Si3N4/SiCw GPS (GPS/PLS)
Additive grade
Lowest-cost route for near-net complex parts; residual porosity and more sintering aid reduce strength and creep resistance.
Values for the GPS condition
Other Si3N4/SiCw grades and fills
Si3N4/SiCw is listed in 6 conditions; see the grade overview at Si3N4/SiCw.
Compare all 6 grades and fillsHide
| Grade · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness |
|---|---|---|---|---|---|
GPSThis page GPS/PLS | Lowest-cost route for near-net complex parts; residual porosity and more sintering aid reduce strength and creep resistance. | — | 380 | 0.13 | — |
10 vol% SiC whisker reinforced | Low whisker loading: easiest to densify and machine, modest toughness gain over monolithic Si3N4. | — | 450 | 0.14 | — |
SiCw20Default 20 vol% SiC whisker reinforced, hot pressed | Standard commercial loading — best balance of toughness, strength and densification; the grade used for cutting inserts and hot-section parts. | — | 500 | 0.15 | — |
30 vol% SiC whisker reinforced | Maximum toughness and thermal conductivity; harder to densify so residual porosity can cap the bend strength. | — | 520 | 0.16 | — |
Hot pressed | Choose for full density and maximum strength in simple plate/billet shapes; whiskers align normal to the pressing axis giving anisotropic properties. | — | 540 | 0.17 | — |
Hot isostatic pressed | Pick when near-zero porosity, isotropic properties and highest Weibull modulus are needed for complex shapes. | — | 560 | 0.17 | — |
What is Si3N4/SiCw GPS?
Si3N4/SiCw GPS is Si3N4/SiCw in the GPS grade — lowest-cost route for near-net complex parts; residual porosity and more sintering aid reduce strength and creep resistance. Si3N4/SiCw GPS has a tensile strength of 380 MPa (55.1 ksi), stronger than 64% of composite grades. Elongation at break is 0.13% and the elastic modulus is 300 GPa (43.5 Msi). Si3N4/SiCw GPS has a density of 3.15 g/cm³ (0.114 lb/in³), heavier than 91% of composite grades. SiCw20 is the default condition FabDigit quotes; GPS is available on request or by drawing note.
Advantages
- Polishes to a fine finish — 90/100, better than 99% of composite grades
- High service temperature — 1,200°C (2,192 °F), better than 94% of composite grades
- Good UV / weathering resistance — 100/100, better than 93% of composite grades
- Stiff — 300 GPa (43.5 Msi), better than 91% of composite grades
- Conducts heat well — 25 W/m·K (14.4 BTU/hr·ft·°F), better than 80% of composite grades
Limitations
- Limited ductility — 0.13%, worse than 98% of composite grades
- Difficult to machine — 6/100, worse than 96% of composite grades
- Heavy — 3.15 g/cm³ (0.114 lb/in³), worse than 91% of composite grades
- High embodied carbon — 30 kg CO₂/kg, worse than 80% of composite grades
Si3N4/SiCw GPS properties
Typical room-temperature values for Si3N4/SiCw GPS; 14 are specific to this condition. Other listed values are Si3N4/SiCw reference data and may not represent this condition. Bars are the position among composite grades.
Physical1
Si3N4/SiCw GPS has a density of 3.15 g/cm³ (0.114 lb/in³), heavier than 91% of composite grades.
Mechanical11
Si3N4/SiCw GPS has a tensile strength of 380 MPa (55.1 ksi), stronger than 64% of composite grades. Elongation at break is 0.13% and the elastic modulus is 300 GPa (43.5 Msi).
Thermal6
Si3N4/SiCw GPS is rated for continuous service to 1,200°C (2,192 °F). It conducts heat at 25 W/m·K (14.4 BTU/hr·ft·°F), better than 80% of composite grades. Thermal expansion is 3.4 µm/m·K (1.89 µin/in·°F).
Electrical3
Si3N4/SiCw GPS has an electrical resistivity of 1×10⁸ Ω·m.
Chemical & Environmental3
Corrosion resistance is excellent (85/100), better than 65% of composite grades. UV resistance is excellent.
Sustainability3
Producing a kilogram of Si3N4/SiCw GPS takes about 400 MJ of energy and emits 30 kg of CO₂ — more than 77% of composite grades. Typical recycled content is 0%.
Manufacturability2
Si3N4/SiCw GPS's machinability is not recommended (6/100, worse than 96% of composite grades).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with Si3N4/SiCw GPS
Is Si3N4/SiCw easy to machine?
Green/pre-sintered machining where possible; fired material needs diamond grinding, ultrasonic or EDM (SiCw content can make it conductive enough for wire EDM), with ample coolant to avoid surface microcracking.
Can Si3N4/SiCw be welded?
Not weldable — join by active-metal brazing (Ti-containing Ag-Cu filler), diffusion bonding or glass-ceramic sealing, matching CTE to avoid residual stress.
Can Si3N4/SiCw be formed, bent or molded?
Whisker slurry mixing/dispersion is critical; densified by hot pressing 1700–1800 °C/20–30 MPa in N2, or by GPS + post-HIP for complex geometry; whisker alignment during pressing creates anisotropy.
What surface finishes work on Si3N4/SiCw?
Diamond lapping/polishing to Ra < 0.05 µm; edge honing for cutting inserts; optional oxidation pre-treatment or CVD SiC/oxide coating for long-term high-temperature service.
Si3N4/SiCw chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| SiC whiskervol %; β-SiC whiskers, 0.1–1 µm dia, L/D 10–50 | 10 – 30 | 20 |
| Y2O3sintering aid, forms Y-Si-O-N grain boundary phase | 3 – 8 | 6 |
| Al2O3sintering aid (may be replaced by MgO or Yb2O3) | 1 – 4 | 2 |
| Si3N4α-Si3N4 matrix powder, converts to β-Si3N4 on sintering | balance | — |
Si3N4/SiCw GPS — frequently asked
What is Si3N4/SiCw GPS used for?
Si3N4/SiCw GPS is typically used for turbocharger rotors, high-temperature bearings, cutting tools and engine valve components. In short: whisker-toughened silicon nitride; creep-resistant to 1300 °C; EDM-machinable ceramic composite.
What is the tensile strength of Si3N4/SiCw GPS?
Si3N4/SiCw GPS has a typical tensile strength of 380 MPa (55.1 ksi) — stronger than 64% of composite grades. Strength varies by condition: see the 6 listed tempers.
Is Si3N4/SiCw GPS easy to machine?
Not especially — machinability is rated not recommended (6/100, worse than 96% of composite grades). Green/pre-sintered machining where possible; fired material needs diamond grinding, ultrasonic or EDM (SiCw content can make it conductive enough for wire EDM), with ample coolant to avoid surface microcracking.
Can Si3N4/SiCw GPS be welded?
Not weldable — join by active-metal brazing (Ti-containing Ag-Cu filler), diffusion bonding or glass-ceramic sealing, matching CTE to avoid residual stress.
What surface finishes work on Si3N4/SiCw GPS?
Diamond lapping/polishing to Ra < 0.05 µm; edge honing for cutting inserts; optional oxidation pre-treatment or CVD SiC/oxide coating for long-term high-temperature service.
Can Si3N4/SiCw GPS be formed, bent or molded?
Whisker slurry mixing/dispersion is critical; densified by hot pressing 1700–1800 °C/20–30 MPa in N2, or by GPS + post-HIP for complex geometry; whisker alignment during pressing creates anisotropy.
What is the maximum service temperature of Si3N4/SiCw GPS?
Si3N4/SiCw GPS is rated for continuous use to about 1,200°C (2,192 °F), and briefly to 1,500°C. Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Sources
- ASM Engineered Materials Handbook Vol.4: Ceramics and Glasses — ASM International (1991)
- Ceramic Matrix Composites: Microstructure, Properties and Applications — Woodhead Publishing (2006)
- ASTM C1421 Fracture Toughness of Advanced Ceramics — ASTM (2018)
- Technical ceramics silicon nitride datasheets — CoorsTek / Kyocera (2023)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.