-sintered silicon nitride grade: SN-GP test_method_note: The datasheet footnotes [2] and [3] appear to point to each other's property labels. method: Manufacturer datasheet value; test-method footnote cross-references are inconsistent in the source status: ground source: qsil-sn-gp where: Section 3, Mechanical Properties, Hardness row - benchmark: compressive_strength label: Compressive strength, gas-pressure-sintered SN-GP value: 3000 unit: MPa scope: material conditions: form: gas-pressure-sintered silicon nitride grade: SN-GP basis: manufacturer's test samples method: Manufacturer datasheet value; no test method is stated for this row status: ground source: qsil-sn-gp where: Section 3, Mechanical Properties, Compressive Strength row - benchmark: flexural_strength label: Bending strength (printed as “Bendig Strength”), gas-pressure-sintered SN-GP value: 670 unit: MPa scope: material conditions: form: gas-pressure-sintered silicon nitride grade: SN-GP basis: manufacturer's test samples method: Value copied as the datasheet's bending-strength row; its [3] method footnote is cross-referenced to hardness and is not used as a test method here status: ground source: qsil-sn-gp where: Section 3, Mechanical Properties, Bendig Strength row - benchmark: weibull_modulus label: Weibull modulus, gas-pressure-sintered SN-GP value: 20 unit: unitless scope: material conditions: form: gas-pressure-sintered silicon nitride grade: SN-GP method: Manufacturer datasheet value status: ground source: qsil-sn-gp where: Section 3, Mechanical Properties, Weibull-Modulus row - benchmark: fracture_toughness label: Fracture toughness, gas-pressure-sintered SN-GP value: 6.2 unit: MPa·m1/2 scope: material conditions: form: gas-pressure-sintered silicon nitride grade: SN-GP method: Calculated from crack length derived from Vickers hardness indentation, according to Niihara, as stated in footnote [4] status: ground source: qsil-sn-gp where: Section 3, Mechanical Properties, Fracture Toughness row and footnote [4] - benchmark: elastic_modulus label: Young's modulus, gas-pressure-sintered SN-GP value: 290 unit: GPa scope: material conditions: form: gas-pressure-sintered silicon nitride grade: SN-GP method: Manufacturer datasheet value status: ground source: qsil-sn-gp where: Section 3, Mechanical Properties, Youngs Modulus row - benchmark: poissons_ratio label: Poisson ratio, gas-pressure-sintered SN-GP value: 0.26 unit: '-' scope: material conditions: form: gas-pressure-sintered silicon nitride grade: SN-GP method: Manufacturer datasheet value status: ground source: qsil-sn-gp where: Section 3, Mechanical Properties, Poisson Ratio row - benchmark: max_service_temp label: Maximum working temperature in air, gas-pressure-sintered SN-GP value: 1200 unit: °C scope: material conditions: form: gas-pressure-sintered silicon nitride grade: SN-GP atmosphere: air basis: manufacturer-stated maximum working temperature method: Manufacturer datasheet value; not a component-specific design allowable status: ground source: qsil-sn-gp where: Section 4, Thermal Properties, Max. Working Temperature, Air row - benchmark: max_service_temp label: Maximum working temperature in inert atmosphere, gas-pressure-sintered SN-GP value: 1400 unit: °C scope: material conditions: form: gas-pressure-sintered silicon nitride grade: SN-GP atmosphere: inert atmosphere basis: manufacturer-stated maximum working temperature method: Manufacturer datasheet value; not a component-specific design allowable status: ground source: qsil-sn-gp where: Section 4, Thermal Properties, Max. Working Temperature, Inert Atmosphere row - benchmark: specific_heat label: Specific heat capacity, gas-pressure-sintered SN-GP value: 620 unit: J/kgK scope: material conditions: form: gas-pressure-sintered silicon nitride grade: SN-GP temperature: not stated in this row method: Manufacturer datasheet value status: ground source: qsil-sn-gp where: Section 4, Thermal Properties, Specific Heat Capacity row - benchmark: thermal_conductivity label: Thermal conductivity at 20 °C, gas-pressure-sintered SN-GP value: 24 unit: W/mK scope: material conditions: form: gas-pressure-sintered silicon nitride grade: SN-GP temperature: 20 °C method: Manufacturer datasheet value status: ground source: qsil-sn-gp where: Section 4, Thermal Properties, Thermal Conductivity row - benchmark: cte label: Mean coefficient of thermal expansion from room temperature to 1000 °C, gas-pressure-sintered SN-GP value: 3.2 unit: 10-6K-1 scope: material conditions: form: gas-pressure-sintered silicon nitride grade: SN-GP temperature_range: RT-1000 °C printed_unit: 10-6 K-1 method: Manufacturer datasheet value, in the unit printed status: ground source: qsil-sn-gp where: Section 4, Thermal Properties, Coeff. of Thermal Expansion, RT-1000 °C row - benchmark: cte label: Coefficient of thermal expansion near room temperature, gas-pressure-sintered SN-GP value: 1.4 unit: 10-6K-1 scope: material conditions: form: gas-pressure-sintered silicon nitride grade: SN-GP temperature_range: RT ± 20 °C printed_unit: 10-6 K-1 method: Manufacturer datasheet value, in the unit printed status: ground source: qsil-sn-gp where: Section 4, Thermal Properties, Coeff. of Thermal Expansion, RT ± 20 °C row - benchmark: thermal_shock_parameter_r1 label: Thermal shock parameter R1, gas-pressure-sintered SN-GP value: 534 unit: K scope: material conditions: form: gas-pressure-sintered silicon nitride grade: SN-GP test_case: critical temperature difference for infinite heat transfer (quenching) method: Manufacturer datasheet value; parameter definition is given in footnote [5] status: ground source: qsil-sn-gp where: Section 4, Thermal Properties, Thermal Shock Parameter R1 row and footnote [5] - benchmark: thermal_shock_parameter_r2 label: Thermal shock parameter R2, gas-pressure-sintered SN-GP value: 12822 unit: W/m scope: material conditions: form: gas-pressure-sintered silicon nitride grade: SN-GP test_case: finite constant heat transfer (slow heating) method: Manufacturer datasheet value; parameter definition is given in footnote [6] status: ground source: qsil-sn-gp where: Section 4, Thermal Properties, Thermal Shock Parameter R2 row and footnote [6] - benchmark: density label: Density, hot-pressed NCX-34 value: 3.37 unit: g cm-3 scope: material conditions: form: hot-pressed silicon nitride grade: NCX-34 temperature: not stated in NIST record method: Manufacturer's indicated value, reproduced in NIST Structural Ceramics Database status: ground source: nist-scd-z00426 where: Material 1, NCX-34 specification and Density (mass) section - benchmark: elastic_modulus label: Elastic modulus, hot-pressed NCX-34 value: 310 unit: GPa scope: material conditions: form: hot-pressed silicon nitride grade: NCX-34 temperature: not stated in NIST record method: Manufacturer's indicated value, reproduced in NIST Structural Ceramics Database status: ground source: nist-scd-z00426 where: Material 1, NCX-34 specification and Elastic Modulus section - benchmark: fracture_toughness label: Fracture toughness, hot-pressed NCX-34 value: 6.35 unit: MPa m1/2 scope: material conditions: form: hot-pressed silicon nitride grade: NCX-34 uncertainty: ± 0.10 MPa m1/2 method: Surface crack in flexure test; unevaluated in the NIST record status: ground source: nist-scd-z00426 where: Material 1, Fracture Toughness section - benchmark: density label: Density, hot-isostatically pressed NBD200 value: 3.16 unit: g cm-3 scope: material conditions: form: hot-isostatically pressed silicon nitride grade: NBD200 temperature: not stated in NIST record method: Manufacturer's indicated value, reproduced in NIST Structural Ceramics Database status: ground source: nist-scd-z00426 where: Material 2, NBD200 specification and Density (mass) section - benchmark: elastic_modulus label: Elastic modulus, hot-isostatically pressed NBD200 value: 320 unit: GPa scope: material conditions: form: hot-isostatically pressed silicon nitride grade: NBD200 temperature: not stated in NIST record method: Manufacturer's indicated value, reproduced in NIST Structural Ceramics Database status: ground source: nist-scd-z00426 where: Material 2, NBD200 specification and Elastic Modulus section - benchmark: fracture_toughness label: Fracture toughness, hot-isostatically pressed NBD200 value: 5.41 unit: MPa m1/2 scope: material conditions: form: hot-isostatically pressed silicon nitride grade: NBD200 uncertainty: ± 0.24 MPa m1/2 method: Surface crack in flexure test; unevaluated in the NIST record status: ground source: nist-scd-z00426 where: Material 2, Fracture Toughness section - benchmark: density label: Density, sintered EC-141 value: 3.22 unit: g cm-3 scope: material conditions: form: sintered silicon nitride grade: EC-141 temperature: not stated in NIST record method: Manufacturer's indicated value, reproduced in NIST Structural Ceramics Database status: ground source: nist-scd-z00426 where: Material 5, EC-141 specification and Density (mass) section - benchmark: elastic_modulus label: Elastic modulus, sintered EC-141 value: 310 unit: GPa scope: material conditions: form: sintered silicon nitride grade: EC-141 temperature: not stated in NIST record method: Manufacturer's indicated value, reproduced in NIST Structural Ceramics Database status: ground source: nist-scd-z00426 where: Material 5, EC-141 specification and Elastic Modulus section - benchmark: fracture_toughness label: Fracture toughness, sintered EC-141 value: 5.22 unit: MPa m1/2 scope: material conditions: form: sintered silicon nitride grade: EC-141 uncertainty: ± 0.18 MPa m1/2 method: Surface crack in flexure test; unevaluated in the NIST record status: ground source: nist-scd-z00426 where: Material 5, Fracture Toughness section - benchmark: density label: Density, reaction-bonded NC-350 value: 2.53 unit: g cm-3 scope: material conditions: form: reaction-bonded silicon nitride grade: NC-350 temperature: not stated in NIST record method: Manufacturer's indicated value, reproduced in NIST Structural Ceramics Database status: ground source: nist-scd-z00426 where: Material 6, NC-350 specification and Density (mass) section - benchmark: elastic_modulus label: Elastic modulus, reaction-bonded NC-350 value: 180 unit: GPa scope: material conditions: form: reaction-bonded silicon nitride grade: NC-350 temperature: not stated in NIST record method: Manufacturer's indicated value, reproduced in NIST Structural Ceramics Database status: ground source: nist-scd-z00426 where: Material 6, NC-350 specification and Elastic Modulus section - benchmark: fracture_toughness label: Fracture toughness, reaction-bonded NC-350 value: 1.65 unit: MPa m1/2 scope: material conditions: form: reaction-bonded silicon nitride grade: NC-350 uncertainty: ± 0.09 MPa m1/2 method: Surface crack in flexure test; unevaluated in the NIST record status: ground source: nist-scd-z00426 where: Material 6, Fracture Toughness section - benchmark: flexural_strength label: Flexural strength (MOR) at 20 °C, NBD-200 value: 900 unit: MPa scope: material conditions: form: hot-isostatically pressed silicon nitride grade: NBD-200 temperature: 20 °C method: CoorsTek material table; the page does not state a test standard status: ground source: coorstek-sn where: Properties table, Flexural Strength, MOR (20 °C) row, NBD-200 column; NIST identifies the NBD200 process as hot isostatic pressing - benchmark: fracture_toughness label: Fracture toughness, NBD-200 value: 5.5 unit: MPa m1/2 scope: material conditions: form: hot-isostatically pressed silicon nitride grade: NBD-200 method: CoorsTek material table; the page does not state a test method status: ground note: The older NIST record for NBD200 gives 5.41 ± 0.24 MPa m1/2; the sources do not explain the difference. source: coorstek-sn where: Properties table, Fracture Toughness row, NBD-200 column; process identified in NIST entry Z00426, Material 2 - benchmark: thermal_conductivity label: Thermal conductivity at 20 °C, NBD-200 value: 29 unit: W/m K scope: material conditions: form: hot-isostatically pressed silicon nitride grade: NBD-200 temperature: 20 °C method: CoorsTek material table; the page does not state a test method status: ground source: coorstek-sn where: Properties table, Thermal Conductivity (20 °C) row, NBD-200 column; process identified in NIST entry Z00426, Material 2 - benchmark: cte label: Coefficient of thermal expansion, NBD-200 value: 2.9 unit: 1x10-6/°C scope: material conditions: form: hot-isostatically pressed silicon nitride grade: NBD-200 printed_unit: 1x10-6/°C method: CoorsTek material table; unit and value copied as printed status: ground source: coorstek-sn where: Properties table, Coefficient of Thermal Expansion row, NBD-200 column; process identified in NIST entry Z00426, Material 2 - benchmark: max_service_temp label: Maximum use temperature, NBD-200 value: 1400 unit: °C scope: material conditions: form: hot-isostatically pressed silicon nitride grade: NBD-200 atmosphere: not stated on CoorsTek table method: Manufacturer-stated maximum use temperature; atmosphere and test method are not stated status: ground source: coorstek-sn where: Properties table, Maximum Use Temperature row, NBD-200 column; process identified in NIST entry Z00426, Material 2 corrosion: - environment: Hot oxygen containing water vapor headline: Water vapor increases passive oxidation of hot-pressed silicon nitride. effect: The review says silicon nitride forms a protective silica scale in oxidation, but its oxidation depends on sintering aids and impurities. For hot-pressed HS-130, the reported parabolic oxidation rate is higher in wet oxygen than in dry oxygen. rating: unknown conditions: form: hot-pressed silicon nitride, grade HS-130 atmosphere: oxygen with water vapor; see Table 22 for the reported partial pressure source: biscay-oxidation where: Section 3.1, Oxidation of Si3N4; Section 3.2, Si3N4 in Hot Gases; Table 22 risks: hazards: - text: The PubChem aggregate for silicon nitride lists the majority of company GHS reports as not meeting hazard criteria, while noting that reports can differ with impurities, additives, and other factors. ghs: [] source: pubchem-sin3n4 where: Safety and Hazards, GHS Classification, CID 3084099 - text: The MilliporeSigma SDS for Aldrich product 334103 (powder) classifies it as not a hazardous substance or mixture and lists no hazards otherwise classified. This is product-specific and does not establish handling requirements for every powder or finished ceramic. ghs: [] source: sigma-sds-sin3n4 where: Sections 1-2 failure_risks: - mode: Brittle contact damage in cryogenic bearings trigger: NASA tests with silicon nitride rolling elements in 57-mm high-pressure oxidizer turbopump bearings consequence: The report describes spalling, striations, locally deformed ball material, and possible scuffing. It says the cause of spalling was not known and discusses a material flaw or high rolling-contact stress as possibilities. source: nasa-tm103524 where: Introduction and Test Results, report pages 1-2 (PDF pages 5-6) side_effects: [] handling: - text: For powder handling, the SDS advises avoiding dust formation and breathing dust, using exhaust ventilation where dust forms, and keeping the container tightly closed in a dry, well-ventilated place. source: sigma-sds-sin3n4 where: Sections 6-7 - text: The SDS recommends appropriate eye protection and gloves for the product powder. Use the SDS for the exact grade and process; these instructions are not a substitute for supplier guidance on machining dust. source: sigma-sds-sin3n4 where: Section 8 mitigations: [] uses: - application: mechanisms device: Rolling elements in cryogenic turbopump bearings example: NASA evaluated silicon nitride balls in flight-type Space Shuttle Main Engine high-pressure oxidizer turbopump bearings. The report describes a test program, not a claim that the tested configuration flew. source: nasa-tm103524 where: Introduction and Test Equipment, report page 1 (PDF page 5) - application: propulsion-and-tanks device: Aerospace propulsion and control components example: CoorsTek lists propulsion and control components among its silicon nitride aerospace and defense applications. source: coorstek-sn where: Sample Applications by Industry, Aerospace & Defense - application: mechanisms device: High-temperature bearings example: PubChem's sources/uses section lists high-temperature ball bearings among reported uses for silicon nitride. source: pubchem-sin3n4 where: Use and Manufacturing, Sources/Uses supply: - subject: Silicon feedstock for silicon nitride; the USGS report does not report silicon nitride production abundance: The USGS says world and domestic resources for silicon metal and alloys are abundant and names silica, including quartzite, as the source. Its narrative estimates China at almost 80% of global silicon materials production in 2025. The producer shares below are computed from the report's separate 2025 silicon-metal production column; they describe feedstock, not silicon nitride output. producers: - country: China share_percent: 87 year: 2025 - country: Brazil share_percent: 3.9 year: 2025 - country: Norway share_percent: 2.8 year: 2025 critical_lists: - list: USGS 2025 List of Critical Minerals (elemental silicon feedstock) listed: true recycling: Not reported for silicon nitride in the sources read. substitutes: [] source: usgs-mcs2026-silicon where: 'Events, Trends, and Issues; World Production; World Resources; critical-minerals discussion. Computed silicon-metal shares: China 4,000/4,600 = 87%, Brazil 180/4,600 = 3.9%, Norway 130/4,600 = 2.8% (2025 column, kt).' documents: - title: Material Data Sheet for Gas Pressure Sintered Silicon Nitride, SN-GP, Revision 07 type: datasheet url: https://qsil.com/wp-content/uploads/2023/04/F_4-4_26_Material-Data-Sheet-SN-GP.pdf year: 2022 - title: Silicon Nitride material page, CoorsTek type: datasheet url: https://www.coorstek.com/en/materials/silicon-nitride/ - title: NIST Structural Ceramics Database, Citation Z00426 type: database url: https://srdata.nist.gov/CeramicDataPortal/Scd/Z00426 - title: NASA TM-103524, An Evaluation of Bearings Operating in a Cryogenic Environment with Silicon Nitride Rolling Elements type: report url: https://ntrs.nasa.gov/api/citations/19910009123/downloads/19910009123.pdf year: 1991 - title: USGS Mineral Commodity Summaries 2026, Silicon type: report url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-silicon.pdf year: 2026 - title: PubChem Compound Summary, Trisilicon tetranitride (CID 3084099), PUG-View record type: database url: https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/3084099/JSON year: 2026 - title: CIAAW 2024 Abridged Standard Atomic Weights type: database url: https://www.ciaaw.org/abridged-atomic-weights.htm year: 2024 - title: Corrosion Characteristics of Silicon Carbide and Silicon Nitride, Journal of Research of NIST type: paper url: https://pmc.ncbi.nlm.nih.gov/articles/PMC4907592/ year: 1993 - title: MilliporeSigma Safety Data Sheet, Silicon nitride, Aldrich 334103, Version 6.3 type: sds url: https://sds.mcmaster.ca/Silicon_Nitride.pdf year: 2022 gaps: - USGS does not report silicon-nitride producer shares or output; the supply section is explicitly silicon feedstock context. - The exact rare-earth oxide/alumina proportions and rare-earth identity in the SN-GP sintering-aid blend are not specified by the datasheet. - The Qsil datasheet's footnotes [2] and [3] appear cross-referenced to the opposite property labels, so those test methods could not be confidently assigned to hardness and bending strength. - No tensile strength values were found for the specific SN-GP, NIST, or NBD-200 grades in the sources read; the 670 MPa Qsil value is labeled as bending strength, and CoorsTek labels its values as flexural MOR. - The hot-gas oxidation evidence read here is for hot-pressed HS-130; corrosion of every listed grade in other gases, molten salts, and chemical environments remains uncharacterized in this profile. - The Sigma SDS applies to one laboratory powder product; finished ceramic and machining-dust guidance for each manufacturer grade was not found. - NIST's legacy material values and current CoorsTek NBD-200 values differ for fracture toughness; the sources do not explain the difference, so the entries remain separate. - Maximum working/use temperatures are supplier table values; component-specific lifetime, atmosphere, geometry, and design allowables were not established by the sources read. sources: qsil-sn-gp: title: Qsil, Material Data Sheet for Gas Pressure Sintered Silicon Nitride, SN-GP, Revision 07 id: F_4-4_26, dated 2022-01-18 url: https://qsil.com/wp-content/uploads/2023/04/F_4-4_26_Material-Data-Sheet-SN-GP.pdf year: 2022 kind: datasheet license: Manufacturer datasheet, linked and cited coorstek-sn: title: CoorsTek Technical Ceramics, Silicon Nitride material page and grade table url: https://www.coorstek.com/en/materials/silicon-nitride/ kind: datasheet license: Manufacturer webpage, cited nist-scd-z00426: title: NIST Structural Ceramics Database, Citation Z00426, silicon nitride entries url: https://srdata.nist.gov/CeramicDataPortal/Scd/Z00426 kind: database license: Public domain (NIST), cited nasa-tm103524: title: NASA TM-103524, An Evaluation of Bearings Operating in a Cryogenic Environment with Silicon Nitride Rolling Elements id: NTRS 19910009123 url: https://ntrs.nasa.gov/api/citations/19910009123/downloads/19910009123.pdf year: 1991 kind: report license: Public domain (NASA), cited usgs-mcs2026-silicon: title: USGS Mineral Commodity Summaries 2026, Silicon id: USGS MCS 2026 url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-silicon.pdf year: 2026 kind: report license: Public domain (USGS), cited pubchem-sin3n4: title: PubChem PUG-View record, Trisilicon tetranitride (CID 3084099) id: CID 3084099; CAS 12033-89-5 url: https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/3084099/JSON year: 2026 kind: database license: Public domain (NCBI), cited ciaaw-atomic-weights: title: Commission on Isotopic Abundances and Atomic Weights, 2024 Abridged Standard Atomic Weights url: https://www.ciaaw.org/abridged-atomic-weights.htm year: 2024 kind: database license: CIAAW reference table, cited biscay-oxidation: title: Corrosion Characteristics of Silicon Carbide and Silicon Nitride, Journal of Research of NIST id: PMCID PMC4907592 url: https://pmc.ncbi.nlm.nih.gov/articles/PMC4907592/ year: 1993 kind: paper license: Publicly accessible NIST journal review, cited sigma-sds-sin3n4: title: MilliporeSigma Safety Data Sheet, Silicon nitride, Aldrich 334103, Version 6.3 id: Revision 25 April 2022; CAS 12033-89-5 url: https://sds.mcmaster.ca/Silicon_Nitride.pdf year: 2022 kind: datasheet license: Supplier safety data sheet, linked and cited license: CC-BY-4.0 updated: '2026-10-20' review: status: draft method: assistant checked_values: 35 unreachable: 0 caveats: 4 note: Each property is tied to a named grade and form. The Qsil bending/hardness footnotes and the two NBD-200 fracture-toughness entries are flagged in the profile. story: recipe: line: 'The compound formula is Si3N4: three silicon atoms and four nitrogen atoms, with CIAAW 2024 abridged standard atomic weights of 28.085 and 14.007 respectively. Qsil''s gas-pressure-sintered SN-GP grade reports 85 to 92 wt% Si3N4 and 8 to 15 wt% combined RE2O3/Al2O3 sintering aids; the sheet does not split that blend further.' parts: - name: Silicon nitride matrix symbol: Si3N4 share_percent: 85 share_high: 92 role: The main ceramic phase in the SN-GP grade. source: qsil-sn-gp where: Section 2, Chemical Composition, Si3N4 (wt.-%) row - name: Silicon symbol: Si atoms: 3 atomic_weight: 28.085 role: Three silicon atoms in each Si3N4 formula unit. source: ciaaw-atomic-weights where: 2024 Abridged Standard Atomic Weights, silicon row; atom count from the Si3N4 formula in PubChem CID 3084099 - name: Nitrogen symbol: 'N' atoms: 4 atomic_weight: 14.007 role: Four nitrogen atoms in each Si3N4 formula unit. source: ciaaw-atomic-weights where: 2024 Abridged Standard Atomic Weights, nitrogen row; atom count from the Si3N4 formula in PubChem CID 3084099 - name: RE2O3/Al2O3 sintering-aid blend share_percent: 8 share_high: 15 role: Combined oxide additions reported for the SN-GP grade; exact blend is not specified. source: qsil-sn-gp where: Section 2, Chemical Composition, RE2O3/Al2O3 (wt.-%) row risk_groups: - title: For people level: 1 verdict: Powder SDS not classified lead: The powder SDS read here says the named product is not hazardous under its GHS classification, and still gives dust-control and personal-protection instructions. points: - label: Powder handling line: Avoid dust generation and inhalation; use the handling instructions on the SDS for the exact powder product. - title: If a bearing part fails lead: A NASA cryogenic test report documents contact damage and leaves its cause unresolved. points: - label: Contact damage line: The report describes spalling, striations, deformed ball areas, and possible scuffing in tested silicon nitride bearing balls. - title: Hot gas exposure lead: Oxidation varies with the sintering aids and impurities, and water vapor can increase it in hot oxygen. points: - label: Oxidation line: A review describes formation of a protective silica scale but cautions that scale behavior depends on composition and environment. why: Silicon nitride is a structural ceramic whose elongated grains and intergranular phases can give it useful strength and toughness. It appears in bearing elements and aerospace propulsion components, where wear, heat, and thermal shock matter. Processing changes density and fracture behavior substantially, so a material name alone is not a design specification. uses: - where: Cryogenic turbopump bearings line: NASA evaluated silicon nitride rolling elements in Space Shuttle Main Engine high-pressure oxidizer turbopump bearings; the cited report describes ground testing. - where: Aerospace propulsion and control line: CoorsTek lists silicon nitride propulsion and control components as an aerospace and defense application. - where: High-temperature bearings line: PubChem's sources/uses record lists high-temperature ball bearings among reported uses for silicon nitride. can_do: - label: Carry bending loads benchmark: flexural_strength line: Datasheets report bending or flexural strength for named grades; the test mode is explicitly kept distinct from tensile strength. - label: Limit thermal shock benchmark: thermal_shock_parameter_r1 line: The Qsil SN-GP sheet reports thermal-shock parameters for separate heating and quenching cases. - label: Conduct heat benchmark: thermal_conductivity line: The Qsil and CoorsTek data give grade-specific thermal conductivity, and the values should be compared only with their listed forms. compare: The data show why silicon nitride needs a form and grade attached to every value. Qsil's SN-GP gas-pressure-sintered grade, NIST's hot-isostatically pressed and sintered records, and the reaction-bonded NC-350 record are separate materials for comparison purposes. The fracture-toughness entries for NBD-200 also differ between the older NIST record and the current CoorsTek table, with no explanation in either source. compare_rows: - label: Density by process and grade benchmark: density - label: Flexural or bending strength by grade benchmark: flexural_strength - label: Fracture toughness by process and grade benchmark: fracture_toughness handling: - 'For powder, follow the exact supplier SDS: avoid dust, use ventilation where dust forms, and keep the container dry and closed.' - Do not transfer a bulk property table directly to a component with a different shape, surface, or processing route; the Qsil sheet explicitly limits its data to test samples. - For hot oxygen environments, account for oxidation and water-vapor effects; the available study is limited to a hot-pressed grade. good_for: - Bearing elements and propulsion hardware where wear resistance and temperature capability matter. - Applications needing low thermal expansion and resistance to thermal shock, provided the selected grade has relevant design data. watch_out: - Do not combine values from reaction-bonded, sintered, hot-pressed, and gas-pressure-sintered forms as though they were one grade. - The Qsil sheet's hardness and bending-strength method footnotes are ambiguous, and the NBD-200 toughness values differ between sources. - No grade-specific tensile strength or silicon-nitride production share was found in the sources read. verdict: Silicon nitride suits demanding bearings and structural parts when its exact grade and processing route are specified. The profile has a strong set of sourced values, including thermal and mechanical data, while the method ambiguity in one datasheet and limited grade-specific oxidation and supply information remain visible.