Mullite/Mullite CHOPPED
Reinforced grade
CHOPPED = chopped / short mullite fiber reinforced mullite
Use chopped short-fibre reinforcement for low-cost complex shapes such as insulation blocks, tooling and seals; it is quasi-isotropic but only 45 MPa, far below continuous-fibre strength and toughness.
Values for the CHOPPED condition
Other Mullite/Mullite grades and fills
Mullite/Mullite is listed in 4 conditions; see the grade overview at Mullite/Mullite.
Compare all 4 grades and fillsHide
| Grade · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness |
|---|---|---|---|---|---|
CHOPPEDThis page Chopped / short mullite fiber reinforced mullite | Use chopped short-fibre reinforcement for low-cost complex shapes such as insulation blocks, tooling and seals; it is quasi-isotropic but only 45 MPa, far below continuous-fibre strength and toughness. | — | 45 | 0.15 | — |
Filament-wound highly porous oxide CMC | Pick the filament-wound form with 25–35 % matrix porosity for bodies of revolution such as liners, nozzles and combustor shells; thermal shock and damage tolerance are excellent, strength and gas tightness low. | — | 100 | 0.4 | — |
2D-WOVENDefault 2D woven mullite fabric / porous mullite matrix laminate | Use for plate and shell parts: Nextel 550/720 plain- or satin-weave layup, slurry infiltrated and sintered, gives balanced in-plane properties at 130 MPa and service to 1200 °C. | — | 130 | 0.35 | — |
Monolithic (unreinforced) sintered mullite | Pick the unreinforced sintered baseline when only high-temperature dimensional stability and insulation to 1500 °C are needed; strength is higher but it is brittle with no thermal-shock tolerance. | — | — | — | — |
What is Mullite/Mullite CHOPPED?
Mullite/Mullite CHOPPED is Mullite/Mullite in the CHOPPED grade — use chopped short-fibre reinforcement for low-cost complex shapes such as insulation blocks, tooling and seals; it is quasi-isotropic but only 45 MPa, far below continuous-fibre strength and toughness. Mullite/Mullite CHOPPED has a tensile strength of 45 MPa (6.53 ksi), weaker than 81% of composite grades. Elongation at break is 0.15% and the elastic modulus is 50 GPa (7.25 Msi). Mullite/Mullite CHOPPED has a density of 2.5 g/cm³ (0.0903 lb/in³), heavier than 81% of composite grades. 2D-WOVEN is the default condition FabDigit quotes; CHOPPED is available on request or by drawing note.
Advantages
- 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
- Good corrosion resistance — 90/100, better than 85% of composite grades
Limitations
- Absorbs moisture — dry before molding — 8%, worse than 99% of composite grades
- Limited ductility — 0.15%, worse than 98% of composite grades
- Difficult to machine — 12/100, worse than 89% of composite grades
- High embodied carbon — 40 kg CO₂/kg, worse than 87% of composite grades
- Heavy — 2.5 g/cm³ (0.0903 lb/in³), worse than 81% of composite grades
Mullite/Mullite CHOPPED properties
Typical room-temperature values for Mullite/Mullite CHOPPED; 14 are specific to this condition. Other listed values are Mullite/Mullite reference data and may not represent this condition. Bars are the position among composite grades.
Physical2
Mullite/Mullite CHOPPED has a density of 2.5 g/cm³ (0.0903 lb/in³), heavier than 81% of composite grades.
Mechanical11
Mullite/Mullite CHOPPED has a tensile strength of 45 MPa (6.53 ksi), weaker than 81% of composite grades. Elongation at break is 0.15% and the elastic modulus is 50 GPa (7.25 Msi).
Thermal6
Mullite/Mullite CHOPPED is rated for continuous service to 1,200°C (2,192 °F). It conducts heat at 1.8 W/m·K (1.04 BTU/hr·ft·°F), better than 57% of composite grades. Thermal expansion is 5.3 µm/m·K (2.94 µin/in·°F).
Electrical5
Mullite/Mullite CHOPPED is an electrical insulator with a dielectric strength of 8 kV/mm (203.2 V/mil) and a resistivity of 1×10¹⁰ Ω·m.
Chemical & Environmental3
Corrosion resistance is excellent (90/100), better than 85% of composite grades. UV resistance is excellent.
Sustainability3
Producing a kilogram of Mullite/Mullite CHOPPED takes about 550 MJ of energy and emits 40 kg of CO₂ — more than 86% of composite grades. Typical recycled content is 0%.
Manufacturability2
Mullite/Mullite CHOPPED's machinability is not recommended (12/100, worse than 89% of composite grades).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with Mullite/Mullite CHOPPED
Is Mullite/Mullite easy to machine?
After sintering, only diamond grinding, ultrasonic machining or abrasive waterjet cutting are practical. Avoid high feed rates, which cause delamination and fiber pull-out; chamfer all hole edges.
Can Mullite/Mullite be welded?
Not weldable; join by mechanical fastening (ceramic or superalloy bolts with compliant spacers), oxide ceramic adhesive, or co-firing as a single integral part.
Can Mullite/Mullite be formed, bent or molded?
Fabric layup with slurry impregnation and vacuum bagging, filament winding, or slip casting, followed by air sintering at 1100–1300 °C. Parts are near-net shape, so sintering shrinkage must be compensated in the tooling.
What surface finishes work on Mullite/Mullite?
An alumina or mullite sealing coat, or an FGI-type coating, can be applied to improve erosion resistance and limit moisture pickup. Surfaces normally retain the fabric texture and are not polished.
Mullite/Mullite 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 |
|---|---|---|
| Al2O3Combined fiber (Nextel 550 ~73%, 720 ~85%) and matrix value | 70 – 85 | 75 |
| B2O3Sintering aid in some alumina-aluminosilicate fibers | 0 – 1 | 0.2 |
| Fe2O3+Na2O+K2OImpurities; affect high-temperature creep | 0 – 0.5 | 0.2 |
| SiO2Mullite stoichiometry 3Al2O3.2SiO2 is 71.8/28.2 | ≥ 15 (balance) | — |
Mullite/Mullite CHOPPED — frequently asked
What is Mullite/Mullite CHOPPED used for?
Mullite/Mullite CHOPPED is typically used for gas turbine combustor liners, industrial kiln furniture, burner nozzles and exhaust components. In short: oxidation-immune oxide CMC; low thermal conductivity, 1200 °C; lower cost than SiC/SiC.
What is the tensile strength of Mullite/Mullite CHOPPED?
Mullite/Mullite CHOPPED has a typical tensile strength of 45 MPa (6.53 ksi) — weaker than 81% of composite grades. Strength varies by condition: see the 4 listed tempers.
Is Mullite/Mullite CHOPPED easy to machine?
Not especially — machinability is rated not recommended (12/100, worse than 89% of composite grades). After sintering, only diamond grinding, ultrasonic machining or abrasive waterjet cutting are practical. Avoid high feed rates, which cause delamination and fiber pull-out; chamfer all hole edges.
Can Mullite/Mullite CHOPPED be welded?
Not weldable; join by mechanical fastening (ceramic or superalloy bolts with compliant spacers), oxide ceramic adhesive, or co-firing as a single integral part.
What surface finishes work on Mullite/Mullite CHOPPED?
An alumina or mullite sealing coat, or an FGI-type coating, can be applied to improve erosion resistance and limit moisture pickup. Surfaces normally retain the fabric texture and are not polished.
Can Mullite/Mullite CHOPPED be formed, bent or molded?
Fabric layup with slurry impregnation and vacuum bagging, filament winding, or slip casting, followed by air sintering at 1100–1300 °C. Parts are near-net shape, so sintering shrinkage must be compensated in the tooling.
What is the maximum service temperature of Mullite/Mullite CHOPPED?
Mullite/Mullite CHOPPED is rated for continuous use to about 1,200°C (2,192 °F), and briefly to 1,300°C. Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Sources
- ASM Handbook Vol.21: Composites — Oxide/Oxide Ceramic Matrix Composites — ASM International (2001)
- 3M Nextel Ceramic Textiles Technical Notebook (550/610/720 fibers) — 3M (2018)
- COI Ceramics / ATK Oxide-Oxide CMC (AS-N720) property sheet — COI Ceramics (2015)
- WHIPOX all-oxide CMC property publications — DLR Institute of Materials Research (2012)
- Mullite ceramic technical data (density, MOR, CTE, thermal conductivity) — CoorsTek / Kyocera (2020)
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.