Boron Fiber Composite B-EP-177
Matrix
Pick when the part or repair must run hot (supersonic skins, engine-area doublers) and a 177 °C autoclave cure is available.
Values for the B-EP-177 condition
Other Boron Fiber Composite grades and fills
Boron Fiber Composite is listed in 7 conditions; see the grade overview at Boron Fiber Composite.
Compare all 7 grades and fillsHide
| Grade · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness |
|---|---|---|---|---|---|
cross-plied boron/epoxy laminate | Choose when biaxial load or dimensional stability in two directions matters more than peak 0° stiffness. | 700 | 780 | 0.7 | 90 Shore D |
boron fiber reinforced aluminium (metal matrix) | Diffusion-bonded MMC for high-temperature, high-conductivity structure (e.g. Shuttle Orbiter truss tubes); heavier, expensive, and requires hot-press consolidation. | 900 | 1,400 | 0.8 | — |
boron fiber in polyimide / bismaleimide matrix | For sustained service above 200 °C where an epoxy matrix would soften; harder to process and lower interlaminar toughness. | — | 1,400 | 0.7 | 92 Shore D |
Boron/carbon hybrid epoxy tape | Use to cut cost and weight versus pure boron while keeping much of the compressive strength; note the carbon makes it electrically conductive again. | — | 1,450 | 0.85 | 89 Shore D |
B-EP-UDDefault unidirectional boron/epoxy prepreg laminate (121 °C cure) | Standard bonded-repair and stiffener material: highest compressive strength per weight, electrically insulating so it can be bonded straight onto aluminium. | — | 1,500 | 0.75 | 90 Shore D |
B-EP-177This page 177 °C-cure high-temperature boron/epoxy | Pick when the part or repair must run hot (supersonic skins, engine-area doublers) and a 177 °C autoclave cure is available. | — | 1,550 | 0.75 | 91 Shore D |
Boron filament | The raw reinforcement itself, bought as a spool for prepregging, wire-wound rocket cases or MMC preforms. | — | 3,600 | 0.9 | — |
What is Boron Fiber Composite B-EP-177?
Boron Fiber Composite B-EP-177 is Boron Fiber Composite in the B-EP-177 condition — pick when the part or repair must run hot (supersonic skins, engine-area doublers) and a 177 °C autoclave cure is available. Boron Fiber Composite B-EP-177 has a tensile strength of 1,550 MPa (225 ksi), stronger than 76% of composite grades. Elongation at break is 0.75% and the elastic modulus is 207 GPa (30 Msi). Boron Fiber Composite B-EP-177 has a density of 2 g/cm³ (0.0723 lb/in³), heavier than 77% of composite grades. Its glass-transition temperature is 195°C (383 °F). B-EP-UD is the default condition FabDigit quotes; B-EP-177 is available on request or by drawing note.
Advantages
- Tough — resists crack growth — 33 MPa·√m (30 ksi·√in), better than 88% of composite grades
- Low moisture uptake — 0.1%, better than 85% of composite grades
- Stiff — 207 GPa (30 Msi), better than 78% of composite grades
Limitations
- High embodied carbon — 95 kg CO₂/kg, worse than 99% of composite grades
- Difficult to machine — 8/100, worse than 94% of composite grades
- Hard to polish — 20/100, worse than 90% of composite grades
- Limited ductility — 0.75%, worse than 84% of composite grades
- Heavy — 2 g/cm³ (0.0723 lb/in³), worse than 77% of composite grades
Boron Fiber Composite B-EP-177 properties
Typical room-temperature values for Boron Fiber Composite B-EP-177; 18 are specific to this condition. Other listed values are Boron Fiber Composite reference data and may not represent this condition. Bars are the position among composite grades.
Physical4
Boron Fiber Composite B-EP-177 has a density of 2 g/cm³ (0.0723 lb/in³), heavier than 77% of composite grades. Its glass-transition temperature is 195°C (383 °F).
Mechanical14
Boron Fiber Composite B-EP-177 has a tensile strength of 1,550 MPa (225 ksi), stronger than 76% of composite grades. Elongation at break is 0.75% and the elastic modulus is 207 GPa (30 Msi).
Thermal7
Boron Fiber Composite B-EP-177 is rated for continuous service to 175°C (347 °F). It conducts heat at 2 W/m·K (1.16 BTU/hr·ft·°F), better than 58% of composite grades. Thermal expansion is 4.5 µm/m·K (2.5 µin/in·°F).
Electrical1
Boron Fiber Composite B-EP-177 has an electrical resistivity of 10,000 Ω·m.
Chemical & Environmental3
Corrosion resistance is excellent (89/100), better than 82% of composite grades. UV resistance is fair.
Sustainability3
Producing a kilogram of Boron Fiber Composite B-EP-177 takes about 1,500 MJ of energy and emits 95 kg of CO₂ — more than 100% of composite grades. Typical recycled content is 0%.
Manufacturability3
Boron Fiber Composite B-EP-177's machinability is not recommended (8/100, worse than 94% of composite grades).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with Boron Fiber Composite B-EP-177
Is Boron Fiber Composite easy to machine?
Extremely abrasive 100–140 µm filaments destroy carbide — use abrasive waterjet, diamond-plated routers/saws and diamond core drills with dust extraction.
Can Boron Fiber Composite be welded?
Not weldable; joints are adhesively bonded (film adhesive) or mechanically fastened with oversized, well-supported holes.
Can Boron Fiber Composite be formed, bent or molded?
Hand-laid unidirectional prepreg tape only (fibres cannot be woven or tightly draped); vacuum-bag/autoclave cure at 121 or 177 °C, or heat-blanket cure for on-aircraft repair patches.
What surface finishes work on Boron Fiber Composite?
Seal edges and paint/prime for UV and moisture protection; the laminate is dielectric, so eddy-current inspection of the metal beneath a bonded patch remains possible.
Boron Fiber Composite 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 |
|---|---|---|
| boron fiber (CVD B on W core)≈50 vol% in UD prepreg; W core ≈ 1–3 wt% of the fibre | 55 – 70 | 65 |
| epoxy matrix121 °C or 177 °C cure aerospace epoxy | ≥ 30 (balance) | — |
Boron Fiber Composite B-EP-177 — frequently asked
What is Boron Fiber Composite B-EP-177 used for?
Boron Fiber Composite B-EP-177 is typically used for aircraft structural repair patches, military aerospace skins and sporting goods (golf shafts). In short: very high compressive strength; dielectric repair patches; extremely abrasive filaments.
What is the tensile strength of Boron Fiber Composite B-EP-177?
Boron Fiber Composite B-EP-177 has a typical tensile strength of 1,550 MPa (225 ksi) — stronger than 76% of composite grades. Strength varies by condition: see the 7 listed tempers.
Is Boron Fiber Composite B-EP-177 easy to machine?
Not especially — machinability is rated not recommended (8/100, worse than 94% of composite grades). Extremely abrasive 100–140 µm filaments destroy carbide — use abrasive waterjet, diamond-plated routers/saws and diamond core drills with dust extraction.
Can Boron Fiber Composite B-EP-177 be welded?
Not weldable; joints are adhesively bonded (film adhesive) or mechanically fastened with oversized, well-supported holes.
What surface finishes work on Boron Fiber Composite B-EP-177?
Seal edges and paint/prime for UV and moisture protection; the laminate is dielectric, so eddy-current inspection of the metal beneath a bonded patch remains possible.
Can Boron Fiber Composite B-EP-177 be formed, bent or molded?
Hand-laid unidirectional prepreg tape only (fibres cannot be woven or tightly draped); vacuum-bag/autoclave cure at 121 or 177 °C, or heat-blanket cure for on-aircraft repair patches.
What is the maximum service temperature of Boron Fiber Composite B-EP-177?
Boron Fiber Composite B-EP-177 is rated for continuous use to about 175°C (347 °F), and briefly to 190°C. Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between Boron Fiber Composite B-EP-UD and Boron Fiber Composite B-AL?
B-EP-UD is the default condition — standard bonded-repair and stiffener material: highest compressive strength per weight, electrically insulating so it can be bonded straight onto aluminium. B-AL: diffusion-bonded MMC for high-temperature, high-conductivity structure (e.g. Shuttle Orbiter truss tubes); heavier, expensive, and requires hot-press consolidation.
Sources
- ASM Handbook Vol. 21: Composites — ASM International (2001)
- CMH-17 (MIL-HDBK-17) Composite Materials Handbook, Vol. 1–3 — SAE International / CMH-17 (2012)
- Boron filament and boron/epoxy prepreg product data — Specialty Materials, Inc. (formerly Textron Specialty Materials) (2020)
- Composite Repair of Metallic Aircraft Structure (Baker & Jones) — AGARD/NATO (1988)
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.